Automatic weaning based on individual solid feed intake: Effects on behavior and performance of dairy calves

Graduate Student Literature Review: Social and feeding behavior of group-housed dairy calves in automated milk feeding systems

Automated milk feeders (AMF) allow farmers to raise calves in groups while generating individual records on milk consumption, drinking speed, and frequency of visits. Calves raised in groups benefit from social interaction, which facilitates learning and adapting to novelty. However, calves in large groups (>12 calves/feeder) experience a higher risk of disease transmission and competition than those housed individually or in smaller groups. Therefore, if group size, grouping strategy, and disease detection are not optimal, the health and performance of calves can be compromised. The objectives of this narrative literature review, from publications available as of February 2023, are to (1) describe the use of AMF in group housing systems for calves and the associated feeding behavior variables they automatically collect, (2) linking feeding behavior collected from AMF to disease risk in calves, (3) describe research on social behavior in AMF systems, and (4) introduce social networks as a promising tool for the study of social behavior and disease transmission in group-housed AMF-fed calves. Existing research suggests that feeding behavior measures from AMF can assist in detecting bovine respiratory disease and enteric disease, which are common causes of morbidity and mortality for preweaning dairy heifers. Automated milk feeder records show reduced milk intake, drinking speed, or frequency of visits when calves are sick. However, discrepancies exist among published research about the sensitivity of feeding behavior measures as indicators of sickness, likely due to differences in feeding plans and disease-detection protocols. Therefore, considering the influence of milk allowance, group density, and individual variation on the analysis of AMF data is essential to derive meaningful information used to inform management decisions. Research using dynamic social networks derived from precision data show potential for the use of social network analysis to understand disease transmission and the effect of disease on social behavior of group-housed calves.

Association of morbidity, mortality, and average daily gain with transfer of passive immunity in dairy-beef crossbred calves up to 60 d of life

Adequate transfer of passive immunity (TPI) is a cornerstone for a proper health status of calves. In the literature, there is limited information on the prevalence of failure of TPI in dairy-beef crossbred calves and its impact on morbidity, mortality, and average daily gain (ADG) during the preweaning period. Therefore, this study aimed to evaluate the association between TPI with morbidity, mortality, and ADG in pre-weaned dairy-beef crossbred calves. A total of 1,055 newborn dairy-beef crossbred calves were enrolled upon arrival at a calf-raising facility in California from January to August 2021. Farm of origin, genetic breed group, sex, and body weight were recorded upon arrival. Blood was collected at 24 ± 1 h post-arrival to evaluate serum IgG concentration, serum total protein (TP), and packed cell volume. Morbidity (diarrhea and respiratory treatment records) and mortality were recorded daily until 60 d of life. Calves were grouped into 2 genetic breed groups: Holstein x Beef (Ho x Be, 49.6%) and Jersey × Beef crossbred calves (Je × Be, 50.4%). Descriptive statistics and Cox proportional hazard models were created to evaluate the association of TPI categories for serum IgG (TPI-IgG: poor: < 10.0 g/L, fair: 10.0 - 17.9 g/L, good: 18.0 - 24.9 g/L, and excellent: ≥ 25.0 g/L) and TP (TPI-TP: poor: < 5.1 g/dL, fair: 5.1 - 5.7 g/dL, good: 5.8 - 6.1 g/dL, and excellent: ≥ 6.2 g/dL), sex, and genetic breed group with morbidity and mortality. Additionally, a mixed linear regression was performed to evaluate the association of sex, genetic breed group, and TPI categories with ADG. Overall morbidity and mortality were 84.8% (n = 895) and 2.5% (n = 26). Calves classified as TPI-IgG excellent were associated with the lowest (43.2% less) hazard of being treated compared with TPI-IgG poor calves. For mortality, dairy-beef crossbred calves with TPI-IgG excellent were associated with a reduction of 82.0% in the hazard of dying compared with TPI-IgG poor. The TPI-IgG poor and TPI-IgG fair calves were associated with a decreased ADG of 101.0 and 98.8 g/d, respectively, in comparison with TPI-IgG good calves. Average daily gain of TPI-IgG good and TPI-IgG excellent calves were not different. In our study, dairy-beef crossbred calves enrolled may have endured challenging conditions that increased morbidity. This reinforces the importance of high IgG levels to decrease morbidity and mortality and maximize ADG in dairy-beef crossbred calves raising systems. Further research should evaluate the long-term effects of TPI categories on the health and performance of dairy-beef crossbred calves.

