Bull breeding, where bulls naturally mate with cows, remains the cornerstone of most cattle operations. However, achieving high fertility rates through bull breeding requires a combination of strategies, ranging from effective herd management to advances in reproductive technologies. By improving fertility, cattle producers can increase productivity, reduce costs and enhance the profitability of their operations.

Fertility in cattle is influenced by several factors, including genetics, nutrition, health and management practices. Even though bulls are naturally designed for breeding, various challenges can affect their ability to impregnate cows successfully. These include poor semen quality, low libido, environmental stress and diseases that affect reproductive health. 

In addition to bull-related factors, cow fertility also plays a significant role. Issues such as postpartum anestrus, inadequate nutrition or hormonal imbalances can prevent cows from becoming pregnant. Therefore, improving fertility in beef herds requires an integrated approach that addresses both bull- and cow-related factors.

Bull health and reproductive soundness

A key factor in improving fertility in bull breeding is ensuring the bulls are in optimal health. Bulls that are sick, undernourished or stressed are less likely to perform well in breeding programs. 

A breeding soundness exam (sometimes referred to as a BSE) prior to the breeding season is crucial for assessing a bull’s semen quality and reproductive health. Along with a physical exam, a breeding soundness exam evaluates semen motility, morphology and concentration, which are all indicators of a bull’s ability to breed effectively. In addition, bulls require nutrition that supports their reproductive health, including adequate levels of protein, minerals, and vitamins. Deficiencies, particularly in trace minerals like zinc and selenium, can negatively affect sperm quality and overall fertility.

Furthermore, managing the bulls’ stress levels is key to ensuring they remain fertile. Bulls constantly exposed to high-stress environments, whether from poor housing conditions, competition with other bulls or travel, may experience reduced libido and semen quality. 

Cow nutrition and supplementation for fertility

Cows need a well-balanced diet to optimize fertility. Underfed or overfed cows may experience irregular estrous cycles, leading to infertility. Proper management of body condition scores (BCS) is crucial. Cows with an ideal BCS (neither too thin nor too fat) are more likely to cycle regularly and become pregnant. 

In certain cases, supplemental feeding can help resolve fertility issues, particularly when cows are facing deficiencies in trace minerals or vitamins. For example, calcium and phosphorus are essential for maintaining healthy reproductive organs, while magnesium plays a role in preventing early pregnancy loss.

Disease management and prevention

Reproductive diseases, such as bovine viral diarrhea (BVD), brucellosis and leptospirosis, can have a significant effect on fertility in both bulls and cows. To improve fertility, it is important to implement a comprehensive herd health program that includes vaccination and regular disease screenings. Vaccination programs should focus on diseases known to affect reproduction, such as BVD and infectious bovine rhinotracheitis (IBR). These diseases can lead to reduced conception rates, abortions, or infertility. Working closely with a veterinarian to develop a herd health plan that minimizes the risk of disease is an important aspect of maintaining high fertility in bull-bred herds.

Bull-to-cow ratio and breeding management

The ideal bull-to-cow ratio is another key factor in ensuring optimal fertility in bull breeding programs. Too many cows per bull can lead to overwork, resulting in reduced breeding efficiency and potential health issues for the bull. On the other hand, too few cows per bull can result in underutilization, reducing the overall breeding potential of the herd. The typical recommendation is one bull for every 25 to 30 cows, though this can vary based on factors such as the bull’s age, health and the cows’ fertility. In large herds, having multiple bulls ensures that breeding is spread out and that bulls are not overburdened, while allowing for genetic diversity.

Improving fertility in cattle herds with bull breeding requires a multifaceted approach, combining genetic selection, proper nutrition, disease management, and reproductive technologies. By ensuring both bulls and cows are in optimal condition, farmers can enhance the reproductive success of their herds, leading to healthier calves, increased productivity and improved profitability. 

As the cattle industry continues to evolve, these fertility improvement mechanisms will play an increasingly important role in helping farmers meet growing demand while maintaining sustainable operations.  

Editor’s note: Cliff Lamb is the animal science department head and a professor at Texas A&M University in College Station, Texas.