title: Effects of breed and harvest age on feed intake, growth, carcass traits, blood metabolites, and lipogenic gene expression in Boer and Kiko goats.
abstract: The objectives of this experiment were to determine the effects of 2 different breeds (BR), Boer and Kiko, and 4 post-weaning harvest ages (HA; Days 0, 29, 56, and 85) on growth, carcass traits, blood metabolites, and lipogenic gene expression. Forty-eight goat (Capra hircus) kids (BW = 23.9 ± 1.50 kg; 3 to 4 mo) were used in a 2 × 4 factorial arrangement of treatments. Goats were stratified by BW within BR and randomly assigned to 4 HA. Kids were born between March 15 and April 7 to purebred does, and were represented by at least 3 purebred sires within each BR. They were fed a grain/hay (80:20) diet once per day. At designated HA, randomly pre-assigned goats (n = 6) from each BR were transported to the Meat Science Lab at Mississippi State University, Starkville, MS, and were harvested. There were no interactions (P > 0.10) between BR and HA. Boer tended (P = 0.08) to have greater initial BW, final BW (P = 0.05), and G/F ratio (P = 0.05). Although the 80:20 grain/hay diet was reinforced by adjusting DMI, both BR had similar total DMI, Boer kept that ratio, while Kiko consumed more (P = 0.001) hay (70:30, grain/hay) and had more (P = 0.001) DMI when expressed as g/kg BW. Boer tended to have greater transportation shrink (P = 0.07), HCW (P = 0.08), and cold carcass weights (CCW; P = 0.08), with greater (P = 0.001) carcass fat. No differences (P > 0.10) were observed in carcass shrink, dressing percentage, 12th rib fat thickness, and LM area between the 2 BR. When expressed as percentage empty BW, carcass bone was similar (P = 0.25), whereas muscle percentage (P = 0.02) was greater for Kiko and fat percentage was greater (P = 0.001) for Boer. Fat as a percentage of CCW remained relatively similar (P > 0.10) for both BR for the 2nd and 3rd HA. Differences were more evident (P = 0.01) at the 4th HA. Boer reached targeted harvest weight (29 kg) at the 3rd HA, while fat deposition continued (P = 0.01) during the 4th HA. Breed had no effect (P > 0.10) on meat color (L*, a*, b*) but HA affected (P = 0.001) all color values. Boer had similar 3-hydroxyl-3-methylglutaryl-CoA synthase mRNA abundance, but was greater (P < 0.03) in acetyl CoA carboxylase compared with Kiko. There was no difference (P = 0.52) in total serum fatty acids (FA, mg/mL) between the 2 BR. As animals aged, their total serum FA increased (P < 0.05) and changed to an undesirable profile. Kiko had a greater (P = 0.02) percentage of muscle and less (P = 0.001) fat in the carcass. We concluded that different BR might need different harvest endpoints and feed input according to consumer acceptability.
authors.affiliation: Department of Agricultural and Environmental Sciences, Tuskegee University,Tuskegee, AL 36088, USA. ssolaim@mytu.tuskegee.edu
authors.forename: S
authors.initials: S
authors.lastname: Solaiman
authors.forename: B R
authors.initials: BR
authors.lastname: Min
authors.forename: N
authors.initials: N
authors.lastname: Gurung
authors.forename: J
authors.initials: J
authors.lastname: Behrends
authors.forename: W
authors.initials: W
authors.lastname: McElhenney
mesh_terms: D000375:Aging; D000818:Animals; D001823:Body Composition / Q000235:genetics*; D004032:Diet / Q000662:veterinary; D004435:Eating / Q000235:genetics* / Q000502:physiology; D005227:Fatty Acids / Q000097:blood / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology; D006041:Goats / Q000097:blood / Q000235:genetics* / Q000254:growth & development*; D050356:Lipid Metabolism / Q000235:genetics*; D008099:Liver / Q000378:metabolism; D008297:Male
chemical_list: D005227:Fatty Acids