Invited review: effects of milk ration on solid feed intake, weaning, and performance in dairy heifers

Producer perceptions of dairy calf management, behavior, and welfare

Approaches for raising calves vary across commercial dairy farms and relate to behavioral opportunities and animal welfare. The objectives of this study were to evaluate how US dairy producers and calf managers perceive (1) the welfare implications of varying management practices (including social housing and milk allowance) and behaviors in dairy calves, and (2) aspects of the human-animal relationship in calf rearing and relationships with on-farm management and personal calf handling habits. Survey questions were primarily quantitative (e.g., Likert scales) and addressed how common calf management practices and observed calf behaviors were related to aspects of welfare, including calf health and comfort. We additionally posed questions addressing respondent habits, management protocols, and perceptions related to human-animal interaction. Responses from 93 dairy producers and calf managers were collected via digital surveys. Social housing was viewed as being generally positive for both calf comfort and health, although this view was stronger with respect to calf comfort. Respondents from farms using social housing (56%) had more positive perceptions of social housing, viewed social play as being associated with better calf comfort and health, and considered access to other calves and "freedom to express natural behavior" as being more important for calves, compared with respondents from farms not providing social housing. Providing greater milk allowances (>7.6 L/d) was viewed as being good for both calf comfort and health, although respondents from farms providing these milk allowances (59%) had more positive perceptions than those who provided lesser allowances. Abnormal oral behaviors were viewed as being associated with both poor calf comfort and health. The welfare importance of various resources which may reduce abnormal oral behaviors (including hay and brushes) was perceived more ambiguously, although respondents from farms providing these resources, compared with those who do not, generally viewed them as more preferred by calves. We observed a positive relationship between how respondents perceived the human-animal bond (i.e., that calves enjoy contact with humans) and stated personal behavior related to calf contact (frequency of contacting calves to scratch or pet them). Respondent demographics were not related to perceptions of the human-animal relationship, but respondents identifying as female described more frequent positive calf interactions. Described aspects of human-animal interactions were not related to implementation of social housing on-farm. Job satisfaction was positively related to perception of the human-animal relationship. Overall, these results suggest that most calf management personnel place a high value on calf welfare, although farms implementing social housing appear to place a greater value on subjective calf well-being, and individual perceptions of animal welfare may depend on practical experience.

Calf performance in a cow-driven cow-calf contact system: Effect of 2 methods to gradually reduce cows' access to their calf

Knowledge is lacking on separation strategies that can best prepare calves to final separation from the dam in cow-calf contact (CCC) systems. This controlled trial compared the effects of 2 different methods to gradually reduce cows' access to their calf termed "debonding" on calf growth in a cow-driven CCC system. Initially, cows (Norwegian Red breed) had 24 h/d computer-controlled access to their calves. In the long debonding (LDB) treatment (n = 16), a gradual reduction of cows' access to their calves was initiated 28 d after calving over a total duration of 28 d; first to 12 h/d (14 d), and then to 6 h/d (14 d). In the short debonding (SDB) treatment (n = 14), reduction was initiated 45 d after calving over a total duration of 10 d; first to 12 h/d (5 d), and then to 6 h/d (5 d). From 6 h/d, access was finally reduced to 0 h/d for 4 d for both treatments, resulting in a study period of 60 d in total. Calves had ad libitum access to concentrate, hay and water throughout the study. Independent of treatment, ad libitum access to whole milk from an automatic feeder was granted once cow access was reduced. Cows and calves had the possibility for fence line contact at all times. The primary outcome variable calf weight gain was registered biweekly. Calf ADG was analyzed with a linear mixed model. The ADG was similar across treatments during 24 h/d access (1.04 ± 0.07 kg). Debonding treatment affected calf growth differently with each gradual reduction in cow access (12 h/d, 6 h/d and 0 h/d); however, no main effect of treatment was detected. The SDB calves had a pattern of increased ADG with the first reduction in access (+0.39 ± 0.18kg), followed by significant growth checks as access was reduced further to 6 h/d and 0 h/d (-0.41 ± 0.20 kg and -1.15 ± 0.31 kg, respectively). The LDB calves only showed significant weight checks at the final reduction in access (0 h/d access), yet at a lower degree (-0.46 ± 0.21 kg) than SDB calves. As expected, ADG was negatively associated with health events but positively associated with intake of concentrate and supplemental milk. Collectively, the results from the present study might point toward a long adaptation to separation which is initiated at a younger age being more favorable for calf performance.

Effect of nonstructural carbohydrates on production performance, rumen metabolism and rumen health in lambs fed with isocaloric and isonitrogenous complete diets

Nonstructural carbohydrates (NSC) are readily fermentable in the rumen and, are a critical factor while preparing protracted feed for higher animal performance. Four isocaloric and isonitrogenous complete feeds were prepared for this investigation to contain varying levels of nonstructural carbohydrates viz., 40.13 (NSC1), 45.21 (NSC2), 50.00 (NSC3) and 55.85 (NSC4) per cent, respectively. The four isocaloric and isonitrogenous complete feeds were tested in 32 Mecheri ram lambs (around three months of age) in a completely randomised block design (n = 8), and the lambs were fed their respective feed for six months. The study revealed that the increased NSC level in the complete diet increased the body weight and weight gain linearly (P < 0.05). The dietary NSC level affected the dry matter consumption in a quadratic manner (P < 0.05) and the lambs of the NSC4 group consumed significantly (P < 0.05) less DM compared to other dietary groups. The overall average feed conversion efficiency differed significantly (P < 0.05) among dietary groups. The correlation between dietary NSC level and faecal score was quadratic (r2 = 62.7, P < 0.05). The rumen pH, total nitrogen and NH3-N concentration were linearly decreased (P < 0.05) and the molar proportion of total short-chain fatty acids and propionic acid were increased (P < 0.05). The energy loss expressed as methane production was significantly (P < 0.01) lower for the high NSC diet-fed lambs. The lambs fed on a low NSC diet had significantly (P < 0.05) lower carcass weights, dressing percentage and loin eye area. The per cent share of rumen weight in the total fore stomach and the rumen papillae measurements length, width and surface area were significantly (P < 0.05) higher in high NSC diet-fed lambs. Increased levels of NSC in the diet increased (P < 0.05) fat deposition in the internal organs. The saturated fatty acids content in the meat was significantly (P < 0.05) lowered, whereas, the oleic acid and linoleic acid were increased (P < 0.05) as the NSC level increased in the diet. The study revealed that as the level of NSC increased in the complete diet there was a concomitant improvement in the final body weight, ADG and feed efficiency of post-weaned Mecheri lambs. It can therefore be recommended that the complete feed with 50 per cent NSC levels would be optimum to reap maximum returns from fattening Mecheri lambs.

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.

Short- and long-term effects of different forage types supplemented in preweaning dairy calves on performance and milk production into first lactation

We investigated the short- and long-term effects of different forage types supplemented in preweaning dairy calves on growth performance, blood metabolites, rumen fermentation, bacterial community, and milk production during first lactation. Sixty healthy 1-mo-old female Holstein calves were blocked by birth date and body weight and randomly assigned to one of 3 groups (n = 20): normal milk and pelleted starter feeding (CON), supplemented with chopped oat hay [75.0 g/d/calf (dry matter (DM) basis); OAH], or alfalfa hay [75.0 g/d/calf (DM basis); ALF]. The forage supplementation started when calves were 30 d old (D1 of the experimental period) and ended when they were 73 d old (D44 of the experimental period when calves were weaned. Milk and feed intakes and fecal consistency scores were recorded daily. Growth performance, rumen fluid, and blood samples were collected bi-weekly. After weaning, all the calves were integrated with the same barn and diets. After calving, the milk production was recorded daily. During the experimental period, the OAH group had greater solid feed and total DM intakes and greater rumen pH than the CON group (P ≤ 0.04), but had lower forage intake and crude protein digestibility than the ALF group (P ≤ 0.04). The ALF group had higher rumen pH and blood β-hydroxybutyrate concentration (P ≤ 0.04), lower fecal score (P = 0.02), and greater ether extract digestibility (P = 0.02) than the CON group. The ALF and OAH groups had lower concentrations of ruminal total volatile fatty acids (P = 0.01). Still, the ALF group had a greater proportion of acetate and a relative abundance of cellulose degradation-related bacteria (Lachnoclostridium_1 and Oribacterium) and a lower relative abundance of inflammation-related bacteria (Erysipelotrichaceae_UCG-009) in the rumen compared with CON. Interestingly, the average milk production from 6 to 200 d in milk (DIM) was greater in the ALF group (P < 0.01) even though no significant effects were found on the rumen fermentation parameters and blood metabolites at 200 DIM. Generally, alfalfa hay supplementation in preweaning dairy calves had positive effects in the short- and long-term in terms of rumen development, health status, and future milk production.

Postnatal Growth and Development of the Rumen: Integrating Physiological and Molecular Insights

The rumen plays an essential role in the physiology and production of agriculturally important ruminants such as cattle. Functions of the rumen include fermentation, absorption, metabolism, and protection. Cattle are, however, not born with a functional rumen, and the rumen undergoes considerable changes in size, histology, physiology, and transcriptome from birth to adulthood. In this review, we discuss these changes in detail, the factors that affect these changes, and the potential molecular and cellular mechanisms that mediate these changes. The introduction of solid feed to the rumen is essential for rumen growth and functional development in post-weaning calves. Increasing evidence suggests that solid feed stimulates rumen growth and functional development through butyric acid and other volatile fatty acids (VFAs) produced by microbial fermentation of feed in the rumen and that VFAs stimulate rumen growth and functional development through hormones such as insulin and insulin-like growth factor I (IGF-I) or through direct actions on energy production, chromatin modification, and gene expression. Given the role of the rumen in ruminant physiology and performance, it is important to further study the cellular, molecular, genomic, and epigenomic mechanisms that control rumen growth and development in postnatal ruminants. A better understanding of these mechanisms could lead to the development of novel strategies to enhance the growth and development of the rumen and thereby the productivity and health of cattle and other agriculturally important ruminants.

