Effect of vitamin D source and amount on vitamin D status and response to endotoxin challenge

The objectives were to test the effects of dietary vitamin D₃ [cholecalciferol (CHOL)] compared with 25-hydroxyvitamin D₃ [calcidiol (CAL)] on vitamin D status and response to an endotoxin challenge. Forty-five Holstein bull calves (5 ± 2 d of age) were blocked into weekly cohorts, fed a basal diet that provided 0.25 µg/kg body weight (BW) CHOL, and assigned randomly to 1 of 5 treatments: control [(CON) no additional vitamin D], 1.5 µg/kg BW CHOL (CHOL1.5), 3 µg/kg BW CHOL (CHOL3), 1.5 µg/kg BW CAL (CAL1.5), or 3 µg/kg BW CAL (CAL3). Calves were fed milk replacer until weaning at 56 d of age and had ad libitum access to water and starter grain throughout the experiment. Treatments were added daily to the diet of milk replacer until weaning and starter grain after weaning. Measures of growth, dry matter intake, and serum concentrations of vitamin D, Ca, Mg, and P were collected from 0 to 91 d of the experiment. At 91 d of the experiment, calves received an intravenous injection of 0.1 µg/kg BW lipopolysaccharide (LPS). Clinical and physiological responses were measured from 0 to 72 h relative to LPS injection. Data were analyzed with mixed models that included fixed effects of treatment and time, and random effect of block. Orthogonal contrasts evaluated the effects of (1) source (CAL vs. CHOL), (2) dose (1.5 vs. 3.0 µg/kg BW), (3) interaction between source and dose, and (4) supplementation (CON vs. all other treatments) of vitamin D. From 21 to 91 d of the experiment, mean BW of supplemented calves was less compared with CON calves, but the effect was predominantly a result of the CHOL calves, which tended to weigh less than the CAL calves. Supplementing vitamin D increased concentrations of 25-hydroxyvitamin D in serum compared with CON, but the increment from increasing the dose from 1.5 to 3.0 µg/kg BW was greater for CAL compared with CHOL (CON = 18.9, CHOL = 24.7 and 29.6, CAL = 35.6 and 65.7 ± 3.2 ng/mL, respectively). Feeding CAL also increased serum Ca and P compared with CHOL. An interaction between source and dose of treatment was observed for rectal temperature and derivatives of reactive metabolites after LPS challenge because calves receiving CHOL3 and CAL1.5 had lower rectal temperatures and plasma derivatives of reactive metabolites compared with calves receiving CHOL1.5 and CAL3. Supplementing vitamin D increased plasma P concentrations post-LPS challenge compared with CON, but plasma concentrations of Ca, Mg, fatty acids, glucose, β-hydroxybutyrate, haptoglobin, tumor necrosis factor-α, and antioxidant potential did not differ among treatments post-LPS challenge. Last, supplementing vitamin D increased granulocytes as a percentage of blood leukocytes post-LPS challenge compared with CON. Supplementing CAL as a source of vitamin D to dairy calves was more effective at increasing serum 25-hydroxyvitamin D, Ca, and P concentrations compared with feeding CHOL. Supplemental source and dose of vitamin D also influenced responses to the LPS challenge.

A scoping review of neonatal calf diarrhea case definitions

Various case descriptions and scoring systems have been used to define neonatal calf diarrhea (NCD) and diverse diarrhea-related outcomes are reported, which limits direct comparison between studies. Therefore, the objective of this scoping review was to characterize the case definitions used for NCD and describe diarrhea-related outcomes to inform future efforts towards standardization. A literature search identified articles using 3 databases (Medline, CAB Direct, Agricola), along with Google and Google Scholar. This returned 16,854 unique articles, which were then screened for eligibility by two independent reviewers, resulting in 555 being selected for data extraction. Among articles, the study populations included mostly dairy-breed calves (88%; n = 486) while the remainder evaluated beef, crossbred, or dual purpose beef/dairy calves (10%; n = 53), or did not report breed (3%; n = 16). Studies used between 1 and 8 metrics to define NCD, with 933 unique metrics extracted in total. The most common metric was fecal consistency alone (30%; n = 281), or with at least 1 other metric (26%; n = 241). To define diarrhea, fecal consistency was either described qualitatively (e.g., "profuse liquid feces"), or semi-quantitatively, for example using a scoring system that frequently included 4 levels (n = 208). Some NCD case definitions included fecal color, volume, or odor (10%; n = 98), physical exam parameters (8%; n = 79), the duration of abnormal feces (7%; n = 67), the presence of abnormal contents (e.g., blood, 7%; n = 61), farm treatment records (6%; n = 54), fecal dry matter (1%; n = 12), or another metric (4%; n = 41). One or more references were cited for the NCD case definition by 49% of studies (n = 273/555), with the most common references being Larson et al. (1977) (n = 85), and McGuirk (2008) (n = 59). In the 555 included articles, 979 unique diarrhea-related outcomes were found, most commonly a binary categorization of calves having or not having diarrhea (49%; n = 483). Other articles reported statistical outcomes calculated from fecal scores (16%; n = 159), multiple diarrhea severities (10%; n = 95), or the age calves first developed NCD (8%; n = 76). This review characterized substantial heterogeneity among NCD case definitions and diarrhea-related outcomes, which limits interpretation and comparison of studies. Future work is required to develop and validate reporting standards for NCD to optimize knowledge synthesis and support rigorous and ethical calf health research.

Use of antimicrobials in the treatment of calf diarrhea: a systematic review

The objective of this study was to conduct a systematic review of the scientific literature evaluating the efficacy and comparative efficacy of antimicrobials (AMs) for the treatment of diarrhea in calves. Eligible studies were non- and randomized controlled trials evaluating an AM intervention against a positive and negative control, with at least one of the following outcomes: fecal consistency score, fever, dehydration, appetite, attitude, weight gain, and mortality. Four electronic databases were searched. Titles and abstracts (three reviewers) and full texts (two reviewers) were screened. A total of 2899 studies were retrieved; 11 studies met the inclusion criteria. The risk of bias was assessed. Most studies had incomplete reporting of trial design and results. Eight studies compared AMs to a negative control (placebo or no treatment). Among eligible studies, the most common outcomes reported were diarrhea severity (n = 6) and mortality (n = 6). Eligible studies evaluated very different interventions and outcomes; thus, a meta-analysis was not performed. The risk of bias assessment revealed concerns with reporting of key trial features, including disease and outcome definitions. Insufficient evidence is available in the scientific literature to assess the efficacy of AMs in treating calf diarrhea.

Clinical Scoring Systems in the Newborn Calf: An Overview

Simple Summary

Clinical scores are gaining increasing popularity in veterinary medicine thanks to their multiple advantages, which include quickness, ease, and convenience of use. This review discusses the applications of some already-known clinical scores in newborn calf management at birth and during the first weeks of age. Clinical scores are employed to assess newborn calf viability and to diagnose and monitor neonatal calf diarrhea and respiratory diseases, helping the clinician promptly recognize calves needing medical assistance. This review discusses limitations pertaining to their use and encourages efforts towards a greater consistency in definition and validation.

Abstract

A scoring system is an instrument that enables the scorers, including farmers, technicians, and veterinarians, to adopt a systematic approach for diagnosis or monitoring, as it decreases bias and confounding and increases objectivity. Practically, it is a number assigned to a patient that correlates with a probability that a diagnosis can be confirmed or that a specific outcome will follow. This article examines the clinical scores designed or adapted to bovine medicine that aim to assess newborn calf viability and to diagnose and monitor neonatal calf diarrhea and respiratory diseases, helping the clinician promptly recognize calves needing medical assistance. Despite the large number of clinical scores described in the literature, these are still barely used in farm animal practice; possibly, the complexity of the scores and missing recommendations for intervention are reasons for their lack of popularity as well as the crosswise lack of consistency among scores designed for the same purpose. Further research is needed in this regard to increase scores validation and encourage their application in bovine calf neonatology.

Longitudinal Study of Fecal Microbiota in Calves with or without Diarrhea Episodes before Weaning

Simple Summary

Animal production is searching for ways to reduce antimicrobial use, and the best way is to avoid their use by maintaining the health of the animals. The microbiota is involved in the host health, and when the fecal microbiota was analyzed in calves that developed or not diarrhea, differences linked to the health status were detected. While changes in the fecal microbiota were observed with time (during the first 2 months of age) in all the calves, the microbiota from the healthy animals presented an earlier stabilization and some changes in low abundant bacteria, which may play a role in the subsequent health status of the animals. Bacteria classified in the families Coriobacteriaceae and Phyllobacteriaceae, and the bacterium Epulopiscium were found in the core of the microbiota of the healthy calves (calves that did not have diarrhea) possibly with a protective probiotic effect. On the other hand, several bacteria, such as Lachnospira, Neisseria and Solibacillus, were found only in the core of the microbiota obtained from calves that had diarrhea, indicating that they could be linked to a higher predisposition to suffer diarrhea. These results can help in the development of new probiotics to promote gut health in calves.

