Effects of Insulin Administered to a Perfused Area of Skin in Angora Goats

R. Puchala¹, S. G. Pierzynowski², T. Wuliji¹, A. L.Goetsch¹, and T. Sahlu¹

¹E (Kika) de la Garza Institute for Goat Research, Langston University, Langston, OK, ²Department of Zoophysiology, Lund University, Lund, Sweden

The effect of insulin infusion on mohair growth of Angora goats was investigated using a skin perfusion technique. Six Angora wethers (average BW 32 ± 4 kg) were implanted bilaterally with silicon catheters into the superficial branches of the deep circumflex iliac artery and vein. For the first 14 d of the experiment, 2.4 mL/h of saline solution was infused into the deep circumflex iliac arteries. The infusate for one side contained insulin, delivered at 48 mU/h and estimated to triple the blood insulin concentration in the perfused region. The area of skin supplied by the deep circumflex iliac artery was approximately 250 cm². An area of 100 cm² within the perfused region was used to determine mohair growth. Two weeks after cessation of infusions, perfused areas were shorn. Greasy and clean mohair production from the perfused region was not affected by insulin infusion compared with the side infused with saline (4.57 vs 4.69 and 3.67 vs 3.74 g/100 cm²/28 d for greasy and clean mohair, respectively; P > 0.10). Similarly, insulin did not change mohair fiber diameter or length (P > 0.10). Plasma glucose concentration was lower (P < 0.05) in blood from the deep circumflex iliac vein on the side infused with insulin (57.2 vs 63.4 mg/dL). Blood flow and plasma concentrations of amino acids were not different between treatments (P > 0.10). The lack of an insulin effect on mohair fiber growth may be due to insufficient supply of amino acids or, similar to IGF-1, insulin may have limited effects on fiber-producing follicles.