Effects of milk replacer powder added to pasteurized whole milk over different durations on dairy calves fed ground starter diet with alfalfa hay

Adding milk replacer powder (MRP) to whole milk during the entire preweaning period can increase growth but raises concern because of low starter feed intake and slumps in average daily gain (ADG) at weaning and postweaning. In the current study, effects of adding MRP to pasteurized whole milk (PWM) during d 10-41 or d 10-59 of age were investigated in comparison with PWM. Calves [24 females and 21 males; 39.8 ± 1.85 kg body weight (BW)] were randomly allocated to 1 of 3 treatments: 1) conventional protocol, 5 L/d PWM from d 3-56, and 2.5 L/d from d 57-59 of age (CONV; TS intake = 31.9 kg), 2) short duration of adding MRP to PWM protocol, 5 L/d PWM from d 3-9, 5 L/d PWM + MRP (18% TS) from d 10-41, 5 L/d PWM from d 42-56, and 2.5 L/d PWM from d 57-59 (SD; TS intake = 42.3 kg), 3) long duration of adding MRP to PWM protocol, 5 L/d PWM from d 3-9, 5 L/d PWM + MRP from d 10-56, 2.5 L/d PWM + MRP form d 57-59 (LD; TS intake = 47.7 kg). The osmolality of PWM and PWM + MRP was 278 and 519 mOsm/L, respectively. Calves were weaned on d 60, and the study terminated on d 75. There was a treatment × time interaction for starter intake, where intake was greater for CONV than other treatments from d 14-41 and was greater in CONV than LD during d 42-48 and d 56-62 of age. Final BW was lower in CONV calves than LD calves. Weaning BW and overall hip height were lower in CONV calves than other treatments. The CONV calves had lower ADG at d 14-27 and 35-41 and SD calves had lower ADG at d 42-48 than other treatments. Calves fed CONV treatment had lower ruminal acetate and greater propionate than SD calves during preweaning. Calves fed LD treatment had lower total volatile fatty acids and tended to have greater ruminal pH than other treatments. Calves fed CONV had greater neutrophils and neutrophils/lymphocytes ratio and lower lymphocytes than other treatments. Glucose concentration was greater for LD versus other treatments at d 56, and lower for SD versus other treatments at d 70 of study. Insulin concentration and homeostatic model assessment of insulin resistance index were greater in LD compared with other treatments during preweaning but were not different postweaning. Serum BHB was greater in CONV than other treatments. Albumin was greater for CONV versus other treatments at d 56, however, it was greater in LD-fed calves at d 70 of study. Results indicate that feeding a PWM + MRP to the calves during the entire preweaning period resulted in lower starter feed intake around weaning, but overall starter intake was similar with a greater final BW and fewer health related issues throughout the study. Shifting a PWM + MRP to the conventional whole milk at d 40 of age decreased the ADG of calves.

Behavioral responses of dairy cows and their calves to gradual or abrupt weaning and separation when managed in full- or part-time cow-calf contact systems

There is growing interest in managing cow and calf together for a prolonged period, but concerns remain about how best to wean and separate the cow and calf to minimize stress. One approach is to progressively reduce suckling opportunity over time, as in nature. There is also interest in part-time contact (suckling for part of the day) to improve milk yield for the farmer and potentially reduce stress at weaning and separation. The primary objective of this study was to compare the behavioral responses of dairy cows to gradual or abrupt weaning and separation, when managed either full or part time with their calves; a secondary focus was the vocal responses of calves under these management conditions. In a 3 × 2 factorial design (n = 14/ treatment), dairy cows and their calves (n = 84 in 7 blocks of 12 cow-calf pairs) were assigned to one of 3 dam-contact treatments at birth: (1) full-time contact between the dam and calf, apart from milking times (total 23 h/d) (2) part-time contact between the dam and calf, between morning and afternoon milking only (total 10 h/d); (3) no contact, where the dam and calf were separated after leaving the maternity pen and had no further contact. At wk 8, one of 2 weaning treatments was assigned: (1) gradual weaning by reduced contact time (50%, then 25% of original dam-contact time in wk 8 and 9, respectively), or gradually reduced milk allowance for no-contact calves (50%, then 25% of estimated 12-L milk intake in wk 8 and 9, respectively) until complete milk removal and dam-calf separation at wk 10; (2) abrupt weaning where milk removal occurred simultaneously with dam-calf separation at wk 10, or only milk removal for no-contact calves. Overall, part-time contact did not reduce weaning and separation distress for cows or calves for either weaning method. Part-time cows showed reduced behavioral responses to separation (greater lying time and less searching behavior), especially on the day of and 24 h after separation, but they showed a similarly strong vocal response to separation as full-time cows. Part-time calves made substantially more high-pitched vocalizations than full-time calves at 24 h after separation. Furthermore, gradual weaning by reducing contact time did not seem to better prepare cows or calves for complete milk removal and separation; most behavioral and vocal responses occurred on the day of separation for gradual-weaning cows and calves, but 24 h later, the reverse occurred for abrupt-weaning cows and there was no difference between gradual- and abrupt-weaning calves. Our results suggest that part-time contact and gradual-weaning conditions likely resulted in hunger and expectation for reunion, which together may have exaggerated behavioral responses at separation. Temporary daily separations may not have increased independence of cow and calf, and the gradual-weaning method here may not have reduced milk intake by calves. These elements are important criteria to facilitate the weaning process, so future work should explore ways to gradually reduce milk intake and promote social independence of cow and calf to minimize weaning distress.

Review: Opportunities and challenges for the genetic selection of dairy calf disease traits

Interest in dairy cow health continues to grow as we better understand health's relationship with production potential and animal welfare. Over the past decade, efforts have been made to incorporate health traits into national genetic evaluations. However, they have focused on the mature cow, with calf health largely being neglected. Diarrhoea and respiratory disease comprise the main illnesses with regard to calf health. Conventional methods to control calf disease involve early separation of calves from the dam and housing calves individually. However, public concern regarding these methods, and growing evidence that these methods may negatively impact calf development, mean the dairy industry may move away from these practices. Genetic selection may be a promising tool to address these major disease issues. In this review, we examined current literature for enhancing calf health through genetics and discussed alternative approaches to improve calf health via the use of epidemiological modelling approaches, and the potential of indirectly selecting for improved calf health through improving colostrum quality. Heritability estimates on the observed scale for diarrhoea ranged from 0.03 to 0.20, while for respiratory disease, estimates ranged from 0.02 to 0.24. The breadth in these ranges is due, at least in part, to differences in disease prevalence, population structure, data editing and models, as well as data collection practices, which should be all considered when comparing literature values. Incorporation of epidemiological theory into quantitative genetics provides an opportunity to better determine the level of genetic variation in disease traits, as it accounts for disease transmission among contemporaries. Colostrum intake is a major determinant of whether a calf develops either respiratory disease or diarrhoea. Colostrum traits have the advantage of being measured and reported on a continuous scale, which removes the issues classically associated with binary disease traits. Overall, genetic selection for improved calf health is feasible. However, to ensure the maximum response, first steps by any industry members should focus efforts on standardising recording practices and encouragement of uploading information to genetic evaluation centres through herd management software, as high-quality phenotypes are the backbone of any successful breeding programme.

Enrichment of medium-quality colostrum by adding colostrum replacer, combined or not with transition milk in the feeding of dairy calves

Fifty Holstein calves were allocated in randomized blocks and distributed in a 2 × 2 factorial arrangement; (A) two sources of Ig: (1) Control: bovine colostrum (25% Brix); (2) Enriched colostrum: mid-quality bovine colostrum (20% Brix) enriched with colostrum replacer to 25% Brix; and (B) two transition feeding diets: (1) Whole milk (WM): supply of 4 L/day of whole milk for 3 days after the colostrum feeding; and (2) Formulated transition milk (FTM): supply 4 L/day of whole milk enriched with 70 g/L of colostrum replacer for 3 days after the colostrum feeding. Blood samples were collected at 0, 24, 48, and 72 h of age to determine total serum protein (TSP), glucose, non-esterified fatty acids (NEFA), erythrocyte and leukocyte concentrations. IgG was measured at 48 h. During the preweaning period, calves received 6 L/day of whole milk. Blood samples were collected weekly to determine TSP, glucose, and lactate. The colostrum protocols were equally efficient for transfer of passive immunity with IgG concentration at 48 h ≥ 49.6 g/L. Colostrum or transition feeding program did not influence the erythrocyte and leukocyte concentrations. The TSP concentration measured until 72 h was higher for calves fed maternal colostrum. Calves fed milk in the transition period had higher glucose concentrations. Calves receiving bovine colostrum and FTM had higher glucose concentrations in the preweaning period, while the enriched colostrum decreased plasma lactate concentrations. In summary, enrichment of mid-quality colostrum is an alternative in situations of a shortage of high-quality colostrum; however, feeding 4 L/day of FTM only for 3 days after colostrum feeding does not show additional benefits.

