Studies On The Relationship Between Different Feed Levels And Performances Of Gain, Metabolism And Slaughter In Yellow Feather Broilers

In order to study the effect of different nutrient feed levels on some production performances of Gansu yellow feather broilers,the gain,metabolism and slaughter experiments were conducted respectively.The gain experiments were carried out for 2 phases.In phase 1 study,broilers at 1～4 weeks of age were divided into 3 groups. Group 1 was fed with high nutrient level of feed,group 2—middle nutrient level of feed and group 3—low nutrient level of feed.The results indicated that at the end of 4 weeks of age,the body weight of group 1 was significantly higher than that of the group 3(p＜0.05),but there was no difference between group 1 and group 2 (p＞0.05).During 5～14 weeks of age,the broilers were divided into 5 groups.Group 1 was fed with high nutrient level of feed,group 2—higher middle level of feed,group 3—middle level of feed,group 4—lower middle level of feed,and group 5—low level of feed.The results revealed that the body weight of groupⅠwas significantly higher than that of the other groups(p＜0.05);no difference was found among groups2～5.In phase 2 study,the middle nutrient level of feed was selected as basatl diet.Broilers were divided into 3 groups.Groups 1 was fed with high level of microelements,group 2o—middle level of microelements,group 3—low level of microelements,The results showed that at the end of 3 weeks of age,the body weight of group 2 was significantly higher than that of the group 1 and group 3(p＜0.05);at the end of 10 weeks of age,there were no differences among the 3 groups(p＞0.05);It is suggested that the middle nutrient level of feed satisfied the growth need of yellow feather broilers;and it has the advantages of lower price and practical effect.Metabolism experiment revealed that the retention rate of crude protein,organic matter,dry matter and energy in middle nutrientlevel of feed was higher in broiers at 3 and 8 weeks of age.Therefore,the middle nutrient level of feed could promote the digestion and absorption of nutrient matters and effectively increase the feed utilization rate in broilers during early or later growing stage.The slaughter experiment was carried out for 2 phases.In phase 1 study,at the end of 14 weeks of age,broilers tested were divided into 5 groups of 10 broilers(5 male and 5 female)each.The results showed that the living weight,carcass weight, slaughter rate,half-viscerated weight,whole-viscerated weight,leg weight,chest muscle weight,leg muscle weight,abdominal fat weight,abdominal fat rate in broilers fed with high nutrient level of feed were the highest,when compared to the other groups(p＜0.05),but the abdominal fat was significantly higher than that of the other groups(p＜0.05).In phase 2 study,at the end of 10 weeks of age,broilers tested were divided into 5 groups of 10 broilers(5 male and 5 female)each.Excepting the items tested in phase 1 study,the water loss rate of chest-leg muscles,acidity of chest-leg muscles,chest muscle area,dry matter of chest-leg muscles were added in phase 2 study.The results indicated that in slaughter rate test,all indices were not different (p＞0.05);the water loss rate of chest muscle was not different in 3 groups(p＞0.05),but water loss rate of chest muscle in broilers fed with middle nutrient level of feed was the lowest;water loss rate of leg muscle was signifcantly different among 3 groups (p＜0.05);water loss rate was highest in broilers fed with low nutrient level of feed, and that was lowest in broilers fed with middle nutrient level of feed.The acidity(pH value)of chest -leg muscles was not different after 45 min and storage for 24hr (p＞0.05).The pH value of leg muscle was higher than that of the chest muscle after storage for 45 min and freezing for 24hr.The chest muscle area in broilers fed with middle and low nutrient level of feeds was significantly different when compared to that of the broilers fed with high nutrient level of feed(p＜0.05).