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THE EFFECT OF LEAN GROWTH SELECTION AND FEED INTAKE ON COMPOSITION AND ENERGY UTILIZATION IN SWINE AND CORRELATED RESPONSES IN CARCASS AND REPRODUCTIVE TRAITS FROM LEAN GROWTH SELECTION IN SWINE
Abstract
Five generations of lean growth selection (based on an index of backfat and average daily gain) was practiced in two lines of pigs (select and lysine). Select (LG) and control lines were fed a 14% protein corn-soybean diet during the test period. Lysine (L) pigs were fed a diet consisting of only opaque-2 corn, minerals and vitamins during the test period. An experiment was conducted to determine the effect of lean growth selection and feed intake on composition and energy utilization in swine and to estimate the energy cost of maintenance (b(,m)), protein deposition (b(,P)) and fat deposition (b(,F)). Fifty-three barrows from the LG and control (C) lines were randomly assigned to three feeding levels at 83 days of age. Thirty-three littermate barrows were slaughtered at the start of the test to establish initial body composition of the fifty-three barrows. During the 105-day trial the feeding levels were appetite (AP), 91% of appetite (AP91) and 82% of appetite (AP82). At slaughter all pigs were dissected into four sections. Each section was weighed sampled and analyzed for chemical composition. All levels of restricted feeding reduced (P < .05) average daily gain (ADG), feed/gain (F/G) and backfat (BF). ADG was higher (P < .01) while F/G and BF were lower (P < .001) for LG than for C pigs. Restricted feeding reduced (P < .05) daily gains of fat, protein and water. Daily gains of protein and water were higher (P < .01) for LG than for C pigs. However, daily fat gain was lower (P < .05) for LG pigs. After the 105-day trial, restricted fed pigs had a greater (P < .001) proportion of body protein and water compared to AP fed pigs. Even at heavier final weights, LG pigs had greater (P < .001) proportions of body protein and water compared to C pigs. The metabolizable energy intake required per kg of edible lean (ME(,I)/leanc) was reduced (P < .05) by restricted feeding. ME(,I)/leanc (25.6 (AP), 23.3 (AP91) and 25.3 (AP82) vs. 31.1 (AP), 27.5 (AP91) and 28.1 (AP82) mcal/kg) was lower (P < .001) for LG than for C pigs. Restricted feeding increased (P < .05) the energy lost per unit of retained energy (EL/RE). EL/RE (1.33, 1.45 and 1.53 vs. 1.24, 1.29 and 1.34 mcal/kg) was higher (P < .01) for LG than for C pigs for the respective feeding regimes. The LG line has a higher (P < .05) b(,m) than line C when expressed as mcal per kg live weight('.75) maintained per day (.079, .082 and .079 vs. .073, .069 and .067) but differences were less when expressed as mcal per kg of lean mass('.83) maintained per day (.078, .079 and .077 vs. .075, .069 and .067) for the respective feeding regimes. Regression estimates of b(,P) and b(,F) did not differ among lines. For the combined data (lines LG and C) b(,P) estimates ranged from 9.02 to 11.25 mcal per kg while b(,F) estimates ranged from 12.73 to 12.88 depending upon the component used to estimate ME(,m). The effect of lean growth selection on number born (NB), number born alive (NBA), number weaned (NW), individual birth weight (IBW), individual weaning weight (IWW), litter birth weight (LBW), litter weaning weight (LWW), nipple number (NN), carcass backfat (CBF), carcass length (CL), ham and loin percentage (%HL) and longissimus area (LA) was determined by the regression of line difference (LG minus control) on generation number (CR). CR estimates were .04 (+OR-) .04, .07 (+OR-) .06, .04 (+OR-) .08, .005 (+OR-) .015, .15 (+OR-) .09, .11 (+OR-) .08, 1.5 (+OR-) .9, -.15 (+OR-) .05, -.08 (+OR-) .04, .10 (+OR-) .08, .30 (+OR-) .16 and .04 (+OR-) .08 for NB, NBA, NW, IBW, IWW, LBW, LWW, NN, CBF, %HL, LA and CL, respectively in line LG. In line LG, CR estimates were in the desired direction with the exception of NN, but were nonsignificant. For line L the CR estimates were nonsignificant.
Subject Area
Livestock
Recommended Citation
CLEVELAND, ERIK RANDOLPH, "THE EFFECT OF LEAN GROWTH SELECTION AND FEED INTAKE ON COMPOSITION AND ENERGY UTILIZATION IN SWINE AND CORRELATED RESPONSES IN CARCASS AND REPRODUCTIVE TRAITS FROM LEAN GROWTH SELECTION IN SWINE" (1981). ETD collection for University of Nebraska-Lincoln. AAI8203211.
https://digitalcommons.unl.edu/dissertations/AAI8203211