Cost of Hot Cows
Recently, I was travelling back from a day in Melbourne. It was a hot evening and herds were leaving the dairies. I observed a number of herds where the cows were struggling to get a drink.
The following article is from: www.coolcows.com.au.
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, live weight loss, higher somatic cell counts, more clinical mastitis cases and other cow health problems can often double these losses.
Benefits of heat stress management
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 embryos
· Increased calf birth weights.
The impacts on cow fertility, health and welfare last well beyond the hot months.
Impact on feed intake and nutrition
The impact of heat on feed intake
↑ 20-30% more maintenance energy needed to compensate for the effort of keeping cool
↓ Dry matter intake drops by 10-20% – short term or long term depending on the length and duration of heat stress
↓ Rumination and cud chewing decreases
↓ Cow’s ability to digest and absorb nutrients in feed decreased
Impact on fertility
↓ 6-week/100 day in-calf rates decreased
↑ Not-in-calf rates increased
↓ Length and intensity of heats decreased
↓ Conception rates decreased
↑ Risk of embryo death increased
↓ Calf birth weight and viability reduced
Impact on milk production
↓ Milk production drop by 10-25% or more in high heat stress and by 40% in extreme circumstances
↓ 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.
Impact on milk quality
↑ Sediment may increase if cows’ teats are allowed to be contaminated with mud and dung
↑ Risk of udder infection increased, which, if occurs, results in increased somatic cell counts
Impact on cow health
↓ Rumen buffering capacity decreased
↓Decrease in rumen pH
↑ Risk of ruminal acidosis and ketosis increased
↑Risk of laminitis increased
↓Immune function suppressed
↑Risk of mastitis increased
What can you do to reduce heat stress?
Natural shade from trees Plant trees on the western side of the dairy yard
Access to cool drinking water Install a large water trough on the exit side of the dairy
Milking times Delay afternoon milking until 5 pm during the hot season.
Wet down the yard On hot days, wet the dairy yard for an hour before cows arrive
Sprinkling Cows Set up a sprinkler system at the dairy yard. Sprinkle cows for 30 to 60 minutes while standing in the dairy yard waiting for afternoon milking on hot days or when cows breathing rate exceeds 60 breaths per minute or the THI is above 78
Summer nutrition program and further information
In hot weather, provide cows with the highest quality pasture available to graze overnight when they are cooler.
Increase your cows grain / concentrate feeding rate, feed high-quality forage fibre and higher-quality protein sources, and increase cows intakes of potassium, sodium and magnesium
Sprinklers In very hot days, if you don’t have a shade shed, bring the milking herd back to the dairy yard around midday and use the sprinkler system to cool cows - if possible give them access to high quality hay or silage.
Mate more cows Mate more heifers to compensate for lower in-calf rates expected in milkers during the hot season to help maintain your desired calving pattern. For more information visit www.coolcows.com.au
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