Effects Of Dietary Compositions On The Performances And Nutrient Digestion Of Hu Sheep And Their Crossbreed Sheep

Heredity and nutrition are key factors influencing the performance and slaughter performance of fattening sheep.There are some differences between sheep from different breeds and their hybrid combinations in the production performance,but it is not clear if the differences are related to nutrient digestibility and microflora of different genetic background sheep,and different genetic backgrounds might lead to varied response to dietary nutritional composition due to their distinct nutritional needs.In this study,three sheep with different genetic backgrounds were selected(Hu sheep,Dorset × Hu sheep,and Australian White × Hu sheep)and fed the same diet to study the differences in productivity,rumen microflora,and nutrient digestion(experiment 1).In addition,the sources of roughage(corn cobs and alfalfa,experiment 2)and energy feed(corn and molasses,experiment 3)were adjusted to examine the production performance,nutrient digestion and meat quality of Hu sheep and Australian White × Hu sheep to define the response of sheep with different genetic backgrounds to feed compositions.The results are as follows:1.Experiment 1: Hu sheep,Dorset × Hu sheep,and Australian White×Hu sheep were selected as the research objects and fed the same diet.The experiment included 3 replicates and 8 sheep in each replicate.The diet was full-grain granule and the fattening period lasted for 84 d.Six sheep were selected from each group for digestion tests at 63 day.The results of the study showed that differences in genetic background of sheep significantly affected the average daily gain,daily weight gain at each stage,and body weight(P<0.01),with Australian White × Hu sheep significantly higher than Hu sheep and Dorset × Hu sheep treatment groups;the difference in breeds significantly influenced slaughter performance.The tail fat and Rib-eye area of Dorset × Hu sheep and Australian white × Hu sheep were significantly higher than that of Hu sheep(P<0.01),whereas other indicators such as slaughter rate,water loss rate,or GR value were not changed significantly(P>0.05).In the nutrient digestion,the ADF digestibility of Dorset × Hu sheep tended to be higher compared with Australian White×Hu sheep(P=0.08);the abundance of rumen microbes from different treatments showed no significant difference(P>0.05).2.Experiment 2: Effects of two dietary fiber sources(corn cobs and alfalfa)on the performance,nutrient digestion and meat quality of Hu sheep and Australian white × Hu sheep were studied.In this experiment,2×2 factor design was applied,and the factors were roughage(corn cobs and alfalfa)and sheep populations(Hu sheep and Australian white × Hu sheep).The experiment included 3 replicates and 8 sheep in each replicate.The results showed that the genetic background of sheep had significant impact on average body weight every 21 days(P<0.01).The above indicators of Australian white × Hu sheep were significantly higher than that of Hu sheep,while diets had no significant effect on performance indicators(P>0.05).In slaughter performance,sheep genetic background had a significant effect on slaughter weight,tail fat,and Rib-eye area(P <0.01),with Australian white × Hu hybrid sheep was higher in slaughter weight and Rib-eye area,but lower in tail fat weight when compared with Hu sheep.Except for the brightness of the flesh was significantly higher in Hu sheep than Australian white × Hu sheep,other indicators of slaughter performance were not changed.Breeds and diets have no impact on the digestion of nutrients.3.Experiment 3: The 2×2 factor design was applied and experimental factors were energy feed(corn and molasses)and sheep populations(Hu sheep and Australian White × Hu sheep hybrid sheep).The aim of this experiment was to study the influence of feed composition on production performance,nutrient digestion and meat quality of Hu sheep and Australian white× Hu sheep.The results showed that the difference in genetic background of sheep had a significant effect on average body weight every 21 days(P<0.01)with Australian White × Hu sheep increased significantly than Hu sheep,while the diet had no influence on production performance.In slaughter performance,the breeds had significant effects on the slaughter weight,carcass weight,tail fat,and pH(P<0.01).Slaughter weight,carcass weight,and pH value were higher in Australian White × Hu sheep hybrid sheep,whereas tail fat weight were lower compared with Hu sheep;Australian white × Hu sheep showed higher GR values than Hu sheep(P = 0.05);diet only affects slaughter performance in tail fat(P<0.01)in which Australian White × Hu sheep were lower than Hu sheep;breeds and diet composition had no effect on nutrient digestion.To sum up,Hu sheep,Dorset × Hu sheep,and Australian White × Hu sheep have significant differences in production performance,slaughter performance,and nutrient digestibility which were mainly influenced by genetic factors,while dietary fiber sources and molasses treatment have no effect on production performance and slaughter performance,and digestion of nutrients.