Advances in Nutrition and Management of Calves and Heifers

Effect of once-a-day milk feeding on behavior and growth performance of pre-weaning calves

OBJECTIVE

The objectives of the present study were to evaluate the effects of once-a-day milk feeding on growth performance and routine behavior of preweaning dairy calves.

METHODS

At 22nd day of age, twenty-four Holstein calves were randomly assigned to one of two treatment groups (n = 12/treatment) based on milk feeding frequency (MF): i) 3 L of milk feeding two times a day; ii) 6 L of milk feeding once a day. The milk feeding amount was reduced to half for all calves between 56 and 60 days of age and weaning was done at 60 days of age. To determine the increase in weight and structural measurements, each calf was weighed and measured at 3 weeks of age and then at weaning. The daily behavioral activity of each calf was assessed from the 22nd day of age till weaning (60th day of age) through Nederlandsche Apparatenfabriek (NEDAP) software providing real-time data through a logger fitted on the calf's foot.

RESULTS

There was no interaction (p≥0.17) between MF and sex of the calves for routine behavioral parameters, body weight and structural measurements. Similarly, there was no effect of MF on routine behavioral parameters, body weight and structural measurements. However, the sex of the calves affected body weight gain in calves. Male calves had 27% greater total body weight and average daily gain than female calves. There was no effect of the sex of the calves on behavioral measurements. Collectively, in the current study, no negative effects of a once-a-day milk feeding regimen were found on routine behavioral and growth parameters of preweaning calves in group housing.

CONCLUSION

Once-a-day milk feeding can be safely adopted in preweaning calves from 22nd day of age.

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

Introduction

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

Methods

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

Results

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

Discussion

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

Preweaning nutrient supply alters mammary gland transcriptome expression relating to morphology, lipid accumulation, DNA synthesis, and RNA expression in Holstein heifer calves

The objective of this study was to analyze the mammary gland transcriptome to determine how preweaning nutrient supply alters the molecular mechanisms that regulate preweaning mammary development. Holstein heifers were fed via milk replacer (MR) either an elevated level of nutrient intake (ELE; on average, 5.9 ± 0.2 Mcal of ME in 8.4 L of MR/d, n = 6) or a restricted amount of nutrients (RES; 2.8 ± 0.2 Mcal of ME in 4 L of MR/d, n = 5) for 54 d after birth, at which point they were slaughtered and samples of mammary parenchyma tissue were obtained. Parenchymal mRNA was analyzed, and the fold change (FC) of 18,111 genes (ELE relative to RES) was uploaded to Ingenuity Pathway Analysis (IPA) software (Qiagen Bioinformatics, Redwood City, CA) for transcriptomic analysis. Using a threshold of P < 0.05, IPA identified that the FC of 1,931 of 18,811 differentially expressed genes (DEG) could be used for the analysis. A total of 18 molecular and cellular functions were relevant to DEG arising from the treatments; the 5 functions most associated with DEG were cell death and survival, cellular movement, cellular development, cellular growth and proliferation, and lipid metabolism. Based on the directional FC of DEG, the mammary gland of ELE heifers was predicted to have increased epithelial-mesenchymal transition (Z = 2.685) and accumulation of lipid (Z = 2.322), whereas the synthesis of DNA (Z = -2.137), transactivation of RNA (Z = -2.254), expression of RNA (Z = -2.405), transcription (Z = -2.482), and transactivation (Z = -2.611) were all predicted to be decreased. Additionally, IPA predicted the activation status of 13 upstream regulators with direct influence on DEG as affected by ELE feeding that were ligand-dependent nuclear receptors (n = 2), enzymes (n = 1), or transcription regulators (n = 10). Of these, 6 were activated (Z > 2) and 7 were inhibited (Z < -2). In summary, feeding ELE preweaning altered the mammary transcriptome of Holstein heifers, affecting cell functions involved in the morphological and physiological development of the mammary gland.

