Effect Of High Temperature On The Follicular Development Of Lyaing Hen

High temperature reduced the egg production and the number of big folliculars which showed that the follicular development was inhibited. On the one hand, high temperature could inhabit follicular development through reducing food intake, but it's unknown. It could also influenced the follicular developm from the elevated body temperature and directly impacted the gonadotropins secretion and/or granular cell gonadotropin receptor expression which also needs to study. This thesis was devoted to make the research from three respects:1. Effect of cyclic of high temperature on the follicular development of laying henOne hundred and eighty 27-week-old hyline brown hens were randomly allotted to 3 treatment(normal thermal group,NT;restricted-feeding group,RT; high temperature group HT,),each treatment represented by 6 replicates of 10 birds each. The hens were housed in controlled environment chambers for 3weeks at 23℃a nd tested for 2weeks. The result showed that the body temperature and feed intake of the laying hen reduced significantly(P<0.05),and also the egg production,ovarian heavy, follicular quantity, endocrine hormones (FSH , LH, E2 and P4), follicular granular cell layer thickness and cell density and follicular gene expression amount (FSHRmRNA, LHRmRNA,P450sccmRNA) significantly reduced (P < 0.05),which showed that cyclic high temperature reduced food intake, elevated body temperatureand inhibited follicular development. The food intake between RF and NT was close,but the egg production, ovarian weight, follicular quantity, endocrine hormone (E2, P4) , follicular granular cell layer thickness and cell density and follicular gene expression(FSHRmRNA, LHRmRNA,P450sccmRNA) amount of RF were significantly reduced (P < 0.05). It was showed that the reduced food intake under high temperature would inhibited follicular development through hormone and receptor.The feed intake between RT and HT had no significant difference (P > 0.05), but the body temperature of the HT was significantly higher than the RT (P < 0.05). The LH, ovarian heavy, follicular quantity, P450sccmRNA expression of the HT hen were less than RT, but not significantly (P > 0.05), as well as follicular granular cell layer thickness and cell density, F3 and F5 follicular FSHRmRNA express quantity and F1 LHRmRNA express quantity were significantly lower than the RT (P < 0.05). This suggested that high temperature may directly affect gonadotropins, restrain the granular cell gonadotropin receptor expression, cause of follicular inhibition.2. Effect of high temperature on the granulosa cell proliferation and differentiationWe investigated effect of high temperature on the granulosa cell proliferation and differentiation in vitro through high temperature group and optimum temperature group. The results showed that high temperature significantly reduced the expresstion of FSHRmRNA, LHRmRNA, P450sccmRNA and P4 secretion (P < 0.05). It showed that high temperature inhibited the granulosa cell gonadotropin receptor expression, influenced the granulosa cell proliferation, differentiation, this may be the environment temperature influence the important factor of follicular layers.3. Effect of different experimental serums on the granulosa cell proliferation and differentiation We investigated effect of different experimental serums on the granulosa cell proliferation and differentiation in vitro. The results showed that the high temperature serum group significantly reduced the expresstion of FSHRmRNA, LHRmRNA, P450sccmRNA and P4 secretion (P < 0.05). It showed high temperature lowered layers of gonadotropins in serum levels of granular cell, influenced of gonadotropins receptor expression, inhibited the granular cell proliferation and differentiation. This may be the important factor of follicular layers that high temperature influenced the follicular development.