Methionine requirement of kittens given amino acid diets containing adequate cystine

Abstract

1. The effects of feeding either high-protein (HP) or low-protein (LP) diets between 1.8 and 15 kg live weight (LW) and a low-energy (LE) or high-energy (HE) intake subsequently on the cellularity of muscle and adipose tissue in pigs growing to 75 kg LW were investigated. 2. The effects of the nutritional treatments on muscle tissue were assessed from the weight and DNA content of the m. adductor . For adipose tissue the total DNA content and fat cell size of the subcutaneous adipose tissue contained in the left shoulder joint were determined. 3. Feeding the LP diets in early life reduced the weight and DNA content of the m. adductor (P < 0.01) and increased fat cell size ( P < 0.01) at 15 kg LW. 4. Subsequent to 15 kg there was an almost linear increase in muscle DNA with increasing LW, and the difference between pigs from the initial protein treatments progressively diminished and was no longer apparent at 60 kg LW. 5. At 30 kg LW, pigs given the LP diets before 15 kg LW contained less DNA in the subcutaneous adipose tissue from the shoulder joint ( P < 0.01) and had larger fat cells ( P < 0.05) than pigs given the HP diets initially. However, adipose DNA and fat cell size increased with increasing LW and the differences resulting from the initial protein treatments progressively diminished. On the LE and HE treatments subsequent to 15 kg these differences were no longer evident at 45 and 60 kg respectively. 6. Pigs given the HE intake subsequent to 15 kg, contained less DNA in muscle tissue ( P < 0·05) at 60 and 75 kg LW and had larger fat cells ( P < 0·05) at 45, 60 and 75 kg LW, than pigs on the LE treatment.