Skeletal muscle metabolomics and blood biochemistry analysis reveal metabolic changes associated with dietary amino acid supplementation in dairy calves

The effects of different amino acid (AA) supplementations of milk protein-based milk replacers in pre-ruminant calves from 3 days to 7 weeks of age were studied. Animals were divided into 4 groups: Ctrl) Control group fed with milk protein-based milk replacer without supplementation; GP) supplementation with 0.1% glycine and 0.3% proline; FY) supplementation with 0.2% phenylalanine and 0.2% tyrosine; MKT) supplementation with 0.62% lysine, 0.22% methionine and 0.61% threonine. For statistical analysis, t-test was used to compare AA-supplemented animals to the Ctrl group. At week 7, body weight and average daily gain (ADG) were measured and blood samples and skeletal muscle biopsies were taken. Blood biochemistry analytes related to energy metabolism were determined and it was shown that MKT group had higher serum creatinine and higher plasma concentration of three supplemented AAs as well as arginine compared with the Ctrl group. GP group had similar glycine/proline plasma concentration compared with the other groups while in FY group only plasma phenylalanine concentration was higher compared with Control. Although the AA supplementations in the GP and FY groups did not affect average daily gain and metabolic health profile from serum, the metabolome analysis from skeletal muscle biopsy revealed several differences between the GP-FY groups and the Ctrl-MKT groups, suggesting a metabolic adaptation especially in GP and FY groups.

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.

Macronutrient and amino acids composition of milk replacers for dairy calves

SUMMARY Other than crude protein (CP), crude energy (CE) and crude fiber (CF) content, the adequate supply of essential amino acids (EAA) is an important factor in milk replacer evaluation. The aim of this study was to analyze milk replacer samples as regard to nutrients, especially EAA, composition and simulate the attainability of calves' requirements in different feeding systems. Forty-one milk replacer samples were collected from 14 brands and analyzed for nutrient composition. The near infrared spectroscopy technique was used for AA content estimation. Samples presented adequate levels of CP (21.2±2.90%) and ether extract (14.5±3.41%) for calves fed according to the conventional (4L/d), but not for intensive milk feeding system (>6L/d). High values of CF were observed in the samples (1.6±0.86%). The EAA composition of milk replacer samples was lower than expected for a liquid feed supposed to replace whole milk. None of the analyzed samples presented adequate lysine (5.72±1.09% CP) or methionine (1.65±0.38% CP) to meet calves' daily requirements, regardless of feeding system. Higher crude protein milk replacers are needed. Alternatively, supplementation of milk replacers with EAA is recommended.

Nitrogen utilization, preweaning nutrient digestibility, and growth effects of Holstein dairy calves fed 2 amounts of a moderately high protein or conventional milk replacer

Studies have shown that calves fed milk replacers (MR) with crude protein (CP) concentrations greater than 20%, as typically found in conventional MR, have higher dry matter intakes (DMI) and greater average daily gains (ADG) but consume less starter, which can lead to stress during weaning and reduced rumen development. The greater amount of CP being fed to preweaned calves may alter their nitrogen (N) balance, and excess N may be excreted in the urine. The objective of this study was to determine N utilization in preweaned calves fed diets varying in the amount of CP and MR fed. This study used 24 newborn dairy heifer calves blocked by birth and randomly assigned to 1 of 3 treatments: (1) 446 g dry matter (DM) of a conventional MR (CON; 20% CP, 20% fat), (2) 669 g DM of a moderately high protein MR (moderate; MOD; 26% CP, 18% fat), or (3) 892 g DM of a moderately high protein MR (aggressive; AGG; 26% CP, 18% fat). All calves had ad libitum access to starter and water. Both MR and starter were medicated with decoquinate. During weaning (d 43–49), the morning MR feeding ceased. On d 50, all MR feedings ended; however, starter and water intakes were continuously recorded until d 56. At 5 wk of age, urine was collected using urinary catheters for 3 d and chromium oxide was administered by bolus at 2 g/d for 7 d to estimate N efficiency. Calves fed MOD and AGG had similar starter intakes, feed efficiencies, and ADG, with the combined treatments having reduced starter intakes (258 vs. 537 g/d), greater ADG (674 vs. 422 g/d), and improved feed efficiency (0.57 vs. 0.45 gain:feed) compared with CON calves preweaning. However, DMI and water intake were similar across all treatments. Results from the N utilization phase showed that MOD and AGG treatments had similar but lower N efficiency compared with CON calves (45.5 vs. 52.7%). This could be due to MOD- and AGG-fed calves having greater urine volume and thereby, greater combined urine N output compared with CON calves (17.6 vs. 12.1 g/d). In summary, feeding >0.66 kg (DM) from a 26% CP MR increased ADG and improved feed efficiency during the preweaning period but reduced starter intake and lowered N efficiency.

