Comparison Of The Meat Performance And Physiological Mechanism Between The F1 Of White Suffolk�hu And Doper�hu Sheep

The determination of cross combinations is the basis of economic crossing and crossbreeding.At present,hybridization experiments on Hu sheep mainly involve in the Doper sheep etc,and no reports have been found with White Suffolk sheep.In order to compare the differences among the different crossbreeding conbinations,and select suitable ones for the use of mutton sheep industry in Central plain areas,four group of hybrid lambs,including the 3 cross-combinations,the F1 of Doper�Hu(DHF1),F2 of Doper�Hu(DHF2),F1 of White Suffolk�Hu(SHF1),as well as a control of Hu sheep(H)were deigned.Thirty animals for each group(half male and half femeal,respectively),and all animals were at age of about 3.5 months and with their weights range from 21~26kg,in good health condition.A90 days of feeding experiments(proceeding days is 7)was conducted.During the feeding period,the food intakes were measured daily.At the Begin day(1d)and the end day(90d),the weight of each animals in every sheep were measured and the blood samples were collected,and the changes of serum hormones and other physiological and biochemical indexes were analyzed.After the feeding experiments,every 6 rams from each cross-combination were randomly chosen out for slaughtering test,calculating the slaughtering performance,meat quality,amino acid and fatty acid content of the eye muscle were determined for comparing the effects of each cross-combination.The main results are as follows:(1)Comparison of fattening performance of different groups: there were significant differences in the overall daily feed intake(male and female combined)among 4 groups(p<0.05),the highest in SHF1 and the lowest in Hu sheep.For the average daily food intake rams alone,Hu ram were the highest and significantly higher than those of the other three groups(p<0.01).For the daily weight gain,SHF1(male and female combined)was markedly higher than that of others(p<0.01);for male only,the highest was also seen in SHF1,and DHF1 and DHF2 next,and the lowest in Hu sheep.In addtion,SHF1(male and female combined)showed the the relatively lower ratio of feed to weight compared with other groups(p<0.05).For male alone,SHF1 also was the best with its superior in the ratio of feed to weight(p<0.05).(2)Comparison of the slaughtering index of rams from different groups: For the live body weight prior to slaughtering and carcass weight,SHF1 was the largest and Hu the lowest(p<0.05).For net meat weight,the difference among the four groups were significant(p<0.01),and the order was DHF2,SHF1,DHF1 and Hu sheep.For the percentage of net meat to carcass,significant differences between groups were found(p<0.05),with DHF2,SHF1,DHF1 and Hu sheep in subsequent decreasing order respectively.There was no significant differences in dressing percentage and bone weight among all groups(p>0.05),but the ratio of meat to bone were significantly differed(p<0.01),that is,DHF2 the highest and Hu sheep the lowest.For the backfat thickness,significant difference exsisted among groups(p<0.05),and DHF2 the maximum and Hu sheep the minimum.For eye muscle areas,significant differences were found among the groups(p<0.05),SHF1 the maximum and Hu sheep the minimum.As the relative weight of skins,SHF1 taken up the largest among the other three groups(p<0.05).For the the percentages of fat in total carcass weight,Hu sheep was significantly higher than DHF2(p<0.05).Finally,the SHF1 owed the a 29.44% higher of relative abomasum weight than Hu sheep(P<0.05),while DHF2 showed higher total gastrointestinal tract percentage than Hu sheep(p<0.05).(3)Comparison of the muscle characteristics of eye muscle from rams of different groups: the difference the flesh color and the marbling among groups were significant(p<0.05),which was the highest in DHF2,followed by SHF1,DHF1 and Hu sheep.For shear stress,DHF2 was significantly higher than that of Hu sheep(p<0.01).There were no significant difference in p H and water rate(p>0.05).(4)Comparison of the amino acids and fatty acids contents of eye muscles from rams of different groups: Among the 8 different necessary amino acids for human body,only Valine show significant differences among groups(p<0.01),and SHF1 was higher than other groups.There was no significant differences in essential fatty acids among two groups(p>0.05).Among all kinds of fatty acids,the content of important n-3 unsaturated fatty acid ALA was relatively higher in SHF1 than in other three groups(p=0.06),and Hu sheep showed the lowest level of ALA.The important GLA(?-Linolenic Acid)was richer in DHF1,significantly higher than those of Hu sheep and SHF1(p<0.05).(5)Comparison of the of serum hormones and other biochemical indexes of different groups: The serum GH levels at the beginning of trial for Hu sheep was significantly higher than those of the other groups(p<0.05),indicating the precocious nature of Hu sheep.At the end of the trial,there ware differences in serum T4 level among groups(p<0.05),and SHF1 was the highest,followed by DHF2 and DHF1.At the end of the experiment,there were also significant differences among the groups for serum P contents(p<0.01),DHF1 and DHF2 in the highest,and SHF1 the lowest.Generally taking to account both the beginning and the end,the serum TG levels for Hu sheep and DHF2 were significantly higher than those of DHF1 and SHF1(p<0.05).The serum HDL-CHO level measured at the beginningof trial for the ewes of DHF1 was the highest,significantly higher than those of other ewes of different groups(p<0.05).Differences in blood physiological and biochemical indexes may reflect differences in prematurity,growth and carcass characteristics among sheep.In general,we suggests that SHF1 and DHF2 are relatively good crossbreeds.SHF1 sheep have excellent fattening characteristics,relatively beteer slaughtering performances and precious mutton quality,while DHF2 shows better fattening performances and excellent dressing percentage,but the meat quality is not as good as that of SHF1's.For Hu sheep,its valuable merits is in the meat quality manifested for its tendeness of meat,the early maturation nature and the prolifacacy and fecundity.Therefore,we should further carry out the more complicated crossbreeding so that combining the precious characterisitcs of white suffolk,Doper and Hu sheep.