Abstract
To study effect of kinds of hay on serum cortisol concentration, five ewes were given seven kinds of hay such as sudangrass (SG), bermudagrass(BG), timothy (TI), prennial ryegrass (PR), oats (OA), Italian ryegrass (IR) and alfalfa (AL) hays, ad libitum. Serum cortisol concentration was determined on the 1st, 7th and 21st days when each hay feeding was commenced. The relationship between serum cortisol level and dry-matter intake (DMI) and time spent for eating and ruminating was investigated. Results were as follows : 1) DMI for AL was the greatest, that is 1.42 kg/day, and that for IR the least, that is 0.72 kg/day. Crude protein content of the hay significantly and positively correlated with DMI. 2) There was no significant difference in serum cortisol level among hays given to sheep. Serum cortisol level showed lower concentration on the 21st day than those on the 1st and 7th days for all hays except for BG. The serum cortisol level on 7th day significantly and negatively correlated with DMI. 3) With the consideration on changes in serum cortisol level, the palatability of hay diets was inferred to have a possible influence on the serum cortisol level of sheep.
