| Goose is a seasonally reproductive poultry and its reproductive performance is influenced by season. Yangzhou goose is the first cultivated breed of goose in China with typically partial long-day breeding characteristics, thus light regulation on the reproduction of Yangzhou goose may have an important implication in goose industry. The objective of this study was to investigate the effect of light regulation on the reproductive performance and physiology of Yangzhou goose. Also, we employed the SSH technology to screen and identify the major genes associated with goose reproductive performance. This study may provide useful information for stable high-yield production of goose and genetic selection on goose reproductive performance.1. The Influence of Natural Light on Laying Pattern, Serum Biochemical Parameters and Reproductive Hormone Levels in Breeding Yangzhou GeeseThe geese were sexually mixed and raised in natural light. Eggs laid by the female geese were collected and counted every month, and laying rate was then calculated. For blood sampling,15female geese and10male geese were randomly selected. Blood was collected from these geese at9:00-10:30am during the11th to15th of a month. Serum biochemical parameters were subsequently determined using the blood samples. Also, other six female geese and ten male geese were slaughtered for harvesting tissues and organs. The hypothalamus and pituitary gland were used for gene expression analysis. The weights of internal organs and reproductive tissues and the lengths of reproductive tissues and organs were measured. The results are showed as follows:①The laying cycle of Yangzhou geese started in November, reached the peak of laying rate in February, and stopped around July to October.②The levels of serum total protein and albumin changed with the length of lighting time. The level of serum total protein in the male geese during the lengthening daytime was higher than that in the geese during the shortening daytime. Similarly, the content of albumin in the breeding geese during the lengthening daytime was significantly greater than that in the geese during the shortening daytime at the first3months of treatment. In addition, the serum uric nitrogen level in the geese treated with the lengthening daytime also changed in the same trend; but in the geese treated with the shortening daytime the trend became opposite.③The serum FSH of male geese was at higher level after3months of light treatment, while the serum FSH of the female geese was at a low level and remained little changed with the length of lighting time. In the second month, the serum LH level of breeding geese greatly changed with the length of lighting time. The LH level in female geese was significantly increased, while that in in male geese was significantly decreased. The serum E2level was in the same trend, while the serum PRL level was in an opposite trend.④The change of heart index with the length of lighting time was opposite between female and male geese. The ovarian index of female geese were in decline during the lengthening daytime, but the ovarian index of geese treated with the lengthening daytime were significantly higher than those geese treated with the shortening daytime. For testis index of male geese, the change patterns were absolutely opposite between the lengthening daytime and the shortening daytime, and the testis index of geese treated with the lengthening daytime were greater than the geese treated with the shortening daytime before4months of treatment. However, the trend of change in testis index was opposite after4months. The index and length of oviduct were increased with the length of lighting time. In addition, the follicle number in the ovary oppositely changed with the length of daytime.⑤The expression of pituitary FSH was on the rise at the first4months of light treatment, and the geese treated with the lengthening daytime had a larger range in the expression of pituitary FSH than those treated with the shortening daytime. However, the expression pattern was changed in an opposite way during5or6months of light treatment.⑥At the first3months of light treatment, the glands in dilated fallopian tube during the lengthening daytime had obvious lumen, but during the5or6months of light treatment, the lumen was obviously decreased, the vacuoles could be founded in magnum cells, and the gland lumen became fuzzy. In contrast, the structure of dilated fallopian tube changed in the opposite trend during the shortening daytime. The effect of lighting time on isthmus and uterus was similar to the fallopian tube.2. Effects of Light and Temperature on Serum Biochemical Variables, Reproductive Hormone Concentrations and Breeding Function in the Breeding Yangzhou Geese In a two factorial arrangement,120adult female geese were randomly divided into six groups group1(0-5℃,8h L), group2(0-5℃,12h L), group3(0-5℃,16h L), group4(25-30℃,8h L), group5(25-30℃,12h L) and group6(25-30℃,16h L), each group included twenty birds. All the geese were kept in a closed house. During the experiment,5geese were randomly selected for collecting blood at9:00-10:00am every10days, and the blood was sit for a while before centrifugation to separate the serum from the blood. The serum was used for biochemical analysis. For each treatment,3geese also were selected and slaughtered for collecting their hypothalamus and pituitaries. These organs were quick-frozen in liquid nitrogen and stored in-70℃for later use. The expression levels of some related genes in these organs were determined subsequently. In addition, some organs including heart and liver were separated and weighed, the reproductive tissues and organs were also separated for length or weight measurement. The results are showed as follows:①Serum total protein, albumin, alkaline phosphatase and urea nitrogen slightly changed with different lighting times and temperatures before20days of treatment, but they were significantly increased after30days of treatment.②There was big difference in the levels of reproductive hormones among the groups at20days of both light and temperature treatments. For example, the serum LH level was increased significantly in group1and2but not in groups. Also, there was a big change in the serum FSH level across the groups at30days of treatment. The serum level of FSH was lower in group3but higher in group4. Moreover, the serum concentrations of PRL were higher at20days of treatment and the difference across groups was large, however, the level of PRL was gradually reduced and remained the same. At last, the change in the serum E2level was gradually increased with the time of light and temperature treatments, and serum E2level was the highest at50days of treatment. However, serum E2level in group2and6only slightly changed.③Different light and temperature had an effect on the heart index of the geese. Heart index in group3was greater, while that in group5was smaller. Different light and temperature also affected the liver index. The change of liver index in group4and5was smaller across the time of treatment, while the liver index in group5was larger than that in group4. In addition, those treatments had an obvious impact on reproductive system of the geese. For example, group4and5had a bigger ovarian index and follicle index, though group1and3had smaller index. The number of follicles in group4and5were also larger than that in group3, and he index and length of oviduct in group4and5were bigger than those in group1and3.④There was a significant influence on serum biochemical parameters of breeding geese at 30days of light and temperature treatments. Serum total protein content was higher in group5than that of group1,2and3(P<0.05), serum ALP content was higher in group4than that in group1and3(P<0.05), the serum urea nitrogen in group5was significantly higher than that in group2(P<0.05), and significantly higher than group1,3and6(P<0.01), Serum urea nitrogen of geese under12h light was significantly higher than that under16h light.⑤There was a certain influence on serum hormone indicators at30days of light and temperature treatment. The group6had a significant higher serum LH levels than group2and4(P<0.05), and the serum PRL levels were higher than that in group1,2and5(P<0.05). Serum LH and PRL of geese in high-temperature group were significantly higher than that in low-temperature group (P<0.01).⑥The change in the internal organ index was smaller at30days of light and temperature treatment. Heart index was significantly larger than that in group2and4(P<0.05). Additionally, there were no significant difference in liver or spleen index (P>0.05).⑦There was a big influence on reproductive system at30days of light and temperature treatment. The ovarian index was bigger in group2and4, both of them were significantly greater than that in group6(P<0.05), the number and index of follicles in group4was significantly greater than that in group3and6(P<0.05), the tubal index in group2and4was significantly greater than that in group3(P<0.05), the tubal length in group2and5was significantly greater than that in group1(P<0.05), the number and index of follicles of geese under12h of light were significantly higher than that in group under16h of light (P<0.05), the number of follicles under8h of light was significantly more than under16h of light (P<0.05), the tubal length of group under12h of light was significantly greater than under8and16h of light (P<0.05). Tubal index of geese under higher temperature was greater than that under lower temperature (P<0.01).⑧At30days of light and temperature treatments, the geese under8h of light had a significantly higher expression of pituitary FSH than that under12and16h of light (P<0.05). In contrast, the geese under16h of light had a significantly higher expression of pituitary PRL than that under8and12h of light (P<0.01).3. The Effect of Constant Light on Serum Biochemical parameters, Reproductive Hormone Concentrations, and Breeding Function in Breeding Yangzhou GeeseIn February, seven geese were selected (6female and1male) and raised in hermetic farm with constant light of12h/d. Blood were collected regularly to measure the serum biochemical variables and hormone concentration. Geese were fed for6months, then five female geese under natural light were slaughtered for hypothalamus and pituitary gland to determine the expression of some related genes. The weights of internal organs and reproductive tissues, and the lengths of reproductive tissues and organs were also measured. The results are showed as follows:①Under constant light, the changes in total serum protein, albumin and cholesterol of breeding geese appeared to be in accordance:rose at first, declined later, and gradually rose again. The estradiol concentration was increased markedly in the second month, reached its peak, followed by a big drop, and remained at a relatively low level.②The concentrations of serum albumin, glutamic oxalacetic transaminase of the breeding geese treated with6month’s constant light were significantly higher than the natural light group (p<0.05). There was a difference in the reproduction hormone index between the two groups of breeding geese, though it didn’t reach the remarkable level.③Liver weight, ovary weight, follicles weight, follicular number, tubal weight and tubal height of the breeding geese treated with6month’s constant light were significantly higher than the natural light group (P<0.05).④Tan or brown positive immunoreactive cells of GnRH and Mel with different forms could be determined in both constant light and natural light group by observing the biopsies of hypothalamus with immunohistochemistry, but the mean gray value of GnRH in constant light group were higher than that in another group.⑤The dilated fallopian tube glands of breeding geese treated with6months constant light had an obvious lumen and intensive vascular network, and the isthmus primary fold was obvious and the uterine folds of uterus also was quite clear, but there were some vacuoles in oviduct magnum cells of the geese under natural light, some appearance such as the fuzzy gland lumen, serious connective in the isthmus, and less vascular and glandular but more melanin in the uterus were also presented,.4. Differentially Expressed Genes in Hypothalamus between laying and Resting GeeseThree pairs of half-sibling geese (3laying geese,3resting geese) were selected and raised under natural light. The geese were in the same family. In the last ten days of June, their hypothalamus tissue samples were harvested and kept in fluid nitrogen for later gene expression analysis. The results are showed as follows:⑥Two hundred and five positive clones were chosen randomly from laying geese library resting geese library. The clones were sequenced. Use the NCBI data to do the BLASTx contrast,101ESTs were found its homologous sequence. Among the sifted piece that had an E value smaller than1E-5as the function-known gene,21functional genes were got from the resting geese library and24from the laying geese library.②The online function clustering analysis was conducted using the sifted and differentially expressed genes. The cellular localization, molecular function and biology function were also predicted. It was shown that the SMARCA4-201gene from the specific library of resting geese could participate in the process of androgen receptor binding, while the LEF1gene from the specific library of laying geese could participate in the process involving estrogen receptor activation and binding. |
PDF Full Text Request