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For cow-calf operations, a major driver of profitability is reproductive efficiency, or the number of calves weaned per cow exposed. There are a lot of factors influencing this outcome, from breeding time through weaning. However, some considerations can be looked at well before the breeding season begins.
After calving, cows will have about 30 to 100 days to recover, resume cycling and be re-bred to calve around the same time the following year. This period through calving and early lactation is when a cow’s requirements for energy and protein are the highest.
Nutritional status is a major factor in cow fertility. Cows in lower body condition at calving will be slower to resume cycling following calving, conceive later in the breeding season, and calve later the next year or remain open if unable to conceive before bulls are pulled. If yearling heifers have not reached around 55 to 65 per cent of their mature body weight by breeding time, their fertility may be lower than expected, resulting in more open heifers.
Trace minerals, specifically copper, manganese and zinc are necessary for reproductive processes in both cows and bulls. Trace mineral deficiency can occur due to low levels of minerals in forage, insufficient intake of mineral supplements, or components in the feed or water which bind trace minerals and decrease their availability to the animal. It is common to find high sulfate water in both dugouts and wells in Saskatchewan. Sulfates can bind copper, contributing to possible copper deficiency in cows, resulting in lower conception rates.
Vitamin A is necessary for reproduction and can comes from the beta carotene in fresh green forage. During the summer months, cows usually consume enough fresh forage to satisfy the requirement for vitamin A. The beta carotene content of stored forages is much lower, making it necessary to supplement vitamin A in the ration during the winter and spring. Vitamin A deficiency can lead to decreased fertility of the cowherd.
If cows are deficient in energy, minerals or vitamins, it can take a significant amount of time of supplementation to correct the issue. It’s often not possible to turn a deficiency around during or right before breeding season. Thinking about nutrition year-round and providing supplementation when needed is a good strategy to ensure cows are ready for breeding.
Chelsey Siemens, livestock and feed extension specialist with the Saskatchewan Ministry of Agriculture, out of the regional office in Kindersley, Saskatchewan.