The effects of different environmental conditions on thermoregulation and clinical and hematological variables in long-distance road-transported calves

A randomized controlled trial evaluating the effect of providing a rest period during long-distance transportation of surplus dairy calves: Part II. Impact on hematological variables

The objective of this randomized controlled trial was to determine if providing a rest stop including provision of feed and water between periods of continuous transportation mitigates the impact of long-distance transportation on markers of energy status and hydration in calves transported by road for 16 h. This study was conducted between September 2022 to January 2023 and included male and female Holstein and crossbred dairy calves ≥7 d old from 2 commercial dairy farms in Ontario, Canada (n = 96). On the day before transportation, calves were enrolled and randomly assigned to one of 2 treatment groups: 1) continuous transportation by road for 16 h or 2) 8 h of transport, 8 h of rest, and a further 8 h of transport to a single calf-raising facility. Calves that received a rest stop were fed 2 L of milk replacer at the time of unloading for the rest period and again immediately before reloading for the second leg of the journey. Blood samples were collected before and after transportation as well as daily for 3 d following arrival to the calf-raising facility. Serum was analyzed for concentrations of β-hydroxybutyrate (BHBA), nonesterified fatty acid (NEFA), haptoglobin, and creatine kinase, while acid-base disturbances were evaluated within 1 h of collection of whole blood to assess glucose, sodium, potassium, ionized calcium, hematocrit, hemoglobin, pH, base excess, pO2, TCO2, HCO3, pCO2, and sO2. Mixed linear regression models with repeated measures were built to assess the effect of treatment group, age at transportation, breed, and sex on these parameters. Immediately after transportation, calves that received the rest period had lower BHBA (-68.04 μmol/L, 95% CI: -99.59 to -36.49), NEFA (-0.14 mmol/L, 95% CI -0.22 to -0.07), and sodium (-1.10 mmol/L, 95% CI = -2.18 to -0.02), and higher glucose (0.48 mmol/L, 95% CI = 0.21 to 0.74), potassium (0.27 mmol/L, 95% CI = 0.11 to 0.43), ionized calcium (0.06 mmol/L, 95% CI = 0.03 to 0.08), and sO2 (8.76%, 95% CI = 1.61 to 15.91) compared with calves that were continuously transported for 16 h. Additionally, calves transported between 11 and 12 d old had lower hematocrit (-1.22%, 95% CI = -2.19 to -0.25), hemoglobin (-3.07 g/L, 95% CI = -5.70 to -0.43), haptoglobin (-0.13 g/L, 95% CI = -0.23 to -0.02), and potassium (-0.13 mmol/L, 95% CI = -0.22 to -0.04) and higher sodium (0.83 mmol/L, 95% CI = 0.03 to 1.63) than 7-8 d old calves. Furthermore, calves that were 13-24 d old at transport had lower haptoglobin (-0.16 g/L, 95% CI = -0.27 to -0.06) and potassium (-0.14 mmol/L, 95% CI = -0.23 to -0.05), and higher sodium (1.02 mmol/L, 95% CI = 0.22 to 1.82) and ionized calcium (0.02 mmol/L, 95% CI = 0.002 to 0.035) compared with calves transported at 7-8 d old. The results of this trial demonstrate that a rest period improves energy status upon arrival to a calf-raising facility, suggesting that the benefit of a rest period may be mostly related to the provision of mid-journey milk meals.

Association of Bovine Respiratory Disease during the Pre-Weaning Period with Blood Cell Counts and Circulating Concentration of Metabolites, Minerals, and Acute Phase Proteins in Dairy Calves Transported to a Calf Raising Facility

Our objective was to investigate the association of bovine respiratory disease (BRD) occurring within the first 56 days of life with blood cell counts and the circulating concentration of metabolites, minerals, and acute phase proteins throughout the pre-weaning period in dairy calves transported to a heifer raising facility within their first week of life. Data from 305 calves transported from dairies in Minnesota to a calf raising facility in New Mexico within their first four days of life were used in this retrospective cohort study. Blood samples were collected at 7, 17, 34, and 56 days of life for the analysis of blood cell counts, biochemistry, and the concentration of acute phase proteins. Blood urea nitrogen, albumin, GLDH, CK, P, Na, K, Cl, Zn, Hp, SAA, and monocyte counts were associated with BRD status throughout or at least at one of the time points evaluated in this study. In conclusion, several hematological variables were associated with BRD status in dairy calves that underwent transportation stress in early life.

Preliminary exploration of the health and behavior around the time of transportation of beef × dairy calves and Holstein bull calves 3 days of age or younger in the western United States

In the western United States, it is common practice for dairy and beef × dairy calves to be sold and shipped within the first few days of life, making transportation one of the first challenges that a calf will experience. To date, no published research has examined the effects of calf transport within the western United States. The objectives of this observational study were to describe the health status of calves leaving the source dairy, characterize transportation conditions and calf behavior during transportation, and determine if age at transportation and transportation duration are associated with dehydration, blood glucose and lactate, and behavior. An observational study was performed on 2 source dairies in the western United States. Initial enrollment consisted of dairy bull calves and beef × dairy calves (n = 126 total) across 16 transport cohorts which were sold and transported to separate calf-raising facilities approximately 80 km from the source dairy. Health exams and measurements were performed on all study participants 2 to 3 h before transport and ≤2 h after transport. Two researchers performed health exams using the Wisconsin calf health score, which included clinical respiratory scores, lung ultrasound, and fecal, navel, and joint scores. Hydration status was assessed using skin tent duration. Blood samples were collected and immediately analyzed for blood glucose and lactate using glucose and lactate meters. Accelerometers were attached at the source dairy on ≤10 calves in each of the 16 transport groups to record movement and behavior during transport (n = 90 had accelerometers attached). Results showed that about half of calves (49%) were identified with at least one health abnormality before transport. Researchers found an association between age and dehydration status in which calves <24 h of age were more likely to be dehydrated compared with calves 1 d of age. Additionally over half of the calves (56%) were identified as dehydrated after transport. To the authors' knowledge, this is the first observational study that investigates the effects of transportation on dairy bull and beef × dairy calf health and welfare in the western United States. Our findings support the need for improved management and decision making before transporting calves to reduce the negative effects of transport.

