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.