![]() Proper angulation in the leg joints also helps to absorb the shocks produced during each step and increases the productive life-span of the bull.įigure 1 illustrates the various parts of the bull’s reproductive tract. A moderate angle in the hock joints is necessary for the bull to thrust properly after mounting. Any disease that impairs the mobility of the bull hinders reproductive performance.Ī conformational problem commonly associated with poor breeding performance is extreme straightness of the rear leg (post-legged). Structural soundness, including functional feet, legs and associated joints, is critical for the bull to effectively travel the breeding pasture and service females in heat. Poor health can affect libido, mating ability, and semen production and quality. General health and structural soundness are important aspects of fertility. There are 5 general factors that can affect bull fertility:Īll are important and a deficiency in any category will negatively affect fertility. The reproductive development and performance of young bulls has gained attention as beef breeders attempt to accelerate improvement of economic traits in cattle and reduce costs by using younger sires. Although bulls that have reached puberty can breed, reproductive capacity increases as the bull continues to mature. Bulls exhibit first sexual interest about 3 weeks prior to puberty and attain mating ability about 6 weeks after puberty. Age and body weight at puberty vary across breeds (Table 1), but scrotal circumference at puberty (an indicator of testes weight) remains constant at 28–29 cm. It is related to age, body weight and testes weight. Puberty is defined as the age at which a bull is first able to produce an ejaculate containing 50 million sperm with a minimum of 10% motility (capable of motion). A few bulls may be sterile, but most have fertility levels ranging from very high to very low. Nevertheless, a bull can be evaluated for breeding soundness and this information used to assess his potential fertility. It is not feasible to determine true fertility before a bull is used in the herd. Actual fertility levels are the result of a combination of genetic potential and environmental factors including nutrition, health, and cow and bull management. All of these results cause serious economic loss to the cow-calf producer.īull fertility is often measured by the percentage of cycling females exposed to the bull and impregnated during a specific time period (usually 60–90 days). Using a subfertile bull may lead to longer calving intervals, a lower number of calves produced and increased costs from wintering open females. Since individual bulls service many females, a deficiency in the breeding ability of one bull has a larger impact on herd productivity than fertility problems in a single female. A key component of efficient calf production is a high fertility level in each breeding animal in the herd. ![]()
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