How can better calf care be realized on dairy farms? A qualitative interview study of veterinarians and farmers

Improving health and welfare outcomes for replacement and surplus dairy calves is important for the sustainability of the dairy industry. Dairy farmers and veterinarians hold expertise in calf management and have valuable perspectives on how to practically motivate improvements. The objective of this study was to determine strategies that could improve the care calves receive on dairy farms from the perspective of dairy farmers and their herd veterinarians. Two veterinary clinics specializing in dairy practice in British Columbia, Canada, and 21 of their client dairy farms participated in the project. Following a meeting in which calf colostrum management was discussed between farmers and their herd veterinarian, participant interviews were conducted. Separate interviews were conducted for the farmers (n = 27 farmers from 21 farms) and their herd veterinarians (n = 7, with 1 to 5 farms that each vet worked with enrolled in the study) using tailored semi-structured question guides. Interviews (n = 42) were transcribed and coded following inductive thematic analysis methodology. The themes identified included strategies for farmers, veterinarians, and calf buyers, as well as contexts that influenced the dairy farmers' internal motivation to provide good calf care. Results indicated that farmers could optimize their calf management through fostering engagement of calf care personnel or by enlisting technology. Veterinarians could provide support to farms by being actively involved in calf monitoring, assisting in developing operating protocols, and setting goals, and especially by using farm-specific data to guide their management recommendations. Calf buyers could communicate with and provide accountability to farmers and improve their purchasing strategies to encourage farms to raise more vigorous surplus calves. Farmers' personal values, social networks, and relationships with different dairy industry stakeholders influenced their concern about the standards of their calf care practices. These findings provide guidance on how dairy farmers could achieve or be prompted to achieve improvements in their calf care practices.

Long-Term Effects of Pre-Weaning Individual or Pair Housing of Dairy Heifer Calves on Subsequent Growth and Feed Efficiency

Our objective in this exploratory study was to evaluate the long-term impacts of pre-weaning social isolation vs. contact on subsequent growth and feed efficiency of Holstein heifers. As pre-weaned calves, 41 heifers were housed individually (n = 15 heifers) or in pairs (n = 13 pairs; 26 heifers). At 18 months of age, heifers were blocked by body weight and randomly assigned to one of three pens within a block (six to eight heifers per pen; six pens total), with original pairs maintained. Body weight (BW), hip height and width, and chest girth were measured at the start and end of the study. Each pen was given 3 days of access to a GreenFeed greenhouse gas emissions monitor to assess potential physiological differences between treatments in enteric methane emissions or behavioral differences in propensity to approach a novel object. During the 9-week study, heifers were fed a common diet containing 62.3% male-sterile corn silage, 36.0% haylage, 0.7% urea, and 1.0% mineral (DM basis). To calculate daily feed intake, as-fed weights and refusals were recorded for individual heifers using Calan gates. Feed samples were collected daily, composited by week, and dried to calculate dry matter intake (DMI). Feed refusal and fecal samples were collected on 3 consecutive days at 3 timepoints, composited by heifer, dried, and analyzed to calculate neutral detergent fiber (NDF), organic matter (OM), and DM digestibility. Feed efficiency was calculated as feed conversion efficiency (FCE; DMI/average daily gain [ADG]) and residual feed intake (RFI; observed DMI-predicted DMI). Paired and individually housed heifers did not differ in DMI, ADG, FCE, or RFI. Although no differences were found in initial or final hip height, hip width, or chest girth, heifers which had been pair-housed maintained a greater BW than individually housed heifers during the trial. Methane production, intensity, and yield were similar between treatments. Pre-weaning paired or individual housing did not impact the number of visits or latency to approach the GreenFeed; approximately 50% of heifers in each treatment visited the GreenFeed within 8 h of exposure. Digestibility of OM, DM, and NDF were also similar between housing treatments. In conclusion, pre-weaning pair housing had no adverse effects on growth, feed efficiency, or methane emissions at 18 to 20 months of age.

Effects of Dietary Fiber Level and Forage Particle Size on Growth, Nutrient Digestion, Ruminal Fermentation, and Behavior of Weaned Holstein Calves under Heat Stress

This experiment was designed to investigate the effects of feeding diets with different fiber content and forage particle size on the performance, health, nutrient digestion, rumen fermentation, and behavioral and sorting activity of Holstein dairy calves kept under elevated environmental temperature. Sixty weaned Holstein female calves (age = 96.7 ± 7.62 days old; body weight = 82.4 ± 10.4 kg) were randomly assigned to one of 4 treatments arranged in a 2-by-2 factorial design in a 70-day experiment. Dietary forage content (moderate, 22.5%; or high, 40.0% on DM basis) and alfalfa hay particle size (short, 4.39 mm; or long, 7.22 mm as geometric mean) were the experimental factors, resulting in the following combinations: (1) high-fiber (HF) diets with forage-to-concentrate ratio of 40:60 and long particle-sized alfalfa hay (LPS; HF-LPS); (2) HF diets with short particle-sized alfalfa hay (SPS; HF-SPS); (3) moderate-fiber (MF) diets with forage-to-concentrate ratio of 22.5:77.5 with LPS (MF-LPS); and (4) MF diets with SPS (MF-SPS). The temperature-humidity index averaged 73.0 ± 1.86, indicating that weaned calves experienced a moderate extent of heat stress. Fiber level and AH particle size interacted and affected dry matter intake, with the greatest intake (4.83 kg/d) observed in MF-SPS-fed calves. Final body weight was greater in calves receiving MF vs. HF diets (164 vs. 152 kg; p < 0.01). Respiration rate decreased when SPS vs. LPS AH was included in HF but not MF diet. Lower rectal temperature was recorded in calves fed MF vs. HF diet. Digestibility of dry matter and crude protein was greater in calves fed MF than HF diets, resulting in lower ruminal pH (6.12 vs. 6.30; p = 0.03). Fiber digestibility was greater in calves fed SPS compared with those fed LPS alfalfa hay. Feeding HF compared with MF diet increased acetate but lowered propionate molar proportions. The inclusion of SPS vs. LPS alfalfa hay decreased lying time in HF diet (920 vs. 861 min; p < 0.01). Calves fed MF vs. HF diets spent less time eating but more time lying, which is likely indicative of better animal comfort. Dietary fiber level and forage particle size interacted and affected sorting against 19 mm particles, the extent of which was greater in HF-SPS diet. Overall, dietary fiber level had a stronger effect than forage particle size on the performance of weaned calves exposed to a moderate degree of heat stress as feeding MF vs. HF diet resulted in greater feed intake, final body weight, structural growth measures, nutrient digestion, as well as longer lying behavior. The inclusion of SPS alfalfa hay in MF diets increased feed consumption.

Effects of starch content of calf starter on rumen properties and blood concentrations of metabolites and hormones in dairy calves under a high plane of milk feeding

The objective of this study was to investigate the effects of calf starters with different starch content on rumen and blood properties in calves fed under a high plane of nutrition program. Twenty-seven Holstein calves (14 female, 13 male) were assigned to one of three starter treatment groups in a randomized block design: high-starch (41.8%) (n = 9), H; medium-starch (31.9%) (n = 9), M; low-starch (22.0%) (n = 9), L. Milk replacer on powder basis was fed up to 1.2 kg/day as fed, gradually reduced from 6 weeks of age; calves were weaned at 8 weeks of age. Each starter (up to 3.5 kg/day as fed) and chopped hay were provided ad libitum from 5 days of age. Blood was collected from 4 to 13 weeks of age. Rumen fluid was collected at 6, 8, 10, and 13 weeks of age. Serum urea nitrogen concentration after weaning was the lowest in H. Plasma IGF-1 concentrations were higher in H than in L. Ruminal pH was not different, but the molar proportion of ruminal propionate was higher in H than in L throughout the study period. In summary, a high-starch starter may increase propionate production and microbial protein synthesis in the rumen, inducing higher plasma IGF-1 concentrations.

Comparing weaning methods in dairy calves with different dam contact levels

Allowing the dam to rear her calf is an alternative practice in the dairy industry where cow and calf may gain welfare benefits from performing natural and highly motivated behaviors. However, this system has been linked to an increased separation and weaning response. Reducing the daily dam-calf contact time may be a way to prepare the calf for weaning and separation. The first aim of the present study was to investigate the effect of 8 wk of half-day dam-calf contact on calf response to weaning and separation, compared with calves reared with whole-day dam-calf contact and an artificially reared, group-housed control with unrestricted access to milk for 20 min twice daily. Weaning off milk and separation from the dam can be viewed as 2 independent stressors. By introducing each stressor separately, it may be possible to reduce the overall behavioral response. The second aim of the present study was to investigate the effect of 1-wk fence-line weaning before permanent separation. The study was conducted with a 3 × 2 factorial design with dam contact treatments (whole-day, half-day, and control) and weaning treatments (simultaneous, and stepwise). Whole-day calves were separated twice daily from their dams during milking, whereas half-day calves were separated daily from the afternoon milking and until next morning milking. Simultaneous weaning and separation were done in wk 9, and stepwise weaning and separation started in wk 8 with calves being fence-line weaned before permanent separation in wk 9. Data were collected on 69 dairy calves in wk 8 and wk 9, and data were summarized over the 2 weeks for analysis. Stepwise weaning and separation reduced the number of high-pitched vocalizations and activity of dam-reared dairy calves but had little effect on control calves. There was no difference between whole-day and half-day calves in their response to separation, but as expected, dam-reared calves reacted more strongly than the control group. This was also reflected in the average daily BW gain the week after weaning, with control calves having higher average daily gains than whole-day, while half-day calves were intermediate. However, the behavioral response did not fully wane within the observation period (0-48 h of interventions). In conclusion, 1-wk fence-line weaning reduced the summed weaning and separation response in dam-reared calves. However, no difference between half-day dam-calf contact and whole-day dam contact was detected in the behavioral response to weaning and separation.

