Effects of dietary protein level and energy intake from 50 to 120 kg on body weight, back fat thickness and body composition in gilts

Abstract

Body composition and body weight at mating plays an important role in reproductive performance and longevity of the sows, and therefore the dietary supply of protein and energy during rearing of the gilts are manipulated to obtain a more optimal body weight and composition at mating. The objective of the present study was to design a smaller but fatter gilt through different levels of dietary protein and different feeding strategies. It was hypothesized that gilts fed a low dietary protein concentration and had a high energy intake would have a lower BW and higher body fatness compared with gilts fed higher dietary protein levels with low energy intake. A total of 44 gilts entered the experiment at a BW of 47.6 ± 2.6 kg and were randomly allotted to one of six treatments in a 3 × 2 factorial experiment. The six dietary treatments consisted of three dietary protein levels (low (LP), medium (MP), high (HP)) and two energy levels (high (HE) and low (LE)). The BW of the gilts was recorded weekly for 84 days and back fat (BF) thickness was measured at day 1, 42 and 84. The body composition of the gilts was measured at day 1 and 84 by dual-energy x-ray absorptiometry (DXA) scans. At day 84 gilts fed HP and HE had the greatest BW (136 kg) and gilts fed LP and MP at LE had the least BW (107–109 kg; P < 0.001). The greatest BF thickness at day 84 was observed in gilts fed LP and HE (12.5 mm), and these gilts had a BW of 123 kg. Gilts fed LP and HE had the greatest body fat content (29.3%; P < 0.001) and the least body lean content (68.3%; P < 0.001). In conclusion, it was possible to design lighter gilts with an increased fat percentage by feeding a low protein diet and high energy from 50 to 120 kg.