Individuality of calves: Linking personality traits to feeding and activity daily patterns measured by precision livestock technology

Animal personality has established connections with animal performance, resilience, and welfare which are related to stable behavioral patterns. Precision livestock technologies introduce the opportunity to measure these behavior patterns automatically and noninvasively. Thus, the primary aim of this study was to determine if personality traits in dairy calves measured via standardized personality assessments were associated with activity measured via a commercially available accelerometer. Secondary aims of this study were to investigate if personality traits were associated with feeding behaviors measured via an automatic feeding system (AFS) and with average daily gain (ADG). We characterized personality traits of Holstein calves (n = 49) utilizing standardized personality (novel environment, novel person, novel object, and startle) tests. Behaviors from these tests were summarized and 3 factors were extracted from a principal component analysis to represent calf personality traits: fearful, active, and explorative. Factor scores were regressed against behaviors from the accelerometer and AFS and with ADG. We found that calves that were more active were associated with taking more steps in the home environment, consuming more calf starter, and with reaching the benchmark of 1 kg of starter consumed in a day at a younger age. The trait active was also associated with greater ADG throughout the study. In addition, calves that were more explorative in the personality tests were associated with less starter consumed and lower ADG specifically during the weaning period. The findings of this research contribute to the existing literature by further establishing the links between personality traits and the daily behavioral patterns and performance of young calves. This study suggests the potential for using precision technology to assess and characterize personality traits, thereby enhancing their practical applicability on farms. Future research should focus on evaluating how personality traits, as measured through standardized assessments and precision technologies, correlate with deviations in behavior observed in dairy calves during stressors.

Invited review: The effect of weaning practices on dairy calf performance, behavior, and health - a systematic review

The aim of this systematic review was to summarize the literature assessing the effects of weaning practices on performance, behavior, and health of dairy calves. Only published, peer-reviewed articles written in English and specifically assessing the effects of weaning treatments on dairy calves were eligible for inclusion. Studies had to include 2 or more treatment groups that addressed at least one of 4 interventions: weaning age (i.e., when milk was fully removed), weaning duration (i.e., number of days from start of milk reduction to when milk was fully removed), weaning criteria (e.g., age vs. intake), or alternative weaning methods (e.g., water dilution). Outcome measures could include starter intake, growth (body weight or average daily gain), behaviors (5 specific sucking behaviors; play behavior; lying behavior; vocalizations; unrewarded visits to an automated milk feeder), and health (mortality rate, diarrhea, and respiratory illness). We conducted 3 targeted searches using Web of Science and PubMed. The articles underwent a 2-step screening process, resulting in a final sample of 44 studies. The majority of studies investigated weaning age (n = 22), followed by weaning duration (n = 13), weaning criteria (n = 9), and other weaning methods such as dilution, linear vs. step-down milk reduction, or meal-based approaches (n = 6). There was consensus for positive effects (or at least no negative effects) on overall growth of calves weaned at later ages, over longer durations, based on starter intake, or weaned using step-down or meal-based milk removal approaches. This is despite reduced starter intake in calves weaned at later ages; most studies found improved starter intake in calves weaned over longer durations. Weaning based on starter intake had superior growth and feed intakes compared with calves weaned at a fixed earlier age. Few studies assessed interactive effects of weaning method and milk allowance. However, weaning after 8 wk appears to support superior weight gain, provided pre-weaning milk allowances are adequate (above 6 L/d). Weaning can lead to hunger-related behaviors and reduced welfare, yet only half of the studies assessed the effects of weaning method on calf behavior. Weaning at later ages can reduce signs of hunger (based on unrewarded visits to the milk feeder), but it is unclear if weaning over longer durations or weaning by starter intake reduces or prolongs hunger. There was little consensus among the few studies that measured oral behaviors of calves. Positive welfare indicators, such as play behavior, were rarely measured, yet are crucial to understanding the emotional states of calves during this potentially stressful diet transition. Health was rarely the primary objective of the study, with low sample sizes to conduct statistical comparisons. Overall, there remains significant knowledge gaps in our understanding of how best to wean calves. A successful weaning program must minimize signs of hunger while promoting high growth and feed intakes, so we encourage future work to include behavioral indicators of hunger and positive welfare to evaluate how weaning methods are experienced by the calf.

Welfare implications on management strategies for rearing dairy calves: A systematic review. Part 1-feeding management

Introduction

Calves are very susceptible to stress in the early stages of life, and it is necessary to ensure maximum welfare. Feeding management has been identified as a major risk factor for calf health and welfare at this stage. However, the management protocol for calf rearing and its impact on animal welfare is unclear. A systematic review of different management strategies for rearing dairy calves according to the three spheres of animal welfare was conducted using an electronic search strategy. In this review, management strategies were studied to identify scientific gaps, to know the welfare problems of these animals in order to prioritize actions and future research and to study the interpretive approach of this management from the three welfare spheres.

Methods

A protocol was used to analyze and extract information from the studies. Of the 1,783 publications screened, only 351 met the inclusion criteria for the management or welfare of calves' items.

Results

The publications identified in the search can be divided into two main groups feeding and socialization, based on the main topic of the publication. The main topics that emerged from the search in the feeding management group were milk replacer, colostrum, and weaning, divided into the three main areas of biological functioning and health, natural life and affective states or cognitive judgement.

Discussion

The main issues to be addressed were the different types of feed consumed by animals from birth to weaning and the weaning management. It has been found that the most researched issues are colostrum and solid starter feed management. Unresolved issues were highlighted, such as the lack of a clear protocol for the administration of milk replacers to reduce hunger and the best management of weaning to reduce stress.