Shaping cow-calf contact systems: Farmers' motivations and considerations behind a range of different cow-calf contact systems

Most dairy farms rear calves artificially by separating the newly born calf from the dam and feeding the calf milk from a bucket. However, the general public and scientific community have begun to question the effects of artificial rearing on animal welfare. Research so far has focused mainly on dam-calf contact, where each cow takes care of her own calf. However, previous studies show that Danish and other European farmers are using and showing interest in a variety of different cow-calf contact (CCC) systems. In the present study, we used qualitative research methods to explore the perspectives of Danish farmers who either had or had tried to establish a version of a CCC system. Farmers were asked about their motivation for establishing the system, what had shaped the system to its current form, and how they perceived the calves to benefit from the system. Practical considerations was the theme most commonly brought up and related to both why farmers chose to have CCC in the first place and in what way they had chosen to organize their CCC system. Practical considerations included a sense of ease, flexibility, and a more natural and therefore rational approach. The economy was also a repeated theme, but although the economy to a large degree shapes the type of CCC chosen (dam-calf contact or foster cow contact), it was rarely mentioned in relation to choosing a CCC system in the first place. Ethical considerations were a strong motivator for farmers with dam-calf contact systems, although less so for farmers with foster cow contact. The farm's image as seen by the consumer was an important motivation for farmers with many on-farm visitors, and with the farm's image in the eyes of the farming community potentially also influencing farmers. Farmers generally perceived the calves to benefit from the care of the cow and no difference was seen in the importance attributed to care, between farmers choosing dam-calf contact and foster cow systems.

Invited review: Total solids concentration in milk or milk replacer for dairy calves

Restricting milk or milk replacer (MR) fed to dairy calves to 10% of body weight at 12.5% total solids (TS) concentration is a common feeding strategy that promotes early weaning and lowers total feed costs for raising young calves. However, this strategy has been associated with inferior performance and compromised welfare. Because a restricted liquid nutrition plan limits calf growth due to limited supply of nutrients, research on increased supply of nutrients from liquid has shown improved growth, health, and welfare of calves. Nutrient supply may be increased by feeding larger amounts of milk or MR averaging 12.5% TS, or by increasing TS above the usual 12.5% TS by increasing MR TS concentration alone (TS+), or by increasing TS concentration and volume simultaneously (TSV+). The objective of this review is to discuss liquid nutrition plans with greater TS concentration in MR or in milk diets, considering the effects of such strategies on performance and digestive tract development before weaning and the future performance of dairy calves. This review will focus on liquid nutrition plans that are based on increased TS concentration (i.e., TS+ or TSV+); therefore, enhanced liquid nutrition plans based only on increased volumes will not be the discussed. Improved growth rates have been observed in calves fed TSV+ programs. However, reduced starter intake preweaning can also have negative effects on dry matter intake, average daily gain, and digestibility postweaning. Feeding a TS+ program may reduce impairment of starter intake and therefore have positive effects on performance, nutrient digestibility, and health. When considering an accelerated nutrition plan with TS+ or TSV+, it is important to consider osmolality of the liquid diet. Further studies are necessary to confirm this hypothesis and the cost-benefit of alternative liquid nutrition plans, as well as the optimal TS concentration of milk or MR fed to dairy calves.

Benefits of barley straw as a forage for dairy calves before and after weaning

The aim of this study was to assess the potential consequences on calf intake, performance, behavior, ruminal microbiome, and ruminal epithelium development of combining the inclusion of chopped barley straw and alfalfa hay during the pre- and postweaning periods keeping concentrate to forage ratio constant among dietary treatments. Forty-five Holstein calves (44 ± 5.7 kg of body weight [BW] and 3 ± 1.5 d of age) individually penned were blocked by BW and randomly assigned to a common pellet concentrate fed ad libitum along with one of following forage feeding strategies: barley straw before and after weaning (S-S), barley straw before and alfalfa hay after weaning (S-A), or alfalfa hay before and after weaning (A-A). All calves received the same milk replacer regimen. Forage was supplied in a separated bucket at the rate of 7.5% (preweaning) and 15% (postweaning) of total solid feed intake of the previous day. Feed intake and BW were recorded daily and weekly, respectively. Rumen samples were obtained via a stomach tube at 53, 66, and 87 d and were composite in 3 samples of 5 animals each for subsequent rumen microbiome analysis. A rumen epithelium sample was taken by endoscopy at 90 d to assess gene expression of OCLN, CLDN4, SLC9A1, SLC9A3, SLC16A1, SLC16A4, IL6, and TGFB1. Data were analyzed with a mixed-effects model accounting for the fixed effects of block, forage, week of study, and their interaction, and calf as a random effect. The type of forage fed did not affect concentrate feed, forage, or total DM intake before weaning. However, S-A and A-A calves consumed less concentrate feed and S-A calves grew at a lower rate after weaning than S-S calves. Expression of the gene coding for SLC16A1 in the rumen epithelium was greatest in S-S among treatments. Rumen microbiome did not differ among treatments, while the relative abundance of Acidaminococcus and Selenomas genera increased, while Alloprevotella, Bifidobaterium, Olsenella, and Succiclasticum genera decreased with age. In conclusion, feeding barley straw before and after weaning was more effective than feeding alfalfa hay in promoting concentrate feed intake after weaning and fostering an increase in the expression of SLC16A1 in the rumen epithelium.

Liver microbial community and associated host transcriptome in calves with feed induced acidosis

Introduction

In the dairy industry, calves are typically fed diets rich in highly fermentable carbohydrates and low in fibrous feeds to maximize ruminal papillae and tissue development. Calves on such diets are vulnerable at developing ruminal acidosis. Prevalent in cattle, liver abscess (LA) is considered a sequela to ruminal acidosis. LAs can cause significant liver function condemnation and decreased growth and production. Currently, we know little about the liver microbiome in calves with feed-induced acidosis.

Methods

Using our established model of ruminal acidosis, where young calves were fed an acidosis-inducing (AC) or -blunting (control) diet starting at birth until 17-week of age, we investigated microbial community changes in the liver resultant from ruminal acidosis. Eight calves were randomly assigned to each diet, with four animals per treatment. Rumen epithelium and liver tissues were collected at 17 weeks of age right after euthanasia. Total RNAs were extracted and followed by whole transcriptome sequencing. Microbial RNA reads were enriched bioinformatically and used for microbial taxonomy classification using Kraken2.

Results

AC Calves showed significantly less weight gain over the course of the experiment, in addition to significantly lower ruminal pH, and rumen degradation comparison to the control group (p < 0.05). In the liver, a total of 29 genera showed a significant (p < 0.05) abundance change (> 2-fold) between the treatments at 17-week of age. Among these, Fibrobacter, Treponema, Lactobacillus, and Olsenella have been reported in abscessed liver in cattle. Concurrent abundance changes in 9 of the genera were observed in both the liver and rumen tissues collected at 17-week of age, indicating potential crosstalk between the liver and rumen epithelial microbial communities. Significant association was identified between host liver gene and its embedded microbial taxa. Aside from identifying previously reported microbial taxa in cattle abscessed liver, new repertoire of actively transcribed microbial taxa was identified in this study.

Discussion

By employing metatranscriptome sequencing, our study painted a picture of liver microbiome in young calves with or without feed induced acidosis. Our study suggested that liver microbiome may have a critical impact on host liver physiology. Novel findings of this study emphasize the need for further in-depth analysis to uncover the functional roles of liver resident microbiome in liver metabolic acidosis resultant from feed-related ruminal acidosis.

Essential oil blend supplementation in the milk replacer of dairy calves: Performance and health

Supplementation of dairy calves with essential oils in the liquid diet can reduce the incidence and severity of infectious diseases and promote better performance. Our objective was to evaluate an essential oil blend containing peppermint, eucalyptus, and menthol crystals and its effect on performance and health during the pre and postweaning period of dairy calves. At birth, 40 dairy calves (34 males and 6 females) were blocked according to sex and birth weight, randomly assigned to one of two treatments-commercial milk replacer diluted at 14% (MR) and the same liquid diet plus essential oil blend (MREO) at a dose of 4 mL per calf per day, divided into two meals during the first 28 days of life. Calves were individually housed and fed 6 L/d of the liquid diet, divided into two meals, and received starter concentrate and water ad libitum. Weaning was gradually reduced by 1L per day at d 51 until complete weaning at 56 days. After weaning, calves were evaluated until 70 days of age, when the experimental period ended. Intake, fecal, and health scores were evaluated daily, weight and body measures were recorded weekly, and blood parameters were evaluated at weeks 1, 2, 3, 4, and 8. Calves fed MREO tended to have higher total dry matter intake during the preweaning period. Furthermore, MREO calves had lower health scores and fewer days with a health score ≥ 4 (suggestive of bronchopneumonia), tended to lower coughing days and fewer veterinary interventions preweaning, and tended to lower health scores postweaning. The supplementation with a blend of essential oils containing peppermint, eucalyptus, and menthol crystals can reduce respiratory problems. Further studies are needed to investigate the dose and the supplementation period.

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

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

Dairy farmer and farm staff attitudes and perceptions regarding daily milk allowance to calves

The benefits of feeding calves more milk are increasingly being recognized by dairy farmers. However, most producers have still not implemented higher feeding plans. The aim of the present study was to gain a deeper understanding of farmer and farm staff attitudes, and the perceptions and factors considered in their decision-making regarding daily milk allowances. We collected data through focus group interviews with dairy farmers, farm managers, and calf-care workers who were selected using purposive and snowball sampling. In total, 40 persons (24 women and 16 men) joined a focus group interview (6 in all, each with 5-8 participants). Interviews were recorded, and recordings were transcribed and analyzed thematically. Participants had contrasting opinions about the minimum, maximum, and recommended daily milk allowances to their calves. Their suggested lowest daily milk allowance to sustain animal welfare ranged from 4 to 8-10 L and the maximum allowance from 6 to 15 L. We found that farmers' and farm staff's choices and recommendations of milk-feeding protocols were influenced by a large number of factors that could be grouped into 4 themes: (1) Life beyond work, (2) Farm facilities and equipment, (3) Care of the calves, and (4) Profitability and production. Participants' considerations were similar and aimed to maximize daily milk allowance based on farm conditions. However, the allowances they described as optimal for their calves often differed from what they considered practically feasible. We found that the care of the calves and the well-being of the owners and the staff was central in the participants' decision-making, but that this care perspective was challenged by the social and economic sustainability of the farm. Most participants fed their calves twice daily and did not think that increasing that number would be practically feasible. Our results indicate that the participants' viewpoints regarding calves were important for their decision-making about milk allowances. We suggest that a more holistic perspective should be used when advising farmers about milk allowances, putting particular emphasis on the caring and social sustainability aspects of the individual farm.

