Study on dose-effect relationship between probiotics supplementation levels and ruminal fermentation parameters in yak calves
The study aimed to explore the dose-effect relationship between different levels of compound probiotics and ruminal fermentation parameters in yak calves,and to determine the appropriate supplementation level.Four healthy three-month-old yak calves were selected,and ruminal fluid was collected through an oral sampling device.An artificial rumen device was used for in vitro fermentation with calf milk replacer powder as the fermentation substrate.Compound probiotics(a mixture of Lactobacillus,Bacillus,and yeast probiotics ≥9.98 × 1011 CFU)were added at levels of 0(control group),0.025％(0.025％group),0.050％(0.050％group),0.100％(0.100％group),0.200％(0.200％group),and 0.400％(0.400％group),respectively.Six sampling time points were set at 3,6,9,12,24,and 48 hours of fermentation to measure fermentation parameters:pH value,gas production(GP),ammonia nitrogen(NH3-N),microbial crude protein(MCP),acetic acid(AA),propionic acid(PA),butyric acid(BA),and total volatile fatty acids(TVFA).A comprehensive index,the Microbial Fermentation Activity Evaluation Index(MFAEI)was calculated based on the fermentation parameters.The results showed a trend of reducing ruminal fermentation pH value with the addition of compound probiotics.The GP of the 0.100％and 0.200％groups from 3 to 24 hours of fermentation was significantly higher than that of the control group(P＜0.05),and the NH3-N concentration was significantly lower than that of the control group(P＜0.05).The MCP concentration from 3 to 12 hours of fermentation was significantly higher than that of the control group(P＜0.05).The TVFA concentration from 6 to 48 hours of fermentation was significantly higher than that of the control group(P＜0.05).The MFAEI values calculated from the fermentation parameters ranked from high to low were:0.100％group＞0.200％group＞0.400％group＞0.050％group＞0.025％group.The study indicates that the addition of compound probiotics can effectively reduce NH3-N concentration,enhance fermentation GP and MCP,and TVFA concentrations,promoting the establishment of microbial fermentation function in the rumen of yak calves.The optimal effect is observed at a supplementation level of 0.100％.
万方数据
维普