Evaluation of nutrition models to estimate performance of young dairy calves: a meta-analytical study under tropical conditions

Mathematical models are important tools to estimate nutritional requirements and animal growth. Very few calf models generated from other countries with different feeding programs, environment and production systems have been evaluated. The objective of this paper is to evaluate two calf models: (i) the National Research Council (NRC) in 2001 and (ii) the updates published by Van Amburgh and Drackley in 2005 and inputted into Agricultural Modeling and Training Systems (AMTS, version 3.5.8). Data from 16 previous studies involving 51 diets for dairy calves under tropical conditions (n=485 calves, initial BW 37.5±4.35 kg and weaning weight of 62.0±10.16 kg) were used. The calves were fed with whole milk, milk replacer or fermented colostrum, plus starter (20.9±1.78% of CP). The accuracy of the average daily gain (ADG) prediction was evaluated by mean bias, mean square prediction error (MSPE), concordance correlation coefficient, bias correction factor (Cb), and regression between the observed and predicted values. The ADG observed from birth to weaning was 0.452±0.121 kg/day. Calves fed with whole milk had greater ADG compared with calves fed milk replacer (0.477 v. 0.379 kg/day) during the milk-feeding period. When all data were pooled (n=51 diets), predictions had a mean bias of -0.019 and 0.068 kg/day for energy-allowable gain using NRC and AMTS models, respectively. The regression equation between observed and predicted values obtained from energy of diets showed an intercept different from zero (P0.05) indicate that the AMTS growth model resulted in accurate predictions for calves fed with milk replacer. However, within these latter two approaches, the goodness of fit (R 2) was low, representing low precision. The weight gain estimated by the energy available from the diet was overestimated by 19 g/day when calculated by the NRC and underestimated by 68 g/day when calculated by AMTS. The reasons for this discrepancy need to be understood, for only then new models could be developed and parameterized to estimate animal performance in tropical conditions more accurately and precisely.

The effect of 2 liquid feeds and 2 sources of protein in starter on performance and blood metabolites in Holstein neonatal calves

The aim of present study was to investigate the effect of 2 liquid feeds and 2 protein sources in starter on the performance and blood metabolite responses of Holstein neonatal calves from birth to 6 wk of age. Calves (20 males and 20 females) based on sex were randomly assigned to 4 treatments in a 2 × 2 × 2 factorial arrangement, including soybean meal (SBM) and meat and bone meal (MB) with either fermented colostrum (or fresh milk. Although sex and liquid feed had no significant effect on feed intake, calves consumed more feed intake on the diet containing SBM (15 ± 0.2 kg) than MB (13 ± 0.2 kg) during the experimental period; also, weight gain was affected by both liquid feed and starter. Liquid feed and starter had significant effects on calf body size, including pin width, hip width, withers height, hip height, and stomach size, but no significant effects were observed on calf body size between the sexes. Plasma glucose concentration was not affected by sex, liquid feed, or starter. Plasma urea nitrogen concentration decreased in the first 3 wk and then started to increase during the last 3 wk, but it was only affected by starter and calves receiving SBM (10.18 mg/dL) had a higher concentration of plasma urea nitrogen than calves receiving MB (9.6 mg/dL) at the end of the experiment. Plasma growth hormone and insulin-like growth factor I concentrations decreased in all treatment groups from d 0 to the end of the study. No significant effects were observed on plasma growth hormone and insulin-like growth factor I concentrations between the 2 sexes, but they were significantly affected by both liquid feed and starter. Results of the present study provide useful information to apply to Holstein neonatal calves during the first 6 wk of life when liquid feed and 2 sources of protein in starter are considered.

Preweaning milk replacer intake and effects on long-term productivity of dairy calves