Effects of intake-based weaning and forage type on feeding behavior and growth of dairy calves fed by automated feeders

The objective of this study was to assess the effects of intake-based weaning methods and forage type on feeding behavior and growth of dairy calves. Holstein dairy calves (n = 108), housed in 12 groups of 9, were randomly assigned to 1 of 3 weaning treatments: milk reduction based on age (wean-by-age), individual dry matter intake (DMI; wean-by-intake), or a combination of individual DMI and age (wean-by-combination). Groups of calves were alternately assigned to 1 of 2 forage treatments: grass hay or a silage-based total mix ration (TMR; n = 6 groups per treatment). Until 30 d of age, all calves were offered 12 L/d of whole milk. Starting on d 31, milk was gradually reduced by 25% of the individual's average milk intake. For wean-by-age calves (n = 31), the milk allowance remained stable until d 62 when milk was again reduced gradually until weaning at d 70. For wean-by-intake calves (n = 35), milk allowance was reduced by a further 25% once calves consumed on average 200, 600, and (finally) 1,150 g of dry matter (DM) per day of calf starter and forage. For wean-by-combination calves (n = 35), milk intake remained stable until calves consumed on average 200 g of DM/d, at which point milk was reduced linearly until weaning at d 70. If calves failed to reach DMI targets by d 62 (n = 10), milk was then reduced gradually until weaning at d 70. Of the 35 wean-by-intake calves, 27 met all 3 DMI targets (successful-intake), and 33 of the 35 calves in the wean-by-combination treatment met the 200 g of DM/d target (successful-combination). Successful-intake and successful-combination calves had greater final body weight (BW) at 12 wk of age than wean-by-age calves (123.7 vs. 122.3 vs. 117.7 ± 3.1 kg, respectively). During weaning, successful-intake calves ate more starter and consumed less milk than successful-combination and wean-by-age calves (starter: 1.19 vs. 0.89 vs. 0.49 ± 0.07 kg of DM/d, respectively; milk: 2.7 vs. 4.2 vs. 5.9 ± 0.17 L/d, respectively). After weaning, successful-combination and successful-intake calves consumed similar amounts of starter; however, wean-by-age calves continued to consume less starter (2.85 vs. 2.78 vs. 2.44 ± 0.10 kg of DM/d, respectively). During weaning, hay and TMR calves ate similar amounts of forage, but hay calves consumed more starter (0.96 vs. 0.75 ± 0.07 kg of DM/d, respectively). After weaning, hay calves continued to consume more starter (2.88 vs. 2.50 ± 0.10 kg of DM/d, respectively), whereas TMR calves consumed more forage (0.33 vs. 0.15 ± 0.02 kg of DM/d, respectively). Hay calves had greater final BW at 84 d compared with TMR calves (124.0 vs. 119.0 ± 1.6 kg, respectively). These results show that the inclusion of a DMI target can improve starter intake and BW for calves that successfully wean, and that forage type can influence the transition onto solid feed. We also found that approximately 10% of calves failed to consume even 200 g of DM/d by 9 wk of age; more research is needed to better understand why some calves struggle to transition onto solid feed.

Effects of Weaning Age on Plasma Biomarkers and Growth Performance in Simmental Calves

Weaning plays a key role in health status and future performance of calves. The aim of this study was to investigate the effects of weaning age (Wa), early (45 d, EW) or conventional (60 d, CW), on growth performance and metabolic profile of ten Simmental calves (5 EW and 5 CW calves). Daily intake of milk and calf starter was recorded. Blood samples and measurements of body weight (BW), heart girth (HG), and wither height (WH) were collected at −25, −15, 0, 6, and 20 days relative to weaning. Growth performances (BW, HG, WH) were affected by Wa, resulting lower in EW calves compared with CW calves (p < 0.05). Average daily gain was affected by overall Wa and Time but also by the interaction Wa × Time (p < 0.05). EW calves had lower paraoxonase and higher oxidation protein products levels, lower glucose levels in the post-weaning period, lower Ca and cholesterol levels at 20 d after weaning, and higher GGT activity at −25 d from weaning (p < 0.05). A significant interaction effect between Wa and Time was reached for glucose, Ca, cholesterol. In conclusion, weaning Simmental calves at approximately six weeks of age might not affect inflammatory status and liver functionality after weaning. As secondary outcome, even though the low number of animals could represent a limitation, the average daily gain obtained by Simmental calves weaned at 45 d supported this strategy (despite the lower body weight at weaning and after was due only to the age difference of 15 days). Hence, in order to reduce rearing costs, early weaning for Simmental calves (dual-purpose breed, milk and beef) might not jeopardize calf development, as long as calves can reach body gains as reported in the present study.

Early life indicators of first lactation milk yield and the effect of treatment for bovine respiratory disease on survivability and risk of pregnancy in Holstein dairy cattle

