Effects of branched-chain volatile fatty acids and fibrolytic enzyme on rumen development in pre- and post-weaned Holstein dairy calves.

The study evaluated the effects of branched-chain volatile fatty acids (BCVFA) and fibrolytic enzyme (FE) on rumen development in calves. Forty Holstein male calves at the same ages (15 ± 2.5 days of age) and weights (45 ± 3.3 kg of body weight [BW]) were assigned randomly to four groups with a 2 × 2 factorial arrangement of treatments. Supplemental BCVFA (0 g/d or 18 g/d) and FE (0 g/d or 1.83 g/d) were fed to calves. Data were analyzed as a 2 × 2 factorial arrangement random design by the mixed procedure of SAS. The BCVFA × FE interaction was observed for ruminal propionate, blood growth hormone (GH) and insulin-like growth factor-1 (IGF-1), and GH receptor (GHR) and IGF-1 receptor (IGF-1R) expression in the rumen mucosa. Dry matter intake was higher for BCVFA addition. The higher average daily gain and ruminal volatile fatty acids were observed for BCVFA or FE addition. Stomach weight and the length and width of rumen papillae were higher for BCVFA addition. The higher expression of GHR, IGF-1R and 3-hydroxy-3-methylglutaryl-CoA synthase 1 in rumen mucosa, and blood GH and IGF-1 were observed with BCVFA or FE addition. Blood ß-hydroxybutyrate and acetoacetate were higher for BCVFA addition. The results indicated that rumen development was promoted by BCVFA, but was not affected with FE addition in calves.

Effects of rumen-protected folic acid and rumen-protected sodium selenite supplementation on lactation performance, nutrient digestion, ruminal fermentation and blood metabolites in dairy cows.

BACKGROUND: Considering the insufficient ruminal synthesis of folic acid (FA), the higher degradability of FA, and the reduction of sodium selenite (SS) by ruminal microbes into non-absorbable elemental Se, this study evaluated the effects of rumen-protected FA (RPFA) and rumen-protected SS (RPSS) on lactation performance, nutrient digestion and blood metabolites in dairy cows. RESULTS: Dry matter (DM) intake and milk composition were unaltered, milk and milk fat yields were higher for both supplements, and milk protein yield was higher for RPFA addition. Digestibility of DM, neutral detergent fibre and acid detergent fibre was higher for both supplements, whereas that of organic matter and crude protein was higher for RPFA addition. Ruminal pH and ammonia N were lower, and concentration of total volatile fatty acids was higher for both supplements. Activity of cellobiase and xylanase was higher for RPFA addition, whereas that of pectinase and protease was higher for both supplements. The populations of total ruminal fungi, protozoa, Ruminococcus flavefaciens and Butyrivibrio fibrisolvens were higher for both supplements. The RPFA × RPSS interaction was significant for α-amylase activity, total ruminal bacteria and R. albus populations; these three variables were increased by RPSS but the increase was greater when cows were also fed RPFA. CONCLUSION: The results indicated that addition of RPFA or RPSS improved lactation performance, nutrient digestibility and ruminal fermentation in dairy cows by stimulating ruminal microbial growth and enzyme activity. © 2019 Society of Chemical Industry.

Effects of rumen-protected pantothenate supplementation on lactation performance, ruminal fermentation, nutrient digestion and blood metabolites in dairy cows.

BACKGROUND: Lactation performance of dairy cow has considerably increased with animal breeding and management improvement in recent years. Ruminal net synthesised pantothenic acid is insufficient to meet the requirement of high producing dairy cows. The objective was to investigate the effects of rumen-protected pantothenate (RPP) on lactation performance, ruminal fermentation, nutrient digestion and blood metabolites in dairy cows. RESULTS: Dry matter (DM) intake tended to increase, whereas milk yields, milk fat percentage and yield, body condition score (BCS) changes and net energy output except for maintenance increased linearly with increasing RPP supplementation. Ruminal pH and ammonia N concentration tended to decrease, total VFA tended to increase, while acetate-to-propionate ratio increased linearly with increasing RPP supplementation. Digestibilities of DM, organic matter and crude protein increased linearly, but neutral detergent fibre and acid detergent fibre digestibility tended to increase. Blood glucose, total protein, non-esterified fatty acids, pantothenic acid, pantothenate kinase, succinyl CoA, acyl carrier protein and acetyl CoA also increased linearly with increasing RPP supplementation. CONCLUSION: The results indicated that supplementary RPP improved lactation performance, nutrient digestion and blood parameters in a dose-dependent manner, and the optimal dose was 12 g RPP per cow per day in the current study. © 2017 Society of Chemical Industry.