The preweaning management of dairy calves over the last 30 yr has focused on mortality, early weaning, and rumen development. Recent studies suggest that nutrient intake from milk or milk replacer during the preweaning period alters the phenotypic expression for milk yield. The objective of this study was to investigate the relationship between nutrient intake from milk replacer and pre- and postweaning growth rate with lactation performance in the Cornell dairy herd and a commercial dairy farm. The analysis was conducted using traditional 305-d first-lactation milk yield and residual lactation yield estimates from a test-day model (TDM) to analyze the lactation records over multiple lactations. The overall objective of the calf nutrition program in both herds was to double the birth weight of calves by weaning through increased milk replacer and starter intake. First-lactation 305-d milk yield and residuals from the TDM were generated from 1,244 and 624 heifers from the Cornell herd and from the commercial farm, respectively. The TDM was used to generate lactation residuals after accounting for the effects of test day, calving season, days in milk, days pregnant, lactation number, and year. In addition, lactation residuals were generated for cattle with multiple lactations to determine if the effect of preweaning nutrition could be associated with lifetime milk yield. Factors such as preweaning average daily gain (ADG), energy intake from milk replacer as a multiple of maintenance, and other growth outcomes and management variables were regressed on TDM milk yield data. In the Cornell herd, preweaning ADG, ranged from 0.10 to 1.58 kg, and was significantly correlated with first-lactation yield; for every 1 kg of preweaning ADG, heifers, on average, produced 850 kg more milk during their first lactation and 235 kg more milk for every Mcal of metabolizable energy intake above maintenance. In the commercial herd, for every 1 kg of preweaning ADG, milk yield increased by 1,113 kg in the first lactation and further, every 1 kg of prepubertal ADG was associated with a 3,281 kg increase in first-lactation milk yield. Among the 2 herds, preweaning ADG accounted for 22% of the variation in first-lactation milk yield as analyzed with the TDM. These results indicate that increased growth rate before weaning results in some form of epigenetic programming that is yet to be understood, but has positive effects on lactation milk yield. This analysis identifies nutrition and management of the preweaned calf as major environmental factors influencing the expression of the genetic capacity of the animal for milk yield.

Effects of Vegetable Fats Versus Lard in Milk Replacers on Feed Intake, Digestibility, and Growth in Finnish Ayrshire Bull Calves

The aim was to study whether vegetable fat mixtures could be used instead of lard [15.2% in dry matter (DM)] in milk replacers without impairing the performance of Finnish Ayrshire bull calves (n = 58). The growth performance of the calves was measured before and after weaning from 14 d to 6 mo of age. The following 3 fat sources in a milk replacer were studied: 1) a mixture of palm, coconut, and rapeseed oil, 2) palm and coconut oil, and 3) lard. The calves were bucket-fed 2 L of milk replacer 3 times per day. The milk replacer contained 116 g of DM/L, resulting in an average DM intake of 4.8 g of DM/kg of body weight0.75 (BW0.75) during the 8-wk trial, after which the calves were weaned. All the calves had free access to water, commercial starter, and grass silage before weaning. The weaned calves had free access to water and grass silage and were given 3 kg/d (air-dry basis) of a commercial concentrate mixture. The concentrate was replaced by barley when the bulls were 4.5 mo old. There were no significant differences between the diets in feed intake and apparent diet digestibility. The health and BW of the calves were similar during the study. The feed conversion rate (kg of DM intake/kg of gain) before weaning was significantly greater for the lard diet compared with the 2 vegetable fat mixtures. After weaning, the feed conversion rate was slightly lower for the diet that included the palm, coconut, and rapeseed oil mixture than for the diet that included palm and coconut oil mixture. The study showed that the 2 mixtures consisting solely of vegetable oils were effective dietary components, thus providing 2 alternative fat mixtures of milk replacers, for use instead of lard in formulating commercial calf milk replacers.

Soybean: feed quality and safety. Part 2: pathology of soybean feeding in animals. A review

Various animal models in farm and laboratory animals indicate the possible pathological effect of soybean feeding. Immunity and tolerance to oral soybean intake and a generalised meta-model of effects are discussed. It seems that FAO/WHO recommendations will have to be considered in assessing the biological value of soybean feed sources. Determination of hull content, antigenic potential, conglycinin and trypsin inhibitor content is warranted in view of the future component pricing of soybean meals.

The effect of ruminal fluid preparations on the growth and health of newborn, milk-fed dairy calves

The objective of this study was to determine the effect of oral doses of ruminal fluid (RF) on the growth and health of newborn, milk-fed heifer dairy calves (0 to 6 wk of age). Calves given 8 ml of RF each day until weaning gained more weight and had fewer scours than controls that did not receive RF. Because RF that was exposed to oxygen or was autoclaved also gave a response, it is unlikely that the preparations were acting as a probiotic. When the RF was centrifuged to separate the cells (RFC) from the fluid (RFS), both fractions had similar activity, and this result indicated that the response was not nutritional; that is, 1) RFC supplied a small amount of protein (approximately 8 mg/d), but RFS had much less protein, and 2) RFS had volatile fatty acid, but RFC had little if any volatile fatty acid. However, both RFS and RFC had bacterial polysaccharide, and bacterial polysaccharide has strong antigenic properties. In the first three studies, treated calves were given RF preparations each day until weaning (6 wk), but a subsequent experiment indicated that calves given autoclaved RF for only 5 d (d 1 to 5) also had greater body weight gains during the first 2 wk of life and fewer scours than untreated controls. Given that the dosage of RF was small and the material could be autoclaved to prevent disease transmission, RF supplementation could be a practical tool for improving calf health.