The primary objective of this study was to evaluate the long-term effects of variables that could be measured early in life events on first lactation milk production. The secondary objective was to evaluate the long-term effects of treatment for bovine respiratory disease (BRD) within the first 120 days of life on survivability to 850 days and reproductive success. Data from Holstein heifer calves was collected from 1 October, 2015 to 31 January, 2020 and included milk consumption (MC; n=10,431), bodyweight (BW; n=9,825), average daily gain (ADG; n=6,194), heifer conception age (n=10,112), and 305 day first lactation milk production (305M; n=5,823), and treatment records for BRD (n=12,485). Calves were fed pasteurized whole milk through an automated calf feeding system for 60 days (range, 48 - 126 days), with a 30% crude protein (CP) and 5% crude fat enhancer added at 20g/L milk. Calves were weighed at birth, weaning, and several other times prior to 2 years of age. Daily BW were predicted for individual animals using a third order orthogonal polynomial to model individual BW regressions. Daily BW predictions were used to calculate ADG and BW predictions on specific days of interest. Season born, ADG (0-400 days), milk production potential, and heifer conception age had a significant impact on 305-day first lactation milk production (all P≤0.05; r² = 0.31). A retrospective cohort study was conducted utilizing data collected from a commercial farm with cohorts defined by BRD status. Calves treated for BRD from 61 to 120 days old had a significantly lower chance of survival to 850 days of age than animals not treated for BRD. Additionally, calves for BRD from 61 to 120 days old had reduced risk of pregnancy. The results show the impact of early life on future milk production, survivability, and pregnancy risk on a commercial dairy herd.

Feeding behavior and activity levels are associated with recovery status in dairy calves treated with antimicrobials for Bovine Respiratory Disease

Calves with Bovine Respiratory Disease (BRD) have different feeding behavior and activity levels prior to BRD diagnosis when compared to healthy calves, but it is unknown if calves who relapse from their initial BRD diagnosis are behaviorally different from calves who recover. Using precision technologies, we aimed to identify associations of feeding behavior and activity with recovery status in dairy calves (recovered or relapsed) over the 10 days after first antimicrobial treatment for BRD. Dairy calves were health scored daily for a BRD bout (using a standard respiratory scoring system and lung ultrasonography) and received antimicrobial therapy (enrofloxacin) on day 0 of initial BRD diagnosis; 10–14 days later, recovery status was scored as either recovered or relapsed (n = 19 each). Feeding behaviors and activity were monitored using automated feeders and pedometers. Over the 10 days post-treatment, recovered calves showed improvements in starter intake and were generally more active, while relapsed calves showed sickness behaviors, including depressed feed intake, and longer lying times. These results suggest there is a new potential for precision technology devices on farms in evaluating recovery status of dairy calves that are recently treated for BRD; there is opportunity to automatically identify relapsing calves before re-emergence of clinical disease.

Effects of Milk Feeding Strategy and Acidification on Growth Performance, Metabolic Traits, Oxidative Stress, and Health of Holstein Calves

Effects of milk feeding strategy and acidification on calf growth, metabolic traits, oxidative stress, and health were evaluated in the first 78 days of life. Holstein calves (N = 48; 12 calves/treatment) were assigned to 1 of the 4 treatments in a 2 × 2 factorial arrangement of milk feeding strategy [6 L/d (MOD) or 12 L/d (HIGH) of milk] and acidification [non-acidified milk (NAM) or acidified milk (ACM)] on day 2. Calves were bucket-fed milk as follows: 6 L/d from days 2 to 49 for MOD and 6 L/d from days 2 to 49, 12 L/d from days 7 to 42, and 8 L/d from days 43 to 49 for HIGH calves. All calves were then fed 4 L/d from days 50 to 56. Starter and water were available ad libitum, while hay was fed at 5% of starter from day 64. Calves were weighed, measured, and blood (except days 14, 42 and 56) sampled on days 2, 14, 28, 42, 49, 56, 63 and 78. Data were analyzed using Mixed PROC of SAS with time as repeated measurements. Fecal scores, checked daily, were examined by the logistic regression using a binomial distribution in GLIMMIX procedure. There were no three-way interactions observed for all the parameters. We detected a milk feeding strategy × time interaction for starter intake, body weight, ADG, ADG/ME, FE, structural measurements, and glucose. Although, overall (558.0 vs. 638.6 g/d), HIGH calves tended to consume less starter compared to MOD, significant differences were only observed in week 8. The HIGH calves had greater ADG during days 2–14 (1.12 vs. 0.75 kg/d) and tended to have greater ADG on days 15–28 (0.79 vs. 0.55) and 29–42 (0.86 vs. 0.60) and lower on days 57–63 (0.11 vs. 0.38) compared to MOD calves. The HIGH calves had greater BW from days 28 to 78 compared to MOD, while NAM were bigger compared to ACM calves from days 49 to 78. The HIGH calves had lower overall feed and metabolizable energy efficiencies compared to MOD. Except for BW and heart girth, no milk acidification × time interaction was observed for starter intake, ADG, FE, or ADG/ME. Blood glucose in calves fed NAM-HIGH and ACM-HIGH were greater compared to those fed moderate milk volumes on day 28 only. Albeit, feeding strategy had no effect, calves fed ACM had lower likelihood of experiencing diarrhea (odds ratio = 1.32; 95% confidence interval: 1.018–1.698) compared to those fed NAM. Overall milk feeding strategy had no effect on growth, while milk acidification reduced growth in calves, despite lowering the likelihood of experiencing diarrhea.

