Effects of dipeptides administered to a perfused area of the skin in Angora goats.

Abstract

The effect of dipeptide infusion on mohair growth of Angora goats was investigated using a skin perfusion technique. Six Angora wethers (average BW 32 +/- 2 kg) were implanted bilaterally with silicon catheters into the superficial branches of the deep circumflex iliac artery and to the deep circumflex iliac vein. For the first 14 d of the experiment, animals received infusions into the deep circumflex iliac arteries of either a mixture of Met-Leu and Lys-Leu (one side) or saline (other side). Infusion rates of amino acids were .72 mg/h Met-Leu and .72 mg/h Lys-Leu. The area of skin supplied by the deep circumflex iliac artery was approximately 300 cm2. An area of 150 cm2 within the perfused region was used to determine mohair growth. Two weeks after the cessation of infusions, perfused areas were shorn, and greasy and clean mohair production, staple length, and diameter were determined. Greasy and clean mohair production from the perfused region were increased by dipeptide infusion compared to the side infused with saline (1.91 vs 1.66 g, P < .05 and 1.56 vs 1.31 g, P < .04, respectively). No significant changes were observed in mohair diameter; however, staple length tended to increase as a result of dipeptide infusion (18.0 vs 16.1, P < .1). Decreased concentrations of Met, Cys, Lys, Phe, Val, Ileu, Leu, and Arg were observed in the venous blood taken from the deep circumflex iliac vein on the side infused with the amino acid mixture compared with blood taken from the saline side (P < .05). There were no treatment differences in triiodothyronine, thyroxine, or insulin concentrations in venous blood taken from the deep circumflex iliac vein. Direct skin infusion with dipeptide may have resulted in mobilization of amino acids for increased protein synthesis, or the infused dipeptides may have acted as growth promoters stimulating skin amino acid uptake and protein synthesis.