G.R. Khorasani

Nutritive value of peas for lactating dairy cattle

The objective of this study was to determine the nutritive value for lactating dairy cows of peas relative to soybean meal (SBM) and barley. Four Holstein cows (200 ± 23 d in milk), fitted with rumen and duodenal cannulae were assigned to four dietary treatments in an experiment designed as a 4 × 4 Latin square with 21 d in each of the four periods. Cows were fed a diet for ad libitum intake with a 50:50 forage:concentrate ratio (DM basis). Peas replaced SBM at the levels of 0, 33.3, 66.7%, and 100% of the concentrate portion in the four test diets. In the 100% pea-based diet, barley was replaced (at 72.35%) to obtain a similar starch content as the SBM-based concentrate. The forage components of the diets consisted of 25% alfalfa silage and 25% bromegrass silage. Dry matter intake (21.6 ± 0.4 kg d–1) and milk yield were not affected by substitution of peas for SBM and barley. Mean rumen pH decreased linearly (P < 0.01) with increasing level of peas in the diet. Substitution of peas for SBM and barley res...

In situ rumen degradation characteristics of sixty cultivars of barley grain

Our objectives were to determine the extent of genetic variability in the rate and extent of ruminal digestion among 60 cultivars of barley, and to evaluate the correlations between ruminal digestion characteristics and chemical composition and test weight of barley cultivars. Barley samples were ground through a 2-mm screen, and bags containing 1 g of ground grains were incubated in the rumen of three late-lactation Holstein cows with rumen cannulae for 0, 1, 2, 4, 8, 12, 16, and 24 h. The rate and extent of ruminal digestion were estimated. The insoluble DM fraction ranged from 33.4 to 56.4%, the degradable DM fraction ranged from 34.1 to 60.2%, and the rate of degradation of DM ranged from 0.200 h−1 to 0.624 h−1. Hulled barley cultivars had lower (P < 0.05) soluble and degradable fractions than hulless cultivars. The soluble fraction was positively correlated to starch content of barley cultivars (P = 0.01) and the degradable fraction was correlated to the test weight and CP content (P < 0.01). The obs...

Effects of source of forage and level of concentrate on chewing activity and milk production response in late lactation cows

Four cannulated Holstein cows in late lactation were used in a 4 × 4 Latin square design experiment to determine the effects of forage source with different NDF concentrations and level of concentrate on chewing activity and milk production. Diets were 65% first-cut alfalfa silage with 54% NDF and 35% concentrate, 50% alfalfa and 50% concentrate, 65% bromegrass silage with 65.5% NDF and 35% concentrate and 50% bromegrass silage and 50% concentrate. Diets were fed in 2 × 2 factorial design (silage sources, alfalfa vs. bromegrass and two levels of concentrate, 35 vs. 50%). Dry matter intake averaged 15.2 kg d−1 and was not affected by either forage source or level of concentrate. Intake of NDF was lower for the cows fed the alfalfa-based diet vs. bromegrass silage but the level of concentrate did not affect NDF intake. Time spent eating was not affected by either forage source or concentrate level of the diet. Time spent eating and ruminating kg−1 NDF intake was higher for cows fed alfalfa-based diets than ...