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.

Invited review: palmitic and stearic acid metabolism in lactating dairy cows.

Energy is the most limiting nutritional component in diets for high-producing dairy cows. Palmitic (C16:0) and stearic (C18:0) acids have unique and specific functions in lactating dairy cows beyond a ubiquitous energy source. This review delineates their metabolism and usage in lactating dairy cows from diet to milk production. Palmitic acid is the fatty acid (FA) found in the greatest quantity in milk fat. Dietary sources of C16:0 generally increase milk fat yield and are used as an energy source for milk production and replenishing body weight loss during periods of negative energy balance. Stearic acid is the most abundant FA available to the dairy cow and is used to a greater extent for milk production and energy balance than C16:0. However, C18:0 is also intimately involved in milk fat production. Quantifying the transfer of each FA from diet into milk fat is complicated by de novo synthesis of C16:0 and desaturation of C18:0 to oleic acid in the mammary gland. In addition, incorporation of both FA into milk fat appears to be limited by the cow's requirement to maintain fluidity of milk, which requires a balance between saturated and unsaturated FA. Oleic acid is the second most abundant FA in milk fat and likely the main unsaturated FA involved in regulating fluidity of milk. Because the mammary gland can desaturate C18:0 to oleic acid, C18:0 appears to have a more prominent role in milk production than C16:0. To understand metabolism and utilization of these FA in lactating dairy cows, we reviewed production and milk fat synthesis studies. Additional and longer lactation studies on feeding both FA to lactating dairy cows are required to better delineate their roles in optimizing milk production and milk FA composition and yield.

Influence of starter protein content on growth of dairy calves in an enhanced early nutrition program.

Our objectives were to determine the effect of starter crude protein (CP) content on growth of Holstein calves from birth to 10 wk of age in an enhanced early nutrition program, and to compare the enhanced program to a conventional milk replacer program. Calves (64 female, 25 male) were assigned to 3 treatments in a randomized block design: 1) conventional milk replacer (20% CP, 20% fat) plus conventional starter [19.6% CP, dry matter (DM) basis], 2) enhanced milk replacer (28.5% CP, 15% fat) plus conventional starter, and 3) enhanced milk replacer plus high-CP starter (25.5% CP, DM basis). Calves began treatments (n=29, 31, and 29 for treatments 1 to 3) at 3 d of age. Conventional milk replacer (12.5% solids) was fed at 1.25% of birth body weight (BW) as DM daily in 2 feedings from wk 1 to 5 and at 0.625% of birth BW once daily during wk 6. Enhanced milk replacer (15% solids) was fed at 1.5% of BW as DM during wk 1 and 2% of BW as DM during wk 2 to 5, divided into 2 daily feedings. During wk 6, enhanced milk replacer was fed at 1% of BW as DM once daily. Calves were weaned at d 42. Starter was available for ad libitum intake starting on d 3. Starter intake was greater for calves fed conventional milk replacer. For calves fed enhanced milk replacer, starter intake tended to be greater for calves fed enhanced starter. During the weaning period, enhanced starter promoted greater starter DM intake than the conventional starter. Over the 10-wk study, the average daily gain of BW (0.64, 0.74, and 0.80 kg/d) was greater for calves fed enhanced milk replacer with either starter and, for calves fed enhanced milk replacer, tended to be greater for calves fed high-CP starter. Rates of change in withers height, body length, and heart girth were greater for calves fed enhanced milk replacer but did not differ between starter CP concentrations. The postweaning BW for enhanced milk replacer treatments was greater for calves receiving the enhanced starter at wk 8 (73.7, 81.3, and 85.8 kg) and wk 10 (88.0, 94.9, and 99.9 kg). Starter CP content did not affect height, length, or heart girth within enhanced milk replacer treatments. Regression analysis showed that gain of BW during the first week postweaning (wk 7) increased with greater 3-d mean starter intake in the week before weaning. Starter with 25.5% CP (DM basis) provided modest benefits in starter intake (particularly around weaning) and growth for dairy calves in an enhanced early nutrition program compared with a conventional starter (19.6% CP).