The influence of personality and weaning method on early feeding behavior and growth of Norwegian Red calves

Some research has described a relationship between personality and feeding behavior at weaning in Holstein dairy calves; our objective was to determine if personality traits, especially sociability, are associated with differences in feeding behavior and growth in Norwegian Red calves. Our secondary objective was to assess the interaction between personality traits and gradual weaning method (by age or by concentrate intake) on the behavior and growth of calves. Twenty-seven Norwegian Red calves were housed in 7 groups of 3 to 5 calves, with group composition based on birthdate to ensure that there were no more than 21 d between the youngest and oldest calves. Calves had access to an automated milk and concentrate feeder with ad libitum access to concentrates, water, hay, and silage. Calves were semi-randomly assigned to be either gradually weaned by age at d 56, or weaned by intake, where weaning was initiated based on reaching specific concentrate intake targets. We measured milk intake, concentrate intake, and the number of unrewarded visits to the automated feeder during each of 5 experimental periods: preweaning (12 L/d; 10-30 d of age), weaning (milk allowance gradually reduced by method until completely weaned), weaning week (3 d before weaning and the first 7 d of 0 L/d milk allowance), postweaning (20 d after complete milk removal), and the total experimental period (10-20 d postweaning). At 21 and 80 d of age, individual behavioral responses toward novelty and isolation (indicative of personality) were recorded in 3 personality tests: novel environment, novel object, and a social motivation test (time taken to return the group). At 83 d of age, a group novel object test was conducted. Principal component analysis revealed 3 factors interpreted as personality traits (playful/exploratory, vocal/active, interactive in group test) that together explained 56% of the variance. Calves that were more playful/exploratory consumed more milk per day preweaning and more concentrate per day over the experimental period. Calves that were more vocal/active (interpreted as a type of sociability trait where vocalizations and pacing serve to communicate with conspecifics when isolated from herd) had lower preweaning milk intakes and lower concentrate intakes over the experimental period. Calves that were more interactive in the group test (interpreted as a type of sociability trait when with other herd mates) had lower preweaning and weaning concentrate intakes. There was no interaction between personality traits and weaning method on feeding behavior or performance outcomes; however, calves that were weaned by intake (successfully reached all concentrate targets) had higher average daily gains postweaning, likely due to consuming more concentrate per day over the entire experiment, than calves who failed to reach all targets, or were weaned by age. We concluded that the sociability traits of Norwegian Red calves were related to individual differences in milk and concentrate intake. Although the relationship between personality and feeding behavior and growth did not depend on weaning method, gradual weaning based on individual concentrate intakes provides an opportunity for calves to wean at a pace that fits the needs of each individual calf.

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.

Preweaning dairy calves' preferences for outdoor access

Adult dairy cattle show a preference for outdoor spaces during summer nights, but little is known about such preferences for dairy calves. Our aim was to determine the preferences of dairy calves for outdoor access during their first 11 wk of age in summer conditions. Calves were paired (n = 10) at 7 d of age and placed in one of 10 pens (7.32 × 2.44 m, deep bedded with bark mulch), each with equally sized outdoor and indoor areas. All feed was provided indoors; calves had ad libitum access to water, hay and concentrate. During the preweaning period, from 5 to 29 d of age, calves were offered 12 L/d of milk divided into 2 feedings. Calves were weaned stepwise, with milk gradually reduced by 1 L/d from d 30 to 35 of age. Calves were fed 6 L/d from 35 to 51 d of age, then milk was again reduced by 1 L/d so that calves were completely weaned by 56 d of age. Calves remained in the trial until, on average (± SD), 72 ± 2 d of age. Pens were continuously video recorded, and behaviors were scored 3 d/wk using 5-min scan samples. Four observers scored whether calves were inside, outside, lying, standing, in the sun or shade (interobserver reliability = 0.97). Sun and shade could not always be detected, so a proportion was calculated as the amount of time in the sun or shade divided by the total time sun or shade was visible. Calves spent approximately one-third of their time outside throughout the experiment, and time spent outside was affected by several factors. Pairs of calves spent less time outside as the amount of rain increased. During the first 6 wk of age, time spent outside increased, but time spent outside decreased between wk 6 and 7, and remained around 200 min/d from wk 7 to 11. Calves with the highest average daily gain and calves that were approximately 50% white appeared to spend more time outdoors. When outside, calves spent similar amounts of time in the sun and shade during the first 8 wk, but after weaning they appeared to spend more time in the shade. When calves were outside they appeared to spend a greater proportion of their time standing than when they were indoors during the first 4 wk. These results indicate that, when given the option in the summer, calves make use of an outdoor space, but this appears to vary with weather, calf age, average daily gain, and coat color.

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.

Understanding Behavioural Development of Calves in Natural Settings to Inform Calf Management

Simple Summary

Animal welfare research is intended to address societal concerns regarding animal care, including natural living concerns. We reviewed the literature on calf behaviour when reared in more naturalistic outdoor systems with their mothers and herd. Understanding calf behaviour in more natural settings may help inform changes in calf management and housing that promote behaviours important to calf welfare.

