Regulation Of Bile Acid Deposition In Eggs And The Effect On Growth Performance And Muscle Fiber Development In Offspring

The meat production potential are closely related to muscle fibers numbers of livestock and poultry, but during postembryonic peride and after birth, the number of muscle fibers was almost fixed. As an oviparous animal, the growth at the early stage of poultry was entirely depended on nutrients in eggs, skeletal muscle is no exception.Previous study in our lab showed that the content of bile acid in the egg has important effect on skeletal muscle development of chicken embryonic. In order to investigate nutrition regulation method of bile acid in eggs, to develop a growth regulated feed additives for broiler breeder, chenodexycholic acid(CDCA) and oil or sterols material were respectively feed to the breeders, their effect on bile acid deposition in egg and muscle development of offspring were studied:1. Eighty sexually mature yellow feather breeder hens(14 weeks of age) were divided into 5 groups randomly. Breeder hens in control group were fed with basal diet, diet of hens in treatment group I, II, III, IV is basal diet supplemented with 10mg/kg, 50mg/kg, 100mg/kg and 500 mg/kg of CDCA respectively for 4 weeks. In the last week of the experiment, fertilized eggs were collected and hatch. The offsprings were divided into 5groups just as the hens. Offspring chickens were raised ad libitum until 12 weeks. The results showed as follow: dietary CDCA had no significant effect on breeder hens' body weight, laying rate and quality of eggs. But 100 mg/kg dietary CDCA cause significantly increased serum triglyceride(TG) of breeder hens, serum very low density lipoprotein(VLDL) concentration was significantly reduced; in ovo, total bile acid(TBA)concentration was significantly reduced, total cholesterol(TC) and low density lipoprotein cholesterol(LDL-C) levels was significantly increased(P<0.05). Supplement of 50mg/kg dietary CDCA could significantly increase muscle fiber density of offspring' gastrocnemius(P<0.05). And 100mg/kg and 500mg/kg dietary CDCA in breeder hens diet couldsignificantly reduce the average daily gain of female offspring(P<0.05). At the same time,CDCA treatment could reduce activity of glucose metabolism enzyme and the protein deposition in offsprings' gastrocnemius muscle in various degrees.2. According to the results of preliminary tests, we found that directly CDCA feed could not increase accumulation of bile acid in eggs, rather reduced the content of bile acid in eggs. In order to find an effectively feed additive to promote the bile acid deposition in egg, we further selected several oil or steroid substances as feed additive for breeders, to analysis the bile acid deposition in egg and changes of cholesterol metabolism related genes in hepatic. Results show that phytosterol esters can significantly increase the bile acid levels in eggs, at the same time, maternal serum bile acid levels and CYP7A1 m RNA expression in maternal liver were significantly elevated,LXR and LRH-1 m RNA expression were significantly inhibi(P < 0.05)t. These results suggest that egg bile acid may increase by increasing maternal bile acid levels.3. In order to further verify effect of increased eggs bile acid on skeletal muscle development of offsprings. Fertilized eggs of breeders fed with phytosterol ester were collected to hatch, and muscle development related indicators were detected of chicken.The results show that compared with the control group, offspring in treatment group had significantly higher average weight gain and weight at 49 day, and muscle fiber density in female offspring was significantly increased. In serum index results, compared with the control group, male offspring in the treatment group had significantly increased serum triglyceride and glucose levels, while IGF-1 and insulin levels of female offspring were also significantly higher. But triglyceride levels was significantly lower.. At the molecular level, the results show that, protein level of decorin, FXR, Myo D, myogenin and TGR5 at49 day and protein level of FXR and decorin at 1 day in gastrocnemius of female offspring were significantly higher compared with the control group.In conclusion, phytosterol ester feed to broiler breeder can promote the synthesis of bile acid in chicken liver, and improve the deposition of bile acids in the egg. When the level of bile acid in eggs was elevated, we found skeletal muscle growth was significantly promoted in female offsprings.