Effects of Maternal Nutrition and Arginine Supplementation on Characteristics of Wool Quality in Offspring
The objectives of this study were to measure effects of maternal nutrition and rumen-protected arginine supplementation on postnatal offspring wool quality and follicle development. We hypothesized that lambs from ewes receiving diets fed to nutrient requirements would have a greater density of wool follicles and improved wool quality compared to lambs from nutrient restricted ewes. We also hypothesized that lambs from restricted ewes receiving a rumen-protected arginine supplement would present similar wool follicle numbers and quality to those lambs from adequately fed dams. To test these hypotheses, multiparous Rambouillet ewes (n = 32; 67.6 ± 6.2 kg) were randomly assigned to one of three treatments at 54 ± 3.9 d of gestation in a completely random design. Dietary treatments included 100% nutrient requirements (control, CON), 60% of CON nutrients (restricted, RES), and RES with the addition of a rumen-protected arginine supplement dosed at 180 mg/kg of body weight once daily (RES-ARG). Ewes were penned individually in a temperature-controlled facility. Immediately post-lambing, lambs were separated from ewes and raised independent of their dam until necropsy at 54 ± 3 d of age. A wool sample was taken for quality analysis, in addition to skin samples (3 cm2) from the side (between the 10th and 12th rib) and britch regions. Following histological preparation and stereological analysis all data were analyzed using the MIXED procedure of SAS. No differences were observed in follicle numbers between treatments for skin samples taken from the side of the lambs (P ≥ 0.17). However, in the britch samples lambs from RES-ARG ewes had more (P = 0.02) follicles present than lambs from CON ewes, with lambs from RES being both intermediate and similar in follicle number (106 vs. 86 vs. 93 ± 6.3 follicles per 1 mm2, respectively). There were no differences among treatments for wool quality measures of mean fiber diameter, fiber diameter SD, or comfort factor (P ≥ 0.32). These data partially support our hypothesis that maternal rumen-protected arginine supplementation may increase the number of developing follicles in offspring, and therefore potentially increase wool production. However, we reject our hypothesis that arginine supplementation will increase wool quality in those lambs from restricted-nutrient dams.
Keywords: arginine, wool, developmental programming