Yearling bulls should never be joined with older bulls—the risk of injury is just too great. They should be joined either by themselves or with other yearlings. If the biggest cows in a joining group fail to conceive, size may be a factor.
The sexual prowess of some small, high-serving, yearling bulls serving dry cows significantly larger than themselves has been witnessed at Trangie Agricultural Research Station, and one wonders how it was physically possible.
Sex is apparently a wonderful motivator! Bulls do not die from too much sex. However, they do lose condition. This will depend on their health, the quality of their feed, the length of the joining period and the number of females they are joined with.
A lot of common sense is needed in order to strike a balance. In extensive areas with only average or poor quality feed, the joining season should be restricted to 6—8 weeks. The use of yearling bulls is limited only by their health and fitness.
If our beef industry is to make progress, we must purge our minds of the belief that a bull has to be fat and well grown to be any good. The value of a bull should be measured by the performance of his offspring—not on what he looks like. After all, when was the last time you saw a fat rabbit, fox or roo? Maintaining bulls in anything fatter than 2 or 3 score condition is wasteful, counterproductive and inefficient.
Bulls that are allowed to get fatter than this are either sexually inactive or under-used. It is surprising how many cattle producers think that young bulls are more likely to sire small calves. They are purchased in the mistaken belief that they can reduce calving difficulties.
Clearly that is not the case. There is no relationship between the age of a bull at joining and the weights of his calves. The birthweight of calves is heritable, so a bull will influence, genetically, the birthweight of his calves. If you are concerned about birthweight, buy a bull that has a low estimated breeding value EBV for birthweight, or one that had a lower birthweight than the average of other bull calves in the same drop.
If data on birthweights is unavailable, select a bull of only moderate size or one that has been successfully delivered by a heifer. In general, larger framed bulls tend to have heavier calves at birth. Mating large-framed bulls to small-framed heifers or cows will increase the risk of calving problems.
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Puberty When bulls reach puberty depends on breed and body weight. Breeding Soundness Examination At least two months before the start of the breeding season, yearling bulls undergo a breeding soundness examination by a veterinarian.
Scrotal Circumference Besides superior genetic qualities, the most important factor when evaluating a young bull for breeding soundness and potential fertility is his scrotal circumference. Breeding Depending on the farm or ranch, bulls are either turned out with a cow herd or semen is collected via artificial insemination. Characteristics of the Santa Gertrudis Bull. Steve Furman and Mr. Dave Mitchell with collection of animal data. Mention of products of companies in this report does not constitute endorsement by the U.
Department of Agriculture to the exclusion of others not mentioned. Lunstra, J. Ford, S. Pubertal factors characterized included body weight, testicular size, hormone concentrations, sexual aggressiveness and sperm production. Brown Swiss bulls were heaviest kg , while Red Poll and Hereford bulls were lightest and kg in body weight at puberty. Breed differences in LH concentration were not observed from 7 months of age through puberty. Breed groups with high average T concentrations between 7 and 13 months of age reached puberty earlier than breed groups with low T concentrations.
Bulls exhibited first sexual interest approximately 3 weeks before reaching puberty, and attained mating ability approximately 6 weeks after reaching puberty. Although rather large differences in age and body weight at puberty existed among breeds, scrotal circumference at puberty It is concluded that measurement of scrotal circumference may be a simple method of assessing puberty in beef bulls, regardless of differences in age, weight and breed, and should be a useful tool in the selection of early maturing bulls with minimal effort.
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