Performance and body composition of finishing gilts (45 to 85 kilograms) as affected by energy intake and nutrition in earlier life: I. Growth of the body and body components.

Forty-eight commercial hybrid gilts were used to determine the effects of energy intake from 20 to 45 kg on the relationship between energy intake and weight gain of the body and body components from 45 to 85 kg. Two groups of 24 gilts received a single diet either at 2.2 (restricted) or 3.7 (control) times maintenance (M) from 20 to 45 kg. From 45 to 85 kg the pigs were fed the same diet at one of six intake levels (1.7, 2.2, 2.7, 3.2, or 3.7 x M, or ad libitum). At 85 kg, the gilts were dissected into organs, lean tissue (trimmed major joints), and other carcass parts (fat fraction). In the restricted gilts, body and lean tissue gain between 45 and 85 kg increased curvilinearly with increasing energy intake from 432 to 1,412 g/d and from 228 to 507 g/d, respectively. In the control gilts, body and lean tissue gain increased from 394 to 1,201 g/d and from 238 to 508 g/d, respectively. The percentage of lean tissue in the carcass decreased curvilinearly with increasing energy intake from 62.9 to 56.5%, and from 62.5 to 53.9% in the restricted and control gilts, respectively. The restricted gilts gained on average 140 g/d faster (P < .001) and their carcass lean tissue content at slaughter was approximately 3% higher (P < .001). These differences increased with increasing energy level between 45 and 85 kg. The increased gain was largely the result of an increase in organ growth and gut contents and was only evident up to 65 kg. The higher lean content at 85 kg in previously restricted gilts was not the result of compensation in lean gain but was already present at the end of the restriction phase at 45 kg.