Form of rumen-degradable carbohydrate and nitrogen on microbial protein synthesis and protein efficiency of dairy cows.

Sixteen multiparous lactating Holstein cows (four with rumen cannulae) were fed diets varying in the content and form of ruminally degradable carbohydrates and N to examine dietary effects on microbial protein synthesis (MPS) and whole animal N efficiency, and to evaluate the use of a model based on milk urea N (MUN) for predicting urinary N excretion and N utilization efficiency (NUE). A replicated Latin square design (consisting of diet and experimental period) was employed. The four diets consisted of two low protein diets with either 20% ground corn (diet LP) or 13.

In situ disappearance of individual proteins and nitrogen from legume forages containing varying amounts of tannins.

In situ degradability of N and proteins were studied in one cultivar of alfalfa and red clover and two cultivars each of birdsfoot trefoil and sericea lespedeza. Concentrations of tannic acid equivalents (percentage of DM) were 0.68 in one cultivar of birds-foot trefoil and 1.

Changes in total and individual proteins during drying, ensiling, and ruminal fermentation of forages.

Effects of wilting, drying, and ensiling on concentrations of proteins in alfalfa, crown vetch, perennial ryegrass, orchardgrass, and tall fescue were studied using SDS-PAGE. Seven to nine proteins were identified in the samples. Wilting forages for 24 h on a laboratory bench had little effect on the relative amounts of proteins.

Evaluation of pearl millet and field peas plus triticale silages for midlactation dairy cows.

A mixture of field peas and triticale was planted in spring, harvested as silage, and followed by a double crop of pearl millet, which also was harvested as silage. Eighteen Holstein cows were fed diets based on pea with triticale, pearl millet, or alfalfa plus corn silages. Dry matter digestibility of the pea with triticale diet was higher than for control (71.

Effects of nitrogen fertilization and maturity of bromegrass on nitrogen and amino acid utilization by cows.

Four nonlactating Holstein cows (593 kg) with ruminal cannulas were fed bromegrass hay that was fertilized with 0 or 89 kg of N/ha and harvested in the late-boot or full-head stage of maturity. Total tract apparent digestibility of N was less for full-head than for late-boot bromegrass (48 vs 64%; P less than .01) and was greater for N-fertilized than for unfertilized bromegrass (60 vs 52%, P less than .