SUPPLEMENTATION OF PASTURE FOR GROWTH

Our goal was to design an optimal supplement for temperate. improved p astures. Nutrients in need of supplementation were identified by forag e analysis and by comparing the nutritional status of foals and weanli ngs fed various forages and supplements. Forage analysis in a survey o f 12 farms indicated that P, tn, Cu and Se were often deficient. Serum analysis confirmed lower P and Se status in weanlings, and lower Zn s tatus during weaning, in horses led pasture and hay only, compared to those supplemented with P, Se and Zn. Serum retinol concentration and a relative dose response test revealed seasonal depletion of vitamin A in weanlings. Seasonal variations in hydrolysable and fermentable car bohydrates were compensated for by a supplement abundant in fat and fi ber as well as vitamin A at twice the National Research Council's requ irement, and minerals in amounts estimated statistically to reach opti mal ranges.