Manure and Nutrient Partitioning, Accretion, and Excretion in Holstein Heifers

Considerable changes have occurred in environmental regulations in recent years, only one of which is the requirement of stand alone heifer operations and feedlots to carry environmental permits. While growth of heifers is a widely researched topic, publications concerning nutrient utilization, partitioning, and excretion are scarce and are becoming necessary. That combined with the fact that feeding programs for heifers are highly variable from region to region and even from farm to farm indicated the need to examine the effects of diet on nutrient utilization. Therefore, the objective of this work was to evaluate how differences in levels of dietary protein and energy will affect growth and nutrient utilization in heifers from birth to calving. Two projects were conducted, one in 20 month old bred heifers where forage level in the diet was altered to provide the required nutrients in less feed and one in young calves where energy and protein content of the milk replacer was altered. Three diets were fed to 18 (n=6), 20 month old heifers who were in late gestation; the first was the high forage (HF) ration which was 90.7% forage and 9.3% concentrate, the second was a by-product (BP) ration which was designed to have the same level of fiber as the HF ration, however soybean hulls and cottonseed hulls were added at the sacrifice of the grain mix which increased the fiber content; the last ration was the low forage (LF) which was 54.7% concentrate and 45.3% forage and was fed at ~89% of the ad libitum intake of heifers fed the HF ration. Heifers fed the HF ration had greater fecal excretion compared to those fed LF, however heifers fed the LF ration exceeded the heifers fed HF and BP by 4.5 and 2.5 times, respectively,