Calf Respiratory Disease and Pen Microenvironments in Naturally Ventilated Calf Barns in Winter

A Clean and Health-Care-Focused Way to Reduce Indoor Airborne Bacteria in Calf House with Long-Wave Ultraviolet

Long-term exposure to a relatively high concentration of airborne bacteria emitted from intensive livestock houses could potentially threaten the health and welfare of animals and workers. There is a dual effect of air sterilization and promotion of vitamin D synthesis for the specific bands of ultraviolet light. This study investigated the potential use of A-band ultraviolet (UVA) tubes as a clean and safe way of reducing airborne bacteria and improving calf health. The composition and emission characteristics of airborne bacteria were investigated and used to determine the correct operating regime of UVA tubes in calf houses. Intermittent exceedances of indoor airborne bacteria were observed in closed calf houses. The measured emission intensity of airborne bacteria was 1.13 ± 0.09 × 107 CFU h-1 per calf. Proteobacteria were the dominant microbial species in the air inside and outside calf houses. After UVA radiation, the indoor culturable airborne bacteria decreased in all particle size ranges of the Anderson sampler, and it showed the highest reduction rate in the size range of 3.3-4.7 μm. The results of this study would enrich the knowledge of the source characteristics of the airborne bacteria in intensive livestock farming and contribute to the environmental control of cattle in intensive livestock production.

Assessment of Ammonia Concentrations and Climatic Conditions in Calf Housing Using Stationary and Mobile Sensors

In calf fattening, housing climate conditions are essential for optimal performance and welfare. Validated methods to measure the long-term housing climate are lacking. The present study investigated climate parameters for 14 weeks in Swiss calf fattening housing with two different ammonia (NH3) sensors: six stationary sensors (Dräger Polytron 8100) were installed at animal level and four mobile sensors (Dräger x-AM 5100) were attached to the calves' heads. Temperature, relative humidity, and carbon dioxide (CO2) concentrations were recorded by two stationary data loggers (testo 160 IAQ). Data were analyzed descriptively, and 4 h mean values of maximum NH3 concentrations of mobile and stationary sensors were compared using the Wilcoxon test for paired data. The 4 h mean values of temperature, relative humidity, and CO2 concentrations and the 4 h mean values of maximum NH3 concentrations of stationary and mobile sensors were analyzed by ANOVA in two linear models. The overall 4 h mean of maximum NH3 concentrations ranged between 5.9-9.4 ppm for measurements of stationary sensors and between 11.3-14.7 ppm for measurements of mobile sensors. The NH3 concentrations measured by mobile sensors showed significantly higher peak values and more fluctuations. Additionally, an interaction effect was observed between the NH3 concentrations measured by either sensor and CO2 concentrations (p < 0.01 (mobile sensors); p < 0.0001 (stationary sensors), temperature values (p < 0.0001 (both sensors)), and relative humidity (p < 0.0001 (both sensors)). The measurements of the implemented method showed that corresponding housing climate parameters fluctuated strongly, and NH3 reached high peak values. Validated measurement methods might allow for a detailed assessment of the housing climate in practice, and for further research on suitable management methods for housing climate optimization in the future.

Exploring herd-level perinatal calf mortality risk factors in eastern Canadian dairy farms

This closed cohort study aimed to identify the associations between dairy calf management practices and herd-level perinatal calf mortality risk. From February 2020 to June 2021, predominantly Holstein dairy farms in Québec (n = 1,832) and New Brunswick (n = 52), Canada, that were registered in the dairy herd improvement program were visited once. A questionnaire covering all aspects of precalving, calving, and colostrum management was administered. Data regarding perinatal mortality were retrieved from the dairy herd improvement program database for each farm for 2021. Perinatal mortality was calculated for each farm as the proportion of calves dead at birth or dying within 24 h after birth. A multivariable negative binomial model was used to assess herd-level factors associated with the risk of perinatal mortality. The final model included the lying surface in the calving area, the typical time to first colostrum intake, typical cow-calf contact time, the proportion of males born, the proportion of assisted calvings, and herd size. Herd-level perinatal mortality risk ranged from 0% to 38.1% (mean ± SE = 7.6% ± 0.1%). A greater proportion of males born, a higher proportion of assisted calvings, and delayed colostrum feeding were associated with increased herd-level perinatal mortality. Factors associated with a decreased herd-level perinatal mortality risk were having a typical cow-calf contact time between 7 and 12 h after calving compared with reduced cow-calf contact time, soft lying surfaces in the calving area compared with concrete and mat-lying surfaces, and an increased number of calvings per year. Our results show that although some of the significant risk factors are not well understood (i.e., calving area lying surface, typical cow-calf contact time), Canadian farmers could focus on the factors under their control (i.e., time to first colostrum feeding, proportion of difficult calvings, males born, and calvings per year) to reduce the risk of perinatal mortality. Future work should focus on qualitative research to understand the dairy farmer motivations and limitations to implementing practices identified in this and other studies to reduce perinatal mortality.

Performance of various interpretations of clinical scoring systems for diagnosis of respiratory disease in dairy calves in a temperate climate using Bayesian latent class analysis

Bovine respiratory disease (BRD) presents a challenge to farmers all over the globe not only because it can have significant impacts on welfare and productivity, but also because diagnosis can prove challenging. Several clinical scoring systems have been developed to aid farmers in making consistent early diagnosis, 2 examples being the Wisconsin (WCS) and the California (CALIF) systems. Neither of these systems were developed in or for use in a temperate environment. As environment may lead to changes in BRD presentation, the weightings and cut offs designed for one environmental presentation of BRD may not be appropriate when used in a temperate climate. Additionally, the interpretation of the scores recorded varies between studies; this may also influence conclusions. Hence, the objective of this work was to investigate the sensitivity (Se) and specificity (Sp) of these tests in a temperate climate and investigate the influence of varying the interpretation on the performance of the WCS. In this prospective study, 98 commercial spring calving dairy farms were recruited (40 randomly, 58 targeted) and visited. Thoracic ultrasound and WCS was performed on 20 randomly sampled calves between 4 and 6 weeks of age on each farm. On a subset of 32 farms, the CALIF score was also undertaken. The data were then used in a hierarchical Bayesian latent class model to estimate the Se and Sp of 5 different interpretations of the Wisconsin clinical score and one interpretation of the California clinical score. In total, 1,936 calves were examined. The Se of the Wisconsin score varied from 0.336 to 0.577 depending on the interpretation used and the Sp varied from 0.943 to 0.977. The Se of the California score was 0.529 (95% Bayesian credible interval (BCI); 0.403, 0.651) and the Sp was 0.903 (95% bci; 0.883, 0.922). In conclusion, the performance of the clinical scores in a temperate environment were similar to previously published work from more extreme climates, however the performance varied widely depending on the score interpretation. Authors should justify their usage of a particular clinical score interpretation to improve clarity in publications.

Literature Review of the Principal Diagnostic Tests to Detect Bovine Respiratory Disease in Pre-Weaned Dairy and Veal Calves

Bovine respiratory disease (BRD) is an infection of the upper and lower respiratory tract, characterized by an inflammation of the lung. Different diagnostic tests can be used to detect BRD, including clinical respiratory scoring systems, thoracic auscultation, and imaging tests like thoracic ultrasonography and thoracic radiography. Although commonly used, none of these diagnostic tests are perfect for detecting BRD. This article reviews the advantages and drawbacks of these techniques and their performance in detecting BRD in pre-weaned dairy and veal calves.

Short communication: Circadian variations and day-to-day variability of clinical signs used for the early diagnosis of pneumonia within and between calves

For rational antimicrobial use, a timely and correct diagnosis of bovine respiratory disease, especially pneumonia, in calves is required. Current approaches often rely on clinical signs observed at a single time point, and do not take potential diurnal patterns in the manifestation of these clinical signs into account. Therefore, the aim of this pilot study was to investigate how clinical signs utilized for the (early) detection of pneumonia vary both within and between calves, throughout the day and across days. A longitudinal study was conducted in which 36 pre-weaned Holstein-Friesian calves were clinically examined eight times over the course of 48 h. The following parameters were considered: respiratory rate, type of respiration, dyspnea, stridor, induced cough (trachea reflex), spontaneous cough, eye and nasal discharge, ear positions, head tilt, rectal temperature, diarrhea, milk residue, body posture, Wisconsin and Davis BRD scorecard. The advent of thoracic ultrasonography (TUS) enables detection of (sub)clinical pneumonia in a more reliable way, compared to the diagnosis based solely on clinical signs. In this study, 14% (5/36) of the calves had an ultrasound confirmed pneumonia (consolidation ≥1 cm in depth). No variations were observed in the prevalence of clinical signs at the various time points of the day. However, we did observe a difference in the manifestation of clinical signs in individual calves (intra) and between (inter) them. Due to the significant intra-calf variability, diagnosing pneumonia based solely on a single observation of clinical signs, is likely to be insufficient. Hence, misdiagnosis might lead to incorrect use of antimicrobials.

Actively ventilating calf hutches using solar-powered fans: Effects on hutch microclimate and calf thermoregulation

Although active ventilation via fans is an effective and widely adopted heat abatement method for use with adult dairy cattle, it has yet to be investigated in outdoor hutch-housed dairy calves despite most US calves being raised in such systems. We investigated a solar-powered fan system for outdoor calf hutches and its effect on hutch microclimate and calf thermoregulation. During summer, a 3 × 3 Latin square was replicated 4 times (n = 12 preweaning heifers) with 4-d exposure periods to minimally (CON; rear windows closed), passively (PASS; rear windows opened), or actively (ACT; solar-powered fan, activated at dry bulb temperature [Tdb] > 21°C) ventilated hutch systems. Hutch microclimate and calf thermoregulation were evaluated either continuously (Tdb, humidity, rectum surface temperature, and behavior) or after a daily 30-min inside restriction (air speed, air particle number, noise level, respiration, and sweating rate, and skin and rectal temperature). Active ventilation substantially increased hutch air speed relative to PASS and CON (1.76 vs. 0.19 vs. 0.05 m/s). However, PASS hutches had the lowest INT Tdb (27.2 vs. 26.4 vs. 27.8°C), whereas ACT INT Tdb was reduced at 0900 and 1000 h relative to CON but not PASS. Similarly, ACT reduced calf respiration rates and lowered rectum surface temperature at 0800 and 0900 h when compared with CON but not PASS. The lack of strong ACT influence on calf outcomes over PASS could partially be explained by the decreased proportion of time ACT calves spent inside their hutch (48.7 vs. 67.3 vs. 64.1% of each hour). Overall, ACT improved hutch microclimate and calf responses relative to CON but not PASS. Either ACT or PASS ventilation may be sufficient to provide heat abatement to continental hutch-housed calves.

