SILICEOUS URINARY CALCULI IN BULLS, STEERS, AND PARTIAL CASTRATES

Abstract

Ninety-six Hereford × Angus bull calves born in May were divided into four groups of 24 each. Calves in one group were castrated at 2 mo of age (early castrates); calves in the second group were partially castrated by Baiburtcjan’s method at 2 mo of age (partial castrates); calves in the third group were castrated at 6 mo of age (late castrates); and calves in the fourth group were left entire (bulls). All calves grazed shortgrass prairie range until 12 mo of age at which time representative animals in each group were killed. The remaining calves were given alfalfa hay and grain until they reached 440 kg about 7 mo later when they also were killed. Two early castrates and one late castrate died of obstruction of the urethra by single large calculi while on range. Calculi were found in all cattle at slaughter at either age but the average weight of material present did not differ significantly between castration treatments. In most animals, kidneys contained a greater weight of calculi than did bladders. At 12 mo of age, the lumens of the urethrae were largest in bulls followed by partial castrates, late castrates, and early castrates in that order. From the differences in urethral diameters, it was calculated that bulls, partial castrates, and late castrates could expel calculi that were heavier by 100%, 50%, and 14% than calculi that could be expelled by early castrates. Thus, bulls and partial castrates had an advantage over steers, not because of differences in their tendency to form calculi, but because of differences in their ability to expel them. In contrast, late castration provided little advantage over early castration.