Effect of intraperitoneal administration of lysine and methionine on mohair yield and quality in Angora goats

Eight mature Angora wethers (average BW 47.2 kg) were used in a 4 X 4 replicated Latin square design to evaluate responses to intraperitoneal (IP) administration of amino acids. The IP treatments consisted of saline (Control) methionine 1 g/d (Met), lysine 2 g/d (Lys), and methionine + lysine (Met + Lys). The amino acids dissolved in Control were infused continuously for the first 14 d of each 28-d period using peristaltic infusion pumps. Average d-28 grease and clean mohair yields (grams/100 square centimeters), and fiber diameter (micrometers) and length (centimeters) measurements during Control administration were 8.8, 7.6, 40, and 2.3, respectively. Mean clean mohair yield and fiber diameter increased by 5.3% (P < .039) and 2.5% (P < .067), respectively, with Met administration but were decreased by 9.2% (P < .033) and 3.8% (P < .001), respectively, by Lys administration; however, mean fiber length was increased (P < .014) 21.7% by Lys infusion. The goats did not exhibit increased grease (P > .939) and clean (P > .477) mohair yields and fiber diameter (P > .619) when treated with Met + Lys. A N balance trial was conducted during d 10 through 14 of each period. Total retained N (grams per day) during Control administration was 18.4 and 24% greater than Met (P > .281) and Lys (P < .061), respectively. When expressed as a proportion of N intake, retained N was lowest (P < .127) in the Lys infusion group. Jugular blood ammonia N and plasma glucose and total protein concentrations were not affected (P > . 10) by treatment. Plasma urea N was less than or equal to 6.7% lower (P < .008) during Met + Lys treatment at 0 and 3 h after feeding than the Control group. Infusion of Met and Lys into the peritoneal cavity of Angora goats altered mohair yield by affecting mohair diameter and length.