Diagnostic and Prognostic Value of Clinical Scoring and Lung Ultrasonography to Assess Pulmonary Lesions in Veal Calves

This study on veal calf respiratory disease assessed the association between an on-farm clinical scoring system and lung ultrasonography with the postmortem inspection of the lungs. The comparisons allowed the calculation of predictive values of the diagnostic methods. In total, 600 calves on an Austrian veal calf farm were examined at the beginning and the end of the fattening period. Overall, the area under the curve (AUC) for ultrasonographic scores was 0.90 (rsp = 0.78) with a sensitivity (Se) of 0.86. The specificity (Sp) was 0.78, and the positive predictive value (PPV) was 0.74. The AUC for the physical examination was 0.76 (rsp = 0.55) with a Se of 0.64, an Sp of 0.81, and a PPV of 0.69. For the combination of ultrasonography and physical examination, an AUC curve of 0.85 (rsp = 0.69) was calculated. A Se of 0.65 and a Sp of 0.88 with a PPV of 0.73 was calculated. This study concluded that both physical and ultrasonographic examination scoring are reliable examination methods for the detection of lung diseases in veal calves.

Effect of ultrasonographic lung consolidation on health and growth in dairy calves: A longitudinal study

Bovine respiratory disease (BRD) is a common and complex disease process in calves. Subclinical disease exists and early detection can be challenging due to inconsistent or nonexistent clinical signs. Thoracic ultrasonography (TUS) is often used and has the potential to improve the identification of respiratory diseases. Combining systematic TUS with clinical examination allows distinguishing BRD, including upper respiratory tract disease (clinical signs of respiratory disease, but no significant lung consolidation), clinical pneumonia (clinical signs of respiratory disease along with lung consolidations), and subclinical pneumonia (no clinical signs, but lung consolidations). Data on subclinical pneumonia are scarce, particularly outside of the North American or European contexts similar to Iran in west Asia with a dry and semi-arid climate and intensive breeding systems similar to North America which breeding calves begin in individual boxes, then moving to group pens, and finally to free stall or open shed housing systems. The first objective of this longitudinal study was to use weekly ultrasonography to monitor calves from birth until weaning in an Iranian dairy herd. The second objective was to look for any association between individual lung consolidation episode or cumulative consolidation episodes on preweaning growth. Thoracic ultrasonography was performed on calves (n = 221) weekly from birth to weaning (8 wk), and scanning occasions for each calf were equally distributed with 1-wk intervals (using consolidation threshold ≥3 cm as a specific lung consolidation definition, and ≥1 cm as a more sensitive threshold). Calf body weights were recorded using a weight tape. Other information recorded were transfer of passive immunity (TPI) using serum Brix (%) ≥8.4% as adequate TPI within the first week after birth and the treatment history of the calves. The main strategy for modeling was to determine how long-term lung consolidation affects average daily gain (ADG) during the preweaning period. A linear model was used to determine the effect of the number of weeks with consolidation on ADG. Using consolidation threshold of ≥3 cm, the mean (±SD) of total ADG for calves with no consolidation episode, 1 consolidation episode, and 2 or more consolidation episodes were 0.45 (±0.10), 0.39 (±0.10), and 0.38 (±0.11) kg/d, respectively. In the final multivariable regression analysis model and based on consolidation threshold of ≥3 cm, calves with 1 and 2 or more consolidation episodes had significantly lower ADG ± standard error (SE) of 0.04 ± 0.02 kg/d, and 0.06 ± 0.02 kg/d, respectively compared with animals with no consolidation episode. A total of 20% of calves (46/229 calves that entered the study) were treated for respiratory disease based on clinical signs (based on farmer examination). The final model also included specific confounders related to ADG and their interactions with lung consolidation (TPI and BRD treatment). An overall of 86% of adequate TPI was obtained. Bovine respiratory disease treatment based on farmer diagnosis had a larger negative effect on preweaning ADG than ultrasonography-diagnosed consolidation episodes (lower ADG ± SE of 0.10 ± 0.03 kg/d). When using a more sensitive consolidation threshold (≥1 cm as consolidation), the number of weeks with consolidation was also negatively associated with the ADG in the multivariable linear regression model with significant difference of 0.05 ± 0.02 kg/d for nonconsolidated calves versus calves consolidated for 2 or more weeks and insignificant difference of 0.01 ± 0.02 kg/d for nonconsolidated calves versus calves with 1 consolidation episode.

A systematic review of the relationship between housing environmental factors and bovine respiratory disease in preweaned calves - Part 1: Ammonia, air microbial count, particulate matter and endotoxins

Bovine respiratory disease (BRD) is one of the leading causes of mortality and morbidity in calves across diverse management systems. Despite expert opinion often citing the influence of housing environment on the level of respiratory disease in calf groups, there have been few reviews of environmental factors that predispose to BRD. This systematic review was undertaken to identify the measurable environmental variables associated with respiratory disease in housed preweaned calves. To achieve this Pubmed, CAB Direct and Scopus databases were searched. To be considered for inclusion, publications had to be fully published in English, published before 24 November, 2022 and include at least one measurable/ manipulated environmental variable and a standardized method of BRD detection. Twelve publications were included in this review. These examined a wide range of risk factors including air microbial count (four publications), air particulate matter (one publication); air endotoxins (one publication) and air ammonia (four publications). From the included publications, a statistically significant relationship to BRD was identified in 2/4 examining air microbial count, 1/1 examining air particulate matter, 1/1 examining air endotoxins and 2/4 examining air ammonia. This review indicated a paucity of evidence from the peer-review literature demonstrating a significant association between the many investigated exposure factors and BRD occurrence. An optimal environment for housed calves could not be clearly identified in this review.

Graduate Student Literature Review: The problem of calf mortality on dairy farms

Calf mortality can be used as an indicator of animal health and welfare on dairy farms. However, several challenges surround the estimation and reporting of this metric, specifically: (1) lack of records or reliable data, (2) methods of data collection, and (3) inconsistencies in calculation and definitions used. Therefore, despite its importance, the lack of consensus on a definition of calf mortality makes it difficult to compare mortality rates between dairy farms or studies. Monitoring factors associated with calf mortality is vital to create preventative strategies. Although common strategies have been set about how to raise dairy calves and manage dairy calves, discrepancies among studies evaluating factors associated with calf mortality still exist. This review summarizes research on the evaluation of calf mortality and associated risk factors, specifically, the lack of reliable data and standardization of the definition of calf mortality. In addition, current strategies to monitor and prevent calf mortality will be presented in this review.

A systematic review of the relationship between housing environmental factors and bovine respiratory disease in preweaned calves - Part 2: Temperature, relative humidity and bedding

Bovine respiratory disease (BRD) is a challenge in all housed farming systems that raise calves. Farm to farm variation in BRD prevalence can be partially attributed to variation in host immunity, pathogens and housing environment. Unlike host immunity and BRD pathogens, housing environment has not been well investigated. The objective of this systematic review was to identify the measurable environmental variables associated with BRD in housed preweaned calves. Pubmed, CAB Direct and Scopus databases were searched. To be considered for inclusion publications had to be published in English, before 24 November, 2022 and include at least one measurable/ manipulated environmental variable and a standardized method of BRD detection. In total 12 publications were included in this review. In this second part of the systematic review the environmental variables identified were; temperature (9 publications); relative humidity (8 publications); bedding (5 publications); ventilation (1 publication); air CO2 concentration (1 publication) and air velocity (4 publications). Of the publications that were examined a statistically significant relationship to BRD was identified in 4/9 publications examining temperature, 3/8 examining relative humidity, 2/4 examining air velocity, 2/5 examining bedding, 0/1 examining ventilation rates and 0/1 examining CO2 concentration. From this review it is clear high airspeed at calf level should be avoided as should deep, wet pack bedding. The relationship between BRD prevalence and both high and low temperature requires more investigation to identify temperature thresholds associated with increased risk of BRD as well as the most influential modifiers. An optimal environment for housed calves could not be clearly identified in this review.

Invited review: Bovine neonatal morbidity and mortality-Causes, risk factors, incidences, sequelae and prevention

The neonatal period may be defined as the first month of the calf's life; it may be considered part of the fourth trimester. It is the most hazardous due to the immaturity of the neonate's immune system and the environmental challenge from infections, the main causes of both bovine neonatal morbidity and mortality. The five most common morbidities causing mortality in neonatal calves are, in descending order, gastrointestinal infections, respiratory infections, abomasal disorders, umbilical infections and developmental abnormalities. This review describes the aetiology, incidence, risk factors and sequelae of these common morbidities and highlights current preventive strategies both at farm and national levels.

Comparison of the welfare of beef cattle in housed and grazing systems: hormones, health, and behaviour

Animal welfare encompasses all aspects of an animal's life and the interactions between animals. Consequently, welfare must be measured across a variety of factors that consider aspects such as health, behaviour, and mental state. Decisions regarding housing and grazing are central to farm management. In this study, two beef cattle systems and their herds were compared from weaning to slaughter across numerous indicators. One herd ("HH") were continuously housed, the other ("HG") were housed only during winter. Inspections of animals were conducted to assess body condition, cleanliness, diarrhoea, hairlessness, nasal discharge, and ocular discharge. Hair and nasal mucus samples were taken for quantification of cortisol and serotonin. Qualitative behaviour assessments (QBA) were also conducted and performance monitored. Physical health indicators were similar between herds with the exception of nasal discharge which was more prevalent in HH (P < 0.001). During winter, QBA yielded differences between herds over PC1 (arousal) (P = 0.032), but not PC2 (mood) (P = 0.139). Through summer, there was a strong difference across both PC1 (P < 0.001) and PC2 (P = 0.002), with HG exhibiting more positive behaviour. A difference was found in hair cortisol levels, with the greatest concentrations observed in HG (P = 0.011), however such a pattern was not seen for nasal mucus cortisol, or for serotonin. Overall, providing summer grazing (HG) appeared to afford welfare benefits to the cattle as shown with more positive QBA assessments, but also slightly better health indicators, notwithstanding the higher levels of cortisol in that group.

A randomized trial on the effects of heat stress abatement on environmental conditions and growth, feed efficiency, and concentration of metabolites of pre-weaned female Holstein calves

Heat abatement strategies for pre-weaned calves are seldom adopted. Our objectives were to determine the effects of adding fans to barns on environmental conditions and growth, feed efficiency, concentration of metabolites and health of pre-weaned female Holstein calves. Calves born from July 15th to 30th of 2019 were eligible for enrollment. At birth (d 0), calves were assigned randomly to: SH (n = 125) - hutch under a barn with no cooling, SHF (n = 101) - hutch under a barn cooled through fans. Body weight (BW) and wither-height were measured at birth and d 68. Calves were evaluated thrice weekly (0700-1000 h) using the Calf Health Scoring Chart (UW-Madison). A sub-sample of hutches (SH = 26, SHF = 25) was evaluated for air velocity and temperature at 1000 and 1600 h thrice weekly and calves housed in these hutches were evaluated for rectal temperature (RT) at 1600 h and respiratory rate (RR) at 1000 and 1600 h. Calves were fed a liquid diet twice a day (d 2-18 = 5.56 L/d; d 19-49 = 7.58 L/d; d 50-56 = 3.84 L/d; d 57-63 = 1.64 L/d) and starter ad libitum starting on d 14. A sub-sample of calves (SH = 56, SHF = 44) had intakes of liquid feed and starter measured daily, BW and wither-height measured weekly from birth to d 68, and blood sampled on d 1, 14, 28, 42, 49, 52, 56, 58, 63 and 65 for the measurement of fatty acids, β-hydroxybutyrate, and glucose concentrations. The SHF treatment increased air velocity by 0.8 m/sec and reduced air temperature by 0.3 ºC. The SHF treatment reduced RT (38.70 ± 0.03 vs. 38.78 ± 0.02 °C) and the percentage of calves with hyperthermia (RT ≥ 39.2 °C; 20.6 ± 1.9 vs. 30.2 ± 2.0%) at 1000 h. Treatment did not affect feed efficiency (SH = 0.53 ± 0.01, SHF = 0.53 ± 0.01 g of BW gained/g of dry matter intake), nor did it affect BW (SH = 81.6 ± 0.7, SHF = 82.9 ± 0.8 kg) and wither-height (SH = 89.5 ± 0.3, SHF = 90.1 ± 0.3 cm) on d 68. Concentrations of metabolites were not affected by treatment. Cooling the environment through fans reduced RT and the risk of hyperthermia at 1000 h but it did not affect performance of pre-weaned Holstein calves.

