Effects Of Dietary Energy And Protein Levels On Growth Performance And Reproduction In Lambs Of Yanshan Cashmere Goats

The study is consisted of two parts,which was conducted to study the effects of different energy and protein levels of diets on growth performance and reproduction in female lambs of Yanshan Cashmere Goat.Part one,the effect of dietary energy level on the performance of Yanshan cashmere goats: Forty five 3-month-old weaned female lambs weight 13.6�2.02 kg were randomly divided into three treatment groups(groups I,II and III)and fed TMR powder diets with different energy levels(9 MJ/kg,10 MJ/kg and 11 MJ/kg,respectively).The pre-feeding period was 14 days,and the formal period was 60 days.0-20 d was the pre-test period,21-40 d was the mid-test period,and 41-60 d was the end of the experiment.The feed intake,body weight and shear weight were recorded during the test period.The results showed that,the total ADG of lambs increased with the increase of energy level.The end weight and ADG of group III were higher than those of group I(P<0.05).The energy level had no effect on the amount of shearing(P>0.05).The DMI of each of the three groups increased with the increase of energy level,and the groups in the first and middle stages were significantly(P<0.05),and the group III was higher than the groups I and II(P<0.05).In each stage,the ADG of each group was increased with the increase of energy level.and the group III was higher than the I and II groups during late stages(P<0.05).The DMI of the three groups were increased first and then decreased,and the DMI of the group II and III were significantly(P<0.05).The ADG of the three groups decreased gradually,and the group I and II had negative growth during late stages.Part two,the effects of dietary energy and protein levels on growth performance and reproduction in female lambs of Yanshan cashmere goats.1)Dietary energy test: 42 lambs of 6 months old were selected and randomly divided into groups I,II and III.The digestible protein levels of the three groups were 9.5% and metabolic energy levels were 9,10 and 11 MJ/kg,respectively.2)Dietary protein test: 42 lambs of 6-month-old were selected and randomly divided into groups I,II and III.Metabolic energy of the three groups were 10 MJ/kg,digestible protein levels were 8.5%,9.5% and 10.5%,respectively.Feed intake and body weight were recorded during the experiment.Blood samples were collected on days 0,10,20 and 40 respectively.At the end of the trial period,estrus was treated at the same time,and estrus rate of each group was counted.The results showed that: 1)The body weight,ADG and DMI of lambs increased with the increase of dietary energy level,in which group III was significantly higher than group I and group II(P < 0.05),group II was significantly higher than group I(P < 0.05),and the ratio of feed to weight gradually decreased with the increase of dietary energy level,group I was significantly higher than group II and group III(P < 0.05),and there was no difference between group II and group III(P > 0.05).Dietary energy level had no effect on the secretion of E2,FSH and LH(P > 0.05),but on the 30 th day,the concentration of P4 in group II was significantly higher than that in group I(P < 0.05),and had no difference with group III(P > 0.05);on the 40 th day,the concentration of P4 decreased with the increase of dietary energy level,and the concentration in group III was significantly lower than that in group I(P < 0.05).Dietary energy level had no effect on estrus rate at the same time,and the estrus rate of each group was 100%.2)Dietary protein level had no effect on body weight and ADG of ewes(P > 0.05).DMI and feed-meat ratio in group III were significantly higher than those in group II(P < 0.05),while those in group II were significantly higher than those in group I(P < 0.05).(2)Dietary protein level had no effect on the secretion of P4,E2,FSH,LH and estrus synchronization rate of ewes(P > 0.05),and the estrus rate of each group was 100%.In conclusion,ADG and DMI of Yanshan cashmere goat ewes increased with the increase of energy level in winter,and cold stress had a significant effect on the growth of ewes.Under the experimental conditions,different levels of energy and protein had no effect on reproductive hormone secretion and estrus synchronization of Yanshan cashmere goats.The suitable ME of Yanshan cashmere goat lambs in winter diet was 11 MJ/kg.DM.The growth performance of female goats was the best when dietary digestible protein and metabolic energy were 9.5% and 11 MJ/kg,respectively.