Extreme heat and drought conditions this summer have taken a heavy toll on beef producers and cow herds throughout the South. Now that summer has come and gone, cow/calf producers will need to guard against a false sense of relief brought on by cooler temperatures. For livestock that have experienced heat and nutritional stress over an extended period of time, the recovery period will take time and careful management this fall and winter.
“The focal point for producers now should be on returning breeding animals to an adequate body condition to support productivity and health,” said John M. Davidson, DVM, professional services veterinarian, Novartis Animal Health. “Nutritional management including vitamin and mineral supplementation is critical to restore—and maintain—body condition scores, particularly in pregnant cows and heifers. Don’t forget that adequately conditioned animals can still have hidden nutritional deficiencies that can impact production.”
Heat and nutritional stress can have profound effects on reproductive performance and significantly reduce pregnancy rates. Drought-stressed pastures or forages are often lower quality and deficient in the key vitamins and trace minerals necessary to support optimal reproduction. With feed challenges, nutritional deficiencies and heat stress, cows are much less likely to conceive and bulls can have a sharp drop in semen quality 60 – 90 days after a period of environmental stress.
“Pregnancy checking is probably more important this year than it’s ever been,” said Davidson. “Given the rising costs to feed and maintain females with limited pasture resources, ranchers really need to work with their veterinarian to preg-check and cull nonproducing females.”
Davidson added that producers who keep more cows than can be fed properly could end up paying in more ways than one. “Certainly there’s an unwanted cost associated with feeding open cows,” he said. “But if those animals aren’t fed in a manner that improves body condition in time for breeding, producers will be faced with an extended calving season and lightweight calves at weaning time.”
The optimum body condition score (BCS) at calving is 5 (on a 9 point scale) for cows and 6 for heifers. Missing the mark here will have an impact down the line. A quick review of the bovine gestation period reminds us that for a cow to calve every 12 months, she must settle by her 80th day postcalving. Studies have shown that nearly half of the cattle that calve at a BCS of 4 or less won’t be cycling by the 80th day. This delays conception and shifts that cow’s calving to later in the season which results in a lighter calf at weaning.