When working to maximize fertility in cattle, cows are often the focus. However, bull fertility is a crucial consideration for any beef operation.
Not only do bulls contribute to the genetic improvement of the herd, but bulls with poor fertility can significantly reduce the pregnancy and weaning percentage of the cow herd, lowering productivity and profitability, said nutritionist Lauren Rensburg.
Many factors, including management, genetics, and even nutrition, can impact both female and male fertility.
The nutritional status of the bull, and even the nutritional status of his dam during her gestation with him, have been linked to the calf’s gains, age of puberty attainment, and semen quality.
While proper energy and protein supplementation is key, the importance of trace minerals cannot be underestimated.
Essential nutrients, including zinc, manganese, copper, and selenium, are known to be involved in hormone secretion and are needed for normal functioning.
Zinc is involved in the production, storage and secretion of hormones that regulate several systems, including immunity. It is the key constituent of insulin and testosterone.
Manganese is involved in cholesterol synthesis, insulin activity, and the production of hormones including estrogen, progesterone, and testosterone.
Copper is essential to the activity of many enzymes, including those involved in immunity and reproduction.
Selenium plays a role in the production of hormones which can affect growth rates and promote reproductive function.
Zinc deficiency can impair sexual function, with lower conception rates, reduced testis growth, and severely impaired sperm maturation.
Manganese deficiency can lower fertility in adult cattle and lead to reproductive failure through impaired estrus, fetal reabsorption, or deformities.
Copper deficiency can be associated with reproductive failure including reduced fertility, delayed or depressed estrus, abortion, and poor semen quality.
Selenium deficiency is related to reproductive problems with estrus, ovulation, embryo fertilization and development, and can also impair sperm motility.
In areas where known trace mineral deficiencies exist, especially regarding zinc, manganese, copper and selenium, supplementation with organic trace minerals can be advantageous.
Organic trace minerals, as opposed to commonly used inorganic types, are more bioavailable and thus better utilized by the animal.
This is less wasteful and more efficient, and it helps prevent harmful excretions of unused minerals into the environment.
Reported improvements in reproductive efficiency with organic trace minerals have included higher pregnancy rates and weaning percentages, fewer open days, and earlier puberty attainment.
Trace mineral supplementation should be a key part of bull management even well before the onset of the breeding season.
For example, it takes approximately 60 days for new sperm to be produced and mature. Therefore, proper supplementation prior to bull turnout is key.
Trace minerals can also have an impact on fetal development and programming.
The development of fertility in both heifers and bulls can be strongly affected by nutrition, starting in utero.
Ensuring proper nutrition for the entire herd, not just the cows, is essential for a successful and profitable breeding season.
Even small changes in overall nutrition, such as the inclusion of organic trace minerals, can pay huge dividends, not only for the immediate calving season but over the productive lifespan of replacement heifers and bulls as well.
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