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This is Why They Call it a Season!

Posted Jun. 4, 2007

Webster's dictionary defines season as "a period of the year characterized by or associated with a particular activity or phenomenon." Note that the definition says "period of the year," not all year.

Shortening the calving season is one of the most cost-effective management practices that can be implemented by a cow-calf producer. For some, the first step to shortening the calving season is to establish a defined breeding season. Bulls should not be left with cows throughout the year. They should work for no more than three months and take vacation for the next nine or so months getting ready for next year's work.

Uniformity is a key component for attaining a high price at market, and long calving seasons (more than 90 days) result in a wide range in calf age and weight at weaning. Calves born early in the calving season will be heaviest at weaning and have the highest weight per day of age. This leads to the conclusion that to increase weaning weights and total pounds of calf weaned, and to increase uniformity in a calf crop, the calving season must be shortened by shortening the breeding season. The difference in average weaning weight between a herd with a long calving season and a herd with a short calving season can be substantial. For example, assume an average birth weight of 80 pounds, an average daily gain of two pounds, and all calves weaned on the same day. The difference in average weaning weight for a 100-cow herd calving in 60 days compared to a herd calving in 120 days is 62 pounds greater for the herd with the shorter calving season. This results in an additional 6,200 pounds - a 13 percent increase in production by simply shortening the calving season!

Another advantage of having a short calving season is the increased efficiency in feeding or supplementing the herd, which is the largest production cost of a cow-calf operation. Nutrient requirements of the cow change throughout the cow's production cycle - early, mid and late gestation, and calving. Cows in a herd with a short calving season can be managed properly as a single group since all of the cows will be in a similar stage of production throughout the year.

Cows in a herd with a long calving season cannot be managed properly as a single group because various stages of production will be represented within that group. For this group of cows to be managed properly, they need to be separated into multiple groups. However, they usually are not separated, and the result is that some cows get more than they need and other cows don't get enough at feeding time. The consequences of this are "wasted" money and feed for the cows that get too much and lower production and lower rebreeding rates for the cows that don't get enough.

The move to a shorter, controlled breeding season does not have to be drastic or done in a year's time. It can be a gradual process achieved over a number of years by progressively shortening the breeding season, removing open cows in the fall, and replacing them with cows that are bred to calve during or before the start of your calving season. To develop a strategy to shorten the length of your calving season or to establish a controlled calving season, contact your Noble Research Institute livestock specialist.

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