Influence of feeding level and of protein level in early life on the cellularity of adipose tissue and body fat content of growing pigs

Abstract

1. The effects of level of feeding and level of protein in the early postnatal period on the cellularity of subcutaneous adipose tissue and body fat content of pigs were investigated in two experiments.2. In Expt 1, piglets were given a common liquid diet at energy intakes equivalent to 2·8 or 5·2 times energy for maintenance (M) between 1·8 and 6·5 kg live weight (LW), and a common dry diet at 2·8 or 4·5 M between 6·5 and 20 kg LW. Between 20 and 75 kg LW all pigs were given a second dry diet at 4·0 M.3. In both experiments the effects of nutritional treatments on fat cell number at 20 and 75 kg LW (Expt 1) and at 45 kg LW (Expt 2) were assessed by measuring the DNA content of the subcutaneous adipose tissue contained in the left shoulder joint. Fat cell size was assessed in the same tissue by measuring the diameter of collagenase-released adipocytes.4. In Expt 1, raising the level of feeding between 1·8 and 6·5 kg LW increased body fat content and average fat cell diameter at both 6·5 (P< 0·01) and 20 kg LW (P< 0·05) but had no effect on either measurement at 75 kg LW. Similarly, raising the level of feeding between 6·5 and 20 kg LW increased body fat content and fat cell size at both 20 (P< 0·01) and 75 kg LW (P< 0·05). There was an almost twofold increase in the DNA content of subcutaneous adipose tisuue between 20 and 75 kg LW. However, it was not significantly affected at either weight by level of feeding before or subsequent to 6·5 kg LW.5. In Expt 2, reducing the level of dietary protein between 1·8 and 6·5 kg LW increased body fat content (P< 0·01) and fat cell size (P< 0·01) at the latter weight. Although level of dietary protein to 6·5 kg LW had no effect on body fat content or the weight of subcutaneous adipose tissue in the shoulder joint at 45 kg LW, pigs given the lowest-protein diet contained less DNA (P< 0·05) in the subcutaneous adipose tissue and had larger (P< 0·05) fat cells than those given the highest-protein diet to 6·5 kg LW. Reducing the protein content of the diet fed subsequent to 6·5 kg LW increased the body fat content (P< 0·01) and fat cell size (P< 0·01) at 45 kg LW.