Abstract

The microbiota plays an important role in the development of diarrhea in pre-weaned calves. The characterization of the fecal microbiota in health and disease can be critical to unravel the bacterial dynamics associated with diarrhea and help with its prevention and control. In this study, we aimed to detect changes in the fecal microbiota of calves that experienced early-life diarrhea episodes. Fecal samples were taken from calves remaining healthy and calves with an episode of diarrhea during the study. We sampled at arrival (12 days of age) and after one and two months of life; also, at the time of the diarrhea episode for the diarrheic calves (day 17). Samples were processed to extract total DNA, submitted to 16S rRNA gene sequencing, and bioinformatically analyzed to infer the bacterial populations. Microbiota changes through time were reported for both groups. However, we detected an earlier stabilization in the healthy group. Moreover, we detected changes within low abundant taxa that may play a role in the subsequent health status of the animals. The fecal microbiota of healthy and diarrheic calves showed different dynamics in the diversity through time that may be the reflections of the variations within low-abundant taxa.

Effects of feeding Saccharomyces cerevisiae fermentation products on the health and growth performance of Holstein dairy calves

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Feeding dairy calves SCFP in milk replacer and solid feeds until 4 mo improved postweaning ADG and feed efficiency.

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SCFP reduced respiratory illness antibiotic treatments in calves.

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Feeding SCFP to calves did not affect daily fecal scores or preweaning growth.

It is essential to reduce antibiotic use in the livestock industry, which leads to a need for alternatives to antibiotics that reduce illness and promote growth in dairy calves. The objective of this study was to evaluate the effect of feeding dairy calves Saccharomyces cerevisiae fermentation products (SCFP) on average daily gain (ADG) and antibiotic use in dairy calves through 4 mo of age. Holstein bull calves (n = 60; 5 ± 3 d old) were blocked by body weight (BW) and serum total protein (STP) and assigned to 1 of 2 treatments. The control treatment (CON) fed a 24% crude protein (CP):17% fat milk replacer (MR), calf starter, grower #1, and grower #2 with no SCFP added. The SCFP treatment fed the same MR with 1 g/d of SCFP, calf starter with 0.8% (dry matter; DM) SCFP, grower #1 with 0.44% (DM) SCFP, and grower #2 with 0.275% (DM) SCFP. Calves were offered 2.84 L (12.5% solids) of MR twice daily (0630 and 1630 h) through d 51 and MR once daily (0630 h) from d 52 to 56, and were weaned on d 57. From d 1 to 56, calves also received ad libitum access to calf starter and water. On d 57, calves were switched to grower #1 and on d 84, calves were switched to grower #2, which contained a lower level of CP and a higher level of neutral detergent fiber (NDF). Individual calf BW, body condition score (BCS), hip height (HH), and hip width (HW) were measured biweekly from d 0 to 112. Feed intake was recorded daily, and feed efficiency (gain:feed) and ADG were calculated. Daily fecal and respiratory scores were recorded for each calf through d 56, and all medical interventions were recorded for the duration of the study and grouped based on illness. We found no effect of treatment on STP, BW, BCS, HH, or HW at d 0 or 56, nor effects on preweaning ADG and feed efficiency. No treatment effect was observed for BCS or HH at d 112; however, BW and HW were increased in SCFP calves at d 112. A treatment tendency was observed for postweaning ADG, with SCFP calves being larger than CON calves and SCFP calves having improved feed efficiency compared with CON calves after weaning. A treatment effect was observed for respiratory treatments postweaning, with SCFP calves being treated less frequently than CON calves. Our results suggest that feeding SCFP to calves improves postweaning growth and feed efficiency, and reduces postweaning respiratory disease interventions.

Diarrhea duration and performance outcomes of pre-weaned dairy calves supplemented with bacteriophage

This study aimed to evaluate lytic bacteriophage supplementation in pre-weaned dairy calves on disease occurrence, performance, and biochemical parameters. Two hundred Holstein × Gyr crossbred female calves were divided into two groups: CON, no supplementation; and PHAGE, bacteriophage supplementation (1 g·d−1) from day 3 until day 70 of life. Calves were monitored daily for age of first diarrheal episode and its duration. Fecal samples were cultured for bacterial isolation and PCR was performed to identify Escherichia coli virulence genes and to confirm Salmonella spp. Performance outcomes were evaluated up to 80 d of age. Blood samples were collected to determine serum levels of total proteins, albumin, cholesterol, γ-glutamyl transferase, and urea. PHAGE group had fewer days with diarrhea (PHAGE: 4.68 d, CON: 6.61 d; P = 0.03). Fecal samples of three animals in PHAGE and nine in CON were positive for E. coli after PCR tests. Average daily gain of PHAGE was higher up to 80 d of life (P < 0.05). PHAGE mean was lower for albumin and higher for urea (P = 0.004 and P < 0.001, respectively). Phage therapy during the pre-weaned period reduced the duration of neonatal diarrhea, providing greater weight gain for calves.

Milk replacer supplementation in early life optimizes the development of intestinal microbes in goats

Colonization and development of the gut microbiome during early life is important in establishing a host-microbial symbiotic relationship. It contributes to maintaining health and well-being throughout the life span. To date, early longitudinal development of intestinal microflora in the ileum micro-ecology of the Yimeng black goats (YBGs) is rare. The purpose of this research was to study the effect of milk replacer with age on the ileal microbiota growth and maturation in YBGs throughout the post-weaning phase. The newborn YBGs (n = 24) were divided into two groups, i.e., milk replacer (R group) and control group (B group). The microbiome of Ileum was observed on days 15, 25, 45, and 75. When compared with baseline (B group), the R group's alpha diversity was lower (day 15, 25, 45), but it gradually approached and exceeded the baseline in the later stages (day 75). On the time axis, the richness of intestinal microflora was increased with age, but there was no statistically significant difference. The relative abundances of Proteobacteria, Firmicutes, Peptoclustridium, Lachnospiraceae, and Prevotellaceae showed a continuous trend of increase initially. They then decreased except Ruminococcaceae, which reflected the gradual maturity of intestinal microbial development. Milk replacer treatment temporarily increased the abundance of Actinomycetes (day 25 and 45), while the relative proportion of several intestinal bacteria such as Parasutterella, Megasphaera, Prevotellaceae, Akkermansia, and Subdoligranulum species were significantly higher in R group than in B group. The major changes in gut microflora composition might reflect positive effect of milk replacer on the development and maturation of the intestine during the early stage, connecting with substrate availability in the gut. Our study provides an effective strategy to promote the development of the gut microbiome, which is helpful for a smooth transition during the early-weaning period in YBGs.

Effects of mixed tocopherols added to milk replacer and calf starter on intake, growth, and indices of stress

Vitamin E comprises 8 fat-soluble isoforms: α-, β-, γ-, and δ-tocopherol and α-, β-, γ-, and δ-tocotrienol. Yet the body preferentially uses α-tocopherol, and only α-tocopherol supplementation can reverse vitamin E deficiency symptoms. However, other isoforms influence many biological functions in the body, including inflammation and stress. Therefore, the study objective was to determine metabolic and performance responses in young calves fed diets containing a constant amount of α-tocopherol and increasing amounts of soybean oil-derived mixed γ- and δ-tocopherols. Holstein calves [n = 48; 2-3 d of age; 40.2 kg of initial body weight (BW), standard error = 0.54] were assigned to receive approximately 0, 5, 10, or 15 mg/kg of BW daily (treatments T0, T1, T2, and T3, respectively) of mixed tocopherols (TMIX) provided in milk replacer (MR) and calf starter. The TMIX liquid contained 86% γδ-tocopherols and 9% α-tocopherol. Milk replacers were formulated to contain approximately 0, 400, 800, or 1,200 mg of TMIX/kg for treatments T0, T1, T2, and T3, respectively. Calf starters were formulated to contain approximately 0, 250, 500, or 750 mg of TMIX/kg for treatments T0, T1, T2, and T3, respectively. Mean consumption of γδ-tocopherols was 0.0, 6.5, 14.3, and 20.5 mg/kg of BW, respectively. Milk replacer contained 24% crude protein (CP) and 20% fat on a dry matter (DM) basis. Calf starters were pelleted and offered for ad libitum consumption from 0 to 56 d. Starters contained 18 to 20% CP and 9 to 12% starch in the DM. On d 28, 4 calves per treatment were randomly selected for slaughter, and necropsy was performed. Samples of liver, duodenum, ileum, and trapezius muscle were collected and stored before analysis for α-, β-, γ-, and δ-tocopherols and δ-tocotrienol. Data were analyzed using a completely randomized design using mixed model ANOVA with orthogonal polynomials to determine linear and quadratic effects of TMIX. Repeated-measures analyses were performed for data collected over time. Increasing dietary TMIX increased or tended to increase change in hip width at 28 and 56 d, respectively, and improved average daily BW gain and gain-to-feed ratio at 56 d. Increasing TMIX reduced plasma xanthine oxidase at 0 h and tended to reduce concentrations at 24 h following vaccination with 2 commercial vaccines on d 28; however, we detected no effect of TMIX following vaccination on d 56. Concentration of α-tocopherol in skeletal muscle declined quadratically with increasing TMIX, whereas ileal and liver γ-tocopherol increased linearly with increasing TMIX. The number of mucin-2 cells in the ileum increased more than 2-fold in calves fed T3. Addition of mixed tocopherols to diets of young dairy calves improved animal growth and altered indices of antioxidant metabolism.