Nutritional Programs for Commercial Replacement Dairy Heifer Operations.

There are a variety of feeding programs that can meet the goal of doubling calf birth weight at the end of 2 months of life. Feeding programs need to take into account the inverse relationship between mil/milk replacer and starter intakes. Water is the most essential nutrient needed in the greatest quantity by calves. Water is consumed at about 4 times dry matter intake and should be fed warm during cold weather. Water and starter should be fed sooner and forage later than the 2014 NAHMS data indicate US dairy producers are doing.

Animal care and use: an issue now and in the future.

Animal rights proponents equate human and animal rights or capacity to suffer pain. Animal welfare is a philosophy that centers on animal well-being, a stewardship role that producers view as affecting profitability but the general public may view as having additional components. The agenda of some animal rights proponents may be positioned under the guise of animal welfare to gain acceptability for portions of their work. Currently, guidelines and accreditation programs targeted at ensuring proper animal care and use increasingly include agricultural animals. Also, public initiatives such as the Massachusetts ballot initiative to curtail animal agriculture and the Physicians Committee for Responsible Medicine's attempts to curtail the use of milk and meat in human diets were defeated by educating the general public. Various organizations have been developed to address animal care and use issues. The Animal Industry Foundation is a broad-based agricultural organization addressing animal rights issues. National biomedical organizations, the Foundation of Biomedical Research and the National Association for Biomedical Research, address education and governmental animal rights issues. State-level coalitions, such as those recently organized in Missouri, of agricultural organizations, academic research units, biomedical institutions, and agribusiness or consumer products companies offer great promise of educating others on animals rights and welfare issues. Animal scientists need to educate themselves on these issues, participate in their own institutional Animal Care and Use Committees, and help to educate the general public through organizations and programs at the local, state, and national level.

Effect of level of energy intake and influence of breed and sex on the chemical composition of cattle.

Chemical composition of the empty body was determined in 159 animals slaughtered at weights ranging from 121 to 706 kilograms. Holstein and Angus bulls, steers and heifers were fed at two energy levels: ad libitum and 65 to 70% ad libitum. The allometric equation, Y = aXb, was used to determine the effect of energy intake and the influence of breed and sex on the accretion rates of the chemical components relative to the growth of the empty body or fat-free empty body. Group comparisons for chemical composition were made after adjustment by regression to a common empty body weight. The expression of the sex influence on the accretion rates of water, protein and ash relative to the empty body depended on the breed and the energy intake level considered. The accretion rate of chemical fat was not influenced by sex. Genetic differences in the accretion rate relative to the empty body were detected only among animals in the high energy intake group. Regardless of sex, the accretion rates of protein and ash were more rapid (P < .05) in Holsteins than in Angus. However, a breed influence on the accretion rate of chemical fat was detected only among bulls, where Angus had a more rapid accretion rate. Feeding animals at two energy levels resulted in different accretion rates relative to the empty body. In the Angus breed, regardless of sex, the accretion rates of water, protein and ash were more rapid (P < .05) in the low intake group, whereas the accretion rate of chemical fat was slower (P < .05). Among Holsteins, the low energy intake level had a less definite effect; for bulls, the accretion rates of water and chemical fat were more rapid (P < .05) and slower (P < .05), respectively; for steers, and accretion rate of protein was more rapid (P < .05), and for heifers, none of the accretion rates was altered.

Variability in delivery of nutrients to lactating dairy cows.

Dairy cows consume feedstuffs from which they derive nutrients to meet their requirements. Water and dry matter intake limit overall nutrient intake. The variability in the nutrient content of forages is recognized by dairy producers and is addressed with a laboratory analysis program. Grains, oilseeds, and by-products vary considerably in nutrient content, most often being below values listed by the NRC. Nevertheless, these ingredients are usually not analyzed prior to delivery or prior to consumption by the lactating dairy cow. Commercial feeds are regulated and must provide certain concentrations of major nutrients and list the ingredients on the feed label. Energy cannot be directly analyzed but has been estimated by in vitro, regression, and summative equations. Conversions from digestibility to metabolizable and net energy are also estimated simply from coefficients or by using empirical models based on the nutritional composition of individual feedstuffs or diets. Storage and handling losses must be accounted for, and variability in feedstuffs must be addressed through the supplier or a check sample laboratory analysis program. Knowledge of ingredients and dietary nutrient content is essential for any method of computing and delivering nutrients to meet the requirements of the lactating dairy cow.

