title: Influence of hatch time and access to feed on intramuscular adipose tissue deposition in broilers.
abstract: The effect of hatch time and subsequent access to feed on intramuscular adipose tissue deposition was studied in the pectoralis major muscle of male Ross 308 broiler chickens. Based on their hatch time chicks were classified as early (EH), midterm (MH), or late (LH) hatchers, with an average incubation duration of 497.7 h for EH, 508.8 h for MH, and 514.5 h for LH birds. Chicks were provided access to feed either immediately at hatch, or 24 h after the conclusion of the hatch window. Expression of the adipogenic regulatory genes peroxisome proliferator-activated receptor gamma (PPARγ), and stearoyl-CoA desaturase (SCD), were measured at the time of hatch, and zero, one, 4, 7, 28, and 40 d. Intramuscular adipocyte cell width and visualization of adipose tissue deposition was observed at 28 and 40 d. Expression of PPARγ was increased in the pectoralis major of LH birds at the time of hatch, zero, and one d. The expression of PPARγ at one and 7 d, and SCD at 7 d were increased in all birds that received delayed access to feed. At 28 d, adipocyte cell width was increased in LH birds with delayed access to feed, compared to EH and MH birds with delayed access to feed and LH birds with immediate access to feed. At 40 d, adipocyte cell width was increased in all birds that received delayed access to feed. Also at 40 d, there was a trend (P = 0.078) for more extensive intramuscular adipose tissue deposition in LH than EH birds, and in birds with delayed access to feed (P = 0.075). These data indicate delayed access to feed increases intramuscular adipose tissue deposition in the pectoralis major muscle, and suggest that hatch time influences this regulation.
authors.affiliation: Faculty of Veterinary Science, The University of Sydney, Camden, NSW 2750, Australia Poultry CRC, PO Box U242, University of New England, Armidale, NSW 2351, Australia dpow1086@uni.sydney.edu.au.
authors.forename: D J
authors.initials: DJ
authors.lastname: Powell
authors.affiliation: Department of Animal Sciences, The Ohio State University/Ohio Agricultural Research and Development Center, Wooster 44691.
authors.forename: S G
authors.initials: SG
authors.lastname: Velleman
authors.affiliation: Faculty of Veterinary Science, The University of Sydney, Camden, NSW 2750, Australia.
authors.forename: A J
authors.initials: AJ
authors.lastname: Cowieson
authors.affiliation: Faculty of Veterinary Science, The University of Sydney, Camden, NSW 2750, Australia.
authors.forename: M
authors.initials: M
authors.lastname: Singh
authors.affiliation: Faculty of Veterinary Science, The University of Sydney, Camden, NSW 2750, Australia.
authors.forename: W I
authors.initials: WI
authors.lastname: Muir
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism*; D000821:Animal Feed / Q000032:analysis; D000822:Animal Husbandry / Q000379:methods*; D000818:Animals; D030161:Avian Proteins / Q000235:genetics / Q000378:metabolism; D002645:Chickens / Q000254:growth & development / Q000502:physiology*; D005247:Feeding Behavior; D015870:Gene Expression; D008297:Male; D010369:Pectoralis Muscles / Q000378:metabolism*; D013997:Time Factors
chemical_list: D030161:Avian Proteins
keywords: adipogenesis; hatch time; intramuscular fat; lipid; transdifferentiation