The effects of colostrum consumption and feed restriction during marketing and transportation of male dairy beef calves: Impact on pre-transport nutritional status and on farm recovery

The aim of this study was to evaluate the effects of colostrum consumption and feed restriction on biomarkers of stress, nutritional and health status, gut functionality, and behavior in male dairy beef calves being marketed and transported. A total of 82 male Holstein calves (42 ± 1.2 kg of body weight and 14 ± 0.9 d of age) were used to study the amount of colostrum given at birth at the dairy farm of origin, the degree of feed restriction suffered at an assembly center simulation (d -4 to d -1), and the effects of a 19 h transportation (d -1). Treatments were as follows: control calves (CTRL; n = 16) were fed 10 L of colostrum at the dairy farm of origin, milk replacer (MR) and concentrate at the assembly center, and were not transported; calves fed high colostrum and milk replacer (HCMR; n = 17) were given 10 L of colostrum at the dairy farm of origin, MR at the assembly center, and transported; calved fed high colostrum and rehydrating solution (HCRS; n = 16) were given 10 L of colostrum at the dairy farm of origin, a rehydrating solution (RS) at the assembly center, and transported; calves fed low colostrum and milk replacer (LCMR; n = 17) were given 2 L of colostrum at the dairy farm of origin, MR at the assembly center, and transported; and calves fed low colostrum and rehydrating solution (LCRS; n = 16) were given 2 L of colostrum at the dairy farm of origin, RS at the assembly center, and transported. Transported calves mimic a 19-h transportation. After transport, all calves were fed 2.5 L of MR twice daily and had ad libitum access to concentrate, straw, and water. Calves' recovery was followed for 7 d. Concentrate intake and health records were collected daily from d -4 until d 7 and body weight (BW) and blood samples were collected on d -4, -1, 0, 1, 2, and 7 of the study. Results showed that the feeding regimen provided at the assembly center reduced BW for the HCRS and LCRS calves compared with the CTRL, HCMR, and LCMR calves. Concentrate intake peaked on d 0 in the transported calves, followed by a reduction of intake on d 1 after transportation. Concentrate intake recovery was lower for the LCRS and LCMR calves. On d -1, nonesterified fatty acids and β-hydroxybutyrate concentrations were greater for the HCRS and LCRS calves compared with the CTRL, HCMR, and HCRS calves. After transportation, serum Cr-EDTA concentration was greater for the HCRS and LCRS calves than the HCMR, LCMR, and CTRL calves. The LCRS calves had the lowest serum concentration of citrulline. Finally, health scores were greater for the LCRS calves from d 0 to 7. In summary, both the greatest degree of feed restriction during the assembly center and the low colostrum consumption at birth negatively affected the recovery of concentrate consumption and BW, gut functionality, health status, and behavior in calves after arrival at the rearing farm.

Effect of source and journey on physiological variables in calves transported by road and ferry between Ireland and the Netherlands

This study aimed to establish baseline variables for calves transported by road and ferry from Ireland to the Netherlands and to investigate the effect of journey [two comparable journeys in April (J1) and May (J2) 2022] and source [source farm or mart (SF/MA)] on these variables. A total of 66 calves from the SF/MA were transported from Ireland to commercial veal farms in the Netherlands. Blood samples were collected at the SF/MA, assembly center (Ireland), lairage (France), and on arrival on the veal farm (Netherlands). They were analyzed for indicator variables related to energy balance, hydration/electrolytes, physical/muscular stress, immunity, and inflammation [glucose, beta-hydroxybutyrate (BHB), non-esterified fatty acids (NEFA), potassium, sodium, magnesium, chloride, urea, haematocrit, total protein, creatine kinase, L-lactate, cortisol, white blood cell, neutrophil, lymphocyte and monocyte counts, serum amyloid-A, and haptoglobin]. Health variables eye and nose discharge, skin tent (a measure of dehydration), and navel inflammation were scored by a trained observer, and calves were weighed at every blood-sampling time point. All blood variables and body weight changed significantly (P < 0.05) during transport, most notably between the assembly center and lairage. Reference ranges were available for 18 variables; 11 of these variables exceeded the reference ranges at the lairage, whilst 10 variables exceeded the reference ranges on arrival at the veal farm. However, health variables did not change during transport. A journey-to-journey comparison indicated much variation; 18 out of 25 variables differed significantly on at least one time point. In total, J1 calves experienced a more severe change in BHB, potassium, strong-ion-difference, L-lactate, and eye and nose discharge than J2 calves. The source of calves also affected their physiology; 12 out of 25 variables studied differed significantly, all of which were confined to the first time point. Specifically, MA calves had elevated levels of NEFA, urea, haematocrit, L-lactate, cortisol, white blood cell, neutrophil, and monocyte counts and lower levels of corrected chloride and lymphocyte count. Overall, calves in this study showed a generalized physiological disturbance beyond reference limits during long-distance transport, but no animal died during transport or for 3 weeks post-arrival.

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.

Transmission of antimicrobial resistance (AMR) during animal transport

The transmission of antimicrobial resistance (AMR) between food-producing animals (poultry, cattle and pigs) during short journeys (< 8 h) and long journeys (> 8 h) directed to other farms or to the slaughterhouse lairage (directly or with intermediate stops at assembly centres or control posts, mainly transported by road) was assessed. Among the identified risk factors contributing to the probability of transmission of antimicrobial-resistant bacteria (ARB) and antimicrobial resistance genes (ARGs), the ones considered more important are the resistance status (presence of ARB/ARGs) of the animals pre-transport, increased faecal shedding, hygiene of the areas and vehicles, exposure to other animals carrying and/or shedding ARB/ARGs (especially between animals of different AMR loads and/or ARB/ARG types), exposure to contaminated lairage areas and duration of transport. There are nevertheless no data whereby differences between journeys shorter or longer than 8 h can be assessed. Strategies that would reduce the probability of AMR transmission, for all animal categories include minimising the duration of transport, proper cleaning and disinfection, appropriate transport planning, organising the transport in relation to AMR criteria (transport logistics), improving animal health and welfare and/or biosecurity immediately prior to and during transport, ensuring the thermal comfort of the animals and animal segregation. Most of the aforementioned measures have similar validity if applied at lairage, assembly centres and control posts. Data gaps relating to the risk factors and the effectiveness of mitigation measures have been identified, with consequent research needs in both the short and longer term listed. Quantification of the impact of animal transportation compared to the contribution of other stages of the food-production chain, and the interplay of duration with all risk factors on the transmission of ARB/ARGs during transport and journey breaks, were identified as urgent research needs.

