饲粮粗蛋白质水平对沂蒙黑山羊生产性能、营养物质消化率及血清生化指标的影响

Effects of Dietary Crude Protein Level on Performance,Nutrient Digestibility and Serum Biochemical Indexes of Yimeng Black Goats

本试验旨在研究饲粮粗蛋白质水平对沂蒙黑山羊生产性能、营养物质消化率及血清生化指标的影响,为确定沂蒙黑山羊泌乳期饲粮粗蛋白质水平提供理论依据。选择胎次(2~3胎)、年龄(2~3岁)、体重[(29±3)kg]相近的即将分娩的80只沂蒙黑山羊,随机分为4组(A、B、C和D组),每组5个重复,每个重复4只母羊。各组分别饲喂粗蛋白质水平为14.15%、15.34%、16.27%和17.47%的试验饲粮。母羊分娩当天即为试验正式开始时间,将母羊的泌乳期(91 d)分为泌乳前期(第1~28天)、泌乳中期(第29~70天)和泌乳后期(第71~91天)。结果表明:1)C和D组泌乳前期和泌乳中期干物质采食量(DMI)显著低于A组(P<0.05)。D组泌乳前期粗蛋白质采食量(CPI)显著高于B和C组(P<0.05),C和D组泌乳前期可消化粗蛋白质采食量(DCPI)显著高于A和B组(P<0.05)。B组泌乳中期CPI显著高于C组(P<0.05),A组泌乳中期DCPI显著低于其他各组(P<0.05)。D组泌乳后期CPI显著高于其他各组(P<0.05),A组泌乳后期DCPI显著低于其他各组(P<0.05)。2)D组第70天和第91天母羊体重显著高于A和B组(P<0.05)。C和D组第28天、第70天和第91天羔羊窝重显著高于A组(P<0.05)。3)泌乳前期、泌乳中期和泌乳后期母羊泌乳量分别在D、C和B组达到最大值,相对于A组增幅分别为36.47%、50.64%和17.04%(P<0.05)。4)C组泌乳前期和泌乳中期粗蛋白质、总能和干物质消化率显著高于A组(P<0.05),B和C组泌乳后期粗蛋白质、总能和干物质消化率显著高于A组(P<0.05)。5)D组泌乳前期、泌乳中期和泌乳后期血清尿素氮含量显著高于A组(P<0.05)。由此可见,饲粮粗蛋白质水平过高会抑制沂蒙黑山羊DMI,降低营养物质消化率,影响不同泌乳期DCPI,从而影响母羊的泌乳量和羔羊的增重速度。泌乳前期沂蒙黑山羊适宜饲粮粗蛋白质水平为16.27%~17.47%,泌乳中期为16.27%,泌乳后期为16.27%~17.47%。

This experiment was conducted to study the effects of dietary crude protein level on performance,nutrient digestibility and serum biochemical indexes of Yimeng black goats,and to provide theoretical basis for determine the dietary crude protein level of Yimeng black goats during lactation.A total of 80 Yimeng black goats about to give birth with similar parity(2 to 3 parities),age(2 to 3 years old)and body weight[(29±3)kg]were randomly divided into 4 groups(groups A,B,C and D)with 5 replicates in each group and 4 goats in each replicate.They were fed experimental diets with crude protein levels of 14.15%,15.34%,16.27% and 17.47%,respectively.The day of ewe delivery was the beginning of the experiment,the lactation period(91 days)of ewes was divided into pre-lactation period(days 1 to 28),mid-lactation period(days 29 to 70)and late-lactation period(days 71 to 91).The results showed as follows:1)the dry matter intake(DMI)during pre-lactation period and mid-lactation period of groups C and D was significantly lower than that of group A(P<0.05).The crude protein intake(CPI)during pre-lactation period of group D was significantly higher than that of groups B and C(P<0.05),and the digestible crude protein intake(DCPI)during pre-lactation period of groups C and D was significantly higher than that of groups A and B(P<0.05).The CPI during mid-lactation period of group B was significantly higher than that of group C(P<0.05),and the DCPI during mid-lactation period of group A was significantly lower than that of other groups(P<0.05).The CPI during late-lactation period of group D was significantly higher than that of other groups(P<0.05),and the DCPI during late-lactation period of group A was significantly lower than that of other groups(P<0.05).2)The body weight of ewes on day 70 and day 91 of group D was significantly higher than that of groups A and B(P<0.05).The litter weight of lambs on day 28,day 70 and day 91 of groups C and D was significantly higher than that of group A(P<0.05).3)The milk yield of ewes during pre-lactation period,mid-lactation period and late-lactation period reached the maximum in groups D,C and B,respectively,and increased by36.47%,50.64% and 17.04% compared with group A(P<0.05),respectively.4)The digestibility of crude protein,gross energy and dry matter during pre-lactation period and mid-lactation period of group C was significantly higher than that of group A(P<0.05),and the digestibility of crude protein,gross energy and dry matter during late-lactation period of groups B and C was significantly higher than that of group A(P<0.05).5)The serum urea nitrogen content during pre-lactation period,mid-lactation period and late-lactation period of group D was significantly higher than that of group A(P<0.05).In conclusion,high dietary crude protein level will inhibit the DMI of Yimeng black goats,reduce the nutrient digestibility,and affect the DCPI in different lactation periods,thus affecting the milk yield of ewes and the growth rate of lambs.The appropriate dietary crude protein level is 16.27% to 17.47% during pre-lactation period,16.27% during mid-lactation period and 16.27% to 17.47% during late-lactation period for Yimeng black goats.