Effect of Restricted Feed Intake on Early Reproductive Development in Large White Gilts

Forty-five Large White gilts were used to study the effect of energy intake from 28 to 176 d of age on body composition and reproductive development. From 28 to 60 d, the gilts were fed ad libitum a 16.6 MJ DE/kg, 24% crude protein and 1.3% total lysine diet. From 61 d of age three dietary treatments were used; 1) ad libitum access to feed (15.6 MJ DE/kg, 21% crude protein and 1.07% total lysine) (H), 2) feed offered at 75% (M) of the previous days intake of H, and 3) feed offered at 60% (L) of the previous days intake of H. ADG from 61 to 176 d of age was (p<0.05) affected by treatment. Although live weight at 176 d of age did not differ (p>0.1) the H gilts had higher (p<0.08) carcass weights than the M or L gilts. Back fat depths were similar (p>0.1) for all treatments at 115 d of age, however by 176 d of age M and H gilts were fatter (p<0.1) than L gilts. The mean lipid deposition (LD) from 115 to 176 d of age for L gilts (78.9 g/d) was less (p<0.05) than for M gilts (143.6 g/d) and H gilts (135.6 g/d). There were no differences between treatments for protein deposition (PD) over the same period. More (p<0.05) H gilts (n=8) attained puberty (first observed estrus) than either M gilts or L gilts (n=4 for both). Follicle numbers were similar (p>0.1) across treatments. For gilts that attained puberty, H gilts had fewer (p<0.05) follicles (13.5) than M gilts (19.7) and L gilts (21.3). For gilts with follicular development, H gilts had the heaviest (458.7 g) reproductive tract weight (RTW). However, for those that attained puberty, L gilts had the heaviest RTW. RTW were lowest for those with no follicular development. Energy restriction had a negative impact on puberty attainment, i.e. it took longer to reach puberty. However, for gilts that attained puberty, the number of follicles was greater for those on r feed intakes. It would appear that rate of fat deposition, but not necessarily the total amount of fat, plays an important role in puberty attainment.