Optimizing dietary rumen-degradable starch to rumen-degradable protein ratio improves lactation performance and nitrogen utilization efficiency in mid-lactating Holstein dairy cows

• DOI: 10.3389/fvets.2024.1330876
• Publication Date: 2024-02-29T13:26:50Z
• Authors: Panliang Chen; Yan Li; Meimei Wang; Yizhao Shen; Mingchao Liu; Hongjian Xu; Ning Ma; Yufeng Cao; Qiufeng Li; Mahmoud M. Abdels...; Zhiyuan Wang; Zihan Huo; Shuai Ren; Linqi Hu; Jie Liu; Yanxia Gao; Jianguo Li
• Keywords: rumen-degradable starch; 0404 agricultural biotechnology; Veterinary medicine; Holstein dairy cows; SF600-1100; lactation performance; rumen-degradable protein; Veterinary Science; nitrogen utilization efficiency; 04 agricultural and veterinary sciences

The dietary rumen-degradable starch (RDS) to protein (RDP) ratio, denoted as the RDS-to-RDP ratio (SPR), has been proven enhance in vitro rumen fermentation. However, effects of SPR vivo remain largely unexplored. This study was conducted investigate effect on lactation performance, nutrient digestibility, fermentation patterns, blood indicators, and nitrogen (N) partitioning mid-lactating Holstein cows. Seventy-two dairy cows were randomly assigned three groups (24 head/group), balanced for (mean ± standard deviation) days milk (116 21.5), parity (2.1 0.8), production (42 2.1 kg/d), body weight (705 52.5 kg). fed diets with low (2.1, control), medium (2.3), or high (2.5) SPR, formulated be isoenergetic, isonitrogenous, iso-starch. consisted a one-week adaptation phase followed by an eight-week experimental period. results indicated that group had lower dry matter intake compared other (p < 0.05). A quadratic increase yield feed efficiency observed increasing 0.05), peaking group. exhibited somatic cell count higher total antioxidant capacity With there improvement 0.05) tract apparent digestibility crude protein, ether extract, starch, neutral detergent fiber, acid fiber. Although no treatment pH, volatile fatty acids concentration microbial synthesis increased quadratically increased. molar proportion propionate linearly = 0.01), while branched-chain decreased 0.01) SPR. (control) urea N, ammonia N than Despite linear decrease urinary intake, led utilization fecal intake. In conclusion, optimizing potential performance efficiency. Based our findings, (with 2.3) is recommended Nevertheless, further research composition metabolites warranted elucidate underlying mechanisms effects.