Self-selection of diets and lysine requirements of growing-finishing swine

Abstract

A growth trial using 240 growing-finishing pigs (22 to 109 kg) was conducted to determine whether pigs offered a choice of low- and high-lysine sorghum-soybean meal diets can select the correct proportion of each to optimize performance and carcass leanness. Pigs on the choice treatments could select from two diets offered simultaneously in identical feeders. In two of the choice treatments, pigs had access only to the low-lysine diet for the first 2 d of each 21-d period to determine whether forced adaptation to the low-lysine diet would alter the proportion of diets selected. These were termed the adjusted treatments. The choice treatments were 1) .50 or 1.10% lysine, 2) .50 or 1.60% lysine, 3) same as 1 but adjusted, and 4) same as 2 but adjusted. Five additional treatments were arranged as a titration study to determine the lysine requirement of the pigs. The dietary lysine levels needed in sorghum-soybean meal diets to optimize performance and carcass leanness of barrows and gilts were .95, .80, and .70% lysine for the 22 to 52, 52 to 78, and 78 to 109 kg weight intervals, respectively. Lysine intake of pigs on the choice treatments exceeded the amounts needed to maximize performance and carcass leanness. The adjustment practice lowered lysine intake, but intake was still excessive. Percentage of lean and gain/feed were less desirable for the choice treatments than for pigs fed the .95-.80-.70% lysine treatment. These reductions, plus the higher lysine intakes, indicate that the choice treatments used in this research are not feasible for commercial swine production.

A comparison of choice and phase feeding for growing–finishing pigs

“…This increased protein intake by choice-fed pigs in the present study was not observed by Kyriazakis (1989) or Bradford and Gous (l99la and 1992), who reported that choice-fed pigs showed a protein intake similar to that of single-fed pigs. On other hand, results recently reported by Owen et al (1994) However, pigs in C3 showed a higher (p < 0.tb; t-n vatue than pigs in Cl during period 3 and the overall experiment.…”

“…These observations were supported by the resulS of Bradford and Gous (1991b), who also suggested that choice feeding appears to have more potential for commercial swine operations than does phase feeding. In contrast, Owen et al (1994) reported ttrat growing-finishing pigs do not have the ability to selert the correct proportions of each diet to optimize performance and carcass leanness when offered a choicebf lowand highJysine sorghum-soybean meal diets. Our previous results (Nam et al 1994) Kyriazakis (1989).…”

Systematic comparison of the empirical and factorial methods used to estimate the nutrient requirements of growing pigs

“…As is also assumed in other pig growth models (Whittemore et al, 2001;van Milgen et al, 2008), the modified InraPorc model used in this study assumed that pigs do not modify feed intake during or after lysine-deficient periods. The assumption that pigs do not increase feed intake to meet their requirements when fed lysine-deficient diets is supported by some authors (Owen et al, 1994;Nam and Aherne, 1994) but not by others (Smith et al, 1999;Cline et al, 2000). Feeding pigs at levels below Lys requirements limits protein growth and pigs become fatter and lighter.…”

Application of Phase Feeding in Swine Production

“…It was mentioned that growing-finishing pigs do not have the ability to select the correct proportions of each diet to optimize performance and carcass leanness when offered a choice of low-and highlysine sorghum-soybean meal diets (Owen et al, 1994). Gourley et al (1993) also reported that choice-fed pigs consumed more protein (lysine) during the finisher period than phased-fed pigs.…”

“…However, more recently, a series of studies have shown that pigs do not have the ability to select a protein intake to meet their requirement when provided a choice of isoenergetic diet differing in protein content (Gourley et aE., 1993;Owen et al, 1994;Nam and Aherne, 1995).…”