Cost of hot cows
How much does heat stress cost you?
Most farmers notice falls in milk production when cows get hot. This results in substantial losses in milk income, but reduced in-calf rates, low milk protein and fat tests, liveweight loss, higher sometic cell counts, more clinical mastitis cases and other cow health problems can often double these losses.
If you can develop an effective heat stress management program there are substantial benefits to be gained. These include:
- higher summer milk production;
- increased 6-week/100-day in-calf rates;
- reduced loss of embroyos; and
- increased calf birth weights.
The impacts on cow fertility, health and welfare last well beyond the hot months.
Impact on feed intake & nutrition
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20-30% more maintenance energy needed to compensate for the effort of keeping cool
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Dry matter intake drops by 10-20% – short term or long term depending on the length and duration of heat stress
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Rumination and cud chewing decreases
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Cow’s ability to digest and absorb nutrients in feed decreased
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Impact on fertility
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6-week/100 day in-calf rates decreased
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Not-in-calf rates increased
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Length and intensity of heats decreased
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Conception rates decreased
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Risk of embryo death increased
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Calf birth weight and viability reduced
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Impact on milk production
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Milk production drop by 10-25% or more in high heat stress and by 40% in extreme circumstances
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Milk composition is affected with high to severe heat stress:
- Milk protein percentage decreased by 0.2-0.4%
- Milk fat percentage is more variable day to day, and may be severely depressed if ruminal acidosis occurs
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Impact on milk quality
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Sediment may increase if cows’ teats are allowed to be contaminated with mud and dung
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Risk of udder infection increased, which, if occurs, results in increased somatic cell counts
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Impact on cow health
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Rumen buffering capacity decreased
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Decrease in rumen pH
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Risk of ruminal acidosis and ketosis increased
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Risk of laminitis increased
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Immune function suppressed
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Risk of mastitis increased
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