INFLUENCE OF YUCCA EXTRACT ON RUMINAL METABOLISM IN COWS

Two trials were conducted to determine the influence of yucca extract on ruminal digestion, fermentation, and ammonia patterns using ruminal ly and duodenally cannulated dairy cows. In Trial 1, urea at 0 or 1% o f the diet and yucca extract at 0 or 4 g/d formed four dietary treatme nts in a 2 x 2 factorial arrangement. The experimental design was a 4 x 4 Latin square with 15-d periods. Duodenal digesta were sampled ever y 6 h during the last 4 d of each period to determine OM and ADF diges tibilities and bacterial protein synthesis in the rumen using Cr2O3 an d N-15 markers. Ruminal digestibilities were (percentage): OM 46.3 vs 43.0%, and ADF 35.9 vs 41.4%, with or without Deodorase(R). Microbial protein entering the duodenum averaged 2.7 vs 3.1 kg/d for the respect ive treatments. Ruminal measurements were not affected by treatment (P > .10). In Trial 2, five cows were used in a 5 x 5 Latin square with 7-d periods. Treatments were 0, 2, 4, 6, and 8 g/d of yucca extract ad ministered via ruminal cannulas. Ruminal fluid was sampled 0, 1, 2, 4, 7, 11, 16, and 22 h after feeding during the last 2 d of each period. Average ruminal NH3 N ranged from 31.4 to 35.4 mg/dL, pH 5.99 to 6.18 , and total VFA from 120 to 129 mM, and all did not differ among treat ments (P > .10). Yucca extract administered at 4 g/d did not significa ntly affect ruminal digestibilities of OM and ADF, and up to 8 g/d did not affect ruminal NH3, pH, or VFA.