Effects of weaning strategies on health, hematology, and productivity in Holstein dairy calves

Weaning strategies in dairy calves vary considerably, though the effect on animal health is unclear. This study examined the effects of calf weaning age (6 vs. 8 wk) and pace (abrupt vs. gradual) on performance, blood, and health parameters in dairy calves. The experiment consisted of a 2 × 2 factorial arrangement of treatments, where the factors included weaning age (early vs. late) and weaning pace (abrupt vs. gradual). Holstein calves (n = 72), blocked by sex and birth weight, were randomly assigned to one of 4 treatments (n = 18 per treatment): early-abrupt (EA), early-gradual (EG), late-abrupt (LA), and late-gradual (LG). Milk replacer (24% crude protein, 17% fat; up to 1,200 g/d) was fed twice daily; water, calf starter (18% crude protein), and chopped alfalfa hay were fed ad libitum. Daily intakes of milk replacer, calf starter, and forage were recorded from birth until end of weaning. Body weight, selected health measures, blood hematology, and fecal scores were obtained 1 d preweaning and 1 d postweaning. Calves were orally bolused with a rumen pH logger for the last 3 d of the weaning transition and rumen pH was measured continuously. Data were analyzed with age, pace, age × pace interaction, birthweight, and sex as fixed effects, and starting date as a random effect. Greater age at weaning increased respiration, whereas gradual-weaned calves had lower respiration rate. Heart rate was lower in gradual than in abrupt weaned groups. Fecal score had a marginal increase in late-weaned groups and significantly increased in gradually weaned groups. No difference was detected in body core temperature by age, pace, or interaction. During the weaning transition, average daily gain was lower in LA than EA and gradually weaned groups had an increased average daily gain. Change in grain intake, but not forage intake, was greater in gradually weaned groups. Mean rumen pH marginally increased from EG to LG and from LA to LG. No difference was detected among treatments in red or white blood cell counts, and hemoglobin. Procalcitonin was marginally highest in the LA group, while blood hematocrit increased in abruptly weaned groups. Overall, calf health is affected by both age and pace of weaning, though the health parameters affected by age and pace differ.

Wound healing and pain sensitivity following caustic paste disbudding in dairy calves

Caustic paste disbudding is increasing in popularity on commercial dairy farms in the United States, but little research has explored the pain and welfare implications beyond the acute period of this procedure. In contrast, researchers have reported it takes 7 to 9 wk, on average, for hot-iron disbudding wounds to re-epithelialize in dairy calves. Our objective was to describe wound healing and sensitivity following caustic paste disbudding. Jersey and Holstein female calves were disbudded using caustic paste (H. W. Naylor Company Inc.) at 3 d of age (n = 18), and control calves received a sham procedure (n = 15). Before disbudding, calves received a local block and a nonsteroidal anti-inflammatory drug. Calves ≥34 kg and <34 kg at birth had 0.3 or 0.25 mL of paste applied per unshaved horn bud, respectively. Following disbudding, wounds were scored 2×/wk for the presence or absence of 8 tissue categories, including the final stages: new epithelium and fully healed. Control calves were removed from the experiment after 6 wk to be hot-iron disbudded. Mechanical nociceptive threshold (MNT) measures were collected weekly to evaluate wound sensitivity until calves were removed from the study or healed. Wounds were slow to re-epithelialize (16.2 ± 5.7 wk, mean ± SD; range: 6.2-32.5 wk) and contract to be considered fully healed (18.8 ± 6 wk, mean ± SD; range: 8.7-34.1 wk). Compared with non-disbudded controls, paste calves exhibited lower MNT values for all 6 wk (mean ± SE; control: 1.46 ± 0.16; paste: 1.18 ± 0.12 N). These data indicate that wounds from caustic paste disbudding are more sensitive than undamaged tissue for at least 6 wk and take twice as long to heal compared with cautery methods described in the literature. In conclusion, caustic paste disbudding wounds took 18.8 wk to fully heal and were more sensitive than intact horn buds for 6 wk. Future work should examine whether aspects of paste application (e.g., amount used, time rubbed in, calf age, pain mitigation) could improve healing time and sensitivity.

Behavioral changes in the first 3 weeks after disbudding in dairy calves

Hot-iron disbudding, the practice of cauterizing horn bud tissue to prevent horn growth in dairy calves, results in behavioral changes indicative of pain in the first few days after the procedure. However, few studies have quantified behavioral changes in the following weeks, while the burn wounds are still healing. Female Holstein calves were disbudded with a heated iron and pain relief (5.5 mL lidocaine cornual nerve block and 1 mg/kg oral meloxicam) at 4 to 10 d of age (n = 19) or not disbudded (n = 19). Calves wore ear tag accelerometers that reported the dominant behavior being performed at 1-min intervals from 3 to 21 d after disbudding. Compared with age-matched controls, disbudded calves tended to spend more time inactive throughout the observation period, ruminated less in the first 3 to 11 d after disbudding, and sucked more from a milk bottle beginning 5 d after disbudding until the end of the 21-d observation period. In addition to the accelerometer data, live observations of sleeping (using a behavioral proxy), lying, and ruminating were collected using instantaneous sampling at 5-min intervals for 24-h periods 3, 10, and 17 d after disbudding. Disbudded calves slept with their head down more on all live observation days and spent more time lying on the 17th d after disbudding, but ruminating did not differ compared with controls, in contrast to the accelerometer results. More time spent inactive, sleeping, and lying, and less time spent ruminating (as indicated by the accelerometer) can be interpreted as attempts to reduce painful stimulation of the disbudding wounds and allocate energy to healing. It is unclear whether the greater amount of sucking in the disbudded calves is nutritive (milk present) or non-nutritive (milk absent), as the algorithm did not distinguish the type of sucking, and further research is needed to explore the factors underlying this effect. We conclude that disbudding alters daily behavior patterns for at least 3 wk, far beyond the duration of recommended pain medication, raising additional welfare concerns about the procedure.

Whole cottonseed inclusion in starter feeds improves performance, inflammometabolic profile, and rumination behavior in Holstein dairy calves

The high energy, protein, and fiber contents of whole cottonseed make it a potential candidate for the inclusion in calf starters to promote the rumen development. This study aimed at assessing whether the inclusion of whole cottonseed in the starter would affect performance, metabolic profile, and rumination time in Holstein dairy calves. From 2 to 55 d of age, 12 heifer calves were fed a constant amount of milk replacer twice daily (8 L/d), whereas from 56 to 65 d (weaning) milk replacer was gradually reduced (from 4 to 1 L/d) and fed in a single meal. Calves were blocked by birth body weight and % Brix of colostrum received and randomly assigned to 1 out of 2 dietary treatments: (1) control starter (CTR); (2) starter with 8% inclusion of whole cottonseed (WCS). Treatments were fed for ad libitum intake. From d 56, TMR and hay were offered ad libitum. At 0, 2, 7, 21, 65, and 80 d, BW was measured and blood samples were collected. Feed intake and rumination time were automatically recorded. Compared with CTR, WCS calves were heavier at weaning and after weaning, and consumed more starter from 59 to 72 d. In the immediate postweaning (from 66 to 72 d of age), rumination time increased more in WCS calves. Overall, WCS calves had greater plasma glucose, β-carotene, and retinol concentrations, whereas ceruloplasmin and myeloperoxidase were lower. Calves in the WCS group had greater glucose concentration at 21 and 65 d and lower urea at 65 d (weaning). Plasma β-carotene concentration was greater at 65 and 80 d in calves of the WCS group compared with CTR calves. At 80 d, WCS calves had lower plasma alkaline phosphatase and greater β-hydroxybutyrate, paraoxonase, and tocopherol. These results suggest that inclusion of WCS in the calf starter might be beneficial for rumen development, leading to greater feed intake and BW. Moreover, WCS inclusion was associated with lower oxidative stress and inflammation, improved energy metabolism and liver functionality, and likely quicker rumen development, as might be indicated by the higher plasma β-hydroxybutyrate and rumination time. These changes occurred mainly after weaning, when no differences in starter intake and average daily gain were detected, suggesting a better efficiency of nutrient utilization at this age.

Physical, Metabolic, and Microbial Rumen Development in Goat Kids: A Review on the Challenges and Strategies of Early Weaning

The digestive system of newborn ruminant functions is similar to monogastric animals, and therefore milk flows into the abomasum instead of rumen for digestion. The rumen undergoes tremendous changes over time in terms of structure, function, and microbiome. These changes contribute to the smooth transition from the dependence on liquid diets to solid diets. Goat kids are usually separated at early ages from their dams in commercial intensive systems. The separation from dams minimizes the transfer of microbiota from dams to newborns. In this review, understanding how weaning times and methodologies could affect the normal development and growth of newborn goats may facilitate the development of new feeding strategies to control stress in further studies.

