Effects of the non-fiberous carbohydrate content of total mixed rations with higher physical characteristics on rumen fermentation, blood metabolites, and milk production in dairy cows
2016
Ikuta, K. | Ishikawa, S. | Yamaguchi, E.
This experiment was conducted to determine the effects of the non-fibrous carbohydrate (NFC) content of total mixed rations (TMR) with higher physical characteristics on rumen fermentation, blood metabolites and milk production in dairy cows. Three primiparous and 7 multiparous in early lactation cows were divided into two experimental groups: cows fed 1) a control diet that included 37.8% NFC (group C; n=5) and 2) a test diet that included 44.2% NFC (group T; n=5) in a crossover design. Each period of crossover lasted for 14 days. The following results were obtained: (1) There was no significant difference in dry matter intake, body weight, or dairy gain between the two groups. (2) There was no significant difference in the ruminal pH, or the total volatile fatty acid concentration between the two groups. Molar percentage of acetate was significantly lower and buthyrate was significantly higher in group T than in group C at pre-feeding. The ruminal ammonia-N concentration, the molar percentage of acetate, and the ratio of acetate/propionate were significantly lower, and the molar percentage of propionate and buthyrate was slightly higher in group T than in group C at post-feeding (after 2 h). (3) The blood urea nitrogen level was significantly higher in group T than in group C. (4) The milk yield was slightly higher in group T than in group C. The milk urea nitrogen level was significantly lower in group T than in group C. The milk lactose percentage was slightly higher in group T than in group C. In conclusion, feeding of the TMR with high levels of NFC and physical characteristics increased milk production, most likely because it enhanced the propionic acid fermentation with high energy efficiency in the rumen without lowering of ruminal pH.
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