Effects of feeding milk replacer at a moderate rate, ad libitum, or with a step-up program on Holstein calf growth performance to 4 months of age

The objective of this study was to evaluate 3 milk replacer (MR) feeding programs on calf performance to 4 mo of age. Male Holstein calves (n = 48; 2-3 d old) were randomly assigned to either a moderate rate of MR (MOD; 0.66 kg/d for 39 d, then 0.33 kg/d for 3 d), an ad libitum rate of MR (ADLIB; offered twice daily between 0630 and 0830 h and between 1430 and 1630 h for 35 d, 0.66 kg/d for 4 d, and 0.33 kg/d for 3 d), or a step-up rate of MR (STEPUP; increased from 0.32 to 0.62 kg/d in first 12 d, 0.66 kg/d for 27 d, and 0.33 kg/d for 3 d). The MR (25% CP, 18% fat) was fed twice daily to d 39 and once daily thereafter. During the nursery phase (0-56 d), calves were housed in individual pens and offered textured starter (40% starch, 21% CP on a DM basis) and water ad libitum. Calf body weight (BW) was measured initially and weekly thereafter. Hip widths (HW) were measured initially and every 2 wk thereafter. In the grower phase, (57-112 d), calves were grouped by previous treatment and moved to group pens (4 calves/pen). The same starter used in the nursery phase was blended with 5% chopped grass hay and offered ad libitum. Calf BW and HW were measured on d 56, 84, and 112. Total MR intake per calf averaged 27, 51, and 25 kg for MOD, ADLIB, and STEPUP programs, respectively, with a range of 42 to 63 kg for ADLIB. In the nursery phase, starter intake and feed efficiency were less for ADLIB versus MOD, whereas fecal scores and abnormal fecal score days were greater for calves fed ADLIB versus MOD. Calves fed STEPUP had lesser average daily gain than calves fed MOD. During the grower phase, initial BW was greater for ADLIB versus MOD, though final BW was not different between MOD and ADLIB or STEPUP. Calves previously fed MOD had greater average daily gain, feed efficiency, and HW change than calves fed ADLIB. In this study, feed efficiency was lower when MR was fed ad libitum, and growth advantages observed at 2 mo were lost by 4 mo of age.

Effects of milk replacer feeding rate and fat content on Jersey calf nutrient digestion and performance to 4 months of age

This study evaluated effects of milk replacer (MR) feeding rate and fat concentration in MR on total-tract digestion (TTD) and growth performance in Jersey calves. Jersey heifer calves (n = 100, 2 blocks of 50; initially 30 ± 3.0 kg of body weight; 4-11 d of age) were randomly assigned to 1 of 4 treatments in a 2 × 2 factorial arrangement of MR feeding rate [454 g for 42 d, and 227 g for 7 d (MOD); or 454 g for 7 d, 681 g for 35 d, and 341 g for 7 d (HI), as-fed basis] and MR fat content (17 or 24% fat as-fed basis). Milk replacers (24% crude protein as-fed basis) were reconstituted to 14% solids and fed in 2 equal feedings for 42 d, and then mornings only for 7 d. Textured calf starter (21% crude protein, 40% starch, dry matter basis) and water were offered for ad libitum consumption. From d 57 to 112, calf starter was mixed with 5% chopped grass hay. Calves were housed individually to d 56 and housed in groups (4-5 calves/pen) from d 57 to 112. Estimates of TTD were measured in 5 calves/treatment (block 1) at wk 3 of the study using acid-insoluble ash as an indigestible marker. From 0 to 56 d, calf starter intake (CSI) was greater for MOD vs. HI and 17 versus 24% fat; average daily gain was greater for HI versus MOD; and hip width change was greater for 17 versus 24% fat. Estimates of organic matter TTD were greater for HI versus MOD, but neutral detergent fiber TTD was greater for MOD versus HI and for 17 versus 24% fat. From 57 to 112 d, hip height change was greater for MOD versus HI, and hip width change was greater for 17 versus 24% fat. In this study, feeding Jersey calves more MR improved preweaning average daily gain, but had a negative effect on CSI and likely rumen development, as neutral detergent fiber TTD was reduced at 3 wk and frame growth was reduced from d 57 to 112. This resulted in similar final calf body weights between MR feeding rates at the end of the study. No benefits were observed for feeding more fat in MR as CSI or for NDF digestibility, and frame growth was reduced.

Technical note: Is fecal consistency scoring an accurate measure of fecal dry matter in dairy calves?

The objective of this cross-sectional study was to evaluate the accuracy of fecal consistency scoring as a measure of fecal dry matter (DM) in dairy calves. This study was conducted at a commercial grain-fed veal facility in southwestern Ontario. A total of 160 calves arrived at the facility in 2 groups of 80 calves each. Calves were fed milk replacer twice daily at 0700 and 1700 h and had ad libitum access from arrival onward to water through nipple drinkers and starter through a shared trough. Fecal consistency scores were evaluated once daily in the first 28 d after arrival before milk feeding. The fecal consistency scoring was conducted using a 4-level scoring scale: 0 = normal (firm but not hard); 1 = soft (does not hold form, piles but spreads slightly); 2 = runny (spreads readily); and 3 = watery (liquid consistency, splatters). Fecal samples were collected from all calves via rectal palpation on d 1, 7, 14, and 21 at 0900 h for determination of fecal DM. Mixed repeated measures linear regression models were built to assess the accuracy of fecal consistency scoring in predicting fecal DM. Over 4 selected time points (d 1, 7, 14, and 21) the 160 calves were observed, 382 (61.6%) had a fecal consistency score of 0, 121 (19.5%) had a score of 1, 85 (13.7%) had a score of 2, and 32 (5.2%) had a score of 3. A fecal score of 0 had a fecal DM of 25.1 ± 8.4%, whereas a fecal score of 1 had a DM of 21.8 ± 8.2%. With respect to calves that had a fecal score of 2 or 3, their fecal DM was 16.0 ± 11.1% and 10.7 ± 6.9%, respectively. In evaluating the pairwise comparisons generated in the repeated measures model that controlled for day of sampling, a fecal score of 0 had a 3.2%, 8.1%, and 12.0% higher fecal DM, respectively, when compared with those that had a fecal score of 1, 2, and 3. In addition, calves with a fecal score of 1 had a 5.0% and 8.8% higher fecal DM than calves with a fecal score of 2 and 3, respectively. Finally, calves with a fecal score of 2 had a 3.8% higher fecal DM than those with a fecal score of 3. This study confirms that using observational fecal consistency scoring can accurately predict diarrhea or a decline in fecal DM.

Effects of conditioner retention time during pelleting of starter feed on nutrient digestibility, ruminal fermentation, blood metabolites, and performance of Holstein female dairy calves

This study evaluated the effects of conditioner retention time during the pelleting process of starter feed on intake, nutrient digestibility, ruminal fermentation, blood metabolites, and growth performance of dairy calves. A total of 30 Holstein female dairy calves [40 ± 1.93 kg of body weight (BW)] were randomly assigned to 1 of 3 treatments: (1) pelleted starter conditioned for 0 min (CON), (2) pelleted starter conditioned for 2 min, and (3) pelleted starter conditioned for 4 min. Three pelleted starter feeds had similar nutritional composition, and the starters were blended with 3% chopped wheat straw and fed to individually housed calves from d 3 to 70 of age. All calves were fed 4 L/d of pasteurized whole milk twice daily at 0800 and 1600 h from d 3 to 50 of calf age, followed by 2 L/d of morning feeding from 51 to 56 d of age. All calves were weaned on d 56 of age and remained in the study until d 70 of age. With the increase of conditioner retention time during pellet processing for 0, 2, and 4 min, the gelatinized starch content of pelleted starter feed linearly increased from 14, 30, and 45%, respectively. Additionally, the pellet durability and hardness also linearly increased with increasing conditioner retention time during pelleting. Feeding pelleted feed prepared using different conditioner retention time did not affect feed dry matter intake, metabolizable energy intake, weaning BW, final BW, or feed efficiency during the study. We observed no differences in the total-tract apparent digestibility of organic matter, neutral detergent fiber, and crude protein around weaning (d 49 to 56 of age) and after weaning (d 63 to 70 of calf cage); however, the digestibility of dry matter and starch after weaning was increased with increasing conditioner retention time during pelleting of starter feed. No difference was found in overall average daily gain (ADG) or growth rates of hip height, withers height, and heart girth. Ruminal volatile fatty acid profile was not affected by pelleting under different conditioner retention times. The ruminal ammonia concentration tended to be lower for calves fed the 4-min diet compared with those fed the CON diet during the postweaning period. The postweaning (d 57-70 of age) ADG was greater for calves fed the 4-min diet compared with those fed the CON diet. In conclusion, the conditioning time during the pelleting process of starter feed increased the gelatinization of starch, durability, and hardness of the pellets but did not influence feed intake, feed efficiency, and skeletal growth during the first 70 d of age. Increasing conditioning time during the pelleting process improved postweaning ADG; however, the final BW of calves was similar among treatments.