Gradually weaning goat kids may improve weight gains while reducing weaning stress and increasing creep feed intakes

Most dairy goat farms rear kids on ad libitum milk replacer; calf research suggests this improves growth and welfare, but solid feed intakes are problematic. Weaning can be gradual (incremental milk reduction) or abrupt (sudden, complete milk removal, which evidence suggests reduces welfare). Three treatments were created: abrupt weaning (AW: ad libitum milk until weaning) and gradual weaning [milk ad libitum until day 35, then milk unavailable 3.5 h/day until day 45 when milk removal was a 7 h/day block (gradual weaning 1: GW1) or two 3.5 h/day blocks (gradual weaning 2; GW2)]; complete milk removal occurred at day 56 for all. Experiment 1 investigated on-farm feasibility, behavior, and average daily gain (ADG). Experiment 2 investigated feed intakes, behavior, and ADG for AW and GW2. Experiment 1 had 261 kids (nine pens of 25-32), CCTV recorded 6 h/day, and group-level scan sampling recorded target behaviors. Kruskal-Wallis tests showed GW2 kids spent more time feeding on solids during weaning (p = 0.001) and displayed lower levels of 'frustrated suckling motivation' PostWean (p = 0.008). However, feeding competition differed PreWeaning (p = 0.007). ADG data from 159 female kids analyzed by a general linear model (fixed factor: treatment; covariate: day 34 weight) found GW2 had the highest ADG from day 35-45 (p ≤ 0.001) and no differences from day 45 to 56, and AW had the highest ADG PostWean (day 56-60). Experiment 2 had two AW pens (9 kids/pen) and two GW2 pens (8 and 9 kids/pen). A computerized feeder recorded milk intakes from day 22 to 56. Pen-level solid feed/water intakes were recorded from day 14-70. General linear models (fixed factor: treatment; covariate: PreWean value) found GW2 kids had higher ADG (p = 0.046) and lower milk intake (p = 0.032) from day 45-55, and PostWean (day 56-70) trended toward GW2 higher ADG (p = 0.074). Mann-Whitney U tests showed pen-level feed intake differences: AW had higher creep and straw throughout, GW2 showed higher creep during weaning (day 35-55), and higher water PostWean (>56 d). Behavioral observations suggest that gradually weaned kids may have enhanced welfare. Pen-level gradual weaning is feasible and, while weight gain results were mixed, it reduced milk intake, increased creep intake, and therefore combined with behavioral evidence can be recommended.

Review: Feeding strategies for rearing replacement dairy goats - from birth to kidding

Goat kid rearing is a key profit driver and the cornerstone of future herd productivity in dairy systems. As goat kids get older, and progress from liquid (i.e., colostrum, milk) to solid feed (i.e., concentrate, hay, pasture), there is a reduction not only in feed cost but also in labour cost, disease susceptibility and mortality rates. Hence, research on rearing dairy goats has traditionally focused on improving early neonatal performance. However, recent research reveals that early-life nutrition may have long-term effects, and consequently, impact the lifetime productive performance and health of dairy goats. Therefore, this literature review has collected research on the various aspects of rearing replacement dairy goat kids in different production systems. It summarises research on areas such as colostrum management (i.e., colostrum quality, time, volume and frequency of colostrum feeding), liquid feeding in preweaned kids (i.e., maternal suckling vs artificial, restricted vs unrestricted), weaning strategies (i.e., abrupt vs step-down), and postweaning to postpubertal nutrition in replacement dairy goats, whilst highlighting gaps in the existing literature, and areas where it would be beneficial to refine and validate current recommendations. Such information can be used in the development of management plans to maximise the benefits of early-life nutrition on the long-term productivity of dairy goats.

Personality of individually housed dairy-beef crossbred calves is related to performance and behavior

The aim of this study was to evaluate differences in behavioral responses of individually housed dairy-beef crossbred calves to standardized personality tests (novel person, novel object, and startle test) and investigate associations of personality traits with performance and home pen behavior. Dairy-beef crossbred (Holstein x Angus) calves (n=29) were individually housed with ad libitum access to water and calf starter. Body weight was measured weekly and calf starter intake was recorded daily from day of arrival (8.5 ± 2.1; experimental day 1) for 76 days. Behavior within the home pen (eating, drinking, non-nutritive oral manipulation) and activity were recorded on experimental days 13, 32, 53, and 67 using a camera and a pedometer. The calves were subjected to standardized personality tests in their home pen at the end of the experimental period (80.7 ± 2.0 d of age), including a novel person test (stationary person in the corner of their home pen) and combined novel object/startle test (remote-controlled car in the pen, that suddenly moved when touched). A principal component analysis on the behaviors recorded from the tests (latency to approach person or object, time spent attentive and touching the person or object, and time spent inactive, playing and grooming) yielded 3 factors that explained 76.1% of the variance, and were interpreted as personality traits labeled “fearful”, “inactive”, and “bold”. These factors were examined in regression analyses for their associations with home pen behavior and performance. The factor “fearful” had negative associations with total average daily gain and average grain intake. In contrast, the factor “inactive” had positive associations with non-nutritive oral manipulation of buckets or walls. The factor “bold” had no significant association with any of the performance or home pen behavior measures. In conclusion, personality traits identified from standardized tests were related to performance and home pen behavior measures in individually housed, crossbred calves. These results complement work in group housed calves suggesting personality testing may be useful selective tools to identify high and low performing calves from an early age.

Effects of starch content of calf starter on feed intake, growth performance, and fecal properties in dairy calves under a high plane of milk replacer feeding

The objective of this study was to investigate the effects of different starch contents in calf starter on the growth, feed intake, and fecal characteristics in dairy calves fed under a high plane of nutrition. Twenty-seven Holstein calves were assigned equally to one of three calf starter treatment groups in a randomized block design: high (H) starch (41.8%); medium (M) starch (31.9%); and low (L) starch (22.0%). Milk replacer was fed up to 1.2 kg/day as fed, gradually reduced from 6 weeks of age; calves were weaned at 8 weeks of age. Each starter (up to 3.5 kg/day as fed) and chopped hay were provided ad libitum from 5 days of age. Fecal samples, along with body measurements, were collected from 4 to 13 weeks of age. The average daily gain after weaning was greater in the H group than in the L group. The average starter intake for 3 days before weaning was not different among treatments but was greater after weaning in the H group than in the L group. Starter starch content did not affect the number of days with diarrhea or fecal starch concentration. The high-starch starter had no adverse effects during the weaning transition.

The development of sleep-like posture expression with age in female Holstein calves

Sleep plays an important role in cattle production and welfare. Therefore, this study aimed to investigate the development of sleep-like posture (SLP) expression in dairy calves from birth to the first calving as an indicator of their sleep behavior. Fifteen female Holstein calves were subjected. Daily SLP was measured eight times (0.5, 1, 2, 4, 8, 12, and 18 months and 23 months or 1 month before the first calving) using an accelerometer. Calves were kept in individual pens until weaning at 2.5 months old and then kept in the group. The daily SLP time decreased rapidly in early life; however, the rate of decrease gradually slowed and eventually reached a stable level of approximately 60 min/day after 12 months old. The daily SLP bout frequency showed the same change as the SLP time. In contrast, the averaged SLP bout duration slowly decreased with age. Longer daily SLP time during early life in female Holstein calves might be related to brain development. The individual expression of daily SLP time differs before and after weaning. Some external and/or internal factors associated with weaning may be involved SLP expression.

Response to ad libitum milk allowance by crossbred dairy and dairy-beef calves in an automated feeding system

The objective of this study was to compare three-breed rotational crossbred calves sired by Holstein, Jersey, Montbéliarde, Normande, Viking Red, and Limousin bulls with Holstein's calves fed a high milk allowance for growth, milk consumption, health scores, and profitability in an automated group feeding system. Breed groups were Holstein (n = 16), crossbreds of Montbéliarde, Viking Red, and Holstein (n = 24), crossbreds of Jersey, Normande, and Viking Red (n = 6), and Limousin crossbred beef × dairy (n = 45) calves. Calves were randomly assigned within the breed to one of two treatments from September 2019 to June 2020 at the University of Minnesota West Central Research and Outreach Center in Morris, MN. The five breed groups were balanced across the two treatment groups. Treatment groups were fed 8 L/d (8 L) or ad libitum (AL) milk allowance, and calves were introduced to the automated feeder at day 5 and were weaned at 56 d. Milk feeding behaviors (drinking speeds) were collected from the automatic feeding system and analyzed by feeding and breed groups. Body weights were recorded at birth and weekly through weaning. The health scores of calves were recorded twice per week. Variables included in the statistical model for analyses were fixed effects of birthweight, the season of birth, breed group, and treatment group. Calves fed AL had a greater weaning weight (P = 0.001; 106.4 kg vs. 91.4 kg) and greater (P = 0.001) average daily gain (ADG; 1.11 kg/d vs. 0.87 kg/d) than calves fed 8 L, respectively. The calves fed AL (1,064 mL/min) had a slower drinking speed (P = 0.01) than calves fed 8 L (1,467 mL/min). Most breed groups were not different for weaning weight or ADG across the 56 d. Daily milk consumption per calf was lower (P = 0.009) for Limousin crossbred calves compared with Holstein and crossbred dairy calves. As expected, AL calves had higher (P = 0.001) milk cost ($189.52) than the 8 L calves ($140.71). The average cost per kilogram of gain was similar for calves fed 8 L ($2.89/kg) compared to AL ($3.00/kg) calves. Overall, the Limousin crossbred calves had the least milk cost ($152.75) compared with Holstein ($175.67) calves and Montbéliarde, Viking Red, and Holstein crossbred calves ($177.13). The results from this study found that although feeding calves AL resulted in greater milk consumption and higher cost than 8 L calves, there may be an economic advantage with costs per kilogram of gain to feeding calves ad libitum if increased growth rates are realized.

