Many studies reported negative effects of heat stress on reproductive performance. They include:

• Reduced duration and intensity of estrus, increasing the difficulty of heat detection.

• Impaired follicle selection.

• Reduced pregnancy and conception rates.

• Negative effects on the early developing embryo post-fertilization.

• Increased embryonic loss.

Make Heat Abatement A Priority

While it is not possible to completely remove heat stress, there are several ways you can take to reduce its detrimental impacts:

1) Cool dry cows

• Dry cows traditionally receive little protection from heat stress because they are not lactating. However, it is not correct to assume they are less prone to heat stress.

• In addition, change in physiological, nutritional and environmental changes will cause additional stress to these cows.

• These changes will increase cow's susceptibility to heat stress and have critical influence on postpartum health, milk production and reproduction.

• Heat stress during this period can also affect endocrine responses that may increase fetal abortions, reduce calf birthweight and postpartum milk yield.

2) Use more than 1 cooling method

• It has been shown that dry cows cooled with feed-line sprinklers, fans and shade compared with cows cooled with only feed-line sprinklers produced more 60-day milk with no difference in body condition score (BCS), incidence of postparturient disorders or serum nonesterified fatty acid (NEFA) concentrations.

3) Isolate the problems

• Use available tools to investigate the locations on your dairy where cows experience heat stress.

• For example, temperature monitoring equipment can be used to record cows'core body temperatures.

• After collecting the data for a few days, analyze to see where on the dairy core body temperatures are elevated.

• Improve cooling strategies based on information gathered.

4) Provide plenty of shade as well as cooling

• Make sure there is a minimum of 38 - 45 square feet of shade per mature dairy cow to reduce solar radiation.

• Spray an fan systems should be used in the holding pen, over the feeding areas.

• Include exit-lane cooling as an inexpensive way to cool cows as they leave the parlour.

• There should be access to clean and fresh water when cows leave the milking parlour.

• Sand bedding provides a more comfortable resting surface and increases the cow's comfort during periods of heat stress.