| This thesis mainly studied the effects of dietary protein levels on the weight change,nutrient digestion,plasma amino acids of female donkeys during late pregnancy,and the growth and development of the foals,in order to provide the basis for the establishment of protein nutritional requirement,and the results of the study had important theoretical and practical significance for improving the protein nutrition of pregnancy donkey,enhancing the growth performance of foals,and improving the production efficiency of female donkeys,further increasing the breeding benefit.This experiment adopted single factor completely random design,and chose 24 Dezhou mares with similar age,weight,parity and due date to divide randomly into three dietary treatment groups with four replicates,2 donkey in each replicate.The three dietary treatment goups were,respectively,high protein group(12.48%,HP),medium protein group(11.52%,MP group)and low protein group(10.54%,LP).The three groups were uniformly fed the same lactation diet within 30 days after delivery.During the experiment,digestion tests were conducted twice,blood samples were collected,and weight of female donkeys and foals were weighed every week after delivery.The study consisted of three parts:Experiment 1 mainly studied the effects of dietary protein level in late pregnancy on nutrient digestibility of female donkeys.The results showed that dietary protein level had no significant effect on feed intake in late pregnancy(P>0.05).Dietary digestibility of DM,NDF,ADF,CP,EE,Ca and P in medium protein group(11.52%)and low protein group(10.54%)was improved in late pregnancy.At week 4 before parturition,the digestibility of DM,CP,EE,ADF and P in MP group was significantly higher than that in LP group and HP group(P < 0.05),and the digestibility of DM and ADF in LP group was significantly higher than that in HP group(P=0.02,P=0.0003).The digestibility of CA in MP group and LP group was significantly higher than that in HP group(P=0.002),but there was no significant difference between MP group and LP group.The digestibility of NDF in LP group tended to be higher than that in HP group(P=0.058).At week 1 before parturition,the digestibility of CP and P in MP group was significantly higher than that in LP group and HP group(P < 0.05),and the digestibility of CP and P in LP group was significantly higher than that in HP group.EE digestibility in MP group was significantly higher than that in LP group and HP group(P < 0.003),but there was no significant difference between LP group and HP group.The digestibility of DM,NDF,ADF and CA in MP group and LP group was significantly higher than that in HP group(P < 0.05),but there was no significant difference between MP group and LP group.In experiment 2,the effects of dietary protein level in late pregnancy on plasma amino acid concentration and serum biochemical indexes of female donkeys were studied.The results showed that at week 4 before parturition,the plasma Gly concentration in MP group and LP group was significantly higher than that in HP group(P=0.029),but there was no significant difference between LP group and MP group.The plasma concentrations of Glu,Val,Met and TAA in HP group were significantly higher than those in MP group and LP group(P < 0.05),but there was no significant difference between MP group and LP group.The plasma concentrations of EAA and FAA in HP group tended to be higher than those in MP group and LP group(P=0.085,P=0.093).At week 1 before parturition,the plasma concentrations of Glu,Leu,EAA,FAA,BCAA,EAA/TAA and EAA/NEAA in HP group were significantly higher than those in MP group and LP group(P < 0.05),but there was no significant difference between MP group and LP group.The contents of Glu,Bun and CTR in serum of female donkey were significantly affected by dietary protein level in late pregnancy,and the contents of Glu,Bun and Cre in serum of female donkey were significantly affected by dietary protein level in late pregnancy.The contents of Glu and Cre in HP group were significantly higher than those in LP group(P=0.035,P=0.084),but there was no significant difference among the three groups.The BUN content in HP group was significantly higher than that in MP group and LP group(P=0.027),but there was no significant difference between MP group and LP group.Experiment 3 mainly studied the effects of dietary protein levels in late pregnancy on postpartum weight loss of female donkeys and growth and development of foals.The results showed that dietary protein level in late pregnancy tended to have significant influence on postpartum weight loss of female donkeys during weeks 1-2,weeks 3-4and weeks 1-4.The proportion of postpartum weight loss in LP group was higher than that in HP group(P=0.083,P= 0.053,P=0.004),but there was no significant difference among the three groups.The daily gain of foals increased with the increase of dietary protein level,and the birth weight,1,2,3 and 4 week weight in HP and MP groups were significantly higher than those in LP group(P < 0.05).There was no significant difference between HP group and MP group.With the increase of dietary protein level,the daily gain tended to increase.The weight gain during the first 2 weeks,the second 2weeks and the average daily gain in HP group and MP group were significantly higher than those in LP group(P=0.005,P=0.042,P=0.035),but there was no significant difference between HP group and MP group.Body height of HP group and MP group was significantly higher than that of LP group(P < 0.05),but there was no significant difference between HP group and MP group.Dietary protein level in late pregnancy had no significant effect on body length,chest circumference and cannon circumference of the foals.In conclusion,the diet with medium protein level(11.52%)in the late pregnancy period of female donkeys can achieve higher protein digestibility,foal birth weight and daily gain.The high protein(12.48%)diet was not conducive to the digestion of nutrients. |
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