The effect of treatment duration on weaning weights in a cow-calf herd with a protracted severe outbreak of diarrhea in calves.

The objective of this study was to describe a multiyear outbreak of calf diarrhea in an Alberta cow-calf herd and the impact of severe diarrhea on calf productivity. A retrospective analysis was performed through the use of detailed individual animal records and laboratory reports. The most significant laboratory finding was Salmonella Typhimurium isolated from the fecal samples of 2 ill members of the treatment crew and from 3 calves on postmortem examination. In 2002, at the peak of the outbreak, 90.3% (325/360) of the calves required treatment and 8.9% (32/360) of the calves died. In 2003, the severity of the problem had declined with only 20.9% (47/225) of the calves requiring treatment and 3.1% (7/225) of the calves dying. In both years, the weaning weights of treated calves were significantly reduced compared with those of nontreated calves. For calves weaned in 2002, after adjusting for the effect of calf sex, calves treated more than 6 times had 200-day adjusted weaning weights that were 15.2 kg (95% CI; 5.8 to 24.4 kg) lighter than of those calves treated only once or not at all (P = 0.0015, n = 321). For calves weaned in 2003, calves were 5.5 kg (95% CI; 0.23 to 10.8, P = 0.04, n = 207) lighter per treatment day with electrolytes, when calf sex and dam age were controlled for. Assuming that increased days of treatment or number of treatments is representative of disease severity, long-term calf performance is negatively affected by severe calfhood disease. The estimated lost revenue and treatment expenses, excluding the cost of labor, cow feed, and maintenance, was $22 800 in 2002 and $1589 in 2003.