Abstract

One important type of animal welfare concern is “natural living” (i.e., that animals are able to express natural behaviours that are important to them, and to engage with aspects of the natural world that they find important). The aims of this narrative review were to describe the behavioural development of calves (Bos taurus) in natural settings and use this to identify characteristics of natural systems that may be important to consider relative to this natural living conception of animal welfare. At birth, calves are licked by their mothers and soon stand to suckle for colostrum, and during the milk-feeding period, calves spend much of their time lying down. In natural systems, calves perform a variety of social behaviours with herd-mates, and slowly transition from their mother’s milk to eating solid food, by gradually increasing time spent grazing and ruminating. In contrast, on most commercial dairy systems, dairy calves are removed from their mothers at birth, housed individually, fed restricted amounts of milk and weaned abruptly at a young age. The results of this review suggest that accommodating key natural behaviours, for example through the use of teat feeding of milk, social housing, and gradual weaning, can help address welfare concerns.

ADSA Foundation Scholar Award: New frontiers in calf and heifer nutrition-From conception to puberty

Dairy calf nutrition is traditionally one of the most overlooked aspects of dairy management, despite its large effect on the efficiency and profitability of dairy operations. Unfortunately, among all animals on the dairy farm, calves suffer from the highest rates of morbidity and mortality. These challenges have catalyzed calf nutrition research over the past decade to mitigate high incidences of disease and death, and improve animal health, growth, welfare, and industry sustainability. However, major knowledge gaps remain in several crucial stages of development. The purpose of this review is to summarize the key concepts of nutritional physiology and programming from conception to puberty and their subsequent effects on development of the calf, and ultimately, future performance. During fetal development, developmental plasticity is highest. At this time, maternal energy and protein consumption can influence fetal development, likely playing a critical role in calf and heifer development and, importantly, future production. After birth, the calf's first meal of colostrum is crucial for the transfer of immunoglobulin to support calf health and survival. However, colostrum also contains numerous bioactive proteins, lipids, and carbohydrates that may play key roles in calf growth and health. Extending the delivery of these bioactive compounds to the calf through a gradual transition from colostrum to milk (i.e., extended colostrum or transition milk feeding) may confer benefits in the first days and weeks of life to prepare the calf for the preweaning period. Similarly, optimal nutrition during the preweaning period is vital. Preweaning calves are highly susceptible to health challenges, and improved calf growth and health can positively influence future milk production. Throughout the world, the majority of dairy calves rely on milk replacer to supply adequate nutrition. Recent research has started to re-evaluate traditional formulations of milk replacers, which can differ significantly in composition compared with whole milk. Transitioning from a milk-based diet to solid feed is critical in the development of mature ruminants. Delaying weaning age and providing long and gradual step-down protocols have become common to avoid production and health challenges. Yet, determining how to appropriately balance the amount of energy and protein supplied in both liquid and solid feeds based on preweaning milk allowances, and further acknowledging their interactions, shows great promise in improving growth and health during weaning. After weaning and during the onset of puberty, heifers are traditionally offered high-forage diets. However, recent work suggests that an early switch to a high-forage diet will depress intake and development during the time when solid feed efficiency is greatest. It has become increasingly clear that there are great opportunities to advance our knowledge of calf nutrition; yet, a more concentrated and rigorous approach to research that encompasses the long-term consequences of nutritional regimens at each stage of life is required to ensure the sustainability and efficiency of the global dairy industry.

Effects of rumen-protected methionine or methionine analogs in starter on plasma metabolites, growth, and efficiency of Holstein calves from 14 to 91 d of age

During weaning, methionine (Met) supply decreases as liquid feed intake is reduced and ruminal function is developing. During this transition, the calf starter should both promote ruminal development and provide adequate nutrients post-ruminally. In mature ruminants, rumen-protected Met (RPM) and the Met analogs, 2-hydroxy-4-(methylthio)-butanoic acid (HMTBa) and HMTBa isopropyl ester (HMBi), are used to increase Met supply, stimulate ruminal fermentation, or exert both effects, respectively. To evaluate the effects of these forms of Met on calf performance during development of ruminal function, 74 Holstein calves were raised until 91 d of age, in 2 enrollment periods. Calves were individually housed from birth and, at 14 d of age, balanced for sex and randomly assigned to receive a starter with no added Met (CTRL, n = 20) or one supplemented with RPM (Smartamine M, Adisseo USA Inc., Alpharetta, GA; n = 16), HMTBa (RumenSmart, Adisseo; n = 19), or HMBi (MetaSmart, Adisseo; n = 19). Milk replacer [28% crude protein (CP), 15% fat] was offered up to 1.6 kg of dry matter (DM)/d and fed 3 times daily. Weaning was facilitated from d 49 to 63. The 4 starters (25% CP, 2.5 Mcal of metabolizable energy/kg of DM) were offered ad libitum, and supplement inclusion was set to provide an additional 0.16% DM of Met equivalents, and equal amounts of HMTBa within the analogs. Body weight and stature were measured, and blood was collected and analyzed for plasma urea nitrogen, β-hydroxybutyrate, and free AA on a weekly basis. Supplementation of RPM and HMBi increased free plasma Met, but no differences in growth or feed efficiency compared with calves fed the CTRL starter could be attributed to the additional Met supply alone. The addition of HMBi in the starter increased feed intake and body weight during the last weeks of the experiment. On the contrary, HMTBa failed to increase plasma Met and depressed intake and growth after weaning, likely because the level included in the diet was too high and intake was greater than previous studies, exacerbating the level of HMTBa ingested. No differences were observed in stature, feed efficiency, or non-AA plasma measurements among groups. These results demonstrate that RPM and HMBi are effective sources of metabolizable Met; however, Met was apparently not limiting calves fed the basal diet in this study. The increased feed intake observed with the inclusion of HMBi in the starter during the weaning and early postweaning period might be mediated by its metabolism in the rumen, and further research is needed to determine the mechanisms involved.

