Growth of protein, moisture, lipid, and ash of two genetic lines of barrows and gilts from twenty to one hundred twenty-five kilograms body weight

¹ Department of Animal Sciences, Purdue University, 915 West State Street, West Lafayette, IN 47907-2054
² The Ohio State University and the Ohio Agricultural Research and Development Center, Columbus, OH 43210-1095

^* To whom correspondence should be addressed. E-mail: aschinck{at}purdue.edu.

	Abstract

Two genetic lines of barrows and gilts with different lean growth rates were used to determine the BW and chemical composition growth from 23 to 125 kg BW. The experiment was a 2 x 2 x 5 factorial arrangement of treatments in a CRD design conducted in 2 replicates. Six pigs from each gender and genetic line were killed at approximately 25 kg intervals from 23 kg BW to 125 kg BW. At slaughter, tissues were collected and weighed. All components were ground and frozen until analyzed for water, protein, lipid, and ash. Serial BW data were fitted to alternative functions of day of age. Based on AIC values, the random effects model BWi, t = (1 + ci) (bo + b1 t + b2 t2) was the best mixed model equation. The chemical component mass data were fitted to alternative functions of BW. The allometric function, chemical component mass = aBWb, provided the best fit to the data. Daily deposition rates of each chemical component were predicted by using the derivatives of the 2 functions. The overall ADG of the 2 genetic lines were not different. Barrows had 0.052 kg/d greater (P = 0.03) ADG than gilts. Allometric growth coefficients for all 4 chemical components were different (P < 0.01) for each genetic line. Allometric coefficients and predicted relative growth (g/kg BW gain) for protein and moisture mass were greater (P < 0.01) for the high lean-gain pigs than the low lean-gain pigs. Allometric coefficients for lipid mass were smaller (P = 0.001) for the high lean-gain pigs than the low lean-gain pigs overall. Allometric coefficients and predicted relative growth rates for lipid mass were greater (P < 0.01) and for moisture and protein mass lesser (P < 0.002) than the gilts. Compared with low lean-gain pigs, high lean-gain pigs had: (1) 32.8% lesser predicted daily rates of lipid deposition (200 versus 305 ± 80 g/d), with the difference increasing from 23 to 37% from 25 to 125 kg BW, (2) 12.3% greater daily rates of protein deposition (118.7 versus 106.0 ± 3.3 g/d), and (3) 18.8% greater predicted daily moisture accretion rates (423 versus 356 ± 9 g/d). Overall barrows had 21.3% greater lipid deposition (279 versus 230 ± 78.2 g/d) than gilts. In this study, barrows and gilts had similar predicted daily moisture, protein, and ash accretion rates.

Key Words: chemical composition, genotype, growth, pigs

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