Welfare of cattle during transport

In the framework of its Farm to Fork Strategy, the Commission is undertaking a comprehensive evaluation of the animal welfare legislation. The present Opinion deals with protection of cattle (including calves) during transport. Welfare of cattle during transport by road is the main focus, but other means of transport are also covered. Current practices related to transport of cattle during the different stages (preparation, loading/unloading, transit and journey breaks) are described. Overall, 11 welfare consequences were identified as being highly relevant for the welfare of cattle during transport based on severity, duration and frequency of occurrence: group stress, handling stress, heat stress, injuries, motion stress, prolonged hunger, prolonged thirst, respiratory disorders, restriction of movement, resting problems and sensory overstimulation. These welfare consequences and their animal-based measures are described. A variety of hazards, mainly relating to inexperienced/untrained handlers, inappropriate handling, structural deficiencies of vehicles and facilities, poor driving conditions, unfavourable microclimatic and environmental conditions, and poor husbandry practices leading to these welfare consequences were identified. The Opinion contains general and specific conclusions relating to the different stages of transport for cattle. Recommendations to prevent hazards and to correct or mitigate welfare consequences have been developed. Recommendations were also developed to define quantitative thresholds for microclimatic conditions within the means of transport and spatial thresholds (minimum space allowance). The development of welfare consequences over time was assessed in relation to maximum journey duration. The Opinion covers specific animal transport scenarios identified by the European Commission relating to transport of unweaned calves, cull cows, the export of cattle by livestock vessels, the export of cattle by road, roll-on-roll-off ferries and 'special health status animals', and lists welfare concerns associated with these.

Simulation of feed restriction and fasting: Effects on animal recovery and gastrointestinal permeability in unweaned Angus-Holstein calves

Feed restriction and fasting experienced during commercial production negatively affect unweaned calves' behavior and health status. Transportation and stays at assembly centers are the main factors generating these disorders. For this study, 20 unweaned Angus-Holstein bull calves [44.1 ± 2.04 kg of body weight (BW) and 14.7 ± 0.63 d of age (± standard error)] were used to evaluate the effects of feed restriction and fasting on performance, energy status [serum concentration of glucose, β-hydroxybutyrate (BHB), and nonesterified fatty acids], and gastrointestinal permeability [serum concentration of citrulline, chromium (Cr)-EDTA, lactulose, and d-mannitol]. Calves were randomly assigned to 1 of 4 treatments that simulated the feed restrictions of an assembly center situation on one hand, and the fasting hours during transportation on the other. Treatments were as follows. Control (CT): from d -4 to -1, calves were fed 2.5 L of milk replacer (MR) twice daily; concentrate and straw were offered ad libitum. Mild (MD): calves were fed only MR (d -4 to -1) as described for CT, and on d -1 calves were subjected to a 9-h feed withdrawal. Moderate (MO): calves were fed only MR (d -4 to -1) as described for CT and on d -1 subjected to a 19-h feed withdrawal. Severe (SV): calves were fed only 2.5 L of a rehydrating solution twice daily (d -4 to -1) and on d -1 subjected to a 19-h feed withdrawal. From d 0 to d 42 (weaning) all calves were fed the same feeding program (MR, concentrate, and straw ad libitum). Results showed that BW was greater for the CT treatment compared with the others from d 0 to d 7, whereas BW of SV was lesser compared with the others from d -1 to d 7. No differences among treatments were observed at weaning. At d 2 concentrate intakes of MD, MO, and SV were lesser compared with CT. By d 4, concentrate intake of SV was similar to that for CT and greater than MD and MO. Similarly to BW, no differences in concentrate intake among treatments were observed at weaning on d 42 of the study. At d -1 for SV and d 0 in all restricted calves, serum glucose concentration was lesser compared with CT. At d -1 and 0, nonesterified fatty acids and BHB serum concentrations were greater in the SV calves compared with the other treatments. By d 2, serum concentrations of nonesterified fatty acids, BHB, and glucose were restored to CT levels. At d -1 serum citrulline concentration was lesser in SV and greater in MD calves. The CT calves had lower serum concentrations of Cr-EDTA (d -1 and d 0), lactulose (d 0), and d-mannitol (d 0) compared with the other restricted calves. Results showed that degree of dietary restriction, type of liquid diet (MR or rehydrating solution), and fasting hours (9 vs. 19 h) affected calves' BW, concentrate intake, and serum concentration of markers indicative of energy status and gastrointestinal permeability.

Navel Healing and Calf Fitness for Transport

Simple Summary

In the dairy industry, for male calves, the costing and balancing of animal welfare and farmers’ interests when determining the optimum age for a calf to leave the farm of origin is a challenge. In the European Union, calves whose navel has not “completely healed” cannot be transported. This study aimed to clarify what is meant by “navel healing”, as no specific definition is provided by the law, giving raise to different interpretations. The navels of 299 dairy calves (55 males, 244 females) aged 0–90 days were examined and scored. Our results show that a completely dry and shriveled navel stump entails a high risk of transporting too young calves, whilst the presence of a scab covering the umbilical wound could be considered acceptable for short journeys, as the risk of transporting calves that are too young is low. “Navel healing” should be defined as the scarring of the umbilical wound, which occurs no earlier than 3–4 weeks of life. Transporting calves with a completely healed navel should be considered best practice because it ensures that calves that are too young are not transported and therefore guarantees higher animal welfare standards.

Abstract

Dairy male calves are at risk of welfare compromise as they are usually transported at a very young age. The European Union has set a “completely healed navel” requirement for calf transport; moreover, a minimum age is established for longer journeys. However, this requirement has proven to be prone to misinterpretation. This study aimed to clarify what is meant by “navel healing” and to provide strong elements for reaching a consensus. The navels of 299 dairy calves (55 males, 244 females) aged 0–90 days were examined and scored 1 to 5 according to their healing status. Based on our results, a completely dry and shriveled navel (score 3) would imply a 25.5–38.0% risk of transporting too young calves. Alternatively, the presence of a scab covering the umbilical wound (score 4) would entail a 4.3% risk of transporting calves less than 10 days old and could be considered good practice for transporting calves (except for journeys exceeding 8 h). Conversely, complete navel healing (score 5) guarantees that calves that are too young are not transported; therefore, it should be considered best practice for transporting calves in general and the minimum requirement for transporting calves for journeys exceeding 8 h.

