| Abstrakt: |
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 resulted in a linear increase in the concentration of rumen acetate, butyrate, isovalerate, and valerate (P< 0.01), and had a quadratic effect on caproate. Rumen bacterial yield and duodenal flow of total N were not affected by treatment. Ruminal fermentation characteristics and digestibility of nutrients suggest that the substitution of SBM and barley grain with peas may alter the site and end-products of digestion; however, the substitution had no significant effects on production parameters. Key words:Peas, digestion, rumen fermentation, dairy cows |
