全株玉米青贮补饲水平及补饲日龄对哺乳期羔羊生长性能和血清指标的影响OA

[Objective]The aim was to study the effects of whole-plant corn silage(WPCS)on the growth performance,serum biochemical and immune indices of lactating lambs.[Method]A total of 168 7-day-old Duhu hybrid F1 generation twin lambs with similar body weights(4.23 kg±0.58 kg)were selected for the experiment and randomly divided into 7 groups,with 4 replicates in each group and 6 lambs in each replicate.The control group(CON)began to feed the lambs with basic starter feed at 14 days of age.The 14-day-old groups(2.5 S14,5 S14,and 7.5 S14)began to feed the experimental diet to the lambs at 14 days of age.The 21-day-old groups(2.5 S21,5 S21,and 7.5 S21)began to feed the experimental diet to the lambs at 21 days of age.The experimental diet was formulated by adding equal amounts of 2.50％,5.00％and 7.50％of WPCS respectively to the basic diet of CON group according to the air-dried basis to replace part of the initial diet.The experimental period was 54 days.During the experiment,lambs were weighed on an empty stomach before morning feeding at 0,14,21,30,45,and 60 days of age respectively.Blood was collected and serum was separated at the end of the experiment to determine the biochemical,antioxidant and immune indicators of the serum.[Result]① Regarding the starting age of supplementary feeding,the body weight of lambs in 2.5 S14 group at 60 days of age was significantly higher than that in 2.5 S21 group(P<0.05);The average daily gain(ADG)of lambs in 5 S21 and 7.5 S21 groups at 21-35 days of age was significantly higher than that in 5 S14 and 7.5 S14 groups,respectively(P<0.05).The ADG of lambs in 2.5 S14 group at 46-60 days of age was significantly higher than that in 2.5 S21 group(P<0.05).In terms of supplementary feeding levels,compared with CON group,the body weights of lambs in 2.5 S14 and 7.5 S14 groups at 35,45,and 60 days of age,as well as the ADG at 36-45 days of age and throughout the entire period,were significantly increased(P<0.05).The body weight of lambs in 5 S21 and 7.5 S21 groups at 35 and 45 days of age,as well as the ADG at 21-35 days of age and throughout the entire period,were significantly increased(P<0.05).In terms of feed intake,the average daily dry matter intake(ADMI)of lambs in 2.5 S21,5 S21,and 7.5 S21 groups at 41-44 days of age was significantly higher than that in 2.5 S14,5 S14,and 7.5 S14 groups respectively(P<0.05).In terms of different supplementary feeding levels,compared with CON group,the ADMI of lambs in 5 S21 and 7.5 S21 groups significantly increased throughout the entire experimental period(P<0.05).② Regarding the age at the start of supplementary feeding,the contents of serum globulin(GLB),urea(UREA),and triglyceride(TG)in 2.5 S21 and 5 S21 groups of lambs were significantly higher than those in 2.5 S14 and 5 S14 groups respectively(P<0.05).The serum lactate(LD)content and alanine aminotransferase(ALT)activity of lambs in 5 S21 and 7.5 S21 groups were significantly higher than those in 5 S14 and 7.5 S14 groups(P<0.05).The activities of superoxide dismutase(SOD),glutathione peroxidase(GSH-Px)and the content of interleukin-2(IL-2)in the serum of lambs in 5 S14 and 7.5 S14 groups were significantly higher than those in 5 S21 and 7.5 S21 groups respectively(P<0.05).In terms of different supplementary feeding levels,compared with CON group,the serum glucose(GLU)content of lambs in 5 S14 and 7.5 S14 groups was significantly increased(P<0.05).The serum SOD activity of lambs in 7.5 S14 group was significantly higher than that in other groups(P<0.05).The total antioxidant capacity(T-AOC)of serum in 7.5 S21 group of lambs was significantly higher than that in other groups(P<0.05).The serum IL-2 content of lambs in 5 S14 group was significantly higher than that in other groups(P<0.05).[Conclusion]Supplementary feeding with WPCS improved the growth performance,feed intake and antioxidant function of lambs,but the effect was jointly regulated by the starting age of supplementation and the addition level.Supplementary feeding at 14 days increased the weight gain and immune factor levels of lambs in the later stage,and supplementary feeding at 21 days was beneficial for the early rapid growth of lambs and enhanced the body's antioxidant capacity.In production,the supplementary feeding plan could be flexibly selected according to the breeding goals.