Invited review: guidelines for measuring and reporting calf and heifer experimental data.

Based on a 5-yr review of published reports, reporting of materials, methods, and data for calf and heifer studies is often not very complete. The number of calves or heifers per treatment was often inadequate to detect meaningful and statistically significant differences with observed variability. A set of guidelines is provided to assist in designing and planning experiments, collection of data, and summation and reporting. The guidelines may also be useful to reviewers as a checkpoint of information needed or desired.

Increased weight gain and effects on growth parameters of Holstein heifer calves from 3 to 12 months of age.

Two trials involving 280 Holstein heifer calves were to determine effects of increasing nutrient intake on growth (weight, height, and heart girth), dry matter intake, and water intake. In trial 1, 80 calves were fed from 60 to 172 d of age. More calf grower fed increased daily gain from .87 to .92 kg. Gain was further increased to .97 kg with higher energy content and to .99 kg with higher energy and higher protein content of calf growers. Alfalfa hay intake decreased as calf grower intake increased. Wither height and heart girth increased proportionally to body weight. Water intake was variable but proportional to dry matter intake. In trial 2, 114 heifers were fed alfalfa hay with either control or higher protein and higher energy heifer (accelerated program) growers from 187 to 369 d of age. Grass hay was fed to 86 heifers from 230 to 369 d of age with the same grower rations. Daily gain increased from .83 to .93 kg with the accelerated program. Hay intake decreased with higher grower intake on the accelerated program. When fed ad libitum on both programs, grass hay intake was about 5% lower than alfalfa hay. Heart girth at 369 d of age was increased on the accelerated program but there was no effect on wither height. Growth of Holstein heifers can be accelerated up to 1 kg daily gain from 3 to 12 mo of age without excessive fattening.

Ad libitum water intake by neonatal calves and its relationship to calf starter intake, weight gain, feces score, and season.

Water intakes and other experimental data over 3 yr encompassing 335 calves raised under an early weaning program at the Purina Research Farm were summarized. Water intake closely paralleled calf starter intake particularly during the last 2 wk of the 4-wk feeding period. Calves with weight gains below the median daily gain of 272 g had reduced water and starter intake. Scouring, due apparently to rotavirus infection, peaked at the end of the 1st wk. Water intake did not change appreciably prior to or after peak scouring. Season of year had minor effect on both water and starter intake. In a feeding study with 41 calves, weight gain was reduced by 38% and starter intake by 31% for calves deprived of water. Extent and duration of scouring did not differ between treatments. Calf feeding and management systems should include ad libitum water to maximize starter intake and weight gain. There is no evidence that scouring will be affected negatively by water intake.

Dry matter intake from parturition to midlactation.

Six years of data from the Purina Research Center were summarized to quantitate relationships among DMI, DIM, BW, and 4% FCM. Cows were fed individually and housed in a tie-stall barn from parturition to 21 wk postpartum. Best overall equation predicting DMI was kg DMI = .008037 x kg BW + .3134 x kg 4% FCM + .2286 x DIM - .002176 x (DIM)2 + .00000705 x (DIM)3, R2 = .64, CV percentage = 11.1. Data were best fit when separate equations were developed for each week postpartum up to 6 wk and then for periods including 6 to 8, 9 to 13, and 14 to 20 wk. The commonly used equation, kg DMI = .02 x kg BW + .33 x kg 4% FCM, overestimated DMI until wk 10 but underestimated DMI thereafter. The NRC multifactor DMI estimates could be lower or higher than equations developed up to wk 8, depending on values chosen within range of several factors. At wk 8 and beyond, NRC estimates were lower than equations developed, even when highest level within range of several factors was chosen. Calculated energy balances resulted in greater and extended energy deficit for cows in their second or later lactation compared with first lactation. Loss of BW alone was a poor indicator of energy status in early lactation.

Relative efficiencies of wither height and body weight increase from birth until first calving in Holstein cattle.

Female Holstein calves from the Purina Research Center herd averaged 74 cm of height at withers and 40 kg of body weight (BW) at birth. At first calving (24 mo of age), calves averaged 138 cm of height at withers, 611 kg at precalving BW, and 547 kg at postcalving BW. Fifty percent of the total height increase occurred from birth to 6 mo of age, 25% occurred during 7 to 12 mo of age, and 25% occurred during 13 to 24 mo of age. Twenty-five percent of the total BW increase occurred from birth to 6 mo of age, 25% occurred from 6 to 12 mo of age, and the remaining 50% occurred from 13 to 24 mo of age. The increase in BW for 2-mo intervals, expressed as a proportion of the BW of the previous 2-mo interval, declined most rapidly during the first 6 mo, intermediately during the second 6 mo, and more slowly and progressively during the final 12 mo. Feed cost per unit of BW gain was lowest during the first 6 mo and then increased at a decreasing rate over the final 18 mo. The proportion of BW to height linearly increased over the 24-mo period. The increase in wither height as a proportion of the wither height during the previous period was greatest during the first 6 mo, intermediate during the second 6 mo, and lowest in the final 12 mo. Feed cost per unit of height increase was lowest in the first 6 mo, intermediate during the second 6 mo, and highest with a rapid increase during the final 12 mo. The increases in relative BW and wither height are the most rapid and cost efficient during the first 6 mo of life.

Ruminal infusion of ammonium chloride in lactating cows to determine effect of pH on ammonia trapping.

Milking rations containing 16 (control), 13.2, and 10.4% protein were fed to four midlactation, rumen-fistulated Holstein cows. Ammonium chloride was infused ruminally for 5 consecutive days after morning feeding when cows were fed milking rations containing 13.2 and 10.4% protein. Amount infused was equivalent to the ammonia in 1 or 2% dietary urea. Rumen and blood samples were taken prior to and following morning feedings. Intake of milking ration was the same across treatments. Initial rumen pH was higher for ammonium chloride treatments. It then declined, as did the control, to the same, lowest pH at 1.5 to 3 h postfeeding. Rumen ammonia increased rapidly for cows receiving both ammonium chloride treatments to .5 h postfeeding and then declined rapidly. Blood urea nitrogen was highest for cows fed the control ration, peaked .5 h postfeeding for cows infused with the low ammonium chloride, then dropped and peaked again 6 h postfeeding. Blood ammonia was highest among treatments for control cows and differed by sampling time only for control cows with a peak .5 h postfeeding. Because lower rumen pH traps ammonia preventing rapid absorption into blood, interpretation of high rumen ammonia must consider effect of rumen pH.

Body weight, body condition score, and wither height of prepartum Holstein cows and birth weight and sex of calves by parity: a database and summary.

Measurements of body weight (BW), body condition score, wither height, calf birth weight, and calf sex were recorded by parity from 728 Holstein cows and heifers at the Purina Research Center during the 8-wk prepartum period. Data were compiled over 5 yr. Mean daily BW gain was 0.93 kg. Loss of BW at parturition was 11.1%. Mean body condition score was 3.35 (five-point scale where 1 = thin to 5 = obese) and did not change during the 8-wk period. However, body condition score was lower for second parity cows than for heifers or cows in third or greater parity. Wither height averaged 138 cm at first parity and increased 3 cm from first to second parity. During fifth and sixth parities, wither height peaked at an additional 2 to 3 cm. Birth weights for all calves averaged 41.4 kg. Male calves were 8.5% heavier than female calves. Calves born to cows in second or greater parity had increased BW by 7 to 8%. Mean BW of twin calves was 15% less than that of single calves.