Productivity of different cow genotypes: culling rates and early calf performance.

Records of Jersey-sired (Jx), Santa Gertrudis-sired (Sx), Charolais-sired (Cx) and straightbred Hereford (H) cows were examined to determine culling rates, birth dates, weaning weights and average daily gains of their first, second and third calves. Culling categories were defined on the basis of number of calves weaned before removal from the herd. Calf performance data were analyzed by cow breed group and cow culling category.

Trypanosoma theileri Laveran, 1902, in Wyoming cattle.

Trypanosoma theileri Laveran, 1902, a cosmopolitan blood parasite of cattle, was found in 86 of 377 Wyoming cattle. Acute infection was experimentally produced in 22 cattle, with blood stream trypanosomes reaching peaks (up to 8,00/ml) in the first 2 weeks of infection. Infection subsided after 3 to 4 weeks.