Effects of incubation lighting with green or white light on brown layers: hatching performance, feather pecking and hypothalamic expressions of genes related with photoreception, serotonin, and stress systems.

The aim of this study was to evaluate the effect of 16L:8D photoperiod with green (GREEN) or white (WHITE) lights during incubation on hatching performance, blood melatonin, corticosterone, and serotonin levels, hypothalamic expressions of genes related to photoreception, serotonin, and stress systems in layers in relation with feather pecking behavior. Dark incubation (DARK) was the control. Eggs (n = 1,176) from Brown Nick breeders in 2 batches (n = 588/batch) were incubated in the experiment. A total of 396 female chicks and 261 hens were used at rearing and laying periods until 40 wk. Incubation lighting did not affect hatchability, day-old chick weight, and length, but resulted in a more synchronized hatch as compared with the DARK. The effect of incubation lighting on blood hormones was not significant except for reduced serotonin in the GREEN group at the end of the experiment. There was no effect of incubation lighting on gentle, severe, and aggressive pecking of birds during the early rearing period. From 16 wk, GREEN hens showed increased gentle pecking with increasing age. WHITE hens had the highest gentle pecking frequency at 16 wk while they performed less gentle but higher severe and aggressive pecks at 24 and 32 wk. At hatching, the hypothalamic expression of CRH, 5-HTR1A, and 5-HTR1B was higher for the WHITE group compared with both GREEN and DARK, however, 5-HTT expression was higher in GREEN than WHITE which was similar to DARK. Except for the highest VA opsin expression obtained for WHITE hens at 40 wk of age, there was no change in hypothalamic expression levels of rhodopsin, VA opsin, red, and green opsins at any age. Although blood hormone levels were not consistent, results provide preliminary evidence that incubation lighting modulates the pecking tendencies of laying hens, probably through the observed changes in hypothalamic expression of genes related to the serotonin system and stress. Significant correlations among the hypothalamic gene expression levels supplied further evidence for the associations among photoreception, serotonin, and stress systems.

Associations between genetic variants of the POU1F1 gene and production traits in Saanen goats.

This study was conducted to determine the polymorphisms of the POU1F1 gene and their relationships with milk yield and components, litter size, birth weight, and weaning weight in goats. For this purpose, a total of 108 Saanen goats from two different farms (Bornova and Manisa) were used as animal materials. Polymorphisms at the exon 6 and the 3 ' flanking region of the POU1F1 gene were determined by using PCR-RFLP with PstI and AluI restriction enzymes and DNA sequencing analyses. Two alleles and three genotypes were identified by AluI or PstI digestions of the POU1F1 gene. The genotypes frequencies of TT, TC, and CC were 64.8 %, 31.5 % and 3.7 % for the PstI locus; 54.6 %, 31.5 % and 13.9 % for the AluI locus, respectively. T allele frequencies (0.56 and 0.88 for the AluI locus, 0.80 and 0.81 for the PstI locus, respectively) were predominant in both loci at the Bornova and Manisa farms. In terms of POU1F1-AluI and POU1F1-PstI loci, two populations were found to be in Hardy-Weinberg equilibrium. In the POU1F1-AluI locus, significant associations were found between genotypes and lactation milk yield and litter size. Similarly, a significant relationship between genotypes and birth weight in the POU1F1-PstI locus ( p < 0.05 ) was determined. The TC and CC genotypes were observed to be higher than the TT genotype for lactation milk yield and litter size at the POU1F1-AluI locus. Birth weight was found to be higher in animals that have the CC genotype at the POU1F1-PstI locus. In conclusion, the POU1F1 gene can be used as a molecular marker for economic features like reproduction, growth, milk content and yield in Saanen goats.