The goal of a breeding program is to wean a calf from each cow exposed to a bull on an annual basis. Breeding programs should also be directed toward maximizing the value of the calf crop by maintaining a compact breeding season to produce a uniform calf crop that will wean off heavier on average than calves from a strung-out calving season.
Toward those ends, a lot of attention is paid to providing adequate nutrition for the cow herd, says Dr. John McKinnon, beef chair at the University of Saskatchewan.
A cow’s success is a direct reflection of her body condition score (BCS) at critical times in her productive cycle. The objective is to reach a BCS of no less than three going into calving. Proper nutrition during the last trimester, particularly during the six to eight weeks prior to calving, will give her adequate energy reserves to calve, produce milk, and begin to cycle early in preparation for the next breeding season.
He indicates that nutrition and management of bulls should be put into the same context as nutrition and management of the cow herd. “The bull’s contribution to reproductive success and genetic improvement of the herd is so much more than that of any one individual cow. That means you have to pay special attention to them because if you turn out bulls that are infertile due to malnutrition, structural defects, or diseases you will end up with a wreck,” he explains.
Today, it is common for purebred breeders to develop young bulls from weaning through to 12 to 14 months of age. Commercial producers have an equally important role in taking yearling bulls through their next stage of development from the first breeding season to maturity.
For example, a 1,300-pound yearling bull might be at 50 to 60 per cent of its mature weight, which you expect will be about 2,350 pounds. As a two-year old, you’d like to turn him out at about 1,750 pounds or 75 to 80 per cent of his mature weight. During the first breeding season — running with 15 cows or so — it’s not unreasonable to see a 150-to 200-pound weight loss. Therefore, between breeding seasons, he has to regain the loss, plus gain another 450 pounds for normal growth and development, McKinnon explains. That could add up to a total required weight gain between breeding seasons of 600 pounds or more depending upon his expected mature weight.
Here again, BCS is the key. Regardless of age, if you manage your bull nutrition program to achieve a BCS of three to 3.5 at turnout, they’ll have that little extra fat reserve to carry them through the breeding season without falling behind too much.
“Don’t wait to pay attention to bull nutrition until it gets close to breeding season,” McKinnon cautions. Rapid weight gain resulting from overfeeding grain to beef bulls will lead to fat deposits at the neck of the scrotum. The fat deposits hinder the temperature regulating function of the testicles and semen quality suffers. Normally, it takes about 60 days for the testicles to generate a new cycle of viable semen, so it will take time to recover full fertility if you overfeed your bulls.
Over-conditioning can also be an issue when purchasing bulls from a test sale or from a purebred breeder. Regardless of age, a fat bull tends to have low-semen quality, be on the lazy side and have reduced libido.
At the end of your breeding season, yearling bulls should be put on good-quality pasture and supplemented with grain or pellets when pasture conditions are poor. During the winter, a steady diet of good-quality forage and
an appropriate supplement targeting a gain of about two pounds a day should be sufficient under average conditions. The goal is to achieve 75 to 80 per cent of mature weight and a BCS of 3.5 at turnout for his second breeding season.
Two-year old bulls need to be given the same consideration, though the nutritional requirements are less stringent because they are closer to their mature weight going into breeding season and the weight loss during breeding season may not be as great that of a yearling bull.
Likewise, three-year-old and mature bulls should be fed to regain weight lost during the breeding season to take them back to a BCS of 3.5 going into the next breeding season.
Bulls that are turned out from May through July for a March-April calving season in the Prairies, require a bit of extra care relative to those that are turned out later in the summer for a May-June calving season. The bulls that go to work later have an advantage because they can be conditioned on high-quality fresh pasture prior to breeding season, whereas those put to work earlier in the spring may require supplemental feeding prior to turn-out with the cows.
“A mineral and vitamin program is just as important on the bull side as it is on the cow side,” McKinnon notes. Providing minerals such as calcium and phosphorous; trace minerals, such as zinc, copper and manganese; and vitamins A, D and E, in a year-round supplementation program is very important with respect to bull fertility and normal growth.
In addition to a sound nutrition program, he advises producers to work with their local veterinarians to ensure the breeding soundness of all herd bulls prior to breeding season.