Long-term impacts of late-gestation maternal heat stress on growth performance, blood hormones and metabolites of newborn calves independent of maternal reduced feed intake

The objective of this study was to evaluate the effects of heat stress in late gestation independent of maternal reduced feed intake on performance, blood hormones and metabolites, and immune responses of dairy calves from birth through weaning. A total of 30 multiparous Holstein cows at 45 d before expected calving were randomly assigned to one of 3 groups: (1) thermal neutral (CL, n = 10) conditions with ad libitum feed intake (10% of refusals on an as-fed basis); (2) pair-fed thermal neutral (CLPF, n = 10) conditions to reduce feed intake to levels similar to the heat stress (HS) group while reared under thermoneutral conditions (80% of the CL group); or (3) heat stress (HS, n = 10) conditions with ad libitum feed intake. Pair-feeding was conducted to quantify the confounding effects of dissimilar feed intake. Calves (10/group) born to cows that were exposed to cooling (IU-CL), pair-feeding (IU-CLPF), or heat stress (IU-HS) were used from birth through weaning. After birth, all the calves were managed under identical conditions. IU-HS calves had lower birth weight, and hip height at birth and 14 d of age. Compared with IU-CL and IU-CLPF calves, IU-HS calves had lower serum concentration of IgG and apparent efficiency of IgG absorption but higher serum insulin concentrations. Cortisol concentration in serum was higher in IU-HS and IU-CLPF calves compared to IU-CL calves. The neutrophil percentage was lower in IU-CL calves than in IU-HS and IU-CLPF calves. Neutrophil-lymphocyte ratio was higher in IU-HS calves compared to IU-CLPF and IU-CL calves. The mRNA expression of TNFα of IU-HS calves was downregulated compared with IU-CL and IU-CLPF calves. In summary, maternal HS during late gestation reduces calf birth weight and dramatically alters blood hormones and metabolites, but its effect on immune system function was not independent of maternal reduced feed intake.

Health and growth of veal calves provided a fatty acid supplement and a dry teat

Veal calves are at a high risk of disease early in life, which can lead to poor growth. Research is needed to determine interventions that can reduce disease and promote the growth of veal calves. The aim of this study was to determine the effects of fatty acid supplementation and the provision of a dry teat on the incidence of bovine respiratory disease (BRD), navel inflammation, and diarrhea, as well as calf growth. Upon arrival to a commercial veal facility (d 0), 240 Holstein bull calves from 2 cohorts were randomly assigned to 4 treatments using a 2 × 2 factorial arrangement (n = 60/treatment): (1) milk replacer (MR) without fatty acid supplementation and without access to a dry teat (control), (2) MR with fatty acid supplementation (NeoTec5g, Provimi, Brookville, OH) and without access to a dry teat (FAS), (3) MR without fatty acid supplementation and with access to a dry teat (TT), or (4) MR with fatty acid supplementation and with access to a dry teat (FAS+TT). Calves were housed in individual pens from 0 to 9 wk and then paired by treatment at wk 9. Milk replacer was fed twice daily using a step-up program. Fatty acid supplement was added to milk replacer at a feeding rate of 0.5 g/kg of body weight per head per day for the FAS and FAS+TT groups. Health exams were conducted twice weekly for 6 wk to diagnose BRD, navel inflammation, and diarrhea. Body weight, body condition score (BCS), and structural measurements were recorded at wk 0, 5, and 10. Average daily gain (ADG) was calculated for wk 1 to 5, wk 5 to 10, and wk 1 to 10. Health data were analyzed using logistic regression and are reported as relative risk. Body weight, BCS, and structural measurements were analyzed using repeated-measures ANOVA, and ADG was analyzed using a generalized linear model. There was no effect of FAS, TT, or their interaction on body weight or BCS. There was no effect of FAS on ADG wk 1 to 5, wk 5 to 10, or wk 1 to 10. There was a tendency for TT to decrease ADG from wk 1 to 5 but not from wk 5 to 10 or wk 1 to 10. There was a tendency for the interaction of FAS and TT to decrease ADG for wk 1 to 5 but not for wk 5 to 10 and wk 1 to 10. There was no effect of FAS, TT, or their interaction on the risk of BRD, diarrhea, or navel inflammation. We saw no effect of our interventions on calf health or growth. More research is needed to determine whether other factors, such as failure of passive transfer, poor ventilation, barren housing, and low milk allowance in the first few weeks after arrival, may have affected the efficacy of our interventions.

Effects of milk replacer feeding rates on growth performance of Holstein dairy calves to 4 months of age, evaluated via a meta-analytical approach

Our objective was to evaluate effects of feeding milk replacer (MR) at 2 feeding rates on digestion, intake, and growth of young dairy calves, via a meta-analytical approach using individual data. A database was developed from 10 published studies from the Nurture Research Center (Provimi; Brookville, OH), in which 26 dietary treatments and 491 calves from 0 to 8 wk of age in 13 nursery trials, and 22 dietary treatments and 485 calves from 8 to 16 wk of age in 13 grower trials occurred. Male Holstein calves (n = 491; initial body weight 42.8 ± 4.9 kg) were randomly assigned to 1 of 2 treatments: (1) moderate (MOD), 0.64 to 0.66 kg of dry matter (DM)/d for the first 35 to 39 d, followed by half the allotment per d for 3 to 7 d, fed at the a.m. feeding only; (2) high (HI), 0.92 to 1.07 kg of DM/d for the first 35 to 44 d, followed by half the allotment per d for 5 to 7 d, fed at the a.m. feeding only. Calves were weaned at 6 to 7 wk of age. Milk replacer ranged from 24.8 to 28.6% crude protein (CP) and 17.6 to 20.2% fat; starter ranged from 17.3 to 22.2% CP and 3.0 to 4.3% fat on a DM basis. On d 56 calves (n = 485) moved into pens (4 calves/pen) by treatments and were fed starter (19.4 to 22.3% CP and 3.4 to 4.6% fat, DM basis) blended with 5% hay until d 112. In all nursery trials (d 0 to 56), calves fed MOD had lower average daily gain (ADG; 0.634 vs. 0.545 kg/d), gain/DMI (0.488 vs. 0.466 kg/kg), and hip width change (0.069 vs. 0.064 cm/d), but greater starter intake (0.473 vs. 0.696 kg/d) compared with calves fed HI. Apparent total-tract digestibility of DM (73.3 vs. 78.4%), organic matter (OM; 74.1 vs. 79.0%), CP (74.8 vs. 78.9%), and neutral detergent fiber (NDF; 40.8 vs. 53.9%) were greater for calves fed MOD vs. HI when estimated during wk 8. In all grower trials (d 56 to 112), ADG (1.015 vs. 0.976 kg/d), gain/DMI (0.375 vs. 0.349 kg/kg), and hip width change (0.089 vs. 0.081 cm/d) were greater, but dry feed intake per kg of BW^0.75 did not differ (87.8 vs. 88.2 g/d) for calves previously fed MOD vs. HI. Apparent digestibility of DM (78.7 vs. 76.0%), OM (79.8 vs. 77.0%), CP (80.5 vs. 78.4%), and NDF (54.8 vs. 45.8%) were greater for calves fed MOD vs. HI when estimated between wk 11 to 13. Over the entire 112-d period, calves fed MOD had lower ADG (0.805 vs. 0.784 kg/d) but tended to have greater hip width change (8.415 vs. 8.589 cm) compared with calves fed HI. Under the conditions of this study, feeding higher MR rates caused calves to partially lose growth advantage during the weaning transition and further decreased BW gain and structural growth in the grower period (d 56 to 112), which could be due to reductions in nutrient digestibility as a result of feeding more MR.

