Study On The Energy Requirements Of Tan Sheep Rams

Tan sheep is a unique and valuable sheep breed for both fur and meat in the Northwest of China.However,research on the energy requirements of Tan sheep rams has been almost blank,and no unified and standardized nutritional requirements parameters have been formed in China.The study aims to explore the energy requirements of Tan sheep rams during mating and non-mating period,and to provide basic parameters for establishing the breeding standard of Tan sheep.In this study,the single-factor randomized group trial design was adopted.Four diets with different energy levels were designed according to 85%（8.50 MJ/kg）,100%（10.00 MJ/kg）,115%（11.50 MJ/kg）and 130%（13.00 MJ/kg）of the recommended amounts in the NY/T 816-2004 Feeding Standard for Meat Sheep and laboratory preliminary research.Sixteen adult rams of similar body weight（56.15±2.12 kg）,good health and were divided into four groups with four replicates,one ram per replicate,and fed the four diets for a total of 110 d.The test period was divided into three periods:period of mating preparation（40 d）,period of mating（40 d）and period of mating recovery（30 d）.The effects of different energy levels in the diets on the production performance,serum biochemical indices and semen quality of the rams were investigated by a combination of feeding tests digestion tests,and metabolizable tests,and a model for predicting the energy requirements of the rams was developed.The results showed the following:（1）The dietary energy level had a significant effect on the daily weight gain of Tan sheep rams,and the daily weight gain increased with the increase of dietary energy level（P<0.05）.Breeding causing rams weight loss,and the weight loss increased with the increase of sperm collection frequency.（2）Dietary energy level has a significant impact on nutrient digestibility of Tan sheep rams.The total energy digestibility increases with the increase of dietary energy level（P<0.05）,while the digestibility of CP has no significant impact.The digestibility of DM and CP have a trend of increasing with the increase of energy level.（3）The level of energy intake had no significant effect on the activity of GPT and GOT of the test rams（P>0.05）.Except that the effect of TC concentration in breeding recovery stage and TC and TG concentration in breeding stage I on the increase of dietary energy level was not significant,the effect of energy intake level on Glu,TG,TC and UN concentration of test rams was significant（P<0.05）during the whole experiment.With the increase of dietary energy level,the concentrations of TC,TG and Glu showed an upward trend,while the concentrations of UN showed a downward trend.（4）The effect of dietary energy level on the ejaculation volume,sperm activity,sperm density,effective sperm number in F₂stage and sperm density in F₃stage were not significant（P>0.05）,but on the ejaculation volume,sperm activity,effective sperm number in F₁and F₃stage and sperm density in F₁stage were significantly different（P<0.05）.The sperm activity,sperm density and effective sperm number in the 10.0 MJ/kg group were the best.The semen quality of the test rams under the frequency of twice five days is better than that of four times five days and eight times five days.（5）The relationship between DE and ME of Tan sheep rams and ADG regression equations were as follows:The period of mating preparation:DEI（MJ/d）=0.557 W^0.75+0.071 ADG（R²=0.802,P<0.01）MEI（MJ/d）=0.450 W^0.75+0.061 ADG（R²=0.799,P<0.01）The period of mating:DEI（MJ/d）=0.557 W^0.75+0.9283nMEI（MJ/d）=0.450 W^0.75+0.7656nThe period of mating recovery:DEI（MJ/d）=0.444 W^0.75+0.046 ADG（R²=0.890,P<0.01）MEI（MJ/d）=0.359 W^0.75+0.039 ADG（R²=0.891,P<0.01）In conclusion,the recommended ME intake for Tan sheep breeding rams should be 9.23 MJ/d.