Effects of step-down weaning implementation time on growth performance and blood metabolites of dairy calves

The current study evaluated the effects of step-down weaning implementation time on starter feed intake, growth performance, blood metabolites, and ruminal pH in dairy calves. A total of 48 Holstein dairy calves (24 male and 24 female; 3 ± 1 d old; 41.2 ± 1.8 kg of body weight) were assigned (n = 12 per treatment; 6 male and 6 female) to 4 experimental treatments in a completely randomized block design. All calves were fed 6 L/d of milk from d 3 to 10 of age, and the treatments consisted of the following: calves were offered 8 L/d of milk from d 11 to 28 of age and then 4 L/d from d 29 to 63 (Step-28; total milk offered = 326 L); calves were offered 8 L/d of milk from d 11 to 42 of age and then 4 L/d from d 43 to 63 (Step-42; total milk offered = 382 L); calves were offered 8 L/d of milk from d 11 to 56 of age and 4 L/d from d 57 to 63 (Step-56; total milk intake = 438 L); and calves were fed 8 L/d of milk from d 11 to 63 of age and abruptly weaned (control; total milk offered = 466 L). All calves were housed individually in pens and had ad libitum access to water and solid feed throughout the experiment. All calves were completely milk weaned on d 64, and their performance was measured until d 80 of age. During the experiment, the starter intake (kg/d and % of body weight) was greater in calves in the Step-28 group compared with those in the other groups. However, the total metabolizable energy intake was greater in the Step-56 calves compared with the other calves. Overall, the average daily gain (ADG), feed efficiency (ADG/dry matter intake), and ADG/total metabolizable energy intake were similar across the treatments. Circulating glucose, β-hydroxybutyrate, blood urea nitrogen, albumin, total protein, alanine aminotransferase, and aspartate aminotransferase, as well as ruminal pH, were not affected by the treatments. The implementation of step-down weaning in early life (4-6 wk of age) could stimulate solid feed intake compared with weaning at a later age with no negative effect on performance.

Symposium review: Precision technologies for dairy calves and management applications

There is an increasing interest in using precision dairy technologies (PDT) to monitor real-time animal behavior and physiology in livestock systems around the world. Although PDT in adult cattle is extensively reviewed, PDT use for the management of preweaned dairy calves has not been reviewed. We systematically reviewed research on the use and application of precision technologies in calves. Accelerometers have the potential to be used to monitor lying behavior, step activity, and rumination, which are useful to detect changes in behavior that may be indicative of disease, responses to painful procedures, or positive welfare behaviors such as play. Automated calf feeding systems can control delivery of nutritional plans to individualize feeding and weaning of calves; changes in feeding behaviors (such as milk intake, drinking speed, and unrewarded visits) may also be used to identify early onset of disease. The PDT devices also measure physiological and physical attributes in dairy calves. For instance, temperature monitoring devices such as infrared thermography, ruminal boluses, and implanted microchips have been assessed in calves, but no herd management-based commercial system is available. Many other PDT are in development with potential to be used in dairy calf management, such as image and acoustic-based monitoring, real-time location, and use of enrichment items for monitoring positive emotional states. We conclude that PDT have great potential for application in dairy calf management, enabling precise behavioral and physiological monitoring, targeted feeding programs, and identification of calves with poor health or behavioral impairments. We strongly encourage further development and validation of commercially available technologies for on-farm application of the monitoring of dairy calf welfare, performance, and health.

Investigation of weaning strategy and solid feed location for dairy calves individually fed with an automated milk feeding system

The objective of this study was to investigate the effect of 2 gradual weaning programs and 2 locations of solid feed within individual calf pens on feed intake, growth, and behavior of calves fed milk by an automated milk feeder. Using a 2 × 2 factorial design, 60 female calves were randomly assigned to 1 of 2 weaning treatments and 1 of 2 solid feed placement treatments. Calves were assigned to a continuous gradual weaning program (CG) or a multi-step gradual weaning program (MG). Calves assigned to the CG treatment had their milk allocation reduced in small, equal increments from 12.5 L/d on d 43 to 2 L/d on d 56. Calves assigned to the MG treatment were offered 10 L/d on d 43 to 45, 8 L/d on d 46 to 49, 6 L/d on d 50 to 52, and 3 L/d on d 53 to 56. Solid feed was placed either at the front of the pen adjacent (ADJ) to where the automated milk feeder offered milk or at the back of the pen on the opposite (OPP) side from where the milk was offered. All calves were offered 12.5 L/d of milk replacer from d 2 to 42, fresh solid feed (5% chopped wheat straw mixed with 95% calf starter pellet) from d 5 onward, and ad libitum water starting d 0. Calves were weaned from d 43 to 56 and additionally monitored from d 57 to 70. No interactions of effects of weaning and feed location treatment were detected. Both MG and CG calves had similar water and solid feed consumption, blood β-hydroxybutyrate concentrations, and behavior. By design, calves on the CG treatment consumed greater amounts of milk during the weaning phase than MG treatment calves (6.7 vs. 6.3 L/d), which resulted in milk drinking behavior differing between the treatments during the weaning phase. Although average daily gain and body weights were similar between treatments, MG calves had greater middle girth gain during wk 7 compared with CG calves (0.6 vs. 0.3 cm/d). Calves on the ADJ treatment consumed 16.7% more solid feed and 0.55 L/d more milk during the preweaning phase compared with OPP treatment calves. In all 3 phases, ADJ treatment calves consumed more water than OPP treatment calves. The ADJ calves spent more time consuming solid feed during the 10-wk period. The ADJ treatment calves had 10% greater average daily gain compared with OPP treatment calves during the preweaning phase. Overall, the results indicate that both gradual weaning treatments resulted in similar performance and behavior. However, placement of solid feed next to the milk source was demonstrated to increase feed, water, and milk intake during the preweaning stage, contributing to greater growth.