Supplementation of milk replacers containing soy protein with threonine, methionine, and lysine in the diets of calves

An attempt was made to improve the protein quality supplied in milk replacers containing soy protein by supplementing Thr, Met, and Lys to the milk replacers fed to calves. Six Holstein x indigenous male calves were fitted with single cannulas at the end of the ileum. Calves were fed milk replacers containing skim milk (86%) and whey (14%) proteins or skim (43%), whey (14%), and soy (43%) proteins either with or without amino acid (AA) supplementation according to a double 3 x 3 Latin square design. Average daily gain, N retention, and ileal digestibilities of dry matter, N, and AA were significantly higher for calves fed the milk replacer containing skim milk protein than for calves fed the milk replacer containing soy protein. Average daily gain, N retention, and ileal digestibilities of dry matter, N, and AA were significantly higher for calves fed the milk replacer containing soy protein plus AA supplementation than for calves fed the milk replacer containing the soy protein without AA supplementation. Therefore, supplementation of a milk replacer containing the soy protein without AA supplementation. Therefore, supplementation of a milk replacer containing soy protein with limiting AA that correspond to the AA found in milk protein can considerably improve the protein quality of that milk replacer for the preruminant calf.

The effect of whey protein concentrate or dried skim milk in milk replacer on calf performance and blood metabolites

Whey protein concentrate and dried skim milk were each evaluated as the major protein source in milk replacer using four treatments (100% skim milk, 67% skim milk and 33% whey protein concentrate, 33% skim milk and 67% whey protein concentrate, and 100% whey protein concentrate). In the first trial, 64 calves were fed only milk replacer from birth to 6 wk of age. In the second trial, 61 calves were fed milk replacer and were allowed ad libitum intake of starter from birth to 6 wk of age. Calves were fed milk replacer at 10% of birth weight for the first 2 wk and at 12% of birth weight thereafter. In trial 1, average daily gains and feed efficiencies were significantly improved for calves that consumed the milk replacers containing 67 and 100% whey protein concentrate over those for calves that were fed the milk replacer containing 100% skim milk. No difference in growth or feed efficiency caused by treatment was detected in trial 2. Average daily gain in trial 2 was correlated with total starter intake. In trial 1, plasma glucose concentrations were correlated with growth rates and were highest for calves fed the milk replacer containing 67% whey protein concentrate. No differences were found for fecal scores or days scoured between trials. When only milk replacer was fed, higher proportions of whey protein concentrate improved calf performance, but, when starter was also provided, no effect of milk replacer was found.

Calf and disease factors affecting growth in female Holstein calves in Florida, USA

A prospective cohort study was undertaken to determine calf-level factors that affect performance (growth) between birth and 14 months of age in a convenience sample of approximately 3300 female Holstein calves born in 1991 on two large Florida dairy farms. Data collected on each calf at birth included farm of origin, birth date, weight, height at the pelvis, and serum total protein (a measure of colostral immunoglobulin absorption). Birth season was dichotomized into summer and winter using meteorological data collected by University of Florida Agricultural Research Stations. Data collected at approximately 6 and 14 months of age included age, weight, height at the pelvis, and height at the withers. Growth in weight and stature (height) was calculated for each growth period; growth period 1 (GP1) = birth to 6 months, and growth period 2 (GP2) = 6 to 14 months. Health data collected included data of initial treatment and number of treatments for the diseases diarrhea, omphalitis, septicemia, pneumonia and keratoconjunctivitis. After adjusting for disease occurrence, passive transfer of colostral immunoglobulins had no significant effect on body weight gain or pelvic height growth. Season of birth and occurrence of diarrhea, septicemia and respiratory disease were significant variables decreasing heifer growth (height and weight) in GP1. These variables plus farm, birth weight and exact age when '6 month' data were collected explained 20% and 31% of the variation in body weight gain and pelvic height growth, respectively, in GP1. The number of days treated for pneumonia before 6 months of age significantly decreased average daily weight gain in GP2 (P < 0.025), but did not affect stature growth. Treatment for pneumonia after 6 months of age did not significantly affect weight or height gain after age 6 months. Neither omphalitis nor keratoconjunctivitis explained variability in growth in either of the growth periods.

