Effects Of Age At Photostimulation On Reproductive Performance In Female Breeders

This work studied the effect of photostimulation(PS)on sexual development,sexual maturation,eggshell quality and performance of White Leghorn and Beijing-you breeders at different ages,aiming at providing scientific guidance for the lighting management in broiler breeders.Two trials were conducted to investigate the effect of age at photostimulation on reproduction performance in layer and yellow feather breeders.Trial 1: Effects of age at photostimulation on reproduction performance in layer breedersA total of 192 14-week-old White Leghorn breeders were randomly allocated to 4 treatments with each treatment having 4 replicates of 12 birds(female).The birds of the 4 treatments were photostimulated at 16(PS16),18(PS18),20(PS20),and 22(PS22)weeks of age,respectively.In the first week of photostimulation,the lighting regimen was 8L:16D and the lighting intensity was increased from 10 lx to 80 lx.From the 2nd to the 4th week of photostimulation,the lighting regimen was changed from 8L:16D to 14L:10D.Light was provided by Light Emitting Diode.In each portion,4 cages were installed in a three-tier battery system.Feed and water were available ad libitum during the experiment.The experiment lasted for 38 weeks.The PS22 had slower ovary index and the number of large yellow follicles than other treatments since photostimulated 0 to 6 weeks.From 0 to 6 weeks of photostimulation,the oviduct index and length of PS16 and PS18 birds had faster speed compared with other treatments.There was no significant effect(P>0.05)of photostimulation on the age at first egg and age at 5% production.Photostimulating birds later reduced the interval between the ages of photostimulation to first egg(P<0.001).PS16 and PS18 had higher trend in the rate of peak period than PS20 and PS22(P=0.056).Hen-day egg production in PS16 and PS18 was higher than that in PS22(P=0.003).Hatchability of setting eggs in PS16 was higher than that in other treatments(P=0.041).The PS20 had higher eggshell thickness(P=0.016)and strength(P=0.044)than PS16 at 20 weeks of age.Age of photostimulation had no effect on eggshell quality at 43 weeks of age(P>0.05).The 4 treatments did not show difference in tibia quality(P>0.05).Trial 2: Effects of age at photostimulation on reproduction performance in yellow feather breedersA total of 384 14-week-old Beijing-you breeders were randomly allocated to 4 treatments with each treatment having 8 replicates of 12 birds(female).The birds of the 4 treatments were photostimulated at 16(PS16),18(PS18),20(PS20),and 22(PS22)weeks of age,respectively.In the first week of photostimulation,the lighting regimen was 8L:16D and the lighting intensity was increased from 10 lx to 80 lx.From the 2nd to the 4th week of photostimulation,the lighting regimen was changed from 8L:16D to 14L:10D.Light was provided by Light Emitting Diode.In each portion,4 cages were installed in a three-tier battery system.Feed and water were available ad libitum during the experiment.The experiment lasted for 38 weeks.The PS22 birds had the faster increase in ovary index,oviduct index,and the number of large yellow follicles than those from the PS16,PS18 and PS20.The PS22 had significantly later age at first egg(P<0.001)and age at 5% production(P<0.001)than PS16 and PS18.The time from photostimulation to the first egg of birds from PS20 and PS22 was shorter than other treatments.The PS22 had higher eggshell thickness(P<0.001)and weight(P<0.001)than PS16 and PS18 at 32 weeks of age.There was no significant effect(P>0.05)of age at photostimulation on performance and contents of tibia calcium and phosphorus of yellow feather breeders(P>0.05).These results indicated that photostimulation at 18 weeks may promote the reproductive performance,including gonad development,sexual maturation,and performance of layer breeders.Over delay photostimulation from 16 to 22 wk of age may restrict the reproductive performance of layer breeders.Beijing-you is a lack of systematic breeding for yellow feather breeders,so the duration of photostimulation can be 16~22-weeks-old.In the future,it is necessary to strengthen the selection and breeding of local breeders.