title: Photoperiodic lighting (16 hours of light:8 hours of dark) programs during incubation: 2. Effects on early posthatching growth, blood physiology, and production performance in broiler chickens in relation to posthatching lighting programs.
abstract: Photoperiodic incubation lighting might improve bird adaptation to a novel environment at hatching for a better start in early posthatching development. We evaluated the effect of 16L:8D lighting for either the whole incubation period (Inc(0-21d)) or the last week of incubation (Inc(14-21d)) on early posthatching growth, blood melatonin, and corticosterone at 6 d as well as malondialdehyde levels in brain tissue, relative asymmetry, and overall broiler performance as an interaction with the posthatching lighting programs. Dark incubation conditions (Inc(Dark)) served as control. There were 3 incubation batches in the experiment. Chicks from 2 of 3 batches were reared either at 16L:8D or under continuous lighting (24 h) through 6 d posthatching. Batch 3 chicks were reared to 35 d under either 16L:8D or 23L:1D. The main finding was a significant incubation × posthatching lighting interaction for 35-d BW in broilers. Although groups had similar BW under continuous lighting, Inc(0-21d) and Inc(14-21d) broilers were respectively 94 and 78 g heavier than Inc(Dark) birds under 16L:8D at 35 d. Lighted incubation groups increased 0 to 6 d of gain and had higher d-6 breast muscle weights with no effect on other traits measured. Posthatching 16L:8D reduced the gain and d-6 breast muscle. Significant incubation × posthatching lighting and posthatching lighting × sampling time interactions for blood melatonin may indicate that Inc(0-21d) affects melatonin diurnal rhythms even at 6 d under continuous light. Lower blood corticosterone levels on d 6 in Inc(0-21d) chicks reared under 16L:8D posthatching may support our hypothesis that incubation lighting can modify the bird stress response, probably affecting the hypothalamic-pituitary-adrenal axis during ontogeny, and may improve adaptation to a similar environment posthatching. The lower malondialdehyde concentration in brain tissue of Inc(0-21d) birds on d 6 may indicate lower lipid peroxidation and thus lower oxidative stress compared with Inc(Dark). These results provide further evidence that Inc(0-21d) may improve both bird adaptation to a similar photoperiodic environment and growth, probably through early entrainment of circadian physiology.
authors.affiliation: Faculty of Agriculture, Department of Animal Science, Ege University, İzmir, Turkey. sezen.ozkan@ege.edu.tr
authors.forename: S
authors.initials: S
authors.lastname: Ozkan
authors.forename: S
authors.initials: S
authors.lastname: Yalçin
authors.forename: E
authors.initials: E
authors.lastname: Babacanoglu
authors.forename: S
authors.initials: S
authors.lastname: Uysal
authors.forename: F
authors.initials: F
authors.lastname: Karadas
authors.forename: H
authors.initials: H
authors.lastname: Kozanoglu
mesh_terms: D000222:Adaptation, Physiological; D000822:Animal Husbandry / Q000379:methods; D000818:Animals; D019521:Body Patterning; D001921:Brain / Q000196:embryology / Q000378:metabolism; D002642:Chick Embryo; D002645:Chickens / Q000254:growth & development* / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology*; D003345:Corticosterone / Q000097:blood / Q000378:metabolism; D005260:Female; D008297:Male; D008315:Malondialdehyde / Q000378:metabolism; D008550:Melatonin / Q000097:blood / Q000378:metabolism; D017440:Photoperiod; D013312:Stress, Physiological / Q000528:radiation effects*
chemical_list: D008315:Malondialdehyde; D008550:Melatonin; D003345:Corticosterone