Fertility is the key to herd productivity and a major driver of profitability. Cows that calve and re-breed every 12 months significantly boost herd productivity. Infertility, or cows that fail to re-breed, can result from various factors including poor nutrition, disease, heat stress, mineral imbalances, or inferior genetics. Ensuring optimal fertility helps maintain a productive and profitable herd.
Common causes of reproductive failure include:
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Poor nutrition: inadequate energy and micronutrient levels in cows.
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Venereal diseases: conditions such as trichomoniasis (trich) and vibriosis (vibrio).
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Infectious diseases: including BVDV, IBR, and leptospirosis.
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Bull issues: infertility, disease, and injury in bulls.
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Breeding season management changes: variations in the length of the breeding season and bull-to-cow ratios.
Heat stress in cow-calf operations
Another significant factor is heat stress. Heat stress in cow-calf operations can significantly impact reproductive performance in a cow-calf beef cattle operation in several ways:
Reduced fertility: heat stress in beef cattle can lower conception rates by affecting both the cows and bulls. In cows, elevated body temperatures can disrupt hormonal balances critical for ovulation and embryo development. In bulls, heat stress can reduce sperm quality and quantity, leading to lower fertility.
Extended calving intervals: heat stress can cause cows to miss estrous cycles or have irregular cycles, resulting in extended intervals between calving. This reduces the number of calves produced annually and impacts overall herd productivity of a cow-calf operation.
Embryo mortality: high temperatures can increase the risk of early embryonic death, leading to higher rates of pregnancy loss in beef cows. This further reduces the number of calves born in a cow-calf
operation and can delay subsequent breeding attempts.
Lower calf birth weight: heat stress during gestation can affect fetal development, resulting in lower birth weights. Calves born lighter may have poorer survival rates and slower growth rates, impacting their weaning weight and overall health.
Weaker immune system: both cows and calves experiencing heat stress can have weakened immune systems, making them more susceptible to diseases. This can lead to higher morbidity and mortality rates, further decreasing reproductive performance and calf crop value.
Nutritional imbalance: heat-stressed cows often reduce their feed intake to cope with high temperatures, leading to nutritional deficiencies. This can affect body condition and milk production, essential for calf growth and development.
To mitigate these impacts, producers can implement strategies such as providing adequate shade, ensuring access to cool and clean water, optimizing nutritional support, and adjusting breeding schedules to cooler periods of the year.