Comparative Study On Early Growth,development And Meat Quality Between A Valley –typed Tibetan Sheep And Suffolk Hybrid Progeny With Grazing Conditions

The valley-typed Tibetan sheep is the original local breed.Both wool and meat are formed under the natural conditions with high altitudes and high coldness.In terms of characteristics,this has coarse feeding tolerances,the early sexual maturity,and mutton without an odd odor.On the other hand,the valley-typed Tibetan sheep has a slow growth rate,a low meat yield and a long feeding cycle.With the improvement of people’s living standards,people have higher requests for mutton production with a high quality.Still the low valley-typed Tibetan sheep production is shortage of meet for approding consumes.Therefore the hybridization of valley-typed Tibetan sheep has been implemented in some areas of Tibet Autonomous Region,China.Improving and establishing a reasonable commercial sheep production system is being built for a developing direction to the meet market demanded.The Suffolk and the valley-typed Tibetan sheep cross lambs and the valley-typed Tibetan sheep are selected for the research object.Early growth and development with grazing conditions,the appropriate growth and development curve model,and detect the apparent index of meat quality and trace elements,vitamins,amino acids,fatty acid types and content were built.The effects of introducing the Suffolk sheep on slaughter performance and the quality of the valley-typed Tibetan sheep meat were discussed.The main results are as followings:（1）The body weight and daily gain of crosses were significantly higher than those of the valley-typed Tibetan sheep（P < 0.05 or P <0.01）.The body weight,body height,abdominal girth,chest girth and hip height of the 7-month-old hybrid were significantly higher than those of the valley typed Tibetan sheep（P < 0.05）,and those of the 18-month-old hybrid were significantly higher than those of the valley-typed Tibetan sheep（P < 0.05）.The live weight before slaughter,the carcass weight,the carcass length,the eye muscle area,the left half bone weight and left half net meat weight of 7-month-old crossbred sheep were significantly higher than the valley-typed Tibetan sheep（P<0.05）.However,there were significantly different from bone/meat ratio and slaughter rate.The live weight,the carcass weight,the carcass length and the left half net meat weight of 18-month-old crossbred sheep were significantly higher than the valley-typed Tibetan sheep（P < 0.05）.There was no significant difference from the eye muscle area,the bone with meat ratio and the slaughter rate.The liver weight,the kidney weight and the kidney weight/bodyweight of the 7-month-old hybrid were significantly higher than those of the valley-typed Tibetan sheep（P < 0.05）,and the liver weight,the lung weight,the kidney weight and the empty stomach weight of 18-month-old hybrid were significantly higher than valley-typed Tibetan sheep（P < 0.05）.The weight of the head,the blood and the hoofs were significantly higher than that of the valley-typed Tibetan sheep（P <0.05）,and the weight of head,the hoofs,the skin and the suet weight of18-month-old hybrid were significantly higher than the valley-typed Tibetan sheep except the flower oil（P < 0.05）.（2）The fitting effect of the Gompertz model was better than the both the Von Bertalanffy model and the logistic model,and the fitting effect of the Von Bertalanffy model was better than the Gompertz model and the logistic model in the body length,the body height and the chest circumference of the hybrid male lamb and the female lamb.The results of the Pearson correlation analysis showed that the body weight of male and the female lambs at 0-1.5 years of age were significantly positively correlated with body size index.From the development stage,the correlation coefficient between chest circumference and body weight were higher,while the correlation coefficient between the tube circumference and the body weight were lower.The weight and the tube circumference of the male were significantly higher than age at 7 months of females（P < 0.01）.The body length and body height of male lamb were significantly higher than the female lambs（P < 0.05）.The body weight,the body length,the tube circumference and the chest circumference of male lambs were significantly higher than female lambs at 1.5 years old（P < 0.01）.The Gompertz model was the best fitting on the effect of the body weight growth curves of males and females lambs of the hybrid offspring,and the Von bertalanffy model was the best fitting effect on the body length,body height and bust growth curves of the male and female lambs of the hybrid offspring.The optimal fattening time,slaughter age and bodyweight of the lower hybrid offspring.（3）The development of weight and the body size indexes of males and females the Tibetan sheep of valley-typed had stages,and the growth rate of weight,the body length,the body height,and the tube circumference of male lambs were faster than female lambs.There was a significant positive correlation between the body weight and the body size.And the correlation between the chest circumference and the body weight was higher in all age groups.The Gompertz,the Logistic,and the Von Bertalanffy models may well fit the growth and development process of body weight and body size of the valley-typed Tibetan sheep from 0 to1.5 years old.From the fitting degree,the Gompertz model fit the best effect on body weight.The Von Bertalanffy’s model fit the best effect on body size.The limit weight of the male lamb was 28.90 kg,the inflection point weight was 10.63 kg,the inflection point month age was 2.99 months,the maximum monthly weight gain was 3.31 kg,and the rapid growth range was 0.99～9.46 months.The limit weight of female lambing was 26.91 kg,inflexion inflection-point weight was 9.90 kg,inflexion inflection-point month age was 3.36 months,maximum monthly weight gain was 2.44 kg,rapid growth range was 0.83～11.53 months.The results indicate that the lactation period is the key period for the early growth and the development of the valley-Typed Tibetan sheep,so it is necessary to strengthen the nutritional requirements of ewe and lamb flock,give full play to the growth advantages of lambs and shorten the growth period.（4）The results under grazing conditions showed as follows:The carcass weight and the left half net meat weight of crossbred Tibetan sheep were significantly higher than the valley typed Tibetan sheep（P < 0.01）.The meat redness of hybrid sheep was significantly higher than that of the valley typed Tibetan sheep（P<0.01）,the drip loss was significantly higher than the valley-typed Tibetan sheep（P< 0.05）.The conjugated linoleic acid-c10c12 and DHA of crossbred sheep were significantly lower than the valley typed Tibetan sheep（P < 0.05）.In conclusion,introducing the Suffolk sheep to improving the valley-typed Tibetan sheep would significantly be improved the meat performance,the meat quality with grazing conditions.（4）Under grazing conditions,the bodyweight of the Suffolk-Tibetan hybrid progeny at 7 and 18 months of age was significantly higher than the river valley-typed Tibetan sheep（P<0.01）.The carcass weight and the left half net meat weight of the Suffolk-Tibetan hybrid progeny was significantly higher than the river valley-typed Tibetan sheep（P<0.01）.The meat redness of the SuffolkTibetan hybrid progeny was significantly higher than river valley-typed Tibetan sheep（P<0.01）,and the drip loss is significantly higher than the valley typed Tibetan sheep（P<0.05）.The conjugated linoleic acid-c10c12 and DHA of Suffolk-Tibetan hybrid progeny were significantly lower than of the valley-typed Tibetan sheep（P<0.05）.It is concluded that the introduction of the Suffolk sheep hybrid with river valley-typed Tibetan sheep under grazing conditions significantly improved the growth performance,the slaughter performance,and the meat quality,and the meat color.Also the aste is improved compared to the river valley-typed Tibetan sheep.