Having a breeding (and calving) season can optimise the reproductive performance of a breeding herd and the pre-wean growth rate of calves. This, in turn, can profoundly influence the profit margin of a beef cattle enterprise.
The aim of a breeding season is to get the maximum number of female animals in calf in a short period, and as cost-effectively as possible, for calving during a time that favours the following:
- Calf survival; and
- Pre-wean growth of calves.
The major factor governing a breeding season is nutrition. The most effective breeding season is one that makes optimal use of the cheapest source of high-quality feed, namely summer grazing.
Many problems can arise if a breeding season starts too late in the year. To begin with, calves born too late may be too small to utilise their dams’ high milk production from peak summer grazing. This will result in lower weaning weights.
In addition, because of the higher nutritional level of the cows at that stage, calves born later in the summer season may have higher birthweights and consequently a higher incidence of dystocia (calving difficulty).
If, on the other hand, the breeding and calving season starts too early, cows will
calve too early; that is, too long before adequate summer grazing is available. This will result in a loss of condition and, consequently, a lower re-conception rate.
The ideal calving time is six to eight weeks before adequate green grazing can be expected.
The disadvantages of calving throughout the year are:
- Summer grass cannot be utilised efficiently, and expensive winter supplements have to be used;
- It is difficult to select effectively for fertility;
- Routine management practices cannot be consolidated;
- Feed-flow planning becomes complicated;
- Performance testing and marketing cannot be accomplished effectively;
The services of a veterinarian are required more often, resulting in higher costs for animal care.
A breeding season
There are numerous advantages to having a breeding season:
- Grazing can be utilised at its peak production period. The best camps can be allocated to the breeding herd, resulting in a higher conception rate, and female animals can be mated at optimal condition and weight, ensuring a higher conception rate;
- The period of the cows’ peak nutritional requirement (six to 14 weeks after calving) can be made to coincide with peak grass production. This would help ensure that the animals maintain their condition, resulting in a higher re-conception rate and higher weaning weights;
- The pre-wean growth period of calves coincides with peak grass production, resulting in higher weaning weights;
- The period of cows’ lowest nutritional requirements (after weaning) coincides with winter, when grazing is least productive. Low nutritional needs in winter also mean that less supplementation is required then;
- Strategic, cost-effective supplementation of breeding cows is possible;
- Feed-flow planning is simplified;
- Routine management practices are also simplified. These include dosing, pregnancy diagnosis, calving observation, identification, inoculation, dehorning, castration, weighing and weaning. With single-sire mating, breeding groups need to be kept separate for only a short period;
- The calving season can be coordinated with other farming enterprises and activities, such as planting or harvesting;
- Attention can be focused on the breeding herd during the breeding and calving season;
- Performance testing can be carried out more effectively because calf groups are larger and the animals are more or less the same age;
- Similarly, marketing can be done more effectively because the calf groups are larger, the animals are approximately similar in weight and age, and cows that are not in calf can be marketed before winter in a good condition;
- Selection for fertility is easier and more effective because sub- or infertile female animals can be identified easily; sub- or infertile bulls and/or bulls lacking libido can be identified easily; female animals not in calf can be culled early; and early- and late-calving cows can be identified.