Effects of colostrum and milk replacer feeding rates on intake, growth, and digestibility in calves

Newborn Holstein male calves (n = 50) born on a single dairy farm were assigned randomly at birth to receive 3 feedings of 1.8 L of pooled maternal colostrum (MC) at 1, 6, and 12 h of age or 1 feeding of 500 g of a colostrum replacer reconstituted to 1.8 L at 1 h of age, followed by 2 feedings of 227 g of a commercial milk replacer (MR) reconstituted to 1.8 L at 6 and 12 h of age (CR). All feedings were administered by esophageal feeder. At 2 to 3 d of age, calves were transported to the experimental facility and assigned within colostrum group to receive 0.66 kg/d dry matter (DM) of MR to 39 d, and then 0.33 kg/d to 42 d (MRM) or 0.77 kg/d of MR DM to d 13, 1.03 kg/d for 22 d, and 0.51 kg/d for 7 d (MRH). The MR contained 25.8% crude protein and 17.6% crude fat (DM basis) and was based on whey proteins and lard as the primary fat source. Calf starter (21.7% crude protein, 15.7% neutral detergent fiber, 37.4% starch, DM basis) and water were available for ad libitum consumption throughout the 56-d study. Serum IgG and total protein were measured at 2 to 3 d of age. Intakes of MR and calf starter were monitored daily. Calf health and fecal scores were also monitored daily. Body weight was measured weekly, and hip width and body condition score were monitored every 2 wk. Digestion of DM, organic matter, crude protein, and ether extract were determined at 1 and 3 wk from 5 calves randomly selected within treatment and using chromic oxide as a digestibility marker added to the MR. Calves fed CR had lower serum IgG and total protein than calves fed MC. Also, calves fed CR grew more slowly, consumed less calf starter, and were less efficient to 56 d than calves fed MC. The number of days calves were treated with veterinary medications was higher when calves were fed CR. Calves fed MC-MRH gained more BW than other calves from 3 to 8 wk of age. Calves fed CR-MRH consumed less calf starter than other calves during wk 7 and 8. Digestion of nutrients at 1 and 3 wk of the study was unaffected by type of colostrum or level of MR fed and did not change from 1 to 3 wk. Over the first 2 mo of life, the calves fed MRH consumed less calf starter than calves fed MRM, but average daily gain or hip width change did not differ. One feeding of CR followed by 2 feedings of MR in the first 24 h likely reduced absorption of IgG from CR and contributed to differences in health and growth. Differences in animal performance observed in this study were unrelated to MR digestibility.

Effects of feeding different amounts of milk replacer on growth performance and nutrient digestibility in Holstein calves to 2 months of age using different weaning strategies

Growth and the digestibility of nutrients can be greatly affected by diet preweaning and the rate at which calves are weaned. A 2 × 2 factorial design [moderate (MOD) or high (HI) milk replacer (MR) feeding rates and abrupt (AB) or gradual (GR) weaning] was used to compare these effects. Calves (n = 50) were randomly assigned to 1 of 4 treatments: MOD-AB, MOD-GR, HI-AB, and HI-GR. Calves assigned to MOD-AB were fed 0.66 kg of MR for the first 42 d and then 0.33 kg for the last 7 d; those assigned to MOD-GR were fed 0.66 kg of MR for 28 d, 0.33 kg for 14 d, and 0.17 kg for the last 7 d; those assigned to HI-AB were fed 0.66 kg of MR for 7 d, 0.82 kg for 7 d, 1.1 kg for 28 d, and 0.66 kg for the last 7 d; and those assigned to HI-GR were fed 0.66 kg of MR for 7 d, 0.82 kg for 7 d, 1.1 kg for 14 d, 0.66 kg for 14 d, and 0.33 kg for the last 7 d. All calves received the same MR [25% crude protein (CP), 17% fat; dry matter (DM) basis] and were given ad libitum access to water and a textured starter (42% starch and 20% CP). On d 26 to 30 and d 45 to 49, a fecal sample was taken from 5 calves in each treatment via the rectum to estimate apparent digestibility coefficients (dC). Apparent dC of DM, organic matter, and fat were greater for HI versus MOD calves. Apparent dC of neutral detergent fiber, acid detergent fiber, and sugar were greater for MOD versus HI calves. Apparent dC of DM was greater for AB versus GR calves [90.9, 89.0 ± 0.5384 (standard error)], and the apparent dC of acid detergent fiber was greater for GR versus AB calves (39.5, 32.3 ± 1.67). Feed efficiency was greater for HI versus MOD and AB versus GR. There were no significant differences between CP or starch dC based on treatment, and no interactions were observed. Starter consumption was greater for MOD calves compared with HI calves, and GR calves consumed more than AB calves. These results suggest that providing calves high amounts of MR preweaning enhanced readily available nutrient dC, but providing moderate amounts of MR resulted in increased fibrous fraction dC. Accordingly, the AB weaning strategy had higher dC for DM and organic matter, but there was a depression in fiber dC.

Effects of fatty acids and calf starter form on intake, growth, digestion, and selected blood metabolites in male calves from 0 to 4 months of age

The objective of this research was to determine if form of calf starter (CS) and addition of a fatty acid blend (FA) influenced intake, growth, digestion, and indices of immune status and stress in calves from 0 to 4 mo of age. Male Holstein calves [n = 48; 41.9 kg of body weight (BW), standard error = 0.7; 2 to 3 d of age] were assigned to receive reconstituted whole milk powder [0.66 kg of dry matter (DM)/d to 39 d, then 0.33 kg of DM/d to weaning at 42 d] without or with added FA. Calf starters were textured (pellet, whole oats, whole corn) or pelleted and were offered for ad libitum consumption from 0 to 56 d, then blended with 5% chopped grass hay and fed from d 57 to 112. Starters contained 20% crude protein (CP) and 38 to 40% starch in the DM. From d 0 to 56, calves were housed individually. From d 57 to 112, calves were grouped into pens by treatment (n = 4/pen). Form of CS during the initial 56 d had no effect on intake or growth, though days with fluid feces (fecal score ≥2.5) were greater when calves were fed textured CS. Feeding FA during the initial 56-d increased average daily BW gain, gain-to-feed ratio, and change in hip width, and reduced the number of days calves were treated with antibiotics. During d 57 to 112, CS form had no effects on any performance measure. Adding FA to CS increased average daily BW gain and hip width change, and tended to improve efficiency of BW gain. Total-tract digestibility was estimated at 4, 6, and 8 wk with 5 calves per treatment, and at 10, 13, and 16 wk of age using pen (n = 3 per treatment) as the experimental unit. Feeding FA increased or tended to increase total-tract digestion of DM, organic matter, starch, neutral detergent fiber (NDF), acid detergent fiber (ADF), CP, and fat at one or more measurement periods. Calves fed a textured CS increased or tended to increase digestion of DM, organic matter, starch, sugar, NDF, ADF, and CP during wk 6 and 8. However, during the second 56-d phase, feeding textured CS reduced or tended to reduce digestion of DM, organic matter, starch, NDF, ADF, and fat during wk 13 and 16. Inclusion of FA in milk increased serum bactericidal activity before weaning. Serum haptoglobin concentration increased 3 d postweaning when calves were fed textured CS. Feeding FA improved animal health, digestion, and performance. Form of CS had few effects on animal performance.

Intake, nutrient digestibility, and growth performance of Holstein dairy calves consuming a milk replacer at moderate or high feeding rates

The objective of this study was to evaluate nutrient intake and digestibility, and growth performance of calves when fed a milk replacer (MR) at 2 feeding rates. Male Holstein calves [n = 49; 45.0 ± 5.2 (mean ± SD) kg of body weight (BW); 3 to 4 d of age] were randomly assigned to 1 of 2 MR [27% crude protein (CP), 18% fat, dry matter (DM) basis; 14% solid] feeding programs: (1) 0.66 kg of DM/d for first 39 d divided into 2 equal a.m. and p.m. meals followed by one-half of the allotment per day for 3 d fed in the a.m. feeding only (moderate); (2) 0.96 kg of DM/d for the first 42 d divided into 2 equal a.m. and p.m. meals followed by one-half of the allotment per day for 7 d fed in the a.m. feeding only (high). A textured starter fed to calves contained whole grains with 20% CP and 44% starch (DM basis). At d 56, calves were moved into groups by treatment (4 calves/pen) and fed the same starter blended with 5% hay until d 112. Data were analyzed as a completely randomized design, or as a completely randomized design with repeated measures when applicable. Over the entire nursery period (d 0-56), there were no differences in average daily gain (0.63 vs. 0.64 kg/d) and hip width change (4.44 vs. 4.57 cm) for moderate- versus high-fed calves. Apparent digestibility of DM (76.5 vs. 70.3%), organic matter (77.4 vs. 71.2%), CP (78.8 vs. 72.6%), and neutral detergent fiber (37.2 vs. 22.7%) differed between moderate- and high-fed calves when estimated at d 51 to 55. From d 56 to 112, average daily gain (0.99 vs. 0.91 kg/d), hip width change (5.32 vs. 4.68 cm), and gain/DM intake (0.335 vs. 0.307 kg/kg) were greater, but DM intake per kg of BW (0.028 vs. 0.028 kg/kg) did not differ for calves previously fed moderate versus high. Feeding calves more than 0.66 kg of DM/d from a 27% CP, 18% fat MR did not improve BW gain and structural growth in the nursery period (d 0-56), and decreased these in the grower period (d 56-112) partially through reduction in digestibility of the starter.