Characterizing the literature surrounding transportation of young dairy calves: A scoping review

Transportation is a stressful event for cattle, as it may involve various handling practices, commingling, deprivation of food and water, and fluctuating temperatures. Calves are particularly susceptible to these stressors because their physiological and immune systems are still developing. There has been no formal synthesis of the scientific literature evaluating the effect of transportation on young dairy calf health and performance; the aim of this scoping review is to describe and characterize this body of work. We targeted both descriptive and analytic studies examining transport of calves, including listing how the effect of transport has been evaluated. Eight databases were searched for relevant articles with eligible studies being primary research articles investigating transportation of calves of either sex who were younger than 60 d of age or weighed less than 100 kg. Two reviewers independently screened the title and abstracts of 6,859 articles with 361 potentially relevant articles screened at full text. Of these, 46 were relevant and had data extracted. Articles reporting study location were conducted in the United States (n = 5), Australia (n = 3), Japan (n = 3), and New Zealand (n = 3). Common transport-related variables evaluated included time in transit (n = 13), distance of transportation (n = 8), vehicle-related factors (n = 8), and age at time of transportation (n = 4). Outcome measures varied greatly, including blood parameters (n = 28), health assessments (n = 20), weight (n = 17), behavioral metrics (n = 14), mortality (n = 7), feed intake following transportation (n = 4), salivary cortisol concentrations (n = 3), morbidity (n = 3), and isolation of Salmonella Dublin in fecal samples (n = 2). Outcome parameters were measured during transport or ranged from immediately after to one year following transportation. As the transport-related risk factors and outcomes measured assessed varied widely between studies, future quantitative synthesis (e.g., meta-analysis) in this area may be limited. Several knowledge gaps were identified, including methods to prepare calves for transportation, such as improving nutrition, administering medication, or transporting calves at an older age or weight. Further research could also focus on consistent and clear reporting of key items related to study conduct and analysis, as well as the development of a core outcome set for calf transport studies.

Effects of stress after road transportation and oral administration of chromium and meloxicam on plasma cortisol concentrations and behavior in dairy calves

Objective

This study was performed to determine the effects of stress after road transportation and oral administration of chromium and meloxicam on growth performance, plasma cortisol, serum metabolites, and behavior in dairy calves.

Methods

A total of 50 Holstein heifers (average body weight [BW]: 172±4.19 kg; average age: 5.53±0.12 months) were randomly assigned to five groups including NL (not transported + D-lactose; 1 mg/kg BW), TL (transported + D-lactose; 1 mg/kg BW), TC (transported + chromium; 0.5 mg/kg dry matter [DM] feed), TM (transported + meloxicam; 1 mg/kg BW), and TMC (transported + combination of meloxicam and chromium; 1 mg/kg BW and 0.5 mg/kg DM, respectively). Doses of D-lactose monohydrate, meloxicam, and chromium were prepared for oral administration by suspension in 15 mL of water in a 20-mL dosing syringe. Blood was collected before transportation, immediately after 120 km of transportation (IAT), and at 6, 24, and 48 h after transportation.

Results

Neither transportation nor administration of meloxicam and/or chromium affected (p = 0.99) average daily gain and feed intake. Plasma cortisol concentrations in the NL group (average 0.13 and 0.18 nmol/L, respectively) were lower (p<0.001) compared to the TL group (average 0.39 and 0.61 nmol/L, respectively) at IAT and 48 h after transportation. At 48 h after transportation, cortisol concentrations were lower (p<0.05) in the TC group (average 0.22 nmol/L) than in the TL group (average 0.61 nmol/L), and TC calves had similar cortisol concentrations to NL calves. Lying duration (min/d) was shorter (p<0.05) in the TL group than in the NL group at 2 d after transportation. Lying duration was longer (p<0.05) for the TC and TMC groups than for the TL group at 2 d after transportation.

Conclusion

Transportation increased cortisol concentrations and affected lying behavior, while chromium administration reduced cortisol concentrations and changed lying behavior. Thus, chromium administration before transportation may be a viable strategy to alleviate stress elicited by road transportation.

Quality, proximate composition, and sensory characteristics of Dorper, domestic commercial crossbred, and Australian sheep meat: a comparative study

The objective of this study was to compare the proximate, quality, and sensory attributes of Dorper sheep meat (Dorper), domestic commercial crossbred (DCC) and Australian commercial crossbred (ACC). A total of 60 untrimmed loins from the three sheep sources were purchased (20 sheep loins/source) and processed. The objective color, objective tenderness [Warner–Bratzler Shear Force (WBSF)], and proximate composition of the sheep meat were evaluated. A consumer panel and a trained sensory panel were also conducted to evaluate the sensory attributes. Dorper had greater (P = 0.04) carbohydrate content compared to DCC, but was not (P = 0.86) different from ACC. In addition, Dorper had the greatest WBSF value, followed by DCC, with ACC having the least WBSF out of the three (P < 0.0001). For the consumer panel, Dorper was rated to be less tender than ACC (P = 0.01), but was not different from DCC (P = 0.76). Dorper was also rated with lower flavor acceptability compared to DCC (P = 0.02), but was not different from ACC (P = 0.86). In addition, Dorper had the lowest overall acceptance rating by the consumers (P = 0.01). Trained sensory panel results followed the same trend as the consumer panel results which rated Dorper to be less tender than ACC (P = 0.002), but was not different from DCC (P = 0.10). Dorper was also rated with greater off-flavor intensity compared to DCC (P = 0.009), but was not different from ACC (P = 0.53). Finally, no differences were found for all other attributes evaluated among the sheep sources. The results indicated that consumers did not prefer Dorper over ACC and DCC. However, additional research with a more controlled environment is needed to shed light on the true palatability traits of Dorper.

