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.

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.

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.

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.

Responses to lipid supplementation differ between dairy breeds and genetic lines suggesting nutrition by genotype interactions. beta-Lactoglobulin phenotype is associated with changes in yield and composition of milk. The response of cows with different beta-lactoglobulin phenotypes to lipid supplementation has not been examined. Furthermore, we examined whether lipid supplementation alters milk protein composition. By using a randomized block design, we fed Holstein cows for 3 wk either a control diet containing 2.8% crude fat (n = 19) or an experimental diet that was supplemented with 4.2% tallow (n = 20). Before randomization, all cows were fed the supplemental tallow diet for at least 2 wk. Dry matter intake, body weight, milk yield, and milk composition were measured in the last week before and during the experimental period. Feeding supplemental tallow increased dry matter intake and yields of milk and milk components, including casein content, without decreasing milk component content or altering milk protein composition. On the low-fat control diet, cows with the beta-lactoglobulin allele B had a greater milk and milk component yield than cows with the A allele, whereas no differences by beta-lactoglobulin phenotype were observed in cows on the tallow supplement diet. Our results suggest that cows that differ in beta-lactoglobulin phenotype respond differently to a low-fat diet and that feeding cows 4.2% of additional tallow increases milk yield without affecting milk component content and milk protein composition.