Nutritional Responses in Wool Sulphur by Four Merino Genotypes Of

Sheep from 4 Merino flocks, different in annual clean fleece production when grazed together, were given several nutritional treatments to compare the relationships of wool sulphur with nutrient intake, and with wool growth and plasma cystine. The sheep were selected from a finewool (Fl), a strong wool (S), and 2 medium-Peppin (MP6 and MPlO) flocks. The nutritional treatments varied intakes of 2 pelleted diets B and F. Diet B consisted of oat grain, lucerne chaff, and oaten straw, while diet F was as for B but fortified with fishmeal. The concentration of sulphur in wool was positively but curvilinearly related to N intake. Sheep from flock Fl had higher levels of sulphur in wool than those from the other flocks at any particular level of N intake. The rate at which wool sulphur concentration increased with either increasing N intake or increasing plasma cystine concentration did not differ between the flocks. However, the daily output of sulphur @g/cm’> by flock Fl was less than that of the other flocks, reflecting the relative wool growth rates. Over 90% of the variation in the daily output of sulphur was attributable to variation in wool growth rate.