Age and Post-Prandial Variations on Selected Metabolites in Dairy Calves Fed Different Liquid Diets

The aim of this study was to evaluate the age and post-prandial variations in selected metabolite concentration that may indicate a shift in metabolism, from pre- to functional ruminant, according to the liquid diet fed to dairy calves. Sixteen newborn Holstein calves were included in the study in a randomized complete block experimental design. The calves were individually housed and fed 6 L/d with whole milk (WM) or milk replacer (MR). Blood samples were collected weekly at 0 h (before feeding), 1 h, 2 h, 4 h, and 8 h after morning feeding to evaluate glucose, β-hydroxybutyrate (BHB), fructosamine, total protein, and albumin. Calves fed WM had higher performance (p < 0.01) than did calves fed MR. The different liquid diets did not affect the average concentrations of plasma glucose. However, BHB was higher for WM-fed calves (p < 0.01). The concentration of plasma glucose reached the highest concentration at 1 and 4 hours after feeding WM or MR, respectively. Thus, these would be the most appropriate sampling times to study the glycemic status of calves according to the liquid diet fed. Fructosamine did not prove to be an informative metabolite to understand the shift in metabolism, as a function of rumen development, due to a small reduction as a function of age and a sampling time effect.

Assessing Performance and Safety of Feeding a Standardized Macleaya cordata Extract to Calves

This study examined the effects of Sangrovit®, a Macleaya cordata plant extract (MCE) preparation on feed intake, growth, blood chemistry, and tissue-residue levels of calves. Twenty male and 20 female calves (~5 d of age) were assigned to one of four daily Sangrovit® doses: 0.0 and 0.0 (CTL), 2.0 and 4.0 (D1), 5.0 and 10.0 (D2), and 10.0 and 20.0 (D3) g/calf in pre-weaning (5 to 49 d of age) and post-weaning (50 to 95 d of age) periods, respectively. Sangrovit® doses were fed in milk replacer pre-weaning and top-dressed on calf starter post-weaning. Milk replacer and calf starter intake was recorded daily. Body weight, hematology, and serum chemistry were measured at 5, 49, and 95 d of age. Calves were slaughtered at 95 d of age for MCE tissue residue analysis. Compared to CTL, D1 increased milk-replacer intake (4.90 to 5.09 L/day), but decreased calf starter intake pre- (0.65 to 0.53 kg/d) and post-weaning (3.42 to 3.20 kg/d). No Sangrovit® dose affected average daily gain. The hematology and blood chemistry of all treatment groups fell within the ranges of healthy calves. Results showed no adverse effects of MCE on health and growth performance of calves when fed up to 10.0 g/calf/day pre-weaning and up to 20.0 g/calf/day post-weaning.

A “Good Life” for Dairy Cattle: Developing and Piloting a Framework for Assessing Positive Welfare Opportunities Based on Scientific Evidence and Farmer Expertise

Simple Summary

There is increasing appetite to understand how we can provide quality of life to farm animals. A framework to evaluate positive welfare opportunities for dairy cattle was developed using a participatory approach where farmer’s recommendations were integrated into a scientific framework and piloted on farm by vets. When provided with the opportunity to collaborate, farmers and scientists broadly agree on what constitutes “a good life” for dairy cattle and worked together to develop an assessment framework. Farmers did not agree equally on the value of each positive welfare opportunity. However, farmers supported positive welfare assessment as a means of recognition and reward for higher animal welfare, within existing farm assurance schemes, and to justify national and global marketing claims of higher animal welfare.

Abstract

On-farm welfare assessment tends to focus on minimising negative welfare, but providing positive welfare is important in order to give animals a good life. This study developed a positive welfare framework for dairy cows based on the existing scientific literature which has focused on developing positive welfare indicators, and trialled a participatory approach with farmers; refining the framework based on their recommendations, followed by a vet pilot phase on farm. The results revealed that farmers and scientists agree on what constitutes “a good life” for dairy cattle. Farmers value positive welfare because they value their cows’ quality of life, and want to be proud of their work, improve their own wellbeing as well as receive business benefits. For each good life resource, the proportion of farmers going above and beyond legislation ranged from 27 to 84%. Furthermore, barriers to achieving positive welfare opportunities, including monetary and time costs, were not apparently insurmountable if implementation costs were remunerated (by the government). However, the intrinsic value in providing such opportunities also incentivises farmers. Overall, most farmers appeared to support positive welfare assessment, with the largest proportion (50%) supporting its use within existing farm assurance schemes, or to justify national and global marketing claims. Collaborating with farmers to co-create policy is crucial to showcase and quantify the UK’s high welfare standards, and to maximise engagement, relevance and uptake of animal welfare policy, to ensure continuous improvement and leadership in the quality of lives for farm animals.

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.

An Evaluation of Nutritional and Therapeutic Factors Affecting Pre-Weaned Calf Health and Welfare, and Direct-Fed Microbials as a Potential Alternative for Promoting Performance—A Review

The priority for calf rearing has been to maintain good health and welfare in order to promote and sustain future production. However, there have been numerous reports of undesirable levels of morbidity and mortality amongst pre-weaned calves. This may be mitigated or exacerbated by nutritional management practices. Some areas of concern include colostrum feeding, utilization of waste milk, and restrictive milk feeding regimes. Antibiotics may be prescribed at lethal or sub-inhibitory doses to treat or prevent disease. However, extensive antibiotic use may disrupt the gastrointestinal microbiota and aid in expanding the antibiotic resistant gene pool. In an attempt to reduce the use of antibiotics, there is a demand to find alternative performance enhancers. Direct-fed microbials, also known as probiotics, may comply with this role. A DFM consists of live microorganisms that are biologically active and able to confer health benefits onto the host. Lactic acid bacteria have been the most frequently investigated; however, this field of research has expanded to include spore-forming bacteria and live yeast preparations. This review aims to provide a comprehensive evaluation of the nutritional management strategies that may increase a calf’s susceptibility to morbidity and mortality, the efficacy and sustainability of antibiotics as a tool for managing calf health and welfare, and the potential for DFMs as a supportive strategy for promoting calf wellbeing.

Performance of Holstein calves receiving equal solids per day from high-solids milk and milk replacer blend once or twice daily combined with dry versus wet fine-particle starter diet

This study examined the effects of frequency of feeding high-solids milk and milk replacer (MMR) blend combined with dry matter (DM) content of starter feed on the performance of dairy calves. Forty-eight Holstein calves (40.2 ± 3.33 kg of body weight) were randomly assigned to 1 of 4 treatments in a completely randomized design. Based on a combination of 2 MMR feeding frequencies (once versus twice daily) and 2 starter DM levels (91.1 and 50% DM), 4 treatments were designed as (1) once daily + dry starter feed (OD), (2) once daily + wet starter feed (OW), (3) twice daily + dry starter feed (TD), and (4) twice daily + wet starter feed (TW). The amount of milk replacer powder added to whole milk was adjusted at each feeding frequency to ensure that calves received similar solids from the MMR blend via the twice-daily (total solids = 18.6%) or once-daily (total solids = 31.0%) programs. Starter intake in the preweaning period did not differ between treatments (average 0.39 kg of DM/d), but the postweaning starter intake was greater in calves fed the wet starter (OW and TW) than in those fed the dry starter (OD and TD). Calves receiving the high-solids MMR blend twice versus once daily grew faster before weaning, which was reflected by a greater weaning weight in the TD and TW groups (88.9 kg) than in the OD and OW groups (83.2 kg). The daily growth rate after weaning did not differ between treatments and averaged 1.15 kg/d. Gain-to-feed ratio during the preweaning period was greater in calves from TD and TW (mean 0.67) than in calves from the OD or OW groups (mean 0.58). Postweaning gain-to-feed ratio was not different among treatments and averaged 0.38. Days to first diarrhea and duration of diarrhea (4.66 ± 0.38), as well as days that animals were treated with antibiotics, remained unaffected with treatments. Although preweaning body weight gain was lower with once-daily milk feeding, calves were twice as heavy at weaning as at birth in both milk feeding programs regardless of starter moisture content, which may qualify the once-daily milk feeding program as a cost-effective management strategy in commercial calf-rearing operations. Feeding solutions with a high solids content (above 15%) may be associated with an increased risk of abomasal bloat and should be used with caution.

Impacts of Reducing Protein Content in Milk Replacer on Growth Performance and Health of Young Calves

In the present study, a drinking amount of 10 L of milk replacer (MR) was allowed to dairy calves in order to approach the natural drinking behavior. The question is: how much protein is required by calves in order to achieve an intended growth rate? For this reason, sixty-eight pre-weaned Holstein calves were divided into two groups and fed with 10 L/d of MR containing either 22% protein (MR22) or 19% protein (MR19) at an almost comparable energy intake. Effects on performance, metabolic status, and health were compared. Feed intake, growth performance, and health status were monitored during the pre-transition, transition, and postweaning phase (until 157 d of age). Total feed intake, and intake of MR, body weight (BW), and average daily gain (ADG) were not significantly different between MR22 and MR19 during the entire experimental period (p > 0.05). At d 42, calves in MR19 group showed greater serum levels of growth hormone (16.2 vs. 22.2 ng/mL; p = 0.02), insulin-like growth factor 1 (262 vs. 291 ng/mL; p = 0.03), and urea (2.86 vs. 3.04 mmol/L; p < 0.01). The results of the present study suggested that when high amounts of MR are provided, the protein content in MR can be reduced to 19% without any adverse effects on growth performance as well as on health status of dairy calves.

Early Stepdown Weaning of Dairy Calves with Glutamine and Branched-Chain Amino Acid Supplementations

Simple Summary

We demonstrated previously that supplementation of glutamine (Gln) at 2.0% of dry matter intake (DMI) increased the rate at which dairy calves achieved ≥1.0 kg/d starter feed intake (SFI) during weaning. Because Gln supplements at <1.0% of DMI or branched-chain amino acid (BCAA) supplements have been shown to improve the performance of weaning piglets, we examined the effects of a lower dose of Gln (8.0 g/d equivalent to 1% of DMI) alone or in combination with BCAA supplementations on SFI and average daily gain (ADG) in this study. Amino acids did not affect SFI or ADG during the supplementations but decreased post-weaning SFI in an additive manner even though the ADG was not affected. The blood analysis on the last day of supplementations revealed a possibility for the Gln and BCAA supplementations to suppress SFI through leptin and serotonin secreted by the gastrointestinal tract.