Key animal welfare issues in commercially raised dairy calves: social environment, nutrition, and painful procedures

Dairy calf welfare concerns are growing and new evidence suggests that the early life environment influences appropriate physical, behavioral, and cognitive development lasting into adulthood. This review highlights key evidence for the impacts of housing, diets, and painful procedures on calf welfare. We argue that these topics are currently critical welfare concerns, but are not the only points of concern. In addition to environmental requirements to maintain optimal health, dairy calves experience other challenges including social and nutritional restrictions. Individual housing is associated with impaired behavioral development and cognitive ability. Pair and group housing can mitigate some of these negative effects and should be encouraged. Restrictive milk allowances (<15% of body weight) lead to poor growth and hunger; these welfare concerns can be addressed with proper enhanced milk allowances and gradual weaning programs. Finally, dehorning is a critical animal welfare issue when pain control is withheld; calves show negative behavioral, physiological, and emotional responses during and after dehorning. The combined use of local anaesthetics and analgesics can mitigate these effects. An industry shift toward providing social companionship, enhanced milk allowances, and pain control during painful procedures would help to improve the welfare of dairy calves in intensive commercial rearing facilities.

Invited Review: Nutritional regulation of gut function in dairy calves: From colostrum to weaning

Purpose

Published literature regarding calf nutrition was reviewed to create an information base for the implementation of proper nutritional management to maximize health and productivity.

Sources

The main source of data and information for this review was peer-reviewed literature.

Synthesis

Feeding a sufficient volume of colostrum during the first hours of life is crucial to calf health and survival; however, less is known about transition milk feeding and the potential benefits of the myriad of bioactive compounds it contains. After feeding colostrum and transition milk, calves are susceptible to diarrhea when moved onto high amounts of milk, and antibiotic use is often necessary to decrease disease. Feeding an elevated plane of milk nutrition results in increased ADG and, in some studies, increased future milk production. Thus, this nutritional strategy is recommended; however, weaning calves from high volumes of milk represents massive changes in the structure and microbiology of the gastrointestinal tract.

Conclusions and Applications

Colostrum and transition milk contain an abundance of bioactive molecules that can positively affect gut development and microbiota. There is significant potential for the use of novel feeding strategies and microbial-based products as alternatives to antibiotics. Calves fed an elevated plane of nutrition in the first month of life have greater productivity and growth. However, weaning should take place later in life. Moreover, applying a proper step-down feeding protocol is recommended, as it allows calves to intake and digest sufficient solid feed for growth and minimize distress at weaning.

Individual characteristics in early life relate to variability in weaning age, feeding behavior, and weight gain of dairy calves automatically weaned based on solid feed intake

Little is known about factors affecting individual variability in weaning age, feeding behavior, and growth of dairy calves. The objectives of this study were to (1) describe early-life individual characteristics of dairy calves and how these relate to weaning age, feeding behavior, and performance during the first 15 wk of age, and (2) to identify which of these individual characteristics predict weaning age of calves automatically weaned based on solid feed intake. Early-life characteristics of calves (n = 43) included scores for vitality at birth, drinking ability, learning ability to use the automated milk feeder in a group pen from d 1 of age, and personality traits assessed using exposure to a novel environment, a human, and an object at d 21 of age. Calves received 12 L/d of milk until d 30 when milk was reduced by 25% relative to the individual's previous 3-d intake average. Calves were weaned based on intake of solid feed (milk reduced by 25% at each of 2 intermediate solid feed intake targets, 225 and 675 g/d), and were weaned when they consumed 1,300 g/d of solid feed, resulting in variable weaning ages. A principal component analysis identified 5 factors that we labeled as low vitality, fearful, strong drinker, slow learner, and exploratory-active. Calves that were slow learners weaned at a later age, whereas fearful calves weaned earlier. No other early-life individual characteristics were associated with weaning age. Other characteristics (low vitality, strong drinkers, and exploratory-active) were associated with some measures of feeding behavior, feed intake, and growth, especially during the preweaning period. Measures of early solid feed intake (age to start eating and total preweaning intake) were best able to predict weaning age of calves. Individual early-life characteristics and measures of early solid feed intake can identify calves likely to do well or struggle during weaning.