By Naomi Paley, BSA, PAg., Regional Livestock Specialist, Yorkton
If a cow is to calve every 365 days, she must be pregnant again within 83 days after calving. That can only happen if she comes through calving in optimal health and body condition. After calving, it takes about 40 days until the uterus is again in condition for pregnancy. That leaves only two heat cycles for cows to rebreed on time. Cows that are short on nutrition are slower to return to normal heat cycles, and have lower conception rates.
Researchers estimate that eggs begin maturing about 100 days before they are actually released, so the start of the next pregnancy begins even before the current pregnancy ends. Minerals play a key role in enhancing fertility. Although beef cows only require three to four ounces (85 to 113 grams) of trace minerals in their daily diet, this little bit of supplement helps ensure that they will rebreed and produce healthy calves. The availability of free choice minerals is critical in the three months prior to calving and during lactation, when the cow has increased energy and protein requirements. To provide minerals cost-effectively, mineral supplements need to be matched to your forage base, which varies in nutritional content each year. Thus, an annual forage analysis should be conducted on your ranch.
A cow’s phosphorus and calcium requirements are high during the winter due to fetal development. Phosphorus will likely be the primary mineral needed because it is generally in short supply in dried winter forages. Matching a mineral supplement to your forage base can be done using the rule of thumb that cows need a 2:1 ratio of calcium to phosphorous in the diet. Since legume-type forages tend to have higher levels of calcium, a 1:1 or 2:1 mineral would be the best fit. Grass-type forages are low in both calcium and phosphorous, so a 3:1 or 2:1 with added limestone would fit the bill in this case. Including a vitamin A and E supplement is also very important as dry forages are often deficient in these as well.
The result of proper nutrition will be healthier, more profitable calves, from cows that will breed back in the first few cycles.
For more information contact your Regional Livestock Specialist.