Abstract

The study objective was to examine the effects of supplementing Gln and BCAA on the SFI and ADG of weaning dairy calves. Holstein heifer calves (11 calves /treatment) at 35 d of age were assigned to: (1) no amino acids (CTL), (2) Gln (8.0 g/d) alone (GLN), or (3) Gln (8.0 g/d) and BCAA (GLNB; 17.0, 10.0, and 11.0 g/d leucine, isoleucine, and valine, respectively) supplementations in whole milk during a stepdown weaning scheme. Calves were weaned completely once they achieved ≥1.0 kg/d SFI. Neither GLN nor GLNB affected SFI or ADG in the first week during weaning. The GLNB decreased SFI compared to CTL, but the SFI was similar between CTL and GLN in the remainder of the weaning scheme. All calves were weaned at 50 d of age. The SFI of GLNB was lower than that of GLN, and the SFI of both GLN and GLNB were lower than CTL post-weaning. The decreased SFI did not alter ADG during weaning or post-weaning. The GLNB tended to have higher plasma leptin and lower plasma serotonin concentrations compared to CTL. Glutamine and BCAA seem to affect the SFI of calves by modulating the secretions of endocrine cells in the gastrointestinal tract.

Graduate Student Literature Review: Role of pain mitigation on the welfare of dairy calves undergoing disbudding

This review synthesizes research findings on the pain and welfare of dairy calves undergoing disbudding procedures. We describe disbudding practices in North America as well as the use and perceptions of pain control for these procedures. Governing bodies across Canada and the United States, including each country's veterinary medical association and nationwide initiatives such as proAction and Farmers Assuring Responsible Management (FARM), recommend or require the use of a local anesthetic, a nonsteroidal anti-inflammatory drug (NSAID), and a sedative for disbudding procedures. Although the use of pain relief for disbudding has increased over the past decade or so, some in the dairy industry still do not believe that pain control for disbudding is necessary. As a painful procedure, disbudding has numerous welfare impacts on the calf both during and following the procedure that can be categorized under all 3 principles of animal welfare: natural living, biological functioning, and affective state. The use of pain control for disbudding; namely, a local anesthetic and NSAID, can improve welfare outcomes such as procedure-induced pain behavior, cortisol concentrations, mechanical nociceptive threshold, emotional states, and so on, compared with no pain control for the procedure. Although extensive research exists on pain control practices for disbudding, this review identified further gaps in knowledge and areas for future research. Mechanical nociceptive threshold can be evaluated around the disbudding wounds and is a reliable test in older calves; however, this outcome in very young calves after caustic paste disbudding has been reported to be inconclusive compared with that in older calves. As well, research evaluating xylazine sedation for disbudding has reported both potentially positive and negative results that are difficult to interpret or base suggestions on for the use of this drug. Finally, wounds caused by disbudding take a long time to heal (up to 13 wk) and have increased sensitivity for the entire healing process. Therefore, future research should aim to (1) determine accurate behavioral tests for calves under 1 wk of age undergoing disbudding to better understand their experience, (2) further attempt to understand the effects of xylazine sedation for disbudding and potential impacts of providing this medication, and (3) determine more ways to reduce the healing time and pain experienced by the calf after disbudding procedures.

Impact of dietary supplementation of β-hydroxybutyric acid on performance, nutrient digestibility, organ development and serum stress indicators in early-weaned goat kids

The objective of this study was to determine the effect of dietary supplementation of β-hydroxybutyric acid (BHBA) on performance, nutrient digestibility, organ development, and serum composition in early-weaned goat kids. Sixty-four goat kids at 30 d of age were assigned to 4 treatments in a completely randomized design: 1) control (basal diet); 2) low (basal diet with 3 g/d per animal BHBA); 3) medium (basal diet with 6 g/d per animal BHBA; and 4) high (basal diet with 9 g/d per animal BHBA). Subsequently, 48 (6 kids per treatment) goat kids were randomly selected and slaughtered at 60 and 90 d of age. Compared with the control group, BHBA at low and high doses increased body weight (P < 0.05), average daily gain (P < 0.01), and average daily starter intake (P < 0.01). The BHBA improved organ development, especially at the lowest dose (P < 0.01). The digestibility of dry matter and crude protein increased with age (P < 0.05). However, BHBA did not affect nutrient digestibility. Compared with the control group, serum ceruloplasmin increased (P < 0.05) with high BHBA level at 90 d of age. However, the serum creatinine (P < 0.05) increased over time but was not affected by BHBA. The serum total antioxidant capacity and superoxide dismutase decreased with the high dose of BHBA at 90 d of age (P < 0.01). In contrast, the serum glutathione peroxidase and malondialdehyde increased with the high doses of BHBA (P < 0.01). Overall, low doses of BHBA were positive for growth performance, organ development, and health status against weaning stress. Whereas high doses of BHBA in the long term could negatively affect antioxidant status.

Sucking and drinking behaviour in preweaned dairy calves in the first five weeks of life

Background

Nursing and sucking are essential for adequate nourishment of preweaned calves and the relationship between sucking indices has not been studied. The goal of this study was to investigate the number of sucks per litre of milk and per minute of drinking and the amount of milk ingested per suck in healthy preweaned calves. Correlation coefficients were calculated for the relationships between these variables. Eighteen healthy calves were used from birth to 5 weeks of age, and five measurements were made at the end of weeks 1 to 5. The calves were randomly divided into three groups and offered milk twice daily in a bucket with a rubber nipple. The amount of milk offered per day was equal to 12% of body weight in group A and 16% of body weight in group B. Calves in group C were offered as much milk as they wanted during each feeding period. The duration of drinking was determined with a stopwatch, and the number of sucks was counted with a handheld tally counter. The variables drinking duration, total amount consumed and the number of sucks required were used to calculate the number of sucks/min, the number of sucks/L, the amount ingested per suck and drinking speed.

Results

The number of sucks/min ranged from 113 to 133 and increased significantly during the study period. The mean number of sucks/L decreased from 204 in week 1 to 141 in week 5 and drinking speed increased from 0.6 to 1.0 L/min. There were significant correlations between the number of sucks/L of milk and the amount of milk ingested per suck, drinking duration, total amount consumed and drinking speed. Drinking speed was positively correlated with the amount of milk ingested per suck and the total amount of milk consumed, and negatively correlated with drinking duration.

Conclusions

These findings show that drinking variables of calves offered different amounts of milk vary little and significant changes occur during the same period with respect to the number of sucks/L of milk and the amount of milk ingested per suck. Several drinking variables are significantly correlated with other variables.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-022-03280-x.

Effect of plane of nutrition and analgesic drug treatment on wound healing and pain following cautery disbudding in preweaning dairy calves

The objective of this study was to determine the effect of a biologically normal plane of nutrition compared with a limited plane on the primary outcome wound healing, and one dose of nonsteroidal anti-inflammatory drug (NSAID) compared with 2 on the secondary outcomes: lying behavior, haptoglobin concentrations, and mechanical nociceptive threshold (MNT) in calves disbudded via cautery iron. Eighty female Holstein calves were enrolled at birth, individually housed, and fed via a Calf Rail system (Förster Technik). A 2 × 2 factorial design was used to assess the effect of plane of nutrition and an additional NSAID. Calves were randomly assigned to a biologically normal plane of nutrition (BN; offered up to 15 L/d) or a limited plane (LP; offered up to 6 L/d) and to receive one or 2 doses of meloxicam. All calves received a lidocaine cornual nerve block and a subcutaneous injection of meloxicam 15 min before cautery disbudding at 18 to 25 d of age, and half the calves received an additional injection of meloxicam (0.5 mg/kg) 3 d after disbudding. Tissue type present, wound diameter, and wound depth were evaluated 2 times per week for 7 to 8 wk as measures of wound healing, lying behavior was recorded beginning 1 to 2 wk before disbudding until 7 to 8 wk after as a behavioral indicator of pain, haptoglobin concentrations were measured once per day for 7 d after disbudding, and MNT was evaluated 2 times/wk for 3 wk. Survival analyses were analyzed using Cox regression models (wound healing) and continuous data were analyzed using mixed-effect linear regression models. Only 12% of horn buds were completely healed by 7 to 8 wk after disbudding and 54% had re-epithelized at this time. At any time, wounds from BN calves were more likely to have had re-epithelization occur compared with wounds from LP calves (hazard ratio: 1.93, 95% CI: 1.18-3.14). Wounds from calves that received only one dose of NSAID were more likely to have re-epithelization occur, compared with wounds from calves given 2 doses (hazard ratio: 1.87, 95% CI: 1.15-3.05). Wounds from BN calves had smaller diameters and depths over time beginning on wk 3 compared with LP calves. Wounds from calves that received an additional NSAID had larger diameters and depths over time beginning on wk 4 and 3 respectively, compared with calves that only received one dose of NSAID. Calves that received an extra NSAID tended to be less sensitive 7, 10, and 17 d after disbudding compared with calves that only received one dose and spent less time lying in the week after disbudding. Calves on the BN milk program were more active compared with LP calves with lower lying times, fewer lying bouts per day, and longer average lying bouts. Our results indicate that a BN milk feeding program for calves can result in faster healing times and more activity, and that providing an extra NSAID 3 d after disbudding appears to slow the healing process but may result in less pain experienced by the calf 1 to 2 wk after the procedure. This study is also among the first to demonstrate that after the complete removal of the horn bud, wounds can take more than 8 weeks to re-epithelize and fully heal.