Body composition and protein and fat accretion in various body components in growing gilts fed diets with different protein levels but estimated to contain similar levels of ideal protein.

Abstract

A comparative slaughter technique was used to determine the effect of dietary protein levels on body composition and protein and fat accretion in various body components in Yorkshire gilts. Diets were formulated to contain similar levels of idea protein. Eight gilts were slaughtered at 20 kg BW to determine initial body composition. Twenty-four gilts were assigned to each of three dietary treatments (16.6, 15.0 and 13.0% CP) during the growing period (20 to 55 kg BW). During the finishing period (55 to 100 kg BW), dietary CP levels were reduced by approximately two percentage units. Eight gilts per treatment were slaughtered at 55 kg BW, and the remaining pigs were slaughtered at 100 kg BW. At slaughter, the pits were divided into three components: carcass, empty gastrointestinal tract, and other non-carcass parts. Half of the carcass was further dissected into retail cuts. None of the carcass retail cuts was affected (P > .10) by the dietary CP levels, except trimmed ham was smaller (P < .05) in gilts fed the 13% CP growing and 11% CP finishing diets. Far content in the empty body (P = .12) and in the carcass (P = .06) was highest and the empty body water accretion rate was lowest (P = .05) in gilts fed the 13% CP growing and 11% CP finishing diets. Other aspects of chemical body composition, protein and fat accretion rates, and estimated lean yields were not affected by dietary CP level (P > .10).