Effects of rearing diet, age at freshening, and lactation feeding system on performance

The effects of disease, management, and nutrition on average daily gain of dairy heifers from birth to four months

The effects of disease, management, and nutrition on the average daily gain of dairy heifers were studied from birth to 4 mo of age for 795 Holstein calves from 21 commercial dairy farms in Pennsylvania during 1991 and 1992. Biweekly visits to the farms yielded information on body weight, nutrient intake, environment, and management practices for each calf. Average daily gain varied throughout the 4-mo period because of many factors, including housing location after separation from the dam, dry matter intake, season, and farm. Dry matter intake was 4.0 kg/kg of body weight gain throughout the period from birth to 4 mo of age. Calves born in winter tended toward higher average daily gain than did calves born in other seasons. Calves born in summer showed a tendency for decreased average daily gain. The practices of tying calves with cows and housing groups of calves in pens were detrimental to average daily gain, but the use of hutches and the practice of tying calves away from cows yielded higher average daily gains. Other variables with significant effects included calving location, parity of the dam, and delivery score at calving.

Body measurements, metritis, and postpartum performance of first lactation cows

Effects of herd, sire, season, body height, BW, age at calving, and metritis on future performance of first lactation cows were evaluated in eight commercial Israeli Holstein herds. Short, heavy first lactation cows had an odds ratio of 3.1 of incidence of metritis at calving compared with all others; 648 first lactation cows were measured at wk 1 postpartum. Sire, herd, age, height, season, and BW contributed to peak milk yield. Metritis did not affect peak yield. Herd, sire, height, and age contributed to mature equivalent corrected 305-d milk yield. No effect was found for BW, season, or metritis. Herd was the only variable contributing to month of peak yield and rate of monthly drop in yield. Interactions between BW, height, and incidence of metritis were significant. Tall, heavy first lactation cows with metritis peaked higher and yielded more than those without metritis. Short, light first lactation cows with metritis yielded less and peaked lower than their healthy counterparts. Metritis did not affect future fertility, but season and the interaction between BW and height did. Tall, heavy first lactation cows had a lower pregnancy rate from first AI, independent of milk yield. The relative importance of height as a predictor of future milk yield is underestimated. The interaction between height and BW may have an antagonistic effect on yield and fertility.