The mean entry rate of cystine was similar for sheep in the two flocks, but was greater in those sheep eating the 1100 g of lucerne daily (73 v. 35 mg/hr: P < 0·05) ...
METABOLISM OF CYSTINE BY MERINO SHEEP GENETICALLY DIFFERENT IN WOOL PRODUCTION 1. COMPARISON OF THE ENTRY RATES OF CYSTINE IN SHEEP FROM FLOCKS
SELECTIVELY BRED FOR HIGH AND LOW FLEECE WEIGHT
By A. J. WILLIAMS*t, R. A. LENG*, and S. K. STEPHENSON* [Manuscript received 27 April 1972] Ab8tract
The rates of entry of cystine into the extracellular compartment, and the concentrations of cystine in this compartment, were measured during 12-14 hr infusions ofL-[35S]cystine in Peppin Merino ewes_ The ewes were sampled from flocks selectively bred for high or low clean fleece weight per head; and were fed either 500 or 1100 g of chaffed lucerne hay daily during the experiment. The mean entry rate of cystine was similar for sheep in the two flocks, but was greater in those sheep eating the 1100 g of lucerne daily (73 v. 35 mg/hr: P < 0·05). The concentration of free cystine in the plasma was approximately 20% less in those ewes from the flock selected for high clean fleece weight, relative to those selected for low clean fleece weight (P < 0·05). Although the concentration of free cystine in plasma increased with the amount of feed given (P
