| Poultry are diurnal animals,and their visual system is very sensitive to light which is one of the most important environmental factors in livestock.In this study we selected cherry valley ducks as the research object,with white LED lights as light source,adopting the method of closed and fixed light intensities,to explore the effects of light intensity on growth performance,bone development,eyes size,anti-oxidant capacities,opsin genes' and melatonin receptor genes' expression in different tissues.This paper aims to explore the suitable illumination intensity of meat-type ducks during breeding,providing the basis setting in the poultry production.We adopted single factor randomized block design,picking out 360 one-day-old cherry valley ducks(180 females and 180 males),which is the same batch of young age,healthy,and close to the average weight.The light intensities are 5,10,20,40 and 80 lx for 5 groups respectively,and each group are 6 repeats including 12 respectively.The period lasted for 21 days with a artificial light intensity controller,of which the light rhythm is 24L:0D(24 hours lighting and 0 hour darkness).Results showed that:(1)Effects of light intensity on the body weight,ADG,ADFI,F/G,breast muscle and thigh muscle yield of 1-21 days cherry valley ducks were no significant difference(P > 0.05).The pancreas index of 5lx group was significantly lower than below 40,80 lx group(P < 0.05),and the kidney index of 10 lx group was significantly higher than group 20,40,80 lx(P < 0.05).(2)Effects of light intensity on the physical properties,crude ash content,calcium content and total phosphorus content were no significant difference of the tibia in the 1-21 days cherry valley ducks(P>0.05).(3)Effects of light intensity on the 1-21 days cherry valley ducks plasma and liver anti-oxidant capacities were no significant difference(P>0.05).(4)Effects of light intensity on the 1-21 days cherry valley ducks plasma corticosterone,glucose levels were no significant difference(P>0.05).The eye diameter in the 5 lx group was significantly higher than 20,40 and 80 lx group(P < 0.05).5-20 lx light intensity within the scope of the liver melatonin levels were higher than 40 and 80 lx group(P < 0.05).(5)Effects of light intensity on the 1-21 days cherry valley ducks melatonin receptor Mel-1a mRNA expression of relative quantity had significant difference in eyes,including 5lx,20 lx and 40 lx group higher than 80 lx group(P < 0.05),10 Lx compared with 80 lx had no difference between groups.However,there was no significant effect on the relative expression of the melatonin receptor Mel-1a mRNA in the hypothalamus,pituitary,liver,duodenum,jejunum and ileum(P>0.05).(6)Effects of light intensity on the 1-21 days cherry valley ducks melatonin receptor Mel-1b mRNA expression of relative quantity had significant difference in duodenal(P < 0.05),among which 5lx and 20 lx groups were significantly lower than 10 Lx group(P<0.05).However,the relative expression levels of the eyes,hypothalamus,pituitary,liver,jejunum and ileum were not affected(P>0.05).(7)Light intensity had significant difference of melatonin receptor Mel-1c mRNA expression of relative quantity on the of 1-21 days cherry valley ducks,20 lx group ileum Mel-1c mRNA relative expression was significantly lower than 5,10,80 lx group(P < 0.05).However,there was no significant effect on the relative expression of Mel-1c mRNA in the eyes,hypothalamus,pituitary,hepatic,duodenum,and jejunal(P>0.05).(8)Light intensity on the 1-21 days cherry valley ducks had significant difference in melatonin synthesis of key genes AANAT mRNA expression of relative quantity(P < 0.05),80 lx group liver AANAT relative expression was significantly lower than 5,10,20,40 lx group(P < 0.05).However,there was no significant effect on the relative expression of the AANAT mRNA in the eyes,hypothalamus,pituitary,duodenum,jejunum and ileal acetyltransferase(P>0.05).(9)There was no significant difference in the relative expression of OPN4-1 mRNA and OPN4-2 mRNA on the eyes of the cherry valley ducks with light intensity(P>0.05).Considering the above results,we recommend meat-type ducks use 10 lx light intensity during 1-21 days to reduce energy consumption and costs. |
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