Welfare of calves

This Scientific Opinion addresses a European Commission request on the welfare of calves as part of the Farm to Fork strategy. EFSA was asked to provide a description of common husbandry systems and related welfare consequences, as well as measures to prevent or mitigate the hazards leading to them. In addition, recommendations on three specific issues were requested: welfare of calves reared for white veal (space, group housing, requirements of iron and fibre); risk of limited cow–calf contact; and animal‐based measures (ABMs) to monitor on‐farm welfare in slaughterhouses. The methodology developed by EFSA to address similar requests was followed. Fifteen highly relevant welfare consequences were identified, with respiratory disorders, inability to perform exploratory or foraging behaviour, gastroenteric disorders and group stress being the most frequent across husbandry systems. Recommendations to improve the welfare of calves include increasing space allowance, keeping calves in stable groups from an early age, ensuring good colostrum management and increasing the amounts of milk fed to dairy calves. In addition, calves should be provided with deformable lying surfaces, water via an open surface and long‐cut roughage in racks. Regarding specific recommendations for veal systems, calves should be kept in small groups (2–7 animals) within the first week of life, provided with ~ 20 m²/calf and fed on average 1 kg neutral detergent fibre (NDF) per day, preferably using long‐cut hay. Recommendations on cow–calf contact include keeping the calf with the dam for a minimum of 1 day post‐partum. Longer contact should progressively be implemented, but research is needed to guide this implementation in practice. The ABMs body condition, carcass condemnations, abomasal lesions, lung lesions, carcass colour and bursa swelling may be collected in slaughterhouses to monitor on‐farm welfare but should be complemented with behavioural ABMs collected on farm.

Pre-Weaned Calf Rearing on Northern Irish Dairy Farms-Part 2: The Impact of Hygiene Practice on Bacterial Levels in Dairy Calf Rearing Environments

Pre-weaned dairy calves are very susceptible to disease in the first months of life due to having a naïve immune system and because of the numerous physiological stressors they face. Hygiene management is a key element in minimizing enteric disease risk in calves by reducing their exposure to pathogens. Samples of milk, concentrate feed and drinking water, boot swabs of bedding and swabs of feed equipment were collected from 66 dairy farms as part of a survey of calf rearing practice and housing design. All the samples were cultured to determine total viable counts (TVC), total coliforms (TCC) and Escherichia coli as indicators of hygiene. Target ranges for levels of TVC, TCC and E. coli were defined from the literature and the sample results compared against them. The TVC targets in milk, MR and water were <4.0 log₁₀ CFU/mL. TCC and E. coli targets of <1.1 log₁₀ CFU/mL (the detection limit) were used for milk, MR, concentrate feed and feeding equipment. For water, the TCC and E. coli targets were <1.0 log₁₀ CFU/100 mL. The targets used for bedding boot swabs were <6.3 log₁₀ TVC CFU/mL and <5.7 log₁₀ TCC or E. coli CFU/mL. Farm management factors were included as fixed effects in a generalized linear mixed model to determine the probability of samples being within each hygiene indicator target range. Milk replacer samples obtained from automatic feeders were more likely to be within the TVC target range (0.63 probability) than those prepared manually (0.34) or milk samples taken from the bulk tank (0.23). Concentrate feed samples taken from buckets in single-calf pens were more likely to have E. coli detected (0.89) than samples taken from group pen troughs (0.97). A very small proportion of water samples were within the indicator targets (TVC 9.8%, TCC 6.0%, E. coli 10.2%). Water from self-fill drinkers had a lower likelihood of being within the TVC target (0.03) than manually filled buckets (0.14), and water samples from single pens were more likely to be within TCC target ranges (0.12) than those from group pens (0.03). However, all self-fill drinkers were located in group pens so these results are likely confounded. Where milk feeders were cleaned after every feed, there was a greater likelihood of being within the TVC target range (0.47, compared with 0.23 when not cleaned after every feed). Detection of coliforms in milk replacer mixing utensils was linked with reduced probability of TVC (0.17, compared with 0.43 when coliforms were not detected) and TCC (0.38, compared with 0.62), which was within target in feeders. Key factors related to increased probability of bedding samples being within TCC target range were use of group calf pens (0.96) rather than single-calf pens (0.80), use of solid floors (0.96, compared with 0.76 for permeable floors) and increased space allowance of calves (0.94 for pens with ≥2 m²/calf, compared with 0.79 for pens with <2 m²/calf). Bedding TVC was more likely to be within the target range in group (0.84) rather than in single pens (0.66). The results show that hygiene levels in the calf rearing environment vary across farms and that management and housing design impact hygiene.

Comparison of environment quality measurements between 3 types of calf housing in the United Kingdom

Preweaning calves are kept in a range of housing types that offer variable protection against the weather and provide differing internal environments. This cross-sectional observational study assessed the effect of housing type (shed, polytunnel, or hutches) on internal environmental parameters, using 2 blocks of 8-wk measurements from 10 commercial dairy farms in the south of England, covering both summer and winter periods. Continuous measurements for internal and external temperature and humidity were recorded by data logger placed within the calf housing and used to calculate the temperature-humidity index (THI). Weekly point readings were also taken for temperature, humidity, light, air speed, ammonia level, and airborne particulate matter. Airborne bacterial levels were determined at wk 2, 5, and 8 by incubating air samples at 35°C for 24 h in aerobic conditions. Data were analyzed using linear mixed models. Housing type influenced THI significantly in both seasons. In summer, calves were exposed to heat stress conditions (THI ≥72) for 39, 31, and 14 of 46 d in polytunnel housing, hutches, and sheds, respectively. The maximum summer temperature (37.0°C) was recorded in both hutch and polytunnel housing, with sheds remaining consistently cooler (maximum 31.0°C). In winter, the lowest minimum internal temperature recorded was in hutches at -4.5°C, with both the sheds and polytunnel, but not hutches, providing a significant increase in temperature compared with the external environment. Hutches remained ≤ 10°C for 86% of the winter study period. Light levels were reduced in all housing types compared with the external environment. The particulate matter in air that is capable of reaching the lungs (particulate matter <10 μm) was highest in sheds, intermediate in hutches, and lowest in polytunnel housing (0.97 ± 3.75, 0.37 ± 0.44, and 0.20 ± 0.24 mg/m³, respectively). This was mirrored by airborne bacterial numbers, which were also highest in sheds (8,017 ± 2,141 cfu/m³), intermediate in hutches (6,870 ± 2,084 cfu/m³), and lowest in the polytunnel (3,357 ± 2,572 cfu/m³). Round, white, catalase-positive, and oxidase-negative colonies were most prevalent, likely indicating Staphylococcus species. This study demonstrated that UK calves are routinely exposed to either heat or cold stress, especially when housed in hutches or polytunnels. Sheds had the highest levels of particulate matter and airborne bacteria, both known contributory factors for respiratory disease. These findings demonstrate that all calf housing systems result in environmental compromises that could have long-term impacts on calf health and growth; therefore, further studies should identify husbandry and housing modifications to mitigate these factors.

Prevalence of respiratory disease in Irish preweaned dairy calves using hierarchical Bayesian latent class analysis

Introduction

Bovine respiratory disease (BRD) has a significant impact on the health and welfare of dairy calves. It can result in increased antimicrobial usage, decreased growth rate and reduced future productivity. There is no gold standard antemortem diagnostic test for BRD in calves and no estimates of the prevalence of respiratory disease in seasonal calving dairy herds.

Methods

To estimate BRD prevalence in seasonal calving dairy herds in Ireland, 40 dairy farms were recruited and each farm was visited once during one of two calving seasons (spring 2020 & spring 2021). At that visit the prevalence of BRD in 20 calves between 4 and 6 weeks of age was determined using thoracic ultrasound score (≥3) and the Wisconsin respiratory scoring system (≥5). Hierarchical Bayesian latent class analysis was used to estimate the calf-level true prevalence of BRD, and the within-herd prevalence distribution, accounting for the imperfect nature of both diagnostic tests.

Results

In total, 787 calves were examined, of which 58 (7.4%) had BRD as defined by a Wisconsin respiratory score ≥5 only, 37 (4.7%) had BRD as defined by a thoracic ultrasound score of ≥3 only and 14 (1.8%) calves had BRD based on both thoracic ultrasound and clinical scoring. The primary model assumed both tests were independent and used informed priors for test characteristics. Using this model the true prevalence of BRD was estimated as 4%, 95% Bayesian credible interval (BCI) (1%, 8%). This prevalence estimate is lower or similar to those found in other dairy production systems. Median within herd prevalence varied from 0 to 22%. The prevalence estimate was not sensitive to whether the model was constructed with the tests considered conditionally dependent or independent. When the case definition for thoracic ultrasound was changed to a score ≥2, the prevalence estimate increased to 15% (95% BCI: 6%, 27%).

Discussion

The prevalence of calf respiratory disease, however defined, was low, but highly variable, in these seasonal calving dairy herds.

Heat abatement during the pre-weaning period: effects on growth, feed efficiency, metabolites, and insulin of male Holstein calves

Heat stress abatement strategies for pre-weaned dairy calves are seldom evaluated. An experiment was conducted to evaluate the effects of housing calves under a barn and provision of fans to calves housed under a barn on calfhood performance. The experiment was conducted in a dairy in southern Georgia, USA. Male Holstein calves (n = 60; 0 to 68 day of age) were assigned randomly at birth (day 0) to 1 of 3 treatments: hutch outdoors with 50% of its area covered with plywood (control = 20), hutch in a barn with no cooling (SH = 21), and hutch in a barn with ceiling fans (SHF = 19). Body weight (BW) was measured at birth, and total serum protein and wither-height were measured 24 to 48 h after birth. A sub-set of hutches was evaluated for air speed and temperature, and rectal temperature (RT) and respiratory frequency (RF) of calves housed in these hutches were measured at 0900 and 1500 h. Intakes of liquid feed (days 14 to 63) and starter (days 14 to 68) were recorded daily, BW and wither-height were measured weekly, and feed efficiency was calculated weekly. Blood was sampled on days 1, 14, 28, 42, 49, 52, 56, 58, 63, and 65 for the measurement of fatty acids, β-hydroxybutyrate, glucose, and insulin. The SHF treatment resulted in air velocity 0.56 to 0.83 m/s greater (P < 0.01) than the control and SH treatments, respectively, whereas the control treatment resulted in air temperature 1.2 to 3.2 °C greater (P < 0.01) than the SH and SHF treatments, respectively. The RT of calves in the control treatment was 0.1 to 1.1 °C greater (P ≤ 0.03) than the SH and SHF treatments, respectively, and the control treatment resulted in RF 39.4 to 60.2 mov/min greater (P < 0.01) than the SH and SHF treatments, respectively. Treatment did not (P ≥ 0.27) affect feed efficiency and concentrations of metabolites and insulin, but calves in the control treatment were 2.6 cm shorter (P = 0.03) than calves in the SHF treatments at weaning. Provision of fans to calves housed under a barn reduced RT, RF, but only had a minute impact on wither-height.

Benchmarking calf health: Assessment tools for dairy herd health consultancy based on reference values from 730 German dairies with respect to seasonal, farm type, and herd size effects

Good calf health is crucial for a successfully operating farm business and animal welfare on dairy farms. To evaluate calf health on farms and to identify potential problem areas, benchmarking tools can be used by farmers, herd managers, veterinarians, and other advisory persons in the field. However, for calves, benchmarking tools are not yet widely established in practice. This study provides hands-on application for on-farm benchmarking of calf health. Reference values were generated from a large dataset of the “PraeRi” study, including 730 dairy farms with a total of 13,658 examined preweaned dairy calves. At herd level, omphalitis (O, median 15.9%) was the most common disorder, followed by diarrhea (D, 15.4%) and respiratory disease (RD, 2.9%). Abnormal weight bearing (AWB) was rarely detected (median, 0.0%). Calves with symptoms of more than one disorder at the same time (multimorbidity, M) were observed with a prevalence of 2.3%. The enrolled farms varied in herd size, farm operating systems, and management practices and thus represented a wide diversity in dairy farming, enabling a comparison with similar managed farms in Germany and beyond. To ensure comparability of the data in practice, the reference values were calculated for the whole data set, clustered according to farm size (1–40 dairy cows (n = 130), 41–60 dairy cows (n = 99), 61–120 dairy cows (n = 180), 121–240 dairy cows (n = 119) and farms with more than 240 dairy cows (n = 138), farm operating systems (conventional (n = 666), organic (n = 64)) and month of the year of the farm visit. There was a slight tendency for smaller farms to have a lower prevalence of disorders. A statistically significant herd-size effect was detected for RD (p = 0.008) and D (p < 0.001). For practical application of these reference values, tables, diagrams, and an Excel^® (Microsoft^®) based calf health calculator were developed as tools for on-farm benchmarking (https://doi.org/10.6084/m9.figshare.c.6172753). In addition, this study provides a detailed description of the colostrum, feeding and housing management of preweaned calves in German dairy farms of different herd sizes and farm type (e.g., conventional and organic).

Air Quality, Management Practices and Calf Health in Italian Dairy Cattle Farms

Simple Summary

Calf mortality is an important factor of economic loss in dairy operations. Among the factors which can affect calf health, air quality in calf housing has rarely been studied. In the present research, the relations among air quality in the calf pens, management practices, microclimatic conditions and calf health and mortality were studied in 25 Italian dairy cattle farms. Microbial air quality in the calf pens was found to be related to temperature and humidity, design and position of the pen, some management practices and calf health and mortality. Maintaining dry bedding and controlling microclimatic conditions in the calf pen can be useful practices to promote good air microbiological quality in the calf pen, improving calf health and reducing mortality.

Abstract

Among factors that can affect calf health, microbial quality of the pen air is poorly studied. In 25 Italian dairy farms, data concerning air quality in the calf pens, hygiene of pens and equipment, microclimatic conditions, calf health and management were collected during the winter season (January-March 2020 and December-March 2021). The average air Standard Plate Count (SPC) of 85 pens was 4.51 (SD = 0.52) log₁₀ cfu/m³ whereas the average air ammonia concentration was 0.66 (SD = 0.53) ppm. Positive correlations were found between average Temperature Humidity Index (THI) in the pen and air SPC, night maximum THI and air SPC and between SPC and yeast, mould and ammonia concentration in the pen air. The concentrations of E. coli, Enterobacteriaceae and yeasts in the pen air were higher and calf cough increased as the renewal interval of bedding material became longer. High bedding dry matter and low THI were associated with low air SPC, good calf health scores and low mortality. Maintaining low bedding humidity and controlling microclimatic conditions can contribute to enhancing air microbiological quality in the pen and reduce calf diseases and mortality.

A comparison of indoor and outdoor calf housing systems using automated and manual feeding methods and their effect on calf health, behaviour, growth and labour

Housing and feeding are integral to calf rearing, and must meet calf needs while remaining functional for the farmer. This study compared health, behavior, growth, and labor requirements of calves housed in groups indoors and fed via an automatic or manual milk feeding system compared to calves manually fed in individual or group hutches outdoors. Seventy-six (49 Holstein Friesian [HF] and 27 HF × Jersey) dairy heifer calves were balanced for birth weight (35.2 ± 4.95 kg), birth date (1 February ± 7.2 d) and breed. The experiment was a randomized block design with four treatments; 1) indoor group housing with automated feeding (IN_AUTO; 12 calves per pen), 2) indoor group housing with manual feeding (IN_MAN; 12 calves per pen), 3) outdoor group hutch with manual feeding (OUT_G_MAN; 8 calves per pen), and 4) outdoor individual hutch with manual feeding (OUT_I_MAN; 6 calves: 1 per pen). Calves in OUT_treatments moved outdoors at 18 d (± 5.9 d). Each treatment was replicated once. Milk allowance increased gradually from 6 to 8 L/day (15% reconstitution rate) with ad libitum fresh water, concentrates, and hay offered from 3 d old. Gradual weaning occurred at 8 wk old. Measurements were divided into period 1; before movement outdoors, and period 2; after movement outdoors. Health was similar among treatments, regardless of period, with the most frequent score being zero (i.e., healthy). Summarized, standing and lying were observed 24.3% and 29.8%, respectively, in OUT_I_MAN calves, compared to 8.0% and 49.1%, for the other systems, which were similar. No difference in bodyweight (BW) existed between treatments, except at weaning where BW was lower for OUT_I_MAN (67.4 ± 2.84 kg) compared to IN_MAN (74.2 ± 2.01 kg), and day 102 where OUT_I_MAN (94.1 ± 2.85 kg) were lighter than IN_AUTO (101.1 ± 2.10 kg) (P = 0.047). Total labor input was greatest for OUT_I_MAN (00:02:02 per calf per day; hh:mm:ss) and least for IN_AUTO (00:00:21 per calf per day) (P < 0.001). The labor for feeding (00:00:29 per calf per day), feeding inspection (00:00:10 per calf per day), and cleaning equipment (00:00:30 per calf per day) was greatest for OUT_I_MAN. All calves showed good health and growth patterns. Differences in behavior expressed by calves in the OUT_I_MAN, compared to other treatments may indicate compromised welfare. Thus, although outdoor group hutches do not negatively impact calves, indoor housing, particularly using automated feeders, can improve labor efficiency.

In seasonal calving dairy systems, cows calve in a period of approximately 12 wk. Demand for calf accommodation and labor is high during this time. Outdoor housing structures, such as robust plastic calf hutches, may offer an alternative to permanent indoor facilities. In this study, we compared indoor housing systems using automated and manual feeding methods and outdoor calf housing systems using manual feeding methods, to examine their effect on calf health, behavior, growth, and labor. Moving calves to their respective outdoor system commenced at approximately 18 d. This reflected a housing system with limited indoor availability, where older calves would be moved outdoors (allowing young calves to remain indoors). The most labor-efficient method of rearing was group housing calves indoors feeding via automatic feeder, followed by group housing indoors feeding via manual feeders, outdoor in group hutches, and outdoor in individual hutches with manual feeding. Calves in all systems showed health and growth patterns consistent with positive development. Calf behavior in the individual hutches outdoor may indicate compromised well-being, compared to all other systems. Thus, although outdoor group hutches do not negatively impact the calf, indoor housing, particularly when using automatic feeders, can provide improved labor efficiency.

Commercial Dairy Calf Management: Impact on Performance and Health

The transition for the calf from the milk-feeding phase to the grouping and dry feed feeding phase is the second most difficult time for a calf, with the most difficult life phase being parturition and the first day of life. Reducing these stress factors directly relates to reduced health problems and better performance during subsequent life phases. This review will discuss some of the key management factors associated with achieving maximum production potential for the commercial dairy calf.

Overview of common practices in calf raising facilities

In this literature review, we overview some of the common management practices associated with calf rearing in specialized operations of the United States. Given the growing importance of dairy-beef calves entering the beef production of the United States, we overview aspects related to housing, nutrition, and health events during the pre- and post-weaning period. Based on data on dairy animals, we hypothesize how early life experiences could impact the feedlot performances of dairy-beef animals. Most of the large calf raising operations, where the majority of dairy-beef animals are raised, are located in the Central Great Plains and West regions of the United States. Approximately 80% of calves are individually housed, but the type of housing (e.g., outside hutch, inside a barn) varies based on location of calf-raising facilities. Milk-replacer is fed in more than 80% of operations, while milk (saleable or nonsaleable) is fed in approximately 30% of calf raising facilities (some operations fed more than one type of liquid diet). In addition to liquid feed, water and calf starter are offered ad libitum to calves. Adequate starter intake at weaning is crucial for feed transition from pre- to post-weaning period, which occurs at approximately 2 months of age. Then, calves are mainly housed in group pens and transition from calf-starter to total mixed ration (TMR). Health challenges such as scours and bovine respiratory disease (BRD) can hinder the performance of calves and are major causes of morbidity and mortality in calf ranches. Transportation at a very young age and comingling with animals from other dairies can increase the risk of diseases. Current research efforts are focusing on determining individual factors such as body weight (BW) at arrival or biomarkers of inflammation and stress that can be predictive of disease morbidity, mortality, and performance of calves. Future research should focus on how to utilize this information to optimize management and to develop targeted preventative strategies to reduce incidence of diseases and mortality and improve performance during the pre-weaned period. Also, more research is needed to understand how colostrum management, housing, and nutrition can impact the adult performance of dairy-beef animals.

Views of Western Canadian dairy producers on calf rearing: An interview-based study

Calf rearing practices differ among farms, including feeding and weaning methods. These differences may relate to how dairy producers view these practices and evaluate their own success. The aim of this study was to investigate perspectives of dairy producers on calf rearing, focusing on calf weaning and how they characterized weaning success. We interviewed dairy producers from 16 farms in Western Canada in the following provinces: British Columbia (n = 12), Manitoba (n = 2), and Alberta (n = 2). Participants were asked to describe their heifer calf weaning and rearing practices, and what they viewed as successes and challenges in weaning and rearing calves. Interviews were recorded, transcribed, and subjected to qualitative analysis from which we identified the following 4 major themes: (1) reliance on calf-based measures (e.g., health, growth, and behavior), (2) management factors and personal experiences (e.g., ease, consistency, and habit), (3) environmental factors (e.g., facilities and equipment), and (4) external support (e.g., advice and educational opportunities). These results provided insight into how dairy producers view calf weaning and rearing, and may help inform the design of future research and knowledge transfer projects aimed at improving management practices on dairy farms.

Antimicrobial Resistance in Isolates from Cattle with Bovine Respiratory Disease in Bavaria, Germany

Patterns of antimicrobial resistance (AMR) regarding Pasteurella multocida (n = 345), Mannheimia haemolytica (n = 273), Truperella pyogenes (n = 119), and Bibersteinia trehalosi (n = 17) isolated from calves, cattle and dairy cows with putative bovine respiratory disease syndrome were determined. The aim of this study was to investigate temporal trends in AMR and the influence of epidemiological parameters for the geographic origin in Bavaria, Germany, between July 2015 and June 2020. Spectinomycin was the only antimicrobial agent with a significant decrease regarding not susceptible isolates within the study period (P. multocida 88.89% to 67.82%, M. haemolytica 90.24% to 68.00%). Regarding P. multocida, significant increasing rates of not susceptible isolates were found for the antimicrobials tulathromycin (5.56% to 26.44%) and tetracycline (18.52% to 57.47%). The proportions of multidrug-resistant (MDR) P. multocida isolates (n = 48) increased significantly from 3.70% to 22.90%. The proportions of MDR M. haemolytica and P. multocida isolates (n = 62) were significantly higher in fattening farms (14.92%) compared to dairy farms (3.29%) and also significantly higher on farms with more than 300 animals (19.49%) compared to farms with 100 animals or less (6.92%). The data underline the importance of the epidemiological farm characteristics, here farm type and herd size regarding the investigation of AMR.

[Colostrum management practices on farms with high calf losses in Lower Saxony, Germany]

OBJECTIVE

The aim of the present study was to record the management of colostrum supply for calves on dairy farms in Lower Saxony facing challenges with increased calf mortality as well as to identify associated problems. Targeted advice concerning possibilities for improving management was provided in order to evaluate whether these consultations would lead to changes in the colostrum management and improve the calves' colostrum supply (measured by the total protein concentration in the blood serum of calves and the incidence of diarrhea).

MATERIAL AND METHODS

Analyses were performed on 56 dairy farms in Lower Saxony, facing a calf mortality of at least 20 % in 2014 and keeping a minimum of 30 dairy cows. Single-housed calves with an average age of 1-14 days were examined. Each farm was visited twice during an interval of 8-10 months, with an identical daily routine at both visits. Data on the topics of colostrum management and calf health were recorded using a questionnaire and the farm was inspected. All single-housed calves were subjected to a clinical examination. The total protein concentration in the blood of calves aged between 1 and 7 days was examined in order to draw conclusions concerning their colostrum supply.

RESULTS

Only few, insignificant changes in management were evident between the 2 visits. Therefore, no conclusions were possible concerning the influence of the provided advice on colostrum management. Nevertheless, the data showed that the colostrum management on a large part of the farms was in need of improvement with regard to the time of feeding, the amount offered, the method of supply and monitoring its effect. The data on measured total protein concentration also showed that at both visits only a small proportion of the farms adequately managed the colostrum supply.

CONCLUSION

Many farmers remain unaware of the pronounced importance of colostrum supply for newborn calves. In many of the surveyed farms with high calf losses, a need for improvement in the area of colostrum management was evident.

Use of ATP luminometry to assess the cleanliness of equipment used to collect and feed colostrum on dairy farms

The objective of this observational cross-sectional study was to describe the cleanliness of various equipment used for colostrum harvest and calf feeding procedures on dairy farms in Québec, Canada. The study was performed on 42 commercial dairy herds also enrolled in another study aiming to determine the transfer of passive immunity over a 14-mo period. Information on colostrum quality (using Brix value) and cleanliness (total aerobic and total coliform count) were recorded as well as various practices focused on colostrum-feeding equipment and preweaning period using a standard questionnaire. During the study period, colostrum and milk-feeding equipment cleanliness was assessed using direct surface swabbing with Hygiena Ultrasnap swabs. A total of 155 swab samples were obtained from 6 pieces of equipment. Adenosine triphosphate collected from the swabbed surface reacts with the luciferase solution present in the swab by bioluminescence, which is proportional to the quantity of ATP present and quantified as relative light units (RLU). The description of feed equipment cleanliness (defined as the maximal RLU found for a specific herd, dichotomized as <1,000 RLU vs. ≥1,000 RLU) was compared with the herds' descriptive characteristics, focusing on the first 2 components of a multiple correspondence analysis. The median (range) RLU for buckets used for colostrum harvest, bucket or bottle used for feeding, tube feeders, milking colostrum line, and internal surface of the nipples were 41 RLU (3-1,625 RLU), 78 RLU (<1-3,765 RLU), 29 RLU (<1-2,177 RLU), 83 RLU (<1-9,968 RLU), and 1,101 RLU (2-9,546 RLU), respectively. The first 2 components of multiple correspondence analysis explained 24.7% of data variances and were related to the farms' hygiene and health (13.0%) and feeding practices (11.7% of data variance). The maximal dichotomized luminometry value (<1,000 RLU or ≥1,000 RLU) was associated with hygiene and health dimension. This study gave promising results concerning the potential application of ATP luminometry for calf rearing practices assessment.

Improving growth rates in preweaning calves on dairy farms: A randomized controlled trial

Previous research has identified key factors associated with improved average daily gain (ADG) in preweaning dairy calves and these factors have been combined to create a web app-based calf health plan (www.nottingham.ac.uk/herdhealthtoolkit). A randomized controlled trial was conducted to determine the effect of implementing this evidence-based calf health plan on both productivity and health outcomes for calves reared on British dairy farms. Sixty dairy farms were randomized by location (North, South, and Midlands) to either receive the plan at the beginning (INT) or after the end of the trial (CON) and recorded birth and weaning weights by weigh tape, and cases of morbidity and mortality. Calf records were returned for 3,593 calves from 45 farms (21 CON, 24 INT), with 1,760 calves from 43 farms having 2 weights recorded >40 d apart for ADG calculations, with 1,871 calves from 43 farms born >90 d before the end of the trial for morbidity and mortality calculations. Associations between both intervention group and the number of interventions in place with ADG were analyzed using linear regression models. Morbidity and mortality rates were analyzed using beta regression models. Mean ADG was 0.78 kg/d, ranging from 0.33 to 1.13 kg/d, with mean rates of 20.12% (0-96.55%), 16.40% (0-95.24%), and 4.28% (0-18.75%) for diarrhea, pneumonia, and mortality. The INT farms were undertaking a greater number of interventions (9.9) by the end of the trial than CON farms (7.6). Mean farm ADG was higher for calves on INT farms than CON farms for both male beef (MB, +0.22 kg/d) and dairy heifer (DH, +0.03 kg/d) calves. The MB calves on INT farms had significantly increased mean ADG (0.12 kg/d, 95% confidence interval: 0.02-0.22) compared with CON farms. No significant differences were observed between intervention groups for morbidity or mortality. Implementing one additional intervention from the plan, regardless of intervention group, was associated with improvements in mean ADG for DH calves of 0.01 kg/d (0.01, 0-0.03) and MB calves of 0.02 kg/d (0.00-0.04). Model predictions suggest that a farm with the highest number of interventions in place (15) compared with farms with the lowest number of interventions in place (4) would expect an improvement in growth rates from 0.65 to 0.81 kg/d for MB, from 0.73 to 0.88 kg/d for DH, a decrease in mortality rates from 10.9% to 2.8% in MB, and a decrease in diarrhea rates from 42.1% to 15.1% in DH. The calf health plan tested in this study represents a useful tool to aid veterinarians and farmers in the implementation of effective management interventions likely to improve the growth rates, health, and welfare of preweaning calves on dairy farms.

A survey of calf management practices and farmer perceptions of calf housing in UK dairy herds

Adoption of optimal management techniques for rearing dairy calves has significant effects on their health, welfare, and productivity. Despite much published literature on best practice, calf morbidity and mortality rates remain high. This survey aimed to establish current calf management practices in the United Kingdom, along with farmer perceptions surrounding different housing types. A survey containing 48 questions was distributed online to UK farmers via social media, online forums, and a convenience sample of veterinary practices and was completed by 216 participants. A descriptive analysis with frequency distributions was calculated, with chi-squared tests, linear regression and multinomial regression performed to assess associations between variables. There was a low level of regular veterinary involvement in day-to-day health decision making for calves (3/216, 1.4%), highlighting the need for appropriate staff training and standard operating procedures to ensure prudent antimicrobial usage. Restricted calf milk feeding remains highly prevalent in the United Kingdom, with most calves fed milk replacer (114/216, 52.8%), twice daily (189/216, 87.5%), initially given milk at 4 L/d (66/216, 30.6%) or 6 L/d (47/216, 21.8%). There was, however, a small number of farmers initially feeding only 2 to 3 L/d (28/216, 13.0%). Euthanasia of bull calves (5/216, 2.3%) and feeding antimicrobial waste milk to calves (8/216, 3.7%) both occurred on some farms. With regard to housing, use of individual calf pens has reduced from around 60% in 2010 to 38.4% in this study (83/216), with this reduction being partly driven by the policy of UK milk buyers. Farmer perceptions indicated that individual housing was thought to help to improve calf health and feed monitoring of calves, suggesting that successful use of group housing requires a higher level of stockmanship. The majority of farmers did not provide fresh bedding to calves on a daily basis (141/216, 65.3%), and relatively few disinfected both the calf housing (38.0%) and ground (47.7%) between calves, suggesting that hygiene practices may require additional attention in farm management protocols.

Influences on the assessment of resource- and animal-based welfare indicators in unweaned dairy calves for usage by farmers

Consumers, industrial stakeholders, and the legislature demand a stronger focus on animal welfare of all livestock at the farm level by using suitable indicators in self-assessments. In order to deduce farms' animal welfare status reliably, factors that influence indicators' results need to be identified. Hence, this study aimed to apply possible animal welfare indicators for unweaned dairy calves on conventional dairy farms with early cow-calf separation and evaluate influencing factors such as age and sex of calves or climatic conditions on the applied indicators' results. An animal welfare assessment using 7 resource-based and 14 animal-based indicators was conducted at 42 typical Western German dairy farms (844 calves) in 2018 and 2019 by two observers. The effect of influencing factors was calculated by binary and ordinal logistic regressions and expressed as odds ratios. Although every unweaned calf was assessed during the farm visits, most farms had relatively few unweaned calves (average number of calves ± standard deviation = 20.1 ± 6.7 calves), with six farms having not more than 10 calves. The small sample sizes question the usage of those indicators to compare between farms and to set thresholds at the farm level. Only one assessed indicator (cleanliness core body) was not statistically affected by the evaluated influencing factors. Calf age was identified as the most decisive factor, as it affected 16 of 21 evaluated indicators, and calf age distribution on-farm varied greatly. Climatic conditions (ambient temperature and rainfall) influenced resource-based indicators such as access to concentrate and water or the cleanliness of feeding implements and bedding as well as animal-based cleanliness indicators and the occurrence of health-related impairments such as coughing and diarrhea. The authors found differences between calves on farms assessed by the different observers not only in resource-based hygiene indicators but also in animal-based indicators such as hyperthermia or hypothermia, highlighting the need for further evaluation of quality criteria in dairy calf welfare assessments. Nevertheless, animal welfare assessments by farmers themselves could be useful tools to sensitize farmers to animal welfare and thereby improve calves' welfare.

Evaluation of inter-rater agreement of the clinical signs used to diagnose bovine respiratory disease in individually housed veal calves

In dairy calves raised for veal, typical clinical signs of bovine respiratory disease (BRD) are ocular discharge, nasal discharge, ear droop or head tilt, abnormal respiration, cough, and increased rectal temperature. Despite the existence of several clinical scoring systems, there are few studies on the variability of human recognition of individual BRD clinical signs. The objective of this study was therefore to assess the inter-rater agreement of BRD clinical signs in veal calves. We hypothesized that BRD clinical signs were not detected equally between veterinarians, technicians, and producers of the veal industry and that some clinical signs have higher inter-rater agreement than others. During 2017-2018, we prospectively recorded 524 videos of physical examinations of random veal calves from 48 different batches in Québec, Canada. A researcher, not involved in the inter-rater assessment, classified each video as presence/absence of each BRD clinical sign except rectal temperature. For each of the 5 clinical signs, 15 videos with and 15 videos without the clinical signs were randomly selected to avoid kappa paradoxes. Those 30 videos were then presented in a random order to experienced raters of BRD in veal calves: 6 veterinarians, 6 technicians, and 6 producers. The raters assessed the clinical signs using scores based on the Wisconsin and California scoring system with modifications (0 = absent, 1 = mild, 2 = moderate, 3 = severe for nasal discharge, ocular discharge, and ear droop or head tilt; and 0 = absent, 1 = moderate, 2 = severe for abnormal respiration and induced cough). We used median percentage agreement (Pa), median Cohen's kappa (κ), and Gwet's agreement coefficient 1 (AC1) to assess inter-rater agreement. The effect of scale combination was also tested to determine the optimal combination (4-scale 0/1/2/3 vs. 3-scale 0/1/2 vs. 2-scale 0/1,2,3; 0,1/2,3; or 0/1,2). The differences of inter-rater agreement between veterinarians, technicians, and producers were estimated by a Wilcoxon rank-sum test. The 2-scale combination (0,1/2,3 or 0/1,2) had the highest inter-rater agreement for all clinical signs. With this combination, induced cough was the clinical sign with the highest inter-rater agreement (Pa = 0.93; κ = 0.79; AC1 = 0.87) and abnormal respiration was the sign with the lowest inter-rater agreement (Pa = 0.77; κ = 0.20; AC1 = 0.74). According to Pa and AC1 values, the 2-scale inter-rater agreement of the 5 clinical signs was good (value > 0.6). According to κ, only ear droop or head tilt and induced cough had a substantial 2-scale inter-rater agreement (κ > 0.6). In general, the 2-scale inter-rater agreement was better among veterinarians than among technicians and producers, except for the ear droop/head tilt, where agreement was better among producers. We concluded that with severity scores assessed on a scale of 2 (0,1/2,3 or 0/1,2), the inter-rater agreement of BRD clinical signs was variable according to the sign in veal calves. BRD clinical signs were not detected equally between veterinarians, technicians, and producers of the veal industry. Future research could determine if this discrepancy could be improved by standardization training.

The Effect of the Climatic Housing Environment on the Growth of Dairy-Bred Calves in the First Month of Life on a Scottish Farm

Simple Summary

The climatic environment within calf housing can have an effect on calf health, but also on growth and performance. Calves have a lower threshold environmental temperature (lower critical temperature, LCT), below which can impact on the calf’s ability to maintain its core body temperature. This can cause the calf to partition more of its available energy into heat production and less into growth. The LCT decreases as the calf gets older. This year-long study followed 299 dairy-bred calves on one farm in Scotland from birth until approximately 28 days of age, and looked at the proportion of time for which the temperature was below the LCT for the individual calf, as well as the daily liveweight gain (DLWG; kg/d) of the calves during this time. For their first 6–14 days of life the calves were individually housed, and then subsequently group housed. Air temperature (°C), relative humidity (%), and wind speed (m/s) were recorded every hour of every day throughout the study, and calves were weighed regularly so that DLWG could be calculated. The study demonstrated that calves that spent a high proportion of their time below their LCT had a lower DLWG compared to calves that spent a low proportion of their time below their LCT.

Abstract

Calf housing is naturally thermodynamic, with interactions between various elements such as wind speed, air temperature, and humidity. This study investigated the effect of the proportion of time for which calves were exposed to effective environmental temperatures below their lower critical temperature (LCT) on their daily liveweight gain (DLWG) within their first month of life. This study used the naturally occurring climatic environment, whereas other such studies have been conducted under climatically controlled conditions. Air temperature (°C), relative humidity (%), and wind speed (m/s) were recorded within the calf housing from birth until approximately 28 days of age, with calves being health-scored and weighed at regular intervals. Calves were housed from birth until 6–14 days old in individual hutches, and then moved into group housing igloo pens. Whilst individually housed, calves that spent less than 32% of their time below their LCT had a DLWG of 0.06 ± 0.34 kg/d (mean ± SE) compared to calves that spent more than 97% of their time below their LCT, which had a DLWG of −0.19 ± 0.045 kg/d. When group housed, calves that spent less than 1% of their time below their LCT had a DLWG of 0.59 ± 0.18 kg/d, whereas calves that spent more than 28% of their time below their LCT had a DLWG of 0.53 ± 0.23 kg/d. The proportion of time for which calves were exposed to effective environmental temperatures below their LCT had a significant effect on DLWG when calves were individually housed. Therefore, exposure to effective environmental temperatures below the LCT can be detrimental to the growth of the calf in the early stages of its life.

Pre-Weaned Calf Rearing on Northern Irish Dairy Farms: Part 1. A Description of Calf Management and Housing Design

The first few months of life are of great importance to the longevity and lifetime performance of dairy cows. The nutrition, environment and healthcare management of heifer calves must be sufficient to minimise exposure to stress and disease and enable them to perform to their genetic potential. Lack of reporting of farm management practices in Northern Ireland (NI) makes it difficult to understand where issues impacting health, welfare and performance may occur in the rearing process. The objective of this study was to investigate housing design and management practices of calves on 66 dairy farms across NI over a 3-month period and also identify areas that may cause high risk of poor health and performance in dairy calves. An initial survey was used to detail housing and management practices, with two subsequent visits to each farm used to collect animal and housing-based measurements linked to hygiene management, animal health and performance. Large variations in key elements such as weaning criteria and method, calf grouping method used, nutritional feed plane, and routine hygiene management were identified. The specification of housing, in particular ventilation and stocking density, was highlighted as a potential limiting factor for calf health and performance. Lack of measurement of nutritional inputs, hygiene management practices and calf performance was observed. This poses a risk to farmers' ability to ensure the effectiveness of key management strategies and recognise poor calf performance and health.

Effect of treatment of pneumonia and otitis media with tildipirosin or florfenicol + flunixin meglumine on health and upper respiratory tract microbiota of preweaned Holstein dairy heifers

The objective of this randomized clinical study was to compare the effect of 2 antimicrobial interventions, tildipirosin or florfenicol + flunixin meglumine, used for treatment of pneumonia and extralabel treatment for otitis on health parameters and upper respiratory tract (URT) microbiota of preweaned Holstein calves. Housed preweaned Holstein heifers diagnosed with either otitis or pneumonia were assigned into 1 of 2 treatment groups, receiving a single subcutaneous injection of either 4 mg/kg of tildipirosin (TLD; n = 444) or 40 mg/kg of florfenicol combined with 2.2 mg/kg of a nonsteroidal anti-inflammatory, flunixin meglumine (FLF; n = 442). Calves were enrolled and treated on the day of diagnosis of the first case of pneumonia or otitis. If a calf had a recurrent case, the opposite drug was administered, respecting an interval of 5 d between drug injections. Blood samples for leukocyte counts were collected at 0, 2, 4, and 6 d after treatment, and rectal temperature was measured daily during the 5 d after treatment. Ear scores were observed from calves with otitis. Additionally, swabs of the URT were collected from a subset of 20 calves in each treatment group at d 0, 3, 6, 9, and 11 following enrollment for analysis of URT microbiota through next-generation sequencing of the 16S rRNA gene and quantitative PCR. Swabs were also collected from a comparative group of 20 healthy calves that did not receive any drug. No differences were observed between groups for recurrence risk of either pneumonia (TLD = 32.4%; FLF = 29.7%) or otitis (TLD = 72.7%; FLF = 73.6%). Similarly, no differences were observed for the total number of treatments for pneumonia (TLD = 1.45; FLF = 1.42) or otitis (TLD = 2.96; FLF = 3.07). On the other hand, both drugs reduced rectal temperature, ear scores, and leukocyte counts, with FLF calves having a greater reduction in rectal temperature within 4 d after treatment. Both TLD and FLF reduced the total bacterial load when compared with healthy untreated calves, but no differences were observed between treatment groups. Furthermore, compared with the untreated group, treated calves had lower mean relative abundances (MRA) of the genera Mannheimia, Moraxella, and Pasteurella within 11, 9, and 3 d after treatment, respectively; however, no significant differences were observed between TLD and FLF. On the other hand, MRA of Mycoplasma was not decreased by both treatments compared to untreated animals, and a higher MRA was observed in the TLD group during 11 d after treatment in comparison to FLF and untreated calves. Based on this data, we concluded that both drugs used in the study were effective in reducing rectal temperature, ear scores, leukocyte counts, and MRA of the genera Mannheimia, Pasteurella, and Moraxella in the URT, and calves treated with FLF had a greater reduction in rectal temperature.

Prevalence of disorders in preweaned dairy calves from 731 dairies in Germany: A cross-sectional study

The objective of this cross-sectional study was to determine the prevalence of disorders in preweaned calves in 3 regions in Germany, exemplary for structural diversity in dairy farming. A farm visit was performed on a single occasion on 731 dairy farms in the northern, eastern, and southern regions of Germany between December 2016 and July 2019. Farms differed in herd size, geographical location, and management. In the northern region, the farms had a median of 90 milking cows and were often run as full-time family businesses, partly with external workers. The eastern region tended to have larger farms (a median of 251 milking cows), which were often large-scale agricultural enterprises with employees. In the southern region, the farms had a median of 39 milking cows and were often traditional family businesses, some of these being part-time businesses. Clinical examinations were performed on 14,164 preweaned dairy calves (median 12 calves per farm) by trained veterinarians. A complete data set was available for 13,656 calves. Almost half (42.0%) of the evaluated calves were classified as being affected by at least 1 of the common calf disorders. Omphalitis (O, 20.9%; n = 2,876) and diarrhea (D, 18.5%; n = 2,670) were the most frequently recorded diagnoses, whereas respiratory diseases (RD) were observed to a lesser extent (8.7%; n = 1,100). A striking feature was the fact that 7.1% (n = 987) of the calves were affected by more than 1 disorder at the same time (multimorbidity, M). The following combinations of disorders were frequently observed: O and D (n = 596), O and RD (n = 164), and D and RD (n = 140). Disorders such as O and D, as well as M, were predominantly observed in calves aged 2 wk. A gradual increase in the frequency of RD was observed with age. For all disorders except RD, male calves were more often affected than females. Omphalitis was predominantly diagnosed in the summer months, whereas RD, D, and M were more common in the fall. We detected several statistically significant differences in the prevalence of clinical signs and disorders in preweaned dairy calves between the 3 exemplary regions. The prevalence of RD was higher in the south (10.8%) than in the north (8.2%) and east (7.4%). In the north (33.2%), O was observed more frequently than in the other regions (east: 18.9%; south: 10.5%), whereas D was found less frequently in the north (13.8%) than in the east (21.6%) and south (20.0%).

Haptoglobin and its association with naturally occurring diseases in Holstein heifer calves

ABSTRACT The present study evaluated the use of haptoglobin (Hp) as an indicator of health and performance in 166 Holstein heifer calves reared in an intensive production system. Calves were evaluated at D6-9; D10-13; D20-23; D35-38 and D65-68, corresponding to the days of life. The absence or presence of diseases was evaluated by physical examination and classification of scores. The performance parameters evaluated were body weight, height at withers and hind width. Hp was measured by spectrophotometric technique. The highest prevalence of diarrhea (59.4%; 98/165) was observed in D10-13, bovine respiratory disease (BRD) was on D35-38 (25.8%; 42/163), and umbilical inflammations in D6-D9 (7.8%; 13/166). Highest values of Hp were observed in animals with diarrhea (P=0.02), and umbilical inflammation (P=0.057), in comparison with the group of healthy calves. A significant negative correlation was observed between Hp and performance index. This protein presented an important relation with diarrhea and performance of the calves, opening perspectives on its utilization as a biomarker of diseases.

Factors associated with daily weight gain in preweaned calves on dairy farms

The preweaning period is vital in the development of calves on dairy farms and improving daily liveweight gain (DLWG) is important to both financial and carbon efficiency; minimising rearing costs and improving first lactation milk yields. In order to improve DLWG, veterinary advisors should provide advice that has both a large effect size as well as being consistently important on the majority of farms. Whilst a variety of factors have previously been identified as influencing the DLWG of preweaned calves, it can be challenging to determine their relative importance, which is essential for optimal on-farm management decisions. Regularised regression methods such as ridge or lasso regression provide a solution by penalising variable coefficients unless there is a proportional improvement in model performance. Elastic net regression incorporates both lasso and ridge penalties and was used in this research to provide a sparse model to accommodate strongly correlated predictors and provide robust coefficient estimates. Sixty randomly selected British dairy farms were enrolled to collect weigh tape data from preweaned calves at birth and weaning, resulting in data being available for 1014 calves from 30 farms after filtering to remove poor quality data, with a mean DLWG of 0.79 kg/d (range 0.49-1.06 kg/d, SD 0.13). Farm management practices (e.g. colostrum, feeding, hygiene protocols), building dimensions, temperature/humidity and colostrum quality/bacteriology data were collected, resulting in 293 potential variables affecting farm level DLWG. Bootstrapped elastic net regression models identified 17 variables as having both a large effect size and high stability. Increasing the maximum preweaned age within the first housing group (0.001 kg/d per 1d increase, 90 % bootstrap confidence interval (BCI): 0.000-0.002), increased mean environmental temperature within the first month of life (0.012 kg/d per 1 °C increase, 90 % BCI: 0.002-0.037) and increased mean volume of milk feeding (0.012 kg/d per 1 L increase, 90 % BCI: 0.001-0.024) were associated with increased DLWG. An increase in the number of days between the cleaning out of calving pen (-0.001 kg/d per 1d increase, 90 % BCI: -0.001-0.000) and group housing pens (-0.001 kg/d per 1d increase, 90 % BCI: -0.002-0.000) were both associated with decreased DLWG. Through bootstrapped elastic net regression, a small number of stable variables have been identified as most likely to have the largest effect size on DLWG in preweaned calves. Many of these variables represent practical aspects of management with a focus around stocking demographics, milk/colostrum feeding, environmental hygiene and environmental temperature; these variables should now be tested in a randomised controlled trial to elucidate causality.

Longitudinal health outcomes for enteric pathogens in preweaned calves on Ohio dairy farms

Calf gastrointestinal disease remains one of the main causes of productivity and economic losses on dairy operations. The majority of pre-weaned calf mortality is attributed to diarrhea or other digestive problems. Five enteric pathogens are commonly associated with diarrhea in dairy calves, including bovine rotavirus, bovine coronavirus, Escherichia coli, Salmonella spp., and Cryptosporidium parvum. Pathogen-associated differences in health outcomes and case fatality rates have not been well-characterized. Additionally, updated prevalence estimates may reflect important changes in the epidemiology of the pathogens on dairy farms. For this cohort study, fecal samples were collected from 276 clinically ill calves across 5 central Ohio dairy farms on the first day of diarrheal diagnosis. Genomic techniques, including reverse transcription polymerase chain reaction (RT-PCR) and droplet digital polymerase chain reaction (ddPCR) were used to test for the presence of the five enteric pathogens. A Poisson regression model was used to estimate the relative risk of mortality, and a survival analysis with a Cox regression model was used to analyze time to return to a healthy clinical status by pathogen. Rotavirus was the most frequently identified at 68.1 % (188/276), followed by F5 (K99)⁺E. coli at 42.5 % (114/268), C. parvum at 28.4 % (66/232), coronavirus at 5.8 % (16/276), and Salmonella had the lowest prevalence at 3.7 % (10/268). Risk of mortality tended to be higher for calves infected with Salmonella (RR = 3.83; 95 %CI: 0.93, 16.02, p = 0.062); however, the time to return to a healthy clinical status was not different for different pathogens. Only farm was a significant predictor of time to return to health (p = 0.017); the within-farm median duration of signs substantially varied between 2 and 7 days. The results suggest that the prevalence and distribution of rotaviral infections is higher than reported in prior studies. With the exception of infections caused by Salmonella spp., pathogen diagnosis on the first day of diarrhea was a poor predictor of the outcome and duration of disease. These results are critical to guide the implementation of prevention measures to detect, treat, and prevent calf diarrhea.

The Health and Behavioural Effects of Individual versus Pair Housing of Calves at Different Ages on a UK Commercial Dairy Farm

Simple Summary

The way in which dairy calves are housed can have a significant impact on their health and productivity. This study compared three different housing groups from birth to weaning; individual housing, pair housing from birth, and pair housing from three weeks of age. Newborn Holstein heifer calves (n = 100) were recruited over a six-month summer period from a single commercial dairy farm in the UK. Each calf had a weekly visit by the researcher over a 10-week period, where they were weighed and assessed for the presence of disease, along with measuring solid feed intake and the time to approach a novel object. Other management aspects including milk allocation were the same across groups. There was no effect of the housing group on average daily liveweight gain (ADLG), the presence of disease or the time taken to approach a novel object. The housing group did impact solid feed intake, with calves pair housed at either time period ingesting significantly more than individually housed calves. This study demonstrated that there were no detrimental effects on the health or growth of calves housed in pairs, with the added benefit of increased solid feed intake for pair housed calves, which is important for a smooth transition over the weaning period.

Abstract

Housing management of dairy calves is one of the factors that contributes to a successful rearing outcome. Individual housing of pre-weaned calves is thought to provide enhanced biosecurity and easier monitoring of the individual, and so remains prevalent in the UK. Behavioural studies have, however, found that pair housing is important for social learning, with positive impacts on health and welfare. This study utilised a single UK commercial dairy farm to establish if individual housing, pair housing from birth, or pair housing from three weeks of age affected health and behavioural parameters. Calves were housed in these allocated groups from birth to eight weeks of age, when they were moved into group pens of five calves for weaning at 10 weeks of age. All management routines other than the housing group were the same for enrolled calves. One hundred Holstein calves were recruited over a six-month period, and systematically allocated to a housing group. Weekly visits were conducted up to 10 weeks of age (weaning) for each calf, with weight, solid feed intake, and presence of clinical disease measured. In addition, a novel object approach test was carried out at six weeks, and a thoracic ultrasound was performed at seven weeks. Housing group had no effect on the average daily liveweight gain (ADLG) (p = 0.74), with an average of 0.66 kg/day over the pre-weaning period. However, on group housing at 8–10 weeks of age, there was a numerical increase in ADLG in the pair housed calves compared to the individually housed calves over the weaning period. Housing group had no significant effect on disease prevalence (p = 0.98) or the time taken to approach the novel object (p = 0.29). However, pair housed calves had increased mean total solid feed intakes from weeks 2–8 (p = 0.011), with 6.2 ± 0.67 kg (standard error of the mean—SEM), 12.7 ± 0.73 kg and 13.6 ± 0.70 kg ingested by individually housed, pair housed from birth and pair housed from three weeks of age, respectively. The overall findings of this study indicate that within a UK commercial dairy management system, there is no detrimental effect of housing calves within pairs (either from birth or three weeks of age) compared to individual housing.

Particulate matter and airborne endotoxin concentration in calf barns and their association with lung consolidation, inflammation, and infection

Agricultural operations are important sources of organic dust containing particulate matter (PM) and endotoxins, which have possible negative health consequences for both humans and animals. Dust concentrations and composition in calf barns, as well as the potential health effects for these animals, are scarcely documented. The objective of this study was to measure PM fractions and endotoxin concentrations in calf barns and study their associations with lung consolidation, respiratory tract inflammation, and infection in group-housed calves. In this cross-sectional study, samples from 24 dairy farms and 23 beef farms were collected in Belgium from January to April 2017. PM_1.0, PM_2.5 and PM₁₀ (defined as particulate matter passing through a size-selective inlet with a 50% efficiency cut-off at a 1.0-μm, 2.5-μm, and 10-μm aerodynamic diameter, respectively) were sampled during a 24-h period using a Grimm aerosol spectrometer (Grimm Aerosol Technik Ainring GmbH & Co. KG). Endotoxin concentration was measured in the PM₁₀ fraction. Thoracic ultrasonography was performed and broncho-alveolar lavage fluid was collected for cytology and bacteriology. Average PM concentrations were 16.3 µg/m³ (standard deviation, SD: 17.1; range: 0.20-771), 25.0 µg/m³ (SD: 25.3; range: 0.50-144.9), and 70.3 µg/m³ (SD: 54.5; range: 1.6-251.2) for PM_1.0, PM_2.5, and PM₁₀, respectively. Mean endotoxin in the PM₁₀ fraction was 4.2 endotoxin units (EU)/µg (SD: 5.50; range: 0.03-30.3). Concentrations in air were 205.7 EU/m³ (SD: 197.5; range: 2.32-901.0). Lung consolidations with a depth of ≥1, ≥3, and ≥6 cm were present in 43.1% (146/339), 27.4% (93/339), and 15.3% (52/339) of the calves, respectively. Exposure to fine (PM_1.0) PM fractions was associated with increased odds of lung consolidations of ≥1 cm (odds ratio, OR: 3.3; confidence interval (CI): 1.5-7.1), ≥3 cm (OR: 2.8; CI: 1.2-7.1), and ≥6 cm (OR: 12.3; CI: 1.2-125.0). The odds of having lung consolidations of ≥1 cm (OR: 13.9; CI: 3.4-58.8) and ≥3 cm (OR: 6.7; 1.7-27.0) were higher when endotoxin concentrations in the dust mass exceeded 8.5 EU/µg. Broncho-alveolar lavage fluid neutrophil percentage was positively associated with PM₁₀ concentration, and epithelial cell percentage was negatively associated with this fraction. Concentration of PM_2.5 was positively associated with epithelial cell percentage and isolation of Pasteurella multocida. Although concentrations of fine dust are lower in calf barns than in poultry and pig housings, in this study they were associated with pneumonia in calves. Dust control strategies for reducing fine dust fractions in calf barns may benefit human and animal respiratory health.

Assessing dairy goat welfare in intensive or semi-intensive farming conditions in Mexico

We aimed to verify whether a low number of relevant animal-based indicators was able to discriminate 33 semi-intensive (grazing during the day and confinement during the night with access to an outdoor paddock; S-INT) and 8 intensive farms (permanent confinement with access to an outdoor paddock; INT) located in the Mexican semi-desert. In addition, we implemented the resource-based assessment scheme Animal Needs Index (ANI) with the identified animal-based indicators to compare the overall level of welfare in INT and S-INT. In particular, we used a protocol made up of 2 parts. The first comprised 4 evaluation sheets (locomotion, flooring, environment, management) and resource-based indicators derived from ANI, and the second one comprised a set of validated animal-based measures focusing on physical conditions and clinical signs of disease derived from the Animal Welfare Indicators scheme and reported in 2 additional sheets. The scoring system was also derived from ANI, with partial scores for each sheet to be summed to obtain the total score. A total of 1,116 dairy goats were assessed. All the observations and recordings were performed by an expert veterinarian evaluator assisted by an auxiliary, and longevity was retrieved from the farm records. The prevalence of animals displaying dirtiness, ocular discharge, abscesses, and claw overgrowth were higher in INT than in S-INT. Disbudding was routinely performed in INT only. Therefore, scurs, indicating improper disbudding, were recorded only in INT. In addition, the longevity of goats raised in S-INT was higher than in INT. Conversely, the prevalence of goats affected by anemia (i.e., FAMACHA scores >2) or lean (i.e., body condition score <2) tended to be higher in S-INT than in INT. No significant differences between the 2 groups of farms were detected for wounds, nasal discharge, integument alterations, fecal soiling, uterine prolapse, and subclinical mastitis. The results obtained using only animal-based measures were confirmed when resource-based variables were also included in the assessment, as 3 out of 6 sheets of the evaluation scheme (i.e., flooring, environment, and health-physical conditions) were scored higher in the S-INT than in the INT. As a consequence, the total score was also higher for S-INT than for INT. We conclude that the selected set of validated animal-based measures was able to discriminate between farms from different production systems. In particular, higher welfare levels were observed in S-INT farms, where the animals were allowed to spend most of the day on natural pasture, compared with INT farms, where the animals were constantly confined. Nevertheless, a certain degree of improvement should also be promoted in terms of anemia and body condition in S-INT farms.

A Cohort Study Risk Factor Analysis for Endemic Disease in Pre-Weaned Dairy Heifer Calves

Simple Summary

Most dairy heifer calves are removed from their dam and reared on milk from birth until weaning at around nine weeks of age. During this period they are susceptible to diseases which reduce their welfare and later performance in the dairy herd and can cause mortality. This study investigated the risk factors for disease on 11 UK dairy farms. Each calf received a weekly clinical examination. Out of 492 heifers recruited, diarrhoea, bovine respiratory disease (BRD) and umbilical disease were recorded in 48.2%, 45.9% and 28.7%, respectively. This was assessed using a composite disease score (CDS), reflecting severity and duration. The CDS for diarrhoea decreased when more calves were born in the same week, but this increased the risk of umbilical disease. The CDS for BRD was reduced by housing calves in fixed groups and feeding them more milk. Being born at a warmer time of year reduced the severity of BRD but increased it for umbilical disease. Calves acquire their initial immunity by ingesting antibodies in colostrum. Better immunity reduced the severity of BRD but failed to protect against diarrhoea or umbilical disease. Calves with a higher circulating concentration of the metabolic hormone insulin-like growth factor 1 (IGF-1) experienced less severe disease. Providing farmers and veterinarians with a better understanding of such risk factors helps them to improve their management practices to reduce disease incidence.

Abstract

Dairy heifer calves experience high levels of contagious disease during their preweaning period, which may result in poor welfare, reduced performance or mortality. We determined risk factors for disease in a cohort study of 492 heifers recruited from 11 commercial UK dairy farms. Every animal received a weekly examination by a veterinarian from birth to nine weeks using the Wisconsin scoring system. Multivariable models were constructed using a hierarchical model with calf nested within farm. Outcome variables for each disease included a binary outcome (yes/no), disease duration and a composite disease score (CDS) including both severity and duration. Diarrhoea, bovine respiratory disease (BRD) and umbilical disease were recorded in 48.2%, 45.9% and 28.7% of calves, respectively. A higher heifer calving intensity in the week of birth reduced the CDS for diarrhoea, with a marginal benefit of improved passive transfer (serum immunoglobulin G (IgG) measured at recruitment). The CDS for BRD was reduced by housing in fixed groups, higher mean temperature in month of birth, increasing milk solids fed, increasing IgG, and higher plasma IGF-1 at recruitment. Conversely, higher calving intensity and higher temperature both increased the CDS for umbilical disease, whereas high IGF-1 was again protective. Although good passive transfer reduced the severity of BRD, it was not significant in models for diarrhoea and umbilical disease, emphasising the need to optimise other aspects of management. Measuring IGF-1 in the first week was a useful additional indicator for disease risk.

Effects of β-Mannanase and Bacteriophage Supplementation on Health and Growth Performance of Holstein Calves

Simple Summary

For sustainable animal agriculture, we need to find ways to increase growth efficiency without using feed antibiotics. Bacteriophages, which are only harmful to specific bacterial strains, have been suggested as a feed additive replacing antibiotics. β-mannanase, which degrades mannan, is known to promote nutrient digestibility, animal growth, or both, thus improving feed efficiency. The objective of this study was to evaluate the effects of dietary supplementation with bacteriophage and β-mannanase on health and growth performance in calves. We assigned 36 pre-weaning male Holstein calves to one of four treatments with a 2 × 2 factorial arrangement: no supplementation, 0.1% β-mannanase, 0.1% bacteriophage, and both 0.1% bacteriophage and 0.1% β-mannanase supplementation in a starter on a dry matter basis. Compared to unsupplemented, the bacteriophage supplemented group showed a tendency to improve the survival rate without growth promotion. Supplementation of β-mannanase, on the other hand, increased the starter intake and the weekly body weight (BW) gain and tended to increase the final BW. Our study indicated that bacteriophage supplementation has a positive effect on survival rate, while β-mannanase supplementation improves growth performance in calves.

Abstract

The objective of this study was to evaluate the effects of dietary supplementation with bacteriophage and β-mannanase on health and growth performance in calves. Thirty-six pre-weaning male Holstein calves were randomly allocated to one of four dietary treatments with a 2 × 2 factorial arrangement: no supplementation, 0.1% β-mannanase, 0.1% bacteriophage, and both 0.1% bacteriophage and 0.1% β-mannanase supplementation in a starter on a dry matter basis. The experiment lasted from 2 weeks before weaning to 8 weeks after weaning. Twenty-two calves survived to the end of the experiment. No interaction was observed between the two different feed additives. The bacteriophage supplementation tended to increase the odds ratio of survival (p = 0.09). The number of Escherichia coli in feces significantly decreased by bacteriophage supplementation one week after weaning. β-mannanase supplementation increased the concentrate intake (p < 0.01) and tended to increase the final BW (p = 0.08). Analysis of repeated measures indicated β-mannanase supplementation increased weekly body weight gain (p = 0.018). We conclude that bacteriophage supplementation may have a positive effect on calf survival rate, while β-mannanase supplementation may increase the growth rate and starter intake by calves just before and after weaning.

Effects of Airspeed on the Respiratory Rate, Rectal Temperature, and Immunity Parameters of Dairy Calves Housed Individually in an Axial-Fan-Ventilated Barn

At many modern dairy farms, calves raised in barns are kept in individual stalls separated by solid partitions, which act as barriers. Ventilation fans blowing air perpendicular to these stalls only provide the optimal airflow to the first few calves, while those further away receive a slower airflow. To ascertain whatever effects different airflow speeds may have on the health of animals kept in stalls located at increasing distances from ventilation fans, we divided a select group of 43 Holstein dairy calves into six subgroups based on age, and each subgroup was subjected to either a specified high-speed or low-speed airflow as follows: (1) Six 3-day-olds received high-speed airflow (D3-HA); (2) Six 3-day-olds received low-speed airflow (D3-LA); (3) Eight 19 (±3)-day-olds received high-speed airflow (D19-HA); (4) Eight 19 (± 3)-day-olds received low-speed airflow (D19-LA); (5) Eight 29 (±3)-day-olds received high-speed airflow (D29-HA); and (6) Seven 29 (±3)-day-olds received medium-speed airflow (D29-MA). These trials show that the rectal temperatures and respiratory rates of D19-LA (39.37 °C; 72.90 breaths/min) were significantly higher than those of D19-HA (39.14 °C; 61.57 breaths/min) (p ≤ 0.05), and those of D29-MA (39.40 °C; 75.52 breaths/min) were significantly higher than those of D29-HA (39.20 °C; 68.41 breaths/min) (p ≤ 0.05). At 33 (±3) days of age, those calves receiving high-speed airflow (p ≤ 0.05) registered significantly higher immunoglobulins A and M than calves receiving low-speed flow. Those calves subjected to a high-speed airflow also registered significantly lower tumor necrosis factor levels than those receiving low-speed flow (p ≤ 0.05). Among the 29 to 43-day-old calves, no significant differences in immunity parameters were found to exist between groups D29-HA and D29-MA. On the basis of these findings, we were able to conclude that in the warm season, when the calves were less than 0.5 months old, low-speed (0.17-0.18 m/s) airflows had no significant effect on calves; when the calves were 1 month old, low-speed airflow (0.20-0.21 m/s) may impair the immune functions; when the calves were 1 to 1.5 months old, the airflow velocity higher than 0.9 m/s can meet the needs of the calf without a negative impact on the calf.