Protein And Energy Requirements Of Tan Sheep During Pregnancy Period

Tan sheep is a unique breed of sheep that combines fur and meat in the northwest China,and has good adaptability to the environmental climate in the northwest region of China.At present,the research on the protein and energy requirements of Tan sheep during pregnancy in China is almost blank,and there is no unified and standardized nutritional requirement parameters.This project aims to investigate the protein and energy needs of Tan Sheep pregnant ewes and serve as a benchmark for developing feeding guidelines.The experiment was divided into two parts:energy requirement study and protein requirement study.Each part is divided into two stages according to pregnancy stage:pre pregnancy（30 d-90 d）and late pregnancy（90 d-150 d）,at each stage,select 16 pregnant Tan sheep with similar weight（39.75±1.58 kg in early pregnancy and 45.49±2.09 kg in late pregnancy）and the same birth order for each stage.16 pregnant Tan sheep with similar weight were selected and randomly divided into 4 groups（4 replicates per group,1 sheep per replicate,single cage feeding）.Diets with different nutritional levels were fed.Crude protein levels in the protein group diet were 7.03%、8.42%、9.31%and 10.36%in the first trimester of pregnancy;they were 8.01%,9.32%,10.66%,and 12.18%in the late pregnancy.In the first trimester of pregnancy,the diet’s energy levels were 7.58MJ/kg、8.64 MJ/kg、9.87 MJ/kg and10.69 MJ/kg;in the second and third trimesters of pregnancy,they were 7.43 MJ/kg,8.65 MJ/kg,9.9 MJ/kg,and 11.14 MJ/kg.（1）.Under the conditions of this experiment,The ADG of ewes in the early pregnancy increased with the increase of dietary nutrient levels,The ADG of group III and IV in the protein group pre pregnancy test was significantly higher than that of group I and II in the test（P<0.05）,the ADG of ewes in the early pregnancy showed an increasing trend with the increase of dietary nutrient levels.The ADG of the protein group in the third and fourth groups in the first trimester of pregnancy was significantly higher than that in the first and second groups of pregnancy（P<0.05）,and the daily weight gain of the four groups in the last pregnancy was significantly higher than each other（P<0.05）,while the daily weight gain of all four groups in the late pregnancy phase was significant（P<0.05）compared to each other.The apparent digestibility of the four groups of protein requirement study in the early pregnancy was not significant（P>0.05）,The protein deposition rate in Group III was significantly higher than that in Groups I and II（P<0.05）,Protein had a deposition rate of25.58%–33.69%,and a digestibility range of 62.80%–64.52%.In late pregnancy,the apparent digestibility of protein in groups III and IV was significantly higher than that in groups I and II（P<0.05）,and the protein deposition rate in groups III and IV was significantly higher than that in groups I and II（P<0.05）.Protein had a deposition rate of33.47%–36.38%and a digestibility range of 63.61%–69.50%.The ADG of ewes in Group IV of the energy group during pregnancy was significantly higher than that in Groups I,II,and III（P<0.05）,while the ADG of Group III was significantly higher than that in Groups I,II（P<0.05）.There was no significant difference between Groups I and II（P>0.05）.In the early pregnancy trial,group IV’s energy digestibility and metabolic rate were significantly higher than those of groups I,II,and III（P<0.05）.The metabolic rate and total energy digestibility were,respectively,54.90%,63.84%,46.03%,and 54.61%.Groups III and IV had total energy digestibility and metabolic rates of 55.07%to 64.30%and 46.24%to 55.22%,respectively,in late pregnancy,which were significantly higher than those of groups I and II（P<0.05）.（2）.The requirements for crude protein and digestible protein of Tan sheep in the first trimester of pregnancy are:CP（g/d）=2.7949W^0.75+0.646ADG（R²=0.915,P<0.01）DCP（g/d）=1.6789W^0.75+0.425ADG（R²=0.914,P<0.01）The requirements for crude protein and digestible protein of Tan sheep in the late pregnancy are:CP（g/d）=2.7949W^0.75+0.646ADG₁+1.013ADG₂（R²=0.909,P<0.01）DCP（g/d）=1.6789W^0.75+0.425ADG₁+0.743ADG₂（R²=0.932,P<0.01）（3）.The nutritional requirements for digestible energy and metabolic energy of Tan sheep in the first trimester of pregnancy are as follows:DE（MJ/d）=0.4768W^0.75+0.041ADG（R²=0.814,P<0.01）ME（MJ/d）=0.3922W^0.75+0.037ADG（R²=0.811,P<0.01）The formula for digestible and metabolic energy nutritional requirements of Tan sheep in the late pregnancy is:DE（MJ/d）=0.4768W^0.75+0.041ADG₁+0.063ADG₂（R²=0.935,P<0.01）ME（MJ/d）=0.3922W^0.75+0.037ADG₁+0.055ADG₂（R²=0.933,P<0.01）（4）.The efficiency of transforming crude protein and digestible protein into deposited protein of pregnancy products during late pregnancy was 18.15%and 24.74%,and the efficiency of transforming metabolic energy into deposited net energy of pregnancy products was 13.24%.