Effects of conditioning, source, and rest on indicators of stress in beef cattle transported by road

Consumers are increasingly concerned about the welfare of farm animals, especially during transportation. The Canadian transport regulations state that weaned cattle require an 8 h rest after 36 h of transport. There are, however, only a few studies that assess the effect of rest on the welfare of beef cattle. The aim of this study was to assess the effect of conditioning, source and rest on indicators of welfare in 7-8-month-old beef calves during long-distance transport. Treatments consisted of a 2 × 2 × 2 factorial design where the main factors were conditioning: conditioned (C; n = 160) or non-conditioned (N; n = 160); source: auction market (A; n = 160) or ranch direct (R; n = 160); and rest: 0 h (0 h; n = 160) or 8 h (8 h; n = 160). Means of non-esterified fatty acids (NEFA), serum amyloid-A, haptoglobin, creatine kinase (CK), and percentage of time standing from N calves were greater than C calves (all p ≤ 0.05). Means of percentage of time standing and CK of R calves were greater than A calves (both p ≤ 0.05). The mean of NEFA of 0 h calves was greater than the 8 h calves (p < 0.01), while the percentage of time standing of 0 h calves was less than 8 h calves (p < 0.01). Statistically significant differences between means of NEFA and standing percentage, were observed between 0 h and 8h calves. Few and inconsistent indicators of reduced welfare were observed between auction market and ranch direct calves, while non-conditioning was associated with greater physiological and behavioural indicators of reduced welfare. Based on these results, conditioning should be implemented as a management practice to improve the welfare of transported calves.

Arrival cortisol measurement in veal calves and its association with body weight, protein fractions, animal health and performance

Male dairy calves are exposed to an accumulation of transport, social and environmental stressors while transferred to fattening units. As a consequence, calves show high cortisol concentrations upon arrival at the veal facility. Whether cortisol levels as measured on arrival can be associated with animal health, welfare and production results is currently unknown. The first objective of this prospective cohort study was to determine possible associations of arrival serum cortisol concentration with health and production variables of veal calves and other arrival predictors like body weight and γ-globulin concentration. The second aim was to investigate potential clustering of arrival risk factors in veal calves for developing bovine respiratory disease (BRD) based on arrival body weight, serum cortisol concentration, total protein and protein fractions. In total, 105 male Holstein calves from two consecutive production cycles in a single, commercial white veal farm were blood sampled directly at arrival on the farm to determine serum cortisol, total protein and protein fractions. All calves were weighed the day after arrival and clinical signs, average daily weight gain (ADG) and carcass weight were collected. Also, all calves of both production cohorts were repeatedly examined by thoracic ultrasonography at the onset of group respiratory disease symptoms (2-3 weeks after arrival) and four weeks later. Linear and logistic mixed models together with k-means clustering were used for statistical analyses. Calves showed on average high, but individually variable serum cortisol concentrations (mean value = 96.6 ng/mL ± standard deviation (SD) = 48.8; Range (R) = 50.0-317 ng/mL). Arrival cortisol, body weight and γ-globulin content were not significantly associated. Serum cortisol and albumin concentrations at arrival were associated with chronic, unresponsive pneumonia. For each increase of serum cortisol concentration by 10 ng/mL, the odds for lung consolidation of ≥1 cm in depth at the second ultrasonography increased, odds ratio (OR) = 1.03 (95 % confidence interval (CI) = 1.01-1.06; P < 0.050). For every decrease in serum albumin concentration by 1g/L, the OR for developing pneumonia was 1.23 (95 % CI= 1.04-1.46; P < 0.015). Additionally, two clusters of calves were identified based upon arrival status: a low risk cluster with below average stress-induced cortisol values, above average body weight, no acute phase response (APR) and no failure of passive immune transfer (FPIT), and a high risk cluster with above average cortisol values, below average body weight, APR and FPIT. High risk calves had higher odds for developing clinical BRD (OR= 3.88 (95 % CI=1.20-12.53; P < 0.020)) and lung consolidation ≥1 cm in depth at week 6-7 after arrival (OR= 3.93 (95 % CI=1.34-11.53; P < 0.013)). Avoiding high cortisol levels upon arrival of calves is important for animal welfare, but also for reduction of the prevalence of chronic, unresponsive pneumonia and the associated need for (repeated) antimicrobial treatment and production losses.

Identification of biomarkers measured upon arrival associated with morbidity, mortality, and average daily gain in grain-fed veal calves

There is a strong need for management strategies that help reduce the incidence of disease and subsequent antimicrobial use in the veal industry. Biomarkers could serve as useful tools that allow producers to take preventative measures before clinical problems occur. The objective of this prospective cohort study was to identify biomarkers measured upon arrival associated with morbidity, mortality, and average daily gain (ADG) in grain-fed veal calves. Upon arrival at a grain-fed veal facility in Ontario, Canada, calves were weighed and health-scored using a standardized health-scoring system. Several metabolites were measured including creatine kinase (CK), cholesterol, haptoglobin, manganese, serum total protein, iron, cobalt, zinc, selenium, molybdenum, and IgG. Farm personnel treated calves according to their farm protocol and weighed them at 78 d after arrival. Performance, treatment, and mortality records from the facility were used for analysis. Multivariable Cox proportional hazard models were created to evaluate metabolic biomarkers associated with morbidity and mortality. A mixed linear regression model was created to determine biomarkers associated with ADG. A total of 992 male dairy calves were evaluated at arrival from January to December 2017. Of the calves evaluated, 74 calves (7.5%) died and 877 (88.4%) were treated for illness over the 11-wk period under observation. Higher levels of haptoglobin and molybdenum were associated with a greater hazard of morbidity, whereas higher weight upon arrival and higher levels of both CK and IgG were associated with a reduced hazard of morbidity. For mortality, higher weight upon arrival and higher levels of cholesterol and IgG were associated with a lower hazard of mortality occurring over the 78-d period of observation. Higher weight, cholesterol, copper, CK, iron, and IgG were associated with increased ADG, whereas increased zinc and haptoglobin were negatively associated with ADG. These results demonstrate that certain biomarkers could be used to identify high-risk calves when measured upon arrival at a veal facility. Future research should focus on determining the utility of these biomarkers to selectively target intervention strategies to improve ADG and reduce morbidity and mortality.

