Staying ahead of the heat this summer

While it has been warm and muggy for the last few weeks, we must remember some of the challenges heat brings on the farm when we talk about disease and hygiene.

There are a number of things we must be mindful of when we are battling the heat in hot and humid conditions. We must remember these are often the conditions a lot of parasites and bugs thrive in.

Remember, cows, sheep, weaned lambs and calves prefer cooler temperatures below 15°C and tend to get more stressed above temperature of 25°C. Growing lambs are particularly more prone to heat stress.

You will often see cows huddling when they are experiencing heat and animals with heat stress will often appear stressed, standing with their mouth open while breathing. Although we will rarely see temperatures high enough to produce clinical heat stress, we must be mindful of some challenges we come across to stay ahead in the summer heat.

Farmers have had a heavy run of summer mastitis over the last three weeks. With the emergence of a lot of flies it seems to be the main problem affecting cattle this month.

The head fly can carry the bacteria which can cause the mastitis. This leads to symptoms from cattle being very depressed and stiff with swollen quarters to much milder symptoms.

In heifers,this can lead to a non-functional quarter after calving, even when we don’t see obvious symptoms.

Flies are also causing issues with pink eye and bothering cattle to the point of them being stressed and not eating.

In sheep, there are lots of reported cases of blowfly or flystrike in the last two weeks. There are many effective fly spot-on products for sheep. You should apply fly spot-on regularly but remember to watch the meat withdrawal dates.

There are many topical preparations also, such as Stockholm tar, peppermint oil and eucalyptus that need to be applied regularly – almost weekly.

My own experience is that fly tags and regular spot-on treatments works best for cattle, with at-risk animals being kept away from very heavy fly populations or fields that are a risk.

Some farms will use homemade fly traps but they need to be put out early and in big numbers.

Cattle and sheep both generate a lot of heat and their rumen is not unlike a boiler in a house. This means that lots of clean drinking water is important.

Water has two key functions – it is critical for rehydration but it is also the main ingredient in an effective rumen. Animals will seek out shade and move less in the heat, meaning that they will not travel long distances for water. When temperatures go over 25°C, the requirement for water goes up by 20% so watch your troughs.

Allow for increased water intakes and check all water troughs daily. Some people suggest supplementing with salt blocks to ensure adequate water intake.

This can be done but only where plenty of fresh, clean water is available. I would focus first, however, on big troughs with good flow rates.

For any dairy cows being buffer-fed or lambs receiving meal it may be worth considering moving to an evening feeding as the midday feeding will dramatically decrease in the heat. Also, an animal’s rumen produces a lot of heat four to six hours after eating, meaning the engine could be hot at midday. Remember, meal will go off quicker in the heat and be less palatable so ensure that all feed troughs are cleaned regularly.

4 Move animals early in the morning or late in the evening: when we move cattle we excite them and raise their body temperature. You should avoid gathering cattle in the midday heat. Remember, when they are on concrete it can be even warmer as the concrete conducts more heat. When transporting animals, you should have all relevant vents open and, again, move them at cooler times in the day.

Never underestimate the effects of stress on animals and heat stress is something most ruminants do not like. Stress does not directly cause disease but it opens the door to it.

This can be the case when animals are indoors and you can also have issues with SCC in dairy herds in hot weather. Warm weather is when we can have more bacterial growth on surfaces, leading to a higher risk of infection. We also must remember that heat stress around milking time can upset cows and affect their immunity. Pay more attention to hygiene protocols during the milking routine in very warm muggy weather.

Sheep and cattle will naturally seek out the shade in warm weather so thinking about fields with shade is important. Unfortunately, shaded fields can often be where flies also like to congregate.

In warm weather cows, in particular, will reduce their heat activity so at the end of the breeding season it is worth considering heat detection aids and more frequent observations. Some farms should consider using hormone synchronisation interventions on late-calvers now.

Remember, your bulls and rams can be prone to heat stress and reduce their activity in very warm weather. Any prolonged stressor such as heat over 30°C can cause fertility issues through slower sperm production and decreased libido.

With very warm and dry weather, we get slower grass growth more soil exposure and the risk of listeria and clostridial diseases (both soil-borne pathogens). Ensure first grazers, at a minimum, have received clostridial vaccinations to protect them against the risk.

Animals indoors during very warm weather need to maximise fresh air supply. This should be done by opening up sheds and, where possible, giving animals more space and reducing stocking densities. Again, feeding animals indoors late in the evening means most heat is created at night when temperatures are cooler

Vaccines, in particular, can be expensive to buy and ensuring we get the best results possible from them is critical. Too often in the summer, vaccines spend too much time in the heat and direct light of the sun. Most vaccines need to be kept cold and out of sunlight. Read your storage instructions and avoid the front seat of the jeep in the heat of the mid-day sun.

While we are lucky that severe heat stress does not occur during our summers, the warm weather is not without its challenges. Remember your own water bottle and sunscreen while outdoