| Our team previously studied the effects of monochrome white light,red light,green light and blue light with a light duration of 16 hours(16L: 8D)on the growth performance of Yangzhou geese.The results showed that the green light treatment group weighed up to 4kg at the time of breeding,which could effectively promote the growth and development of geese and improve meat quality.However,it is not clear whether prolonged light duration will further improve the growth performance of meat geese.Therefore,this experiment investigated the regulation of growth,meat quality and mechanism of monochrome green light and white light and different light duration.The aim of this study was to investigate the effects of monochromatic green light and white light and light duration on growth performance,growth regulation mechanism and meat quality of meat geese,so as to obtain a better light scheme and provide reliable light parameters for intensive breeding technology of commercial meat geese in China.A total of 720 healthy one-day-old Yangzhou geese with similar average body weight were selected from the same batch.The experiment lasted for 75 days.720 goslings were randomly divided into 4 groups using a2×2 two-factor crossover design: There were 6 replicates in each group and 30 geese in each replicate,with white light(16 L:8 D)in the control group,white light(22 L:2 D)in the experimental group,green light(16 L:8 D)in the experimental group and green light(22 L:2 D)in the experimental group in half and half.The test results are as follows:1.Effects of monochrome green light,white light and different light durations on growth performance and related blood biochemical indexes of Yangzhou geese: At 75 days of age,the average live weight of the 22-hour green light treatment group was as high as4.133 kg,significantly higher than that of the 22-hour white light treatment group(3.856 kg,P < 0.05),and the average live weight of the 16-hour green light treatment group was 3.969 kg.It was significantly higher than that of the white light 16 h control group at 3.750 kg(P< 0.05).Bivariate analysis showed that the green light group significantly increased the average live weight at the field field at 75 days of age compared with the white light group(P < 0.01),and the 22 h treatment group significantly increased the average live weight at the field field at 75 days of age compared with the 16 h treatment group(P < 0.05).Light color and duration had no significant effects on the average feed intake of each treatment group(P > 0.05).During the experiment period,there was no significant difference in feed conversion rate among all treatment groups(P > 0.05).However,the lowest feed conversion rate in the 22-hour green light treatment group was 2.63,followed by 2.66 in the16-hour green light treatment group.Therefore,green light treatment can improve the feed conversion rate.At each stage,the concentrations of GH and IGF-1 in the 16-hour green light treatment group were significantly higher than those in the 16-hour white light treatment group(P < 0.05),and those in the 22-hour green light treatment group were significantly higher than those in the 22-hour white light treatment group(P < 0.05).The differences between the green light treatment group and the white light group were significant(P < 0.05).2.Effects of monochrome green light and increasing light duration on growth-related gene expression levels of geese: at 50 days of age,GHRH m RNA expression level in hypothalamus of green light 16 h treatment group was significantly higher than that of white light 16 h treatment group(P < 0.05);At 50 days of age,the pituitary GH m RNA expression level of green light 16 hours treatment group was significantly higher than that of white light 16 hours group(P < 0.05),and at 75 days of age,green light 22 hours treatment group was significantly higher than that of two white light groups(P < 0.05).At50 and 75 days of age,the expression level of IGF-1 m RNA in liver of two green light treatment groups was significantly higher than that of white light 16 h group(P < 0.05),but there was no significant difference between the two green light treatment groups and white light 22 h group(P > 0.05).At 75 days of age,the m RNA expression of IGF-1R in breast muscle of green light 16 h group was significantly higher than that of white light 22 h group(P < 0.05),but there was no significant difference compared with the other two groups(P > 0.05);The m RNA expression level of Myo G in breast muscle of two green light groups was significantly higher than that of white light 16 h group(P < 0.05).The expression of PAX7 m RNA in breast muscle of green light and white light groups was significantly higher than that of white light 16 h group(P < 0.05).3.Effects of monochrome green light and increased light duration on the quality of Yangzhou goose meat: At 75 days of age,geese were slaughtered and breast meat was detected.The results showed that the cooking loss of 22-hour light treatment group was less than that of 16-hour light treatment group,and the difference was significant(P < 0.05).Other physical indexes(p H value,meat color,shearing force)had no significant effects(P > 0.05).The breast protein content of 22-hour green light treatment group was the highest(19.367),followed by that of 16-hour white light treatment group,22-hour white light treatment group and 6-hour green light treatment group(19.22,19.00 and 18.57,respectively),but the difference was not significant(P > 0.05).The fat content of white light treatment group was higher than that of green light treatment group.The content of guanosine in the 22-hour treatment group was higher than that in the 16-hour white light treatment group,the difference was significant(P < 0.05).The content of guanosine in the green light treatment group was higher than that in the white light treatment group,the difference was extremely significant(P < 0.01).The methionine content of green light treatment group was significantly higher than that of the other three treatment groups(P <0.05).The methionine content of green light treatment group was significantly higher than that of white light treatment group(P < 0.01).The methionine content of 22 hours treatment group was significantly higher than that of 16 hours treatment group(P < 0.01).Conclusion:1.The green light to the hypothalamus photoreceptor regulate the secretion of GHRH,GHRH promote pituitary GH release so as to increase GH m RNA expression,increase of GH secretion,promote the liver IGF-1 so as to promote the development of liver.The up-regulated levels of GH and IGF-1 in liver and blood promoted the proliferation and differentiation of skeletal muscle satellite cells,which was the direct reason for the acceleration of muscle growth caused by green light in meat geese.The expression of the above-mentioned growth and development related factors in the 22-hour treatment group was up-regulated compared with the 16-hour treatment group,thereby increasing the average live weight of the 75-day-old slaughter and increasing the feed conversion rate.2.22 hours green processing,reduce the chest meat cooking loss,improve the meat is tender,raise content of chest muscle guanylic acid,methionine,thereby increasing the meat flavor and freshness. |
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