Strategies for Feeding Unweaned Dairy Beef Cattle to Improve Their Health

In order to answer the question of whether nutritional interventions may help to reduce the incidence of respiratory disease in dairy beef calves at arrival, the present review is divided in three sections. In the first section, the nutrition of calves previous to the arrival from the origin farm to the final rearing farm is reviewed. In the second section, the possible consequences of this previous nutrition on gut health and immune status upon arrival to the rearing farm are described. The main consequences of previous nutrition and management that these unweaned calves suffer at arrival are the negative energy balance, the increased intestinal permeability, the oxidative stress, the anemia, and the recovery feed consumption. Finally, in the third section, some considerations to advance in future nutritional strategies are suggested, which are focused on the prevention of the negative consequences of previous nutrition and the recovery of the gut and immune status. Moreover, additional suggestions are formulated that will be also helpful to reduce the incidence of bovine respiratory disease (BRD) that are not directly linked to nutrition like having a control golden standard in the studies or designing risk categories in order to classify calves as suitable or not to be transported.

Hot topic: Health and welfare challenges in the marketing of male dairy calves-Findings and consensus of an expert consultation

A diverse group of Canadian experts was convened for a focused 2-d discussion on potential health and welfare problems associated with the marketing (i.e., transportation and sale) of male dairy calves. Written notes and audio recording were used to summarize the information provided on transport times and marketing practices. Content analysis was used to develop a consensus statement on concerns, possible solutions, and recommendations to improve male dairy calf marketing. The group noted that calves across all Canadian regions are commonly transported at 3 to 7 d of age and undergo transport for 12 to 24 h or longer depending on the location of their dairy farm of origin. Calves in some regions are marketed almost exclusively through auction markets, whereas others have more direct sales. A need was identified for better criteria for calf fitness for transport, maintaining farm biosecurity, reducing the use of antimicrobial therapy in calf production, and improving education for farmers and veterinarians on the importance of neonatal care for male dairy calves before transportation. Experts noted that major changes in male dairy calf marketing will be required to comply with amendments to the federal Health of Animals Regulations (Part XII) on animal transportation; collaborative effort will be needed to safeguard animal health and welfare as this transition is made.

Assessing the utility of leukocyte differential cell counts for predicting morbidity, mortality, and growth in a grain-fed veal facility: A prospective single cohort study

Selective antimicrobial treatment strategies present a means to reduce antimicrobial use at the time of arrival at a veal or dairy beef operation. On-farm machine leukocyte differential cell counts (DCC) that can be acquired quickly may be useful to augment calf risk identification protocols. The objective of this study was to assess the utility of DCC taken at the time of arrival at a grain-fed veal facility and 72 h postarrival for determining morbidity risk, mortality risk, and growth during the production cycle. Data were collected between June and October 2018 from 240 calves upon arrival and from a subset of 160 calves 72 h postarrival at a commercial grain-fed veal facility in Ontario, Canada. Blood samples were evaluated using the QScout BLD test for leukocyte DCC (Advanced Animal Diagnostic, Morrisville, NC). All calves were screened using a standardized health examination, and a blood sample was collected to evaluate serum total protein and DCC. Cox proportional hazards models were constructed for both morbidity and mortality outcomes. Mixed linear regression models were constructed to evaluate average daily gain. Results from data collected at the time of arrival suggest that total protein values ≥5.2 g/dL reduced the hazard of mortality and that a rectal temperature >39.6°C was associated with an increased hazard of morbidity. Calves that were dehydrated gained less, whereas calves with an increased lymphocyte count had a higher rate of growth. Results from DCC collected 72 h postarrival suggest that lymphocyte counts between 4.8 and 5.8 × 10⁹ cells/L decreased the hazard of mortality and counts >7.0 × 10⁹ cells/L decreased the hazard of morbidity, whereas neutrophil counts >6.0 × 10⁹ cells/L increased the hazard of mortality. This study demonstrates that machine DCC at the time of arrival and 72 h after arrival has potential for use in identifying high-risk calves that might require treatment, as part of selective antimicrobial therapy protocols, with the purpose of reducing antimicrobial use without sacrificing animal health in veal facilities.

Effects of pretransport diet, transport duration, and type of vehicle on physiological status of young veal calves

This study aimed to investigate effects of pretransport diet (rearing milk vs. electrolytes), type of vehicle (open vs. conditioned truck), and transport duration (6 vs. 18 h) on physiological status of young calves upon arrival at the veal farm. A total of 368 calves were transported in 2 consecutive batches from a collection center to a veal farm. Blood samples were collected from calves before transport; immediately posttransport (T0); and 4, 24, and 48 h, and 1, 3, and 5 wk posttransport. Blood was analyzed for glucose, urea, lactate, nonesterified fatty acids (NEFA), β-hydroxybutyrate (BHB), creatine kinase, albumin, total protein, osmolality, calcium, sodium, magnesium, and hematological variables. Body weight, rectal temperature, and skin elasticity were determined before and immediately posttransport. Blood glucose, NEFA, and urea concentrations at T0 showed an interaction between pretransport diet and transport duration. Milk-fed and electrolyte-fed calves transported for 18 h did not significantly differ in plasma glucose concentration or serum NEFA concentrations. However, after 6 h of transport, milk-fed calves had higher plasma glucose and lower serum NEFA concentrations (4.71 mmol/L and 586.5 µmol/L, respectively) than electrolyte-fed calves (3.56 mmol/L and 916 µmol/L, respectively). After 18 h of transport, milk-fed calves had lower urea concentrations (5.40 mmol/L) than electrolyte-fed calves (7.38 mmol/L). In addition, at T0, after 6 h of transport, milk-fed calves gained weight (Δ = 0.41 kg), whereas electrolyte-fed calves lost weight (Δ = -0.16 kg). After 18 h of transport, both milk-fed and electrolyte-fed calves showed body weight losses (Δ = -0.67 and -0.74 kg, respectively). Type of vehicle had a limited influence on blood parameters. Concentrations of NEFA and BHB reached the maximum values at T0 and then decreased until wk 5 posttransport. The increase in NEFA and BHB concentrations between prior to and just posttransport (T0) was less pronounced in calves transported for 6 h (746.1 µmol/L and 0.38 mmol/L, respectively) than in calves transported for 18 h (850.6 µmol/L and 0.50 mmol/L). Overall, the recovery rate of calves at the veal farm seemed rapid; all blood parameters returned to (below) pretransport values within 48 h posttransport. We concluded that feeding milk before short-term transport helps young veal calves cope with transport, whereas this is not the case during long-term transport.