Invited review: Completeness of reporting of experiments: REFLECTing on a year of animal trials in the Journal of Dairy Science

Reproducibility is an essential element of the scientific process, and it requires clear and complete reporting of study design, conduct, and analysis. In the human and animal health literature, incomplete reporting is associated with biased effect estimates. Moreover, incomplete reporting precludes knowledge synthesis and undervalues the resources allocated to the primary research. The Reporting Guidelines for Randomized Controlled Trials for Livestock and Food Safety (REFLECT) statement, published in 2010, is a checklist developed by expert consensus to provide guidance on what study elements should be reported in any intervention trial (designed experiment) involving livestock. The Journal of Dairy Science (JDS) has recently endorsed the use of reporting guidelines. To assess the status of reporting of controlled experiments in JDS and to provide a baseline for future comparison, we evaluated the reporting of 18 items from the REFLECT statement checklist in a sample of 137 controlled trials published in JDS in 2017. Two reviewers independently screened titles and abstracts for relevance and then evaluated a sample of 120 papers reporting controlled trials (experimental studies involving at least one intervention and one comparison or control group), using yes or no questions. Although some items, such as treatment details and statistical analysis, were well reported, other areas, including sample size justification, allocation concealment, blinding, study flow, baseline data, and ancillary analyses, were often not reported or were incompletely described. This work highlights the need for authors and reviewers to take advantage of guidelines and checklists for reporting. Adherence to reporting guidelines can help improve the completeness of reporting of research, expedite and better inform the peer-review process, increase clarity for the reader, and allow for knowledge synthesis, such as meta-analysis, all of which serve to increase the value of the work conducted.

Effects of milk replacer feeding rate and long-term antibiotic inclusion in milk replacer on performance and nutrient digestibility of Holstein dairy calves up to 4 months of age

The objectives of this study were to evaluate calf performance and diet digestibility when feeding a milk replacer (MR; 25% crude protein, 18% fat, dry matter basis) at a moderate (MOD) and high (HI) rate, along with MOD with neomycin-oxytetracycline inclusion (1.43 each g/kg; NTMOD). Male Holstein calves (n = 48; 45 ± 1.0 kg of body weight; 3 to 4 d of age) were housed in individual pens for 56 d. All calves were initially fed 0.66 kg of dry matter from MR for the first p.m. and following a.m. feeding, then randomly assigned to 1 of 2 feeding programs: (1) 0.66 kg of dry matter/d for first 39 d divided into 2 equal a.m. and p.m. meals and 0.33 kg for 3 d fed once daily in the a.m. feeding only (MOD, NTMOD); (2) 0.85 kg of dry matter/d for the first 4 d divided into 2 equal a.m. and p.m. meals, 1.07 kg of dry matter/d for the next 31 d divided into 2 equal a.m. and p.m. meals, and 0.48 kg for 7 d fed once daily in the a.m. feeding only (HI). Calves were fed a textured starter containing whole grains (20% crude protein, 43% starch, dry matter basis). Fecal samples were collected for 5 individual calves per treatment between d 47 to 51 to estimate digestibility. Calves were moved into groups by treatment (4 calves/pen) at 56 d and fed the same starter blended with 5% hay until d 112. Data were analyzed as a completely randomized design with repeated measures when applicable using mixed models. Milk replacer dry matter intake averaged 27.4 kg for MOD and NTMOD and 40.3 kg for HI per calf. Preweaning starter intake was less for calves fed HI versus MOD. Preweaning calf BCS change was greater for calves fed HI versus MOD. Preweaning medical treatment days were fewer for calves fed NTMOD versus MOD. Postweaning starter intake was less for calves fed HI versus MOD. Postweaning average daily gain was less for calves fed NTMOD versus MOD. Over the 56-d nursery trial, calves fed HI had less starter intake than calves fed MOD. Digestibility of dry matter, organic matter, acid detergent fiber, and neutral detergent fiber were greater for calves fed MOD versus NTMOD or HI during d 47 to 51 postweaning. Additionally, digestibility of fat was greater for calves fed MOD versus HI. During d 56 to 112, hip width change was greater for calves fed MOD versus NTMOD or HI. Over 0 to 112 d, body weight gain was 100, 98, and 102 kg, whereas hip width change was 10.2, 9.0, and 9.2 cm for calves fed MOD, NTMOD, and HI, respectively. Any preweaning improvements from feeding NTMOD or HI over MOD were lost during the postweaning period, which could be partially explained by reductions in diet digestibility.

Effects of gradual and later weaning ages when feeding high milk replacer rates on growth, textured starter digestibility, and behavior in Holstein calves from 0 to 4 months of age

The objectives of this study were to evaluate calf performance, diet digestibility, and behaviors when feeding 4 milk replacer (MR) programs with different MR rates, weaning ages, and MR reduction steps. Male Holstein calves (n = 96; 40 ± 1 kg of body weight; 1 to 2 d of age) were housed in individual pens for 56 d. Feeding programs for MR were 0.66 kg for 35 d; then 0.33 kg for 7 d fed only in the a.m. (0.6 kg); 0.66 kg for 7 d, 0.82 kg for 35 d, 0.33 kg for 4 d in a.m. only, and 0.22 kg for 3 d in a.m. only (0.8 kg); 0.66 kg for 7 d, 0.82 kg for 7 d, 1.1 kg for 21 d, 0.82 kg for 7 d, 0.33 kg for 4 d in a.m. only, and 0.22 kg for 3 d in a.m. only (1.1 kg); and ad libitum allowance for 35 d, 0.82 kg for 7 d, 0.44 kg for 4 d in a.m. only, and 0.22 kg for 3 d in a.m. only (ad lib). Calves were fed a common MR [25% crude protein, 17% fat, dry matter (DM) basis]. A textured calf starter with whole corn and oats (20% crude protein and 39% starch, DM basis) and water were fed for ad libitum intake during the nursery trial. Daily behavior duration (rumination, eating, and activity) was continuously recorded from d 1 to 55 for 4 calves/treatment using ear tag accelerometers (CowManager SensOor; Agis, Harmelen, the Netherlands). All calves were moved into groups by MR program (4 calves/pen) at 56 d and fed the same starter blended with 5% grass hay. Fecal samples were collected from individual calves between d 52 to 56 and from pen floors on d 66 to 70 to estimate total-tract digestibility. Data were analyzed as a randomized complete block design with repeated measures when appropriate. Intake of MR averaged 25.3, 35.3, 40.9, and 46.5 kg of DM per calf for 0.6 kg, 0.8 kg, 1.1 kg, and ad lib treatments, respectively. Starter intake was greatest for 0.6 kg compared with others and average daily gain (ADG) differed among all 4 programs with 0.6 kg < 0.8 kg < 1.1 kg < ad lib during d 0 to 56. Intake of MR for ad lib was highly variable and was reflected in ADG. Daily rumination, eating, and activity durations did not differ among treatments from d 1 to 55 of the nursery trial. Digestibility of DM, organic matter, acid and neutral detergent fiber, and sugar at d 52 to 56 were greater for 0.6 kg versus ad lib. Digestibility of DM at d 66 to 70 differed for all treatments with 0.6 kg > 0.8 kg > 1.1 kg > ad lib and was mostly influenced by fiber digestibility. During the grower trial (d 56 to 112), ADG was greater for 0.6 kg versus 1.1 kg and ad lib. Hip width change was greater for 0.6 kg versus other treatments. Feeding more than 0.6 kg/d of MR increased ADG preweaning, but reduced diet digestibility postweaning resulted in similar calf BW and frame size by 4 mo of age among MR feeding programs.

