Effects of sodium chloride on sheep. 1. Diet composition, body mass changes and wool production of young Merino wethers grazing

摘要

Supplementary salt (NaCI) and crude protein (CP) were provided to young Merino wethers grazing native pasture. Twenty-eight wethers were divided into 7 groups and given the following supplements daily via rumen cannulae: 0, 5 (Control), 15 and 30 g NaCl; and 5, 15 and 30 g NaCI + 20 g CP each. During the experimental period (1 year) the wethers gained respectively 44,4%, 67,1%, 52,6%, 40,7%, 70,1%, 57,2% and 47,6% in body mass. The effect of NaCI on the growth rate of the wethers became evident within 4 weeks. Rate of clean wool production (g day-l) by the wethers during the first 9 months was 9,02, 10,85, 9,32, 7,65, 10,53,9,42 and 9,06, respectively. It was evident that young sheep grazing native grass pasture in the central Orange Free State do have a nutritional requirement for NaCl, but excessive ingestion from licks could depress growth rate and wool production. Furthermore, supplementary CP, in combination with high levels of NaCl, alleviated the adverse effect of NaCI to some extent.