Evaluation of muscle tissue and liver glycogen of cattle submitted to transport over long distances and subjected to emergency slaughter

ABSTRACT The study evaluated the effect of transportation over long distances on cattle muscle tissue of submitted to emergency slaughter in slaughterhouses in northern Tocantins, Brazil. The evaluations consisted in pH, muscle and liver glycogen, muscle histopathology and creatine kinase (CK), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activity. Animals were placed into two groups: Experimental Group (EG), consisting of 19 bovines intended for immediate emergency slaughter, and Control Group (CG), composed of 24 bovines slaughtered in accordance with the normal flow. CK and ALT levels were high in EG. AST did not differ between groups. EG showed higher muscle pH and mean of degenerate fibers, mainly on the intercostal. However, muscle and liver glycogen did not differ between groups. In conclusion, cattle transported over long distances and subjected to immediate emergency slaughter showed markedly stress condition, with changes in biochemical parameters in the muscle tissue, determined by cellular degeneration.

Effects of transportation on cattle health and production: a review

The goal of this review is to present a concise and critical assessment of the literature related to physiologic responses in cattle that are subjected to transportation. Over two-thirds of US cattle are transported. Understanding trends in circulating physiologic parameters is an important part of mitigating the negative effects of transportation. For the producer, linking these effects after transportation to morbidity outcomes within the first 45 days on feed (i.e. especially development of bovine respiratory disease) is critical. Physiologic parameters in circulation are of primary importance and may have value for prediction of bovine respiratory disease on arrival and for the understanding of disease pathogenesis. The results of our literature survey indicated that post-transportation immune function, increased acute phase proteins, glucocorticoids, and inflammation are a pivotal starting point for understanding disease. These potential biomarkers may have utility in identifying disease for targeted therapeutics so that traditional protocols that rely heavily on metaphylaxis can be avoided. Additional research is needed to develop strategies for physiological marker identification, treatment methods, or predictive behaviors to prevent respiratory disease before and after transport. This review examines the significant deleterious effects of transportation handling and stress, and current immune system translation and non-antimicrobial mitigation strategies.

Hemato-biochemical profile of meat cattle submitted to different types of pre-loading handling and transport times

Pre-loading handling and conditions of transport are related to welfare, disease risk and product quality of production animals. These steps continue to be one of the major animal management problems in Brazil. This study evaluated the effects of different types of pre-loading handling and road transport times on the haematological and biochemical traits of cattle. Eighteen male cattle were submitted to three travel times (24, 48 and 72 h) in a truck soon after load using different types of pre-loading handling: traditional (rough handling), training (gentle handling) and use of flags to movement cattle. Haematological traits, blood biochemical measures as well as blood and faecal cortisol were analysed in order to assess animal welfare and physiological status. The traditional management showed to be more stressful, also had animals with a greater number of neutrophils and lower numbers of lymphocytes than handling with flags, showing that animals submitted to more stressful situations can have compromised immune system. Serum aspartate aminotransferase concentrations were within the reference levels and when taken together with increased creatine kinase patterns observed indicate muscle damage in traditional management. Decrease in glucose concentrations over time from traditional management to flag management was observed, while fructosamine was increased in traditional management with 72 h of travel. When taken together, all reported factors, immune, enzymatic, energetic and hormonal, indicate that the quality of pre-loading handling and time of transport were determinant for animal welfare, its homeostatic balance and sanitary conditions.

Effects of transport stress on physiological responses and milk production in lactating dairy cows

Objective

This study was conducted to investigate the effect of transport stress on physiological and hematological responses and milk performance in lactating dairy cows.

Methods

Ten lactating dairy cows were randomly divided into 2 groups. The treatment group (TG) was transported 200 km for 4 h by truck, and the control group (NTG) was restrained by stanchion for 4 h in Konkuk University farm. Blood and milk samples were collected at 24 h pre-transport; 1, 2, and 4 h during transport; and 2, 24, and 48 h post-transport. Milk yields were measured at 24 h pre-transport, 0 h during transport, and 24, 48, and 72 h post-transport.

Results

Leukocyte, neutrophil, and monocyte numbers in the TG were significantly higher than those of the NTG at each experimental time point. Lymphocyte numbers in the TG were significantly (p<0.05) higher than those of the NTG at 48 h post-transport. Additionally, the neutrophil:lymphocyte ratio of the TG was 45% and 46% higher than that of the NTG at 4 h during transport and 2 h post-transport, respectively. There were no significant differences in erythrocyte numbers, hemoglobin concentrations, platelet numbers, and hematocrit percentages between two groups. Cortisol levels in the TG were significantly (p<0.05) higher than those in the NTG. Milk yields in the TG were lower than those in the NTG. The somatic cell count (SCC) of the TG was significantly (p<0.05) higher than that of the NTG at 1 and 2 h during transport; that of the TG increased dramatically at 1 h during transport and gradually decreased subsequently.

Conclusion

Transport stress increased blood parameters including leucocyte, neutrophil, and monocyte numbers by increased cortisol levels, but did not affect erythrocytes, hemoglobin and hematocrit levels. Additionally, transport resulted in a decrease in milk yield and reduced milk quality owing to an increase in milk SCC.

Evaluating Potential Biomarkers of Health and Performance in Veal Calves

Veal calves undergo many challenges in the early stages of their life. Such challenges, including mixing procedures and transportation of calves to the veal farm, may have a negative influence on growth rate, feed intake, metabolism, immunity and disease susceptibility of calves. As a consequence, many hematological, physiological, metabolic and immunological parameters of stressed calves might be altered on arrival at the veal farm. Some of these response variables might be useful as biomarkers of performance of calves at the veal farm as they might provide information about an ongoing disease process, or may predict future diseases. Biomarkers might be helpful to group and manage calves in different risk categories after arrival. By adopting treatment decisions and protocols on a risk-group or individual basis, it would be possible to improve animal health and reduce both disease incidence and antibiotic use. Moreover, the use of biomarkers might be an economically feasible approach as some of them do not need invasive techniques and others can be measured in blood already taken during routine checks. Previous literature mainly assessed the physiological responses of calves to transportation. However, information on the link between on-farm arrival data and future health and performance of veal calves is limited. This review, therefore, examined a wide range of papers and aimed to identify potential biomarkers of future health and performance.

