| In this experiment,we chosed183-month old and185-month old Doper×Hu sheep crossbred ewes.These sheep were randomly distributed into3groups.Each group was comprised of6sheep.These three groups were calssified into ad libitum group(AL), low-restriction group(LR) and high-restriction group(HR) according to requirement of nutrition,age and target of weighting of sheep crossbred ewes.The whole experiment consisted of two periods:one was10-day preliminary feeding and the other was52-day formal experiment.Three experiments were conducted to determinethe effects of different levels of feed intake on production performance,slaughter performance and meat quality of two different ages of Dorper and Hu sheep crossbred ewes in F1generation:Experiment1evaluated the effect of different feed intake levels on production performance, and the effect of two ages on the production performance of Doper X Hu sheep crossbred ewes (F1). The results showed that final weight and the net weight for the experimental group sheep increased consistantly with the level of feed intake for both two ages and they were increased siginificantly in AL group compared with LR group (P<0.05).The average daily gain and average daily feed intake were also increased significantly with the different feed intake level(P<0.05). However,the ratio of feed to gain was decreased when the intake level increased,and the HR group was significant higher than other2groups (P<0.05).Under the same level of feed intake,the FG and the NG of the lamb in the AL group were significant higher than those of the lamb hog(P<0.05).However,the ADG and F/G of the lamb in AL group were lower than those of the lamb hog (P<0.05).In addition,AL group does not show any difference (P>0.05).The objective of Exp.2was to identify the effect of different feed intake levels on slaughter performance and growth of organ for two ages Doper×Hu sheep crossbred ewes (F1).The results showed that both living weight and carcass weight were increased with the increasing feed intake level,and they were significant higher in AL group than in LR group (P<0.05). There was no difference among dressed percentage,net meat percentag and ratio of meat to boneof the lamb in3feed intake level groups (P>0.05)..However, both dressed percentage and ratio of meat to bone of the lamb hog were significant higher in AL group than in HR group (P<0.05). With the increasing level of feed intake,the weight of organ will increase at both two ages,and the differences in the weight of rumen, small intestine,large intestine, lungs and head&feet were significant (P<0.05).Under the same level of feed intake, livingweight,carcass weight,dressed percentage,visceral fat percentage and visceral feat weight were extremely significant higher (P<0.01) for the lamb.In AL group,ratio of meat to bone was significant higher for (P<0.05). Intriguingly ratio of meat to bone was extremely significant higher in high-restriction group (P<0.01).The weight of organ isincreased significantly with the growth of the experimental sheep inthe weight of rumen,large intestine, liver, kidneys, head&feet and skin&wool were in3different feed levels (P<0.05).However,organ indexis opposite (P<0.05).In Exp.3,we in estigated the effect of intake levels on meat qualityand the difference in meat quality of two ages on Doper×Hu sheep crossbred ewes (F1).The results indicated that the tenderness of longissimus dorsi and psoas muscle of the lamb hog were significant different among3feed intake groups,and it was significant higher in AL group than in other2groups (P<0.05).In addition, protein, fat, ash, and amino acid in the meat was increased with the improvement of the feed intake level and both meat fat and amino acid were significant different (P<0.05).The three parts of muscle meat tenderness of the lamb were better than those of the lamb hog,and were extremely significant different in psoas muscle (P<0.01).Both pH and drop loss of psoas and gluteus muscle were extremely significant higher of the lamb than those of the lamb hog (P<0.01).In summary,the productive performances and meat quality of low-restriction on Doper X Hu sheep crossbred ewes (F1) were improved,and there was a greater impact on productive performances and meat quality of the lamb hog. |
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