Effects of Level of Corn- and Barley-Base Diets on Performance and Body Composition of Swine

Abstract

Two experiments were conducted to study the effects of corn- and barley-base diets fed at varying levels of intake on rate and efficiency of gain, and on carcass characteristics and tissue composition. Pigs fed the corn diet gained faster (600 vs. 490 gm./day), required less feed per unit of gain (3.95 vs. 4.51), yielded a higher percent of the live weight as carcass (69.5 vs. 68.0), yielded a lower percent as ham and loin (37.9 vs. 39.3), and their carcasses had more backfat (3.50 vs. 3.20 cm.) as compared with pigs fed the barley diet. With increasing levels of feeding, there was a linear increase in average daily gain (440, 540 and 650 g) and backfat thickness (3.27, 3.35 and 3.56 cm.) and a linear decrease in percent of ham and loin (39.6, 38.7 and 37.4). In experiment 2 there was a linear decrease in feed per unit of gain with increasing levels of feed intake. There was a significant quadratic effect of level of feeding on the fatty acid composition of the outer layer of backfat for the total saturated fatty acids present (37.7, 37.0 and 40.3) and for the total unsaturated acid content (62.3, 63.0 and 59.7) with increasing levels of feed intake. In comparison with the pigs full hand-fed in the same trial, pigs offered feed ad libitum gained faster (780 vs. 610 gm/day) on similar amounts of feed per unit of gain (4.10 vs. 4.11) and yielded a similar percent of live weight as carcass (68.9 vs. 68.7). Carcasses were similar in backfat thickness (3.48 vs. 3.50 cm) and percent of ham and loin (38.3 vs. 38.1). The outer layer of backfat of the pigs offered feed ad libitum had a higher percent of saturated fatty acids (41.5 vs. 40.3) and a lower percent of unsaturated acids (59.5 vs. 597), as compared with the full hand-fed pigs. Saturated fatty acids in the 1. dorsi muscle were similar (39.4 vs. 39.4%) for the pigs allowed feed ad libitum or those full hand-fed.