Physiological and endrocine parameters in beef cattle: breed, sex and year differences.

Plasma corticoids, potassium and sodium, thyroid activity and hemoglobin and hematocrit values were determined at slaughter over a period of four years in 1612 animals representing the following sire groups: Short-horn, Charolais, Simmental, Limousin, Red Angus, Beefmaster, Brown Swiss, Chianina and Jersey. Differences among years and among breeds of sire were significant for all the parameters studied. Hematocrit values were the highest in females and the lowest for entire males, while hemoglobin levels were the lowest in females and the highest for bulls. Plasma corticoid levels were lower for entire males as compared to steers and heifers. Plasma sodium and potassium levels were the highest for females and the lowest entire males. The values reported in this study for several blood components, based on a large number of animals, could serve as clinical guides and as a basis for further research.