Effects of road transportation on metabolic and immunological responses in Holstein heifers

This study examined the effects of road transportation on metabolic and immunological responses in dairy heifers. Twenty Holstein heifers in early pregnancy were divided into non-transported (NT; n = 7) and transported (T; n = 13) groups. Blood was collected before transportation (BT), immediately after transportation for 100 km (T1) and 200 km (T2), and 24 h after transportation (AT). The T heifers had higher (P < 0.05) blood cortisol and non-esterified fatty acid concentrations after T1 and T2 than did NT heifers. By contrast, the T heifers had lower (P < 0.05) serum triglyceride concentrations after T1 and T2 than had the NT heifers. The serum cortisol and triglyceride concentrations returned (P > 0.05) to the BT concentrations at 24 h AT in the T heifers. The granulocyte-to-lymphocyte ratio and the percentage of monocytes were higher (P < 0.05) after T2 in the T heifers than in the NT heifers, suggesting that transportation stress increased the numbers of innate immune cells. T heifers had higher (P < 0.01) plasma haptoglobin concentrations than NT heifers 24 h AT. In conclusion, transportation increased cortisol secretion and was correlated with increased metabolic responses and up-regulation of peripheral innate immune cells in dairy heifers.

Relationship between cortisol and acute phase protein concentrations in female rabbits

Rabbit meat production in Europe is usually based on a semi-intensive system, in which lactation and gestation overlap. The demands of lactation and pregnancy are likely to be relatively stressful for female rabbits and may compromise the immune system and reproductive performance. The present study was designed to characterise circulating levels of cortisol, haptoglobin (Hp), C-reactive protein (CRP), and serum amyloid A (SAA) in non-lactating and lactating female rabbits at first and second mating, and to determine whether any relationship exists between these biomarkers and litter size. Serum cortisol concentrations were at their greatest (mean ± SEM = 39.5 ± 3.9 nmol/L) in animals at the end of lactation. However, after weaning, cortisol concentrations were not significantly different compared to nulliparous females (19.9 ± 3.6 vs. 16.3 ± 2.2 nmol/L, respectively). The highest concentrations of circulating Hp (0.14 ± 0.01 g/L) were seen in early lactating primiparous females, and lower in nulliparous females and in rabbits after weaning. In contrast, nulliparous female rabbits showed the highest plasma CRP values (13.1 ± 1.1 mg/L). No significant differences were found for SAA. Nulliparous females had smaller litter sizes than early lactating and non-lactating primiparous female rabbits. CRP and SAA showed a positive correlation (r = +0.24, P = 0.011) and were negatively related to litter size (r = -0.23, P = 0.017 and P = 0.032, respectively). Cortisol and Hp were not related to CRP, SAA, nor to litter size. These results suggest a closer association between the mechanisms that regulate release of CRP and SAA, compared to those that regulate Hp production. Thus, lactation is associated with changes in several stress biomarkers. CRP and SAA might be more useful for evaluating animal welfare and for predicting subsequent reproductive performance of female rabbits.

Effect of lairage time ( 0h, 3 h, 6 h or 12 h) on glycogen content and meat quality parameters in suckling lambs

The effect of slaughter at arrival (L0) or after 3 (L3), 6 (L6), 12 (L12) h of lairage on carcass and meat quality of suckling lambs has been studied. Lairage time had a slight effect on carcass quality traits, but most of the meat quality parameters at 24h post mortem were affected. Weight losses increased and glycogen content of liver and longissimus muscle decreased as lairage time increased. Longissimus muscle from L3 lambs had the highest pH, shear force and toughness and the lowest b* and C* values, at 24h post mortem. L3 and L6 had the higher proportion of expelled juice, or low water holding capacity (WHC), at 24h post mortem. Texture parameters and WHC were similar among groups after 5 days of storage. Despite the fact that the effects of lairage time on meat quality disappears after storage, from the point of view of weight losses the slaughter of suckling lambs at arrival is recommended.

Effect of induced ruminal acidosis on blood variables in heifers

BACKGROUND

Ruminal acidosis is responsible for the onset of different pathologies in dairy and feedlot cattle, but there are major difficulties in the diagnosis. This study modelled the data obtained from various blood variables to identify those that could indicate the severity of ruminal acidosis. Six heifers were fed three experimental rations throughout three periods. The diets were characterised by different starch levels: high starch (HS), medium starch (MS) and low starch, as the control diet (CT). Ruminal pH values were continuously measured using wireless sensors and compared with pH measurements obtained by rumenocentesis. Blood samples were analysed for complete blood count, biochemical profile, venous blood gas, blood lipopolysaccharide (LPS) and LPS-binding proteins (LBP).

RESULTS

The regression coefficient comparing the ruminal pH values, obtained using the two methods, was 0.56 (P = 0.040). Feeding the CT, MS and HS led to differences in the time spent below the 5.8, 5.5 and 5.0 pH thresholds and in several variables, including dry matter intake (7.7 vs. 6.9 vs. 5.1 kg/d; P = 0.002), ruminal nadir pH (5.69 vs. 5.47 vs. 5.44; P = 0.042), mean ruminal pH (6.50 vs. 6.34 vs. 6.31; P = 0.012), haemoglobin level (11.1 vs. 10.9 vs. 11.4 g/dL; P = 0.010), platelet count (506 vs. 481 vs. 601; P = 0.008), HCO3(-) (31.8 vs. 31.3 vs. 30.6 mmol/L; P = 0.071) and LBP (5.9 vs. 9.5 vs. 10.5 μg/mL; P < 0.001). A canonical discriminant analysis (CDA) was used to classify the animals into four ruminal pH classes (normal, risk of acidosis, subacute ruminal acidosis and acute ruminal acidosis) using haemoglobin, mean platelet volume, β-hydroxybutyrate, glucose and reduced haemoglobin.

CONCLUSIONS

Although additional studies are necessary to confirm the reliability of these discriminant functions, the use of plasma variables in a multifactorial model appeared to be useful for the evaluation of ruminal acidosis severity.