The Effects Of Adding Cysteamine Into Feed On Sheep Growth And Development

Cysteamine(cysteamine, CS) is a new additive which can affect growth and digestion and metabolism of animal. In order to study the effect of CS and its related mechanism on the growth of sheep, this experient through continuous adding different doses of CS in Suffolk sheep to research the influences of production performance and growth hormones levels and intestinal digestive function, determine the optimum amount of additive CS in sheep, At the same time, it also discusses the mechanism of promoting growth of CS, and provides theoretical basis for its application in production. 1. Effect of different doses of cysteamine on the growth performance and growth promoting hormone levels in sheep30 6-month-old male Suffolk sheep were random Ly divided into five groups, added 0,10,15,20 and 40 mg/kg body weight of CS in supplementation, weighed fasting state and blood were cllected at the 7d, 14 d, 21 d and 28 d after the first start of the test. Testing the content of serum growth hormone(GH), somatostatin(SS), triiodothyronine(T3), tetraiodothyronine(T4) and insulin-like growth factor(IGF-I) by usd radioimmunoassay. The results showed that the body weight gain of the10 mg/kg, 15 mg/kg and 20 mg/kg groups were significantly higher than the control group(P < 0.05); the body weight gain of the 40 mg / kg body group compared with the control group, but the difference was not significant(P > 0.05); the body weight gain of the10 mg/kg group was the highest. Four blood hormone test results showed that the serum SS content of the10,15,20 and 40 mg/kg groups were significantly decreased than the control group(P < 0.05); serum T3 were not sensitive to the control group, serum GH and T4 were improved in varying degrees compared with the control group, but the differences were not significant(P > 0.05); the serum T3 content of the 20 mg/kg and 40 mg/kg groups were significantly higher than the control group(P < 0.05). 2. Effect of dietary supplementation of cysteamine on morphology and function of the small intestine in sheepAt the end of the above CS feeding experiment in sheep, slaughtering and sampling the control group and 10 mg / kg CS group of 12 sheep. Makeing each segment of intestinal tissue paraffin sections and measured villus height, crypt depth, mucosal thickness and calculated villus height / crypt depth ratio. Detecting the activities of mucosal amylase, lipase, trypsin and chymotrypsin. Using western blotting technique to determine the protein expression of sodium-dependent glucose transporter 1(SGLT1) and glucose transporter 2(GLUT2) in intestinal epithelial. The results showed: duodenal villus height, crypt depth and mucosal thickness of the experimental group were significantly higher than the control group(P < 0.05); amylase, trypsin and chymotrypsin activities in duodenal of the experimental group were significantly higher than the control group(P < 0.05); amylase and lipase activities in jejunum also showed that the experimental group was significantly highert than the control group(P < 0.05); the protein expression of GLUT2 in duodenum of the experimental group was significantly higher than the control group(P < 0.05); the protein expression of SGLT1 was not significantly different(P > 0.05); compare with control group, the protein expression of SGLT1 in jejunum of the experimental group was significantly higher(P < 0.01), but the protein expression of GLUT2 was not significantly different(P > 0.05); the protein expression of SGLT1 and GLUT2 in ileum of the experimental group had no significant differences with control group(P > 0.05).All the analysis shows that feeding different doses of CS continuously in sheep had different effects on body weight. CS can prove weight and significantly reduce the level of serum somatostatin of the sheep, increase the level of serum GH and T4. The 10 mg/kg amount of weight gain has the most significant effect on sheep. The mechanism of promoting growth may be that CS can improve the contents of GH, T4 and IGF-I by inhibiting the activity of SS, and promote the absorption of nutrients by improving intestinal morphology and digestive enzyme activities. This study laid a theoretical foundation for CS application in our region sheep production practices.