Effects of breed and harvest age on feed intake, growth, carcass traits, blood metabolites, and lipogenic gene expression in Boer and Kiko goats.
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Effects of breed and harvest age on feed intake, growth, carcass traits, blood metabolites, and lipogenic gene expression in Boer and Kiko goats.
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Authors:
Address: Department of Agricultural and Environmental Sciences, Tuskegee University, Tuskegee, AL 36088.
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The objectives of this experiment were to determine the Effects of two different breeds (BR) Boer and Kiko, and four post-weaning harvest ages (HA; d 0, 29, 56 and 85) on growth, carcass traits, blood metabolites, and lipogenic gene expression. Forty-eight goat kids (BW = 23.9 ± 1.50 kg; 3-4 mo) were used in a 2 x 4 factorial experiment. goats were stratified by BW within BR and randomly assign to four HA. Kids were born between March 15 and April 7, to purebred does, and were represented by at least three purebred sires within each breed. They were fed a grain:hay (80:20) diet once a day. At designated HA, randomly pre-assigned goats (n = 6) from each BR were transported to the Meat Science Lab., Mississippi State University, MS and were harvested. There were no interactions between BR and HA. Boer BR tended (P = 0.08) to have greater initial BW, final BW (P = 0.05) and greater G:F ratio (P = 0.05). Although the 80:20 grain:hay diet was reinforced by adjusting DMI, both BRs had similar total DMI, Boer BR kept that ratio, while Kiko BR consumed more (P = 0.001) hay (70:30) and had more DMI when expressed as g/kg BW. Boer BR 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 were observed in carcass shrink, dressing percentage, 12(th) rib fat thickness, and LM area between two BR. When expressed as % empty BW, carcass bone was similar (P = 0.25), while muscle % (P = 0.02) was greater for Kiko and fat % was greater (P = 0.001) for Boer BR. Fat as a % of CCW remained relatively the same (P > 0.10) for both BR for 2(nd) and 3(rd) HA. Differences were more evident (P = 0.01) at the 4(th) HA. Boer BR reached targeted harvest weight (29 kg) at 3(rd) HA while fat deposition continued (P = 0.01) during 4(th) HA. Breed had no effect on meat color (L(*), a(*), b(*)) but HA affected (P = 0.001) all color values. Boer BR had similar 3-hydroxyl-3-methylglutaryl-CoA synthase mRNA abundance, but was greater (P < 0.03) in acetyl CoA carboxylase compared to Kiko BR. There was no difference (P = 0.52) in total serum fatty acids (mg/mL) between the two breeds. As animals aged, their total serum fatty acids increased (P < .05) and changed to an undesirable profile. Kiko BR had a greater percentage of muscle and less fat in the carcass. We concluded that different breeds might need different harvest endpoints and feed input according to the consumer acceptability.
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