Effects of Dietary Crude Protein Level on Growth Performance,Nutrient Apparent Digestibility and Rumen Fermentation Parameters of Growing Water Buffalo Aged 5 to 9 Months and Its Digestible Crude Protein Requirement Prediction
The aim of this experiment was to investigate the effects of dietary crude protein(CP)level on growth performance,nutrient apparent digestibility and rumen fermentation parameters of growing water buffa-lo aged 5 to 9 months,and to project the digestible crude protein(DCP)requirement of growing water buffa-lo.Twenty-four healthy growing water buffalo with the body weight of(210.61±6.43)kg and similar body condition were selected for the experiment.They were randomly divided into three groups:low CP level(12.72％)diet group(LP group),medium CP level(15.87％)diet group(MP group),and high CP level(19.02％)diet group(HP group),with 8 replicates per group and one buffalo per replicate.The pre-experi-mental period was 15 days,and the formal experimental period was 50 days.At the end of the feeding trial,each group randomly selects 5 buffalo for a 5-day digestion trial,collecting fecal and diet samples.Based on the CP content in the fecal and diet samples,the DCP intake was calculated and a prediction model for the re-quirement of DCP was established according to the principle of factorization.The results showed as follows:1)the average daily gain(ADG)of growing water buffalo in the MP and HP groups was significantly higher than that of the LP group(P＜0.05);the dry matter intake(DMI)of the MP and HP groups was significantly higher than that of the LP group(P＜0.05).2)The apparent digestibility of crude protein(CP)and dry mat-ter(DM)in the MP group was significantly higher than that in the LP group(P＜0.05);the apparent digesti-bility of ether extract(EE)in the MP and HP groups was significantly higher than that in the LP group(P＜0.05);the apparent digestibility of neutral detergent fiber(NDF)in the MP group was significantly higher than that in the LP and HP groups(P＜0.05).3)The concentration of rumen fluid ammonia nitrogen(NH3-N)in the HP group was significantly higher than that in the LH and MP groups(P＜0.05);the concen-tration of rumen fluid acetate in the LP group was significantly higher than that in the HP group(P＜0.05);the concentrations of rumen fluid isobutyrate,isovalerate and valerate in the LP group were significantly higher than those in the MP and HP groups(P＜0.05),and at the same time,the concentrations of rumen fluid isobu-tyrate,isovalerate and valerate in the MP group were significantly higher than those in the HP group(P＜0.05);the butyrate/total volatile fatty acids(TVFA)ratio in the MP and HP groups was significantly higher than that in the LP group(P＜0.05).4)The maintenance DCP requirement for growing buffaloes(256 kg)was calculated as 3.51 g/(kg W075·d)according to the analytical factorization method,which was 266.87 g of DCP per kg of weight gain.In conclusion,feeding a diet containing 15.87％CP can improve the apparent digestibility of DM,CP,EE and NDF of growing water buffalo aged 5 to 9 months.It also can increase the concentrations of acetate,isobutyrate,isovalerate and valerate in the rumen fluid,which is beneficial for en-hancing the activities of rumen microorganisms.This,in turn,it can improve the feed conversion efficiency and promote the absorption of nutrients from the diet of growing water buffalo.The prediction model for DCP requirement of growing buffalo from 5 to 9 months of age is DCP=3.51W0.75+266.87△W(in the model,DCP is digestible protein requirement,g/d;W0 75 is metabolic weight,kg;△W is daily gain,kg/d).[Chinese Journal of Animal Nutrition,2024,36(6):3713-3724]
growing water buffalocrude protein levelgrowth performanceapparent digestibility of nutri-entsdigestible crude protein requirement
万方数据
维普