A 100-Year Review: Calf nutrition and management

The first calf paper, published in the May 1919 issue of the Journal of Dairy Science (JDS), described factors affecting birth body weight of different breeds of calves. Other studies were done on nonmilk ingredients, growth charts were developed, and early weaning was followed to conserve milk fed to calves. Calf papers did not report use of statistics to control or record variation or to determine whether treatment means were different. Many experiments were more observational than comparative. Typically fewer than 5 calves, and sometimes 1 or 2 calves, were used per treatment. During the next 20 yr, calf studies increased and included colostrum feeding, milk and milk replacer feeding, minerals and vitamins, and fats and oils. Many concepts fundamental to current knowledge and understanding of digestion, rumen development, and milk replacer formulation were developed during this period. In addition, the concept of using antibiotic growth promoters in dairy calf diets was first evaluated and developed during the 1950s. During the 20-yr period of January 1957 through December 1976, a large number of universities in the United States and 1 in Canada contributed almost 150 papers on a variety of calf-related topics. These topics included genetics, physiology of the calf, review of calf immunity, antibiotic feeding, and milk replacer ingredients. This became the golden era of calf rumen development studies, which also engendered studies of calf starter rations and ingredients. A classic review of management, feeding, and housing studies summarized research related to calf feeding and management systems up to that point with an emphasis on maintaining calf growth and health while reducing labor and feed costs. It was also during this period that metric measurements replaced English units. In the 20-yr period from 1977 to 1996, more than 400 articles on calf nutrition and management were published in JDS. With the growing research interest in calves, a paper outlining standardized procedures for conducting and reporting data from calf experiments was first published. A very active area of calf nutrition research from the late 1970s to the mid 1980s was colostrum quality, feeding, and preservation; more than 60 such research articles were published in the journal during this time. Various nonmilk protein sources were evaluated. Extensive studies were done evaluating trace and major mineral requirements in calves along with some vitamin studies. Throughout the 1970s, 1980s, and 1990s, the primary objective of most calf research was how to wean healthy, adequately grown calves at an early age-generally less than 30 d of age. This program was reviewed in a 1979 publication. Research on calf starter ingredients, nutrient composition, and additives was minimal in the 1980s and 1990s given the importance of starter intake to the success of early weaning, but the role of water intake in starter intake and growth was established. Research on issues with calves continued to increase during the last 20-yr period as evidenced by publication of more than 580 articles in JDS as well as many more in other refereed journals. In addition to papers contributed by several universities in the United States and Canada, the number of papers authored by scientists at universities and institutes in other countries increased dramatically during this period. Factors influencing colostral antibody absorption, heat treatment of colostrum, and efficacy of colostrum supplements and replacers were reported. Most studies in this period related to nutrition. Studies were published supporting greater neonatal growth rates from feeding more milk replacer but with a higher crude protein content than traditional. Protein energy effects on growth and body composition were evaluated in concert with greater growth rates. Milk and nonmilk protein sources in milk replacers along with AA supplementation were evaluated. Limited studies were done with fat sources and fatty acid supplementation along with trace minerals and fat-soluble vitamins. Waste milk feeding and heat treatment became more prevalent. Studies established starter ingredient palatability and use of forage when fed with pelleted starters. With the advent of automatic milk and milk replacer feeders, factors influencing how and when to wean were established. Research programs established factors affecting calf behavior and welfare. Several databases were evaluated along with various published studies, and established calf growth during the first 2 mo was subsequently reflected in first- and later-lactation milk production of those calves. A new area of calf research that emerged from 1997 on was the effects of maternal environment and nutrition on calf health, growth, and future productivity. From a mechanistic standpoint, the field of epigenetics seems likely to explain many of these phenomena. Some possibilities for future calf nutrition and management were elaborated.

Case Study: Control of respiratory disease in male Holstein calves with tildipirosin and effect on health and growth from 0 to 4 months of age

In trial 1, phase 1, 48 male Holstein calves initially 2 to 4 d of age were transported 3.5 h to the research facility. Calves were randomly selected to either receive a s.c. injection of Zuprevo (Merck Animal Health, Summit, NJ; 4 mg of tildipirosin/kg of BW; TIL) the day after arrival (d 0) and again at weaning (d 42) or receive no injections (CON). Calves were fed 0.66 kg of milk replacer DM daily for 39 d and then 0.33 kg daily for 3 d. A starter was fed free choice for the 56 d of phase 1. In trial 1, phase 2, the same calves from phase 1 grouped by CON and TIL were moved to group pens (4 pens per treatment, 4 calves per pen) for the next 56 d. The starter was blended with 5% chopped grass hay and fed free choice. Trial 2 was similar to trial 1, phase 2 and used 48 two-month-old male Holstein calves. Calves were randomly selected to receive either a s.c. injection of Zuprevo (4 mg of tildipirosin/kg of BW; TIL) on d 0 or no injections (CON). In trial 1, phase 1, preweaning ADG and BCS change; postweaning starter intake and hip width change; overall starter intake, ADG, and hip width change; final hip width; and final BCS were greater for TIL than CON. During phase 2 of trial 1 and trial 2, calf ADG and hip width change were greater for TIL than CON. Overall, in transported Holstein calves, TIL improved ADG and structural growth by approximately 13%.

Effects of different dietary ratio of metabolizable glucose and metabolizable protein on growth performance, rumen fermentation, blood biochemical indices and ruminal microbiota of 8 to 10-month-old dairy heifers

Objective

The aim of this experiment was to evaluate the effects of different dietary ratio of metabolizable glucose (MG) to metabolizable protein (MP) on growth performance, blood metabolites, rumen fermentation parameters and the ruminal microbial community of 8 to 10-month-old heifers.

Methods

A total of 24 Holstein heifers weighing an average of 282.90 kg (8 month of age) were randomly assigned to four groups of six. The heifers were fed one of four diets of different dietary MG/MP (0.97, 1.07, 1.13, and 1.26).

Results

The results showed that the ratio of MG/MP affected the growth performance, blood metabolites, rumen fermentation parameters and the ruminal microbial community of heifers. The average daily gain of heifers was enhanced by increasing the ratio of MG/MP (p<0.05). The concentration of blood urea nitrogen, cholesterol, and low density lipoprotein cholesterol as well as the concentration of total volatile fatty acid in the rumen fluid of heifers decreased with the improvement in the ratio of dietary MG/MP (p<0.05). However, the relative amount of Ruminococcus albus and Butyrivibrio fibrisolvens in the rumen of heifers was increased significantly (p<0.05) when the dietary MG/MP increased. At the same time, with the improvement in dietary MG/MP, the amount of Fibrobacter succinogenes increased (p = 0.08).

Conclusion

A diet with an optimal ratio (1.13) of MG/MP was beneficial for the improvement of growth, rumen fermentation, dietary protein and energy utilization of 8 to 10-month-old dairy heifers in this experiment.

Effect of weaning age and milk feeding level on pre- and post-weaning growth performance of Sahiwal calves

The Sahiwal cow is a tropical dairy breed native to Pakistan. The objective of the present study was to evaluate pre- and post-weaning growth of Sahiwal calves weaned either at 8 or 12 weeks and offered milk at either 10% or 15% of bodyweight (BW) from birth to weaning. Colostrum fed Sahiwal calves (n = 48) were randomly allocated to four treatments of 12 calves each. Calves were offered milk either at 10% (low-milk) or 15% (high-milk) of BW in two weaning programs (early or late). Early weaned calves were offered milk until Day 35, adjusted weekly for liveweight and then reduced by one-third in each subsequent week until weaned at Day 56 (early weaned). Late-weaned calves were offered milk until Day 63 and were weaned at Day 84 (late-weaned) by reducing milk offered by one-third in each subsequent week. Calves were offered a concentrate ration (21% crude protein and 2.93 metabolisable energy, Mcal/kg) from Day 28 to Day 112. Final BW at 16 weeks was highest (77.6 ± 1.8 kg; P < 0.01) in high milk-fed late-weaned calves and lowest in low milk-fed early weaned calves (60.2 ± 1.8 kg). High-milk early weaned and low milk late-weaned calves had comparable final BW (70.7 ± 1.8 vs 72.0 ± 1.8 kg), although lower than that of high-milk late-weaned calves, but still at an acceptable lower feeding cost to gain per kg liveweight (US$ 3.2 vs 2.5). Thus, offering milk to Sahiwal calves at 15% of BW and weaning at 8 weeks saves milk and labour required for additional days to feed these calves.

Case Study: Control of bovine respiratory disease in dairy calves with tulathromycin and effect on calf health and performance from 0 to 4 months of age

In phase 1, 96 male Holstein calves at risk for bovine respiratory disease initially 2 to 4 d of age from a single dairy farm were transported 3.5 h to southwest Ohio. Calves were randomly assigned to receive a s.c. injection of Draxxin (2.5 mg of tulathromycin/kg of BW; Zoetis, Florham Park, NJ; TUL) at arrival (d −1) and again at weaning (d 42) or receive no injections (CON). Milk replacer was fed at 0.66 kg of DM daily for 39 d and then 0.33 kg of DM daily for 3 d. A high-grain, textured starter and water were fed free choice for the first 56-d phase. In phase 2, the same calves from phase 1 were grouped by CON and TUL and moved to group pens (4 pens per treatment; 4 calves per pen) for the next 56 d. The same starter from phase 1 was blended with 5% chopped grass hay and fed free choice. In phase 1, postweaning starter intake and BW gain, overall BW gain, and final BW were greater for TUL than CON. Medical treatments did not differ. During phase 2, DMI (% of BW) was greater for CON than TUL. Calf BW gain, final BW, feed efficiency, and hip width change were greater for TUL than CON. Over the 112 d of both phases, TUL calves gained 9.0 kg (9%) more BW (106.4 vs. 97.4 kg) and 0.8 cm (8%) more hip width (10 vs. 9.2 cm) than CON calves, but TUL did not improve calf health.

Crude glycerin as a replacement for corn in starter feed: performance and metabolism of pre-weaned dairy calves

The purpose of this study was to evaluate the effect of partial replacement of corn in the starter feed with crude glycerin on performance and energy metabolism of liquid-fed dairy calves. Twenty-four newborn individually housed Holstein calves were blocked according to weight and date of birth and randomly assigned to different starter feed treatments during 8 weeks: no crude glycerin; 5% crude glycerin; 10% crude glycerin on dry matter basis. All calves were individually fed daily 4 L of a commercial milk replacer (22.3% crude protein and 19.3% fat). Calves had individual access to starter diet and ad libitum access to water daily. Individual feed intake and faecal scores were recorded daily. Bodyweight and corporal measurements (heart girth, hip width, and withers height) were weekly recorded. From the second week of age, blood samples were collected weekly, 2 h after morning feeding, for determination of plasma glucose and β-hydroxybutyrate concentrations. Ruminal fluid was collected at 4, 6 and 8 weeks of age for determination of pH and short-chain fatty acids. At the end of the eighth week, animals were harvested to evaluate development of the proximal digestive tract. Feed intake, average daily gain, bodyweight or body measurements were not affected (P > 0.05) by the inclusion of crude glycerin in the starter feed. Faecal scores indicated that most of the calves had mild diarrhoea, with no treatment effect. Total short-chain fatty acids and the concentration of individual acids, as well as blood parameters, were not affected (P > 0.05) by the feed treatments. The total forestomach weight, the average weight of each compartment, the maximum capacity of reticulum-rumen, and papillae number, height and width were not affected (P > 0.05). In conclusion, crude glycerin can be used as an alternative energy source, replacing corn up to 10% in the starter feed for liquid-fed dairy calves without affecting growth, rumen development or metabolism.

Effect of milk replacer program on calf performance and digestion of nutrients with age of the dairy calf

Calves fed large amounts of milk replacer (MR) gain more body weight preweaning than calves fed less-aggressive programs; however, postweaning growth may be reduced. Limited research suggests that less than optimal digestion of the postweaned diet due to large amounts of MR with reduced dry feed intake preweaning may contribute to growth impairment postweaning. Current research was conducted to compare growth and postweaning digestion in 3-d-old male Holstein calves fed various MR programs. The MR programs were a conventional [CON; 0.44 kg of dry matter (DM) 21% crude protein (CP), 21% fat powder fed for 42d], moderate (MOD; 0.66 kg of DM 27% CP, 17% fat powder fed for 42d), and aggressive program (AGG; up to 0.87 kg of DM 27% CP, 17% fat powder fed for 49d). All calves were fed a 20% CP textured starter and water ad libitum for 56d. The trial used 96 calves (initially 41 ± 1.9 kg of body weight) received 5 wk apart in 2 groups of 48 calves. During d 51 to 56, fecal samples were collected from 5 calves per treatment randomly selected from calves in the first group. Selected nutrients and acid-insoluble ash (used as an internal flow marker) were analyzed in the starter and feces to estimate digestibility. Data were analyzed as a randomized complete block design with starting time of each group of calves as a block. Repeated measure analysis was performed on overall (0 to 56d) data. Means were separated with a protected least significant difference test. Pen was the experimental unit. Calves fed CON had the least average daily gain [CON=0.35, MOD=0.51, and AGG=0.55 kg/d; standard error of the mean (SEM)=0.018], feed efficiency (CON=0.35, MOD=0.49, and AGG=0.48 gain/feed, SEM=0.016), and change in hip width (CON=3.3, MOD=4.1, and AGG=4.1cm, SEM=0.20) compared with calves fed other programs. Calves fed AGG had the greatest change in BCS and least starter intake compared with calves fed the other programs. Digestibility of organic matter was 79, 78, and 68% and neutral detergent fiber was 54, 51, and 26% for calves fed programs CON, MOD, and AGG, respectively, and were least for calves fed AGG. These results indicate that postweaning digestion is lower than optimal and contributes to lower postweaning growth in calves fed aggressive compared with conventional or moderate MR programs.

Effect of frequency of feed delivery on the feeding behaviour, growth, and rumen temperature of limit-fed dairy heifers

Greter, A. M., AlZahal, O., Duffield, T. F., McBride, W. B., Widowski, T. M. and DeVries, T. J. 2014. Effect of frequency of feed delivery on the feeding behaviour, growth, and rumen temperature of limit-fed dairy heifers. Can. J. Anim. Sci. 94: 11–20. The objective of this experiment was to determine the effect that frequency of provision of feed, provided in a restricted amount, had on feeding and lying behaviour, growth, and rumen temperature of growing dairy heifers. Twenty-four Holstein heifers (178.2±9.3 d of age; mean±SD), divided into six groups of four, were assigned to each of three treatments using a 3×3 Latin square design with 28-d periods (21-d adaptation, 7-d data collection). Treatments were delivery of daily allotment of total mixed ration (fed at 2.0% of body weight): (1) once per day (1×; 0800), (2) twice per day (2×; 0800 and 1600), and (3) four times per day (4×; 0800, 1200, 1600, and 2000). Average daily gain (ADG) was similar across treatments (0.8 kg d−1). There was a tendency for within-pen variation of ADG (average, per pen, of the absolute difference between individual heifer ADG and pen mean ADG) to be greater with 4× (0.3 kg d−1) and 2× (0.3 kg d−1) compared with 1× (0.2 kg d−1). Both feeding (63.1 vs. 44.2 vs. 51.5 min d−1) and unrewarded (presence at the feed bunk when no feed was present; 49.5 vs. 27.7 vs. 33.1 min d−1) time at the feed bunk decreased with increasing frequency of feed delivery (1×, 2×, and 4×, respectively). Frequency of displacements (3.1 displacements d−1) and number of displacements per unit of feeding time (0.06 displacements min−1) were similar between treatments. Lying time was similar between treatments (802.5 min d−1), while there was an increase in the amount of time spent standing without eating as frequency of feed delivery increased (558.9 vs. 590.0 vs. 604.7 min d−1 for 1×, 2×, and 4×, respectively). Thus, feeding 1× d−1 may prove beneficial for limit-fed heifers as it increases the time spent feeding, and decreases time spent standing without eating and within-pen variation in ADG.

Comparison of supplementation of n-3 fatty acids from fish and flax oil on cytokine gene expression and growth of milk-fed Holstein calves

The ability to reduce incidence of disease in calves and improve early vaccination strategies is of particular interest for dairy producers. The n-3 fatty acids have been reported to reduce inflammatory diseases in humans but limited research has been done in calves. The objective of this study was to compare supplementation of n-3 fatty acids from fish and flax oil on gene expression of whole blood cells and growth of milk-fed Holstein calves. Forty-eight Holstein bull calves from a commercial dairy were randomly assigned to 1 of 3 diets beginning at 4d old: (1) control milk replacer (MR) with all pork fat, (2) MR with 2% flax oil, and (3) MR with 2% fish oil. All MR were 17% fat, 27% crude protein on a dry matter (DM) basis, with all protein from whey sources. Calves were each fed 654g DM of MR daily for the first 25d and then 327g/d for d26, 27, and 28. On d28, calves were challenged with a Pasteurella vaccine and the temperature response to the vaccine was recorded. Milk and feed intake and fecal scores were recorded daily, and body weight and hip width were recorded weekly. Blood was collected from all calves on d25. One tube of collected blood was incubated with endotoxin (lipopolysaccharide; LPS) for 2h and frozen with a second tube of control blood. Quantitative real-time PCR was used to assess the effects of LPS stimulation on cytokine gene expression. During the 28 d, calves supplemented with flax oil had a greater growth rate and feed efficiency than calves fed fish oil (0.52±0.02 vs. 0.48±0.02g of gain:g of feed). Fish oil tended to decrease LPS stimulation of tumor necrosis factor-α expression. Flax oil, but not fish oil, decreased the expression of IL-4 and tended to decrease expression of osteopontin and IL-8. Flax oil tended to reduce the increase in rectal temperature in response to a Pasteurella vaccine. In conclusion, our data support the idea that supplementation with n-3 fatty acids affects cytokine gene expression.