Effects of rumen-protected folic acid and branched-chain volatile fatty acids supplementation on lactation performance, ruminal fermentation, nutrient digestion and blood metabolites in dairy cows

• Published in: Animal feed science and technology 2019-01, Vol.247, p.157-165
• Main Authors: Wang, C., Liu, Q., Guo, G., Huo, W.J., Zhang, Y.L, Pei, C.X., Zhang, S.L
• Format: Article
• Language: English
• Subjects: Blood metabolites; Branched-chain volatile fatty acids; Dairy cows; Folic acid; Lactation performance; Ruminal fermentation
• ISSN: 0377-8401; 1873-2216
• DOI: 10.1016/j.anifeedsci.2018.11.015

•Supplementation of branched-chain VFA with or without rumen protected folic acid was evaluated.•Milk yield, true protein content and yield as well as feed efficiency increased with both supplements.•Ruminal fermentation characteristics, cellulolytic bacteria and enzyme activities were improved.•Serum GHRH, GH, IGF-1 and total protein increased with both supplements.•There was no interaction detected between branched-chain VFA and rumen protected folic acid. This study evaluated the effects of branched-chain volatile fatty acids (BCVFA) and rumen protected folic acid (RPFA) supplementation on lactation performance, ruminal fermentation, nutrient digestion and blood metabolites in dairy cows. Fifty-six multiparous Chinese Holstein cows (3.2 ± 1.1 of parity, 631 ± 16.4 kg of body weight [BW], 65 ± 2.6 days in milk [DIM] and 30.2 ± 2.1 kg of milk yield per day, mean ± SD) were blocked by lactation number, milk yield per day and DIM and were arranged into one of four groups in a randomized block design with a 2 × 2 factorial arrangement. Supplemental BCVFA (0 g/d [BCVFA-] or 80 g/d [BCVFA+]) and RPFA (0 mg/d [RPFA-] or 128 mg/d [RPFA+]) were hand-mixed into the top one-third of total mixed ration. Dietary concentrate to forage ratio was 50:50 based on a dry matter (DM) basis. Experimental periods comprised 105 days with 15 d of adaptation followed by 90 d of data collection. DM intake was increased with BCVFA supplementation, but was unaffected by RPFA. The BW changes were similar among treatments. Yields of milk, milk fat and lactose were increased, and milk true protein yield tended to increase with BCVFA or RPFA supplementation. Milk fat percentage was increased with BCVFA supplementation, but was unaffected by RPFA. Percentage of milk true protein was increased, lactose was unaltered and feed conversion ratio was decreased with BCVFA or RPFA supplementation. Ruminal pH and ammonia N concentration were decreased, but total volatile fatty acids concentration was increased with BCVFA or RPFA supplementation. Molar proportion of acetate was increased and propionate was decreased, resulting in an increased ratio of acetate to propionate with BCVFA supplementation. Acetate and propionate molar proportion and the ratio of acetate to propionate were not affected by RPFA. Digestibilities of DM, organic matter, crude protein, non-fiber carbohydrates, neutral detergent fibre and acid detergent fibre were increased with BCVFA or RPFA supplementation. Similarly, activi