Milk replacers with or without animal plasma for dairy calves

Holstein calves (n = 68; 40 heifers) at two locations were used to evaluate effects of the addition of plasma protein to milk replacers on growth, intake, feed efficiency, and fecal scores. Milk replacers were formulated to contain 20% CP and 20% fat. Plasma was added to milk replacers to provide 0 or 25% of CP and replaced whey protein. Calves were fed colostrum for 3 d and then milk replacer (10% of BW/d) for 56 d. Initial mean BW was 38.0 kg. Commercial calf starter was offered for ad libitum consumption throughout the study. Composition of the milk replacer had no effect on weekly BW, BW gain, intake of milk replacer or calf starter, efficiency of BW gain, or fecal scores. Mean BW gain during the 56-d study was 473 g/d, and mean BW at 56 d was 65.8 kg. Calves consumed 534 and 575 g of DM/d of milk replacer and calf starter, respectively, during the 56-d trial. Inclusion of plasma proteins at 25% of CP supported growth equal to that of whey protein.

A study of the use of milk replacers for dairy calves in the United States

This study focused on aspects of the National Dairy Heifer Evaluation Project that involved neonatal feeding practices and types of milk replacers utilized on dairy farms. Types of milk replacers and the management practices associated with their feeding were studied. Nearly 60% of US dairy farms use milk replacers for some or all of the feeding program for neonatal calves. Regional differences existed in the types of liquid feeds and milk replacers fed to calves. Western producers fed less milk replacer, and western and northeast producers fed replacers with less total CP. Many characteristics of management utilized along with these products reflect accepted management and nutrition practices. During the study period from 1991 to 1992, 11.2% of replacers contained casein. A greater proportion of these were found in the West during the first 6 mo of the study, reflecting changes in the milk replacer formulations during that time.

Plasma proteins and a probiotic as ingredients in milk replacer

Milk replacers containing all milk protein, 25% of protein from porcine plasma protein, 25% of protein from bovine plasma protein, or all milk protein plus probiotic were compared in a 6-wk experiment using 120 Holstein bull calves approximately 7 d of age. All replacers contained an antibiotic except the one that contained probiotic. Calf starter always was available, and calves were weaned when they consumed 680 g/d of starter. Ten calves were selected randomly from each group for sampling of jugular blood at d 1 and 10 of the experiment. A complete blood count was conducted on the samples, and protein fractionation by electrophoresis was performed on sera harvested from the samples. Mean BW gains started to differ at the end of wk 3, and by the end of wk 6 the difference of 2.6 kg was significantly greater for those calves fed porcine or bovine plasma than for calves fed all milk protein (with or without probiotic). The same response was noted for starter consumption; the difference increased to 4.15 kg by the end of wk 6. Most measurements of blood did not differ by treatment; those that were different did not suggest an apparent difference in performance response. Growth performance of calves fed probiotic was not different from that of calves fed antibiotic when both replacers contained all milk protein. Either porcine or bovine plasma protein was an acceptable source of protein.

Raising dairy replacements to meet the needs of the 21st century

Producing high quality replacement heifers at minimum cost will be one of the many challenges facing the dairy farm of the 21st century. Because replacement heifers represent a large portion of the total cost of milk production, dairy farmers will have to meet the replacement needs of their lactating herds at minimum cost to maintain the farm's profitability. To keep the US dairy industry competitive into the 21st century, researchers, extension, industry, and producers must examine the database of research in order to determine how to apply the known information to current production and research efforts. Important research is needed to improve the dairy heifers of the future. This review summarizes research of the past 12 yr related to dairy replacements and incorporates those findings into possible scenarios for future dairy calf and heifer management systems. Additional research is needed to determine how dairy replacement raising systems affect the lifetime productivity and profitability of the dairy cow.

Factors affecting pregnancy rate in Holstein-Friesian cattle mated during summer in a tropical upland environment

The relationships between some environmental factors and reproductive rates of dairy cattle during summer in a tropical upland area were studied using records for Holstein-Friesian milking cows and non-lactating growing heifers maintained at the Kairi Research Station on the Atherton Tableland in north Queensland. The Station is situated in a tropical upland environment with warm, wet summers and dry, cool winters. Data were collected over a 12-year-period (1977 to 1988) for cows grazing nitrogen (N)-fertilised grass pastures and receiving either no supplement or about 3.5 kg molasses/cow/day. Cattle were mated over a 10-week period starting from mid-January to early February, with 32 to 36 cows and 5 to 42 heifers used in each year. There was considerable variation among years in the pregnancy rate after 3 inseminations, with a low of 39% and a high of 94% pregnancy. This variation from year to year was reduced for cows grazing pastures receiving 300 kg N/ha/yr after molasses feeding commenced in 1984-85. Pregnancy rates after molasses introduction were higher for cows grazing pastures receiving 300 compared with 100 kg N/ha/yr. Pregnancy rate in cows and heifers was reduced from 80 to 55% as mean daily maximum temperature increased from 26 degrees C to 27.5 degrees C. At mean maximum temperatures above 27 degrees C for cows and 27.6 degrees C for heifers pregnancy rates to 3 inseminations were consistently below 60%. Much of the year to year variation in pregnancy rate was related to rainfall during the mating period.(ABSTRACT TRUNCATED AT 250 WORDS)

Response of young dairy calves with lasalocid delivery varied in feed sources

Growth, age at weaning, fecal scores, and blood metabolites of young dairy calves were measured to determine the most effective method of lasalocid administration. Forty Holstein bull calves were blocked by date of birth and assigned randomly to one of four treatment groups: no lasalocid; lasalocid in starter; lasalocid in prestarter and starter; or lasalocid in milk, prestarter, and starter for a 12-wk period. Calves were fed milk twice daily until they consumed 227 g/d of prestarter, at which time the p.m. milk feeding was discontinued, and starter was offered for ad libitum intake as a mixture with the 227 g/d of prestarter. When total dry feed consumption reached 1.3% of birth weight, the calf was weaned. When the calf was 5 wk of age, the prestarter was discontinued. Daily gain tended to be greatest during the first 6 wk for the calves receiving lasalocid in milk, prestarter, and starter. These calves also were weaned with less variation in days to weaning. By wk 8 through 12, there were no differences in gain among the treatment groups.

Replacement nutrition management

The basic principles of dairy cow feeding apply equally to the dairy heifer. Ration balancing must be accomplished in order to formulate least-cost, nutrient-balanced rations for each age group of heifers. Forage testing enables rations to be developed that utilize the various quality forages that are available on a farm and allows optimum allocation of forages for maximum profitability of the farm feeding system. In addition to feeding management, housing, ventilation, health care, grouping, cleanliness, and many other management factors can complement a sound heifer nutrition program.

Causes of adverse responses to soybean milk replacers in young calves

Sixty Holstein bull calves were randomly assigned to one of three treatment groups following an initial 3-d colostrum feeding period. They were fed either whole cows' milk or ethanol-extracted or hexane-extracted soy flour in milk replacers to 6 wk of age. These products were used to identify possible causative factors associated with adverse responses to soybean in milk replacers. Average weight gains to 6 wk of age were 13.8, 7.3, and 2.8 kg and mortality was 0/20, 4/20, and 9/20 for calves fed milk, ethanol-extracted soy, and hexane-extracted soy, respectively. Heart rates (beats/min) were increased by the soy flours: 99.1 (ethanol extracted) and 116.3 (hexane extracted) versus 87.6 (milk). There was also an increased respiratory rate (breaths/min) with 67.6 and 61.1 versus 41.6 for the same treatment groups. Intradermal wheal growths verified an allergic sensitivity to the soybean products. Serum prostaglandin F2 alpha was 22% higher in the serum of calves fed the hexane-extracted soy milk replacer than in the serum of calves fed milk. Phenolic compounds in the soybean flour were implicated as possible causative factors in the adverse responses to the soybean milk replacers. Ethanol extraction of the soy flour was more effective than hexane extraction in removing phenolic compounds (2.19 vs. 1.00% phenolics).

Dietary ascorbic acid and immune response in dairy calves

Colostrum-fed, colostrum-deprived, and colostrum-fed and colostrum-deprived calves fed ascorbic acid (1.75 g/d) in whole, raw milk to 6 wk of age were sampled from 0 to 8 wk of age in order to determine whether ascorbate supplementation would increase plasma Ig concentrations, antibody response to immunization, and disease resistance. Plasma IgG concentrations were lower at 14 and 28 d of age in calves fed ascorbate compared with plasma concentrations in calves not receiving ascorbate supplementation, irrespective of colostrum feeding. Colostrum feeding had no effect on antibody titer to keyhole limpet hemocyanin at any age, but ascorbate-supplemented calves had lower plasma antibody titers to keyhole limpet hemocyanin at 35 and 56 d of age. Calves fed ascorbate had lower clinical scores for diarrhea. Dietary ascorbate does not appear to be immunostimulatory in dairy calves to 56 d of age and appeared to inhibit antibody synthesis. However, at 14 d of age there was an interaction of ascorbate supplementation and colostrum feeding; plasma IgG concentrations were higher in colostrum-deprived calves fed ascorbate then in colostrum-deprived calves not fed ascorbate.

Increased solids intake and feeding frequency for calves in hutches during cold weather

Seventy-seven Holstein calves born during October through March were used to evaluate increased solids intake from liquid feed and once versus twice daily feeding on weight gains and health of calves. Dietary treatments were 3.6 kg whole milk fed once daily (A) or in two feedings (B), 3.6 kg whole milk plus 113 g whey-fat blend powder fed once daily (C) or in two feedings (D), and 4.5 kg milk daily fed in two feedings (E). Calves fed diets A and B received .45 kg of solids daily in their liquid feed, whereas those fed diets C, D, and E received .56 kg of solids. These amounts were fed for 4 wk starting 3 d after birth, then amounts were reduced by half during the 5th wk. Weight gains during wk 1 to 5 (.36, .47, .48, .57, and .61 kg/d) were highest for calves fed additional solids and were greater when fed liquid twice instead of once daily. Weight gains were similar for all calves during wk 6 to 10, although weight gains during the entire 10 wk (.67, .70, .72, .81, and .82 kg/d) reflected the differences of the initial 5 wk. Dry feed consumption was similar for all treatment groups during all periods. Incidence of diarrhea tended to be lower in calves fed twice daily, although diarrhea was not a major problem for any treatment group. For optimum growth and health, calves housed in hutches during cold weather should be fed at least .56 kg of solids daily in two or more liquid feedings.

Effect of protein source in calf milk replacers on morphology and absorptive ability of small intestine

Holstein calves were fed milk or one of four milk replacers with one-third of the total protein supplied by casein, soy protein concentrate, soy flour, or fish protein concentrate. The remainder of the protein in each replacer was from milk sources. Milk and milk replacers (13% solids) were fed at 10% of body weight daily. No dry feed or bedding was provided. Absorptive ability of small intestine was evaluated by xylose absorption test at 2-wk intervals. With calves under general anesthesia, a biopsy of small intestine was taken after each xylose test to examine morphological changes in mucosa by scanning electron microscopy. Villi were long, tapering, and uniform in calves fed milk. Calves fed casein had greater variation in size and conformation of villi. Gradual deterioration in villous integrity was seen in calves fed soy proteins. Calves fed fish protein concentrate performed poorly and had abnormal villi. Diets were changed to milk to test for reversal of effects after marked alterations in intestinal structure had been observed. Atrophy was reversed as villi returned toward normal size and shape within 2 wk after milk feeding began. The surgical procedure apparently did not cause harmful effects of villi. Absorption of xylose and daily gain were greater, and feces firmer, in calves fed milk than in those fed milk replacers.

Milk replacers for the neonatal calf

A rather long list of broad generalizations exist regarding milk replacers for calves. At least two more general statements should be added to that list. Most broad generalizations regarding milk replacers should be applied cautiously; and if young calves (less than 2 to 3 weeks) are to be fed milk substitutes, the products should be of high quality. Our primary goal in feeding baby calves should be health oriented--that is, not to pre-dispose to or cause diarrhea through diet. This means using milk-source ingredients in milk substitutes targeted for young calves. The preponderance of data presented in this article underscores that statement. Milk replacers containing nonmilk sources of major nutrients are better fed to older calves.

Animal health and management and their impact on economic efficiency

Relationships between animal health and economic efficiency were examined using data from genetic investigations and management studies. Genetic investigations have indicated that cows bred for high production do require more health care, but that increased costs for health care negate only a small fraction of the greater returns from cows that are genetically superior for yield traits. These same studies have identified age of cow and stage of lactation as important sources of variation in health care costs. Health care costs increase with age and are highest at parturition and immediately thereafter, and decrease to much lower levels as lactation progresses. Animal health issues considered from a management perspective were macro-environment (climate, housing, facilities), nutrition-reproduction complex, replacement management, mastitis and udder health, and herd health preventive medicine programs. Most advances in management of animal health were beneficial, but some are economical only for large herds. Improvement of udder health through continued and expanded research on milking procedures and equipment design is an area of unusual promise. Additional research appears needed to cope with stress and fatigue to legs and feet in modern facilities. Preventive medicine programs become more cost effective as herds become larger and should be used by a larger percentage of dairy producers. The economic efficiency of many management practices is uncertain due to a paucity of data. Animal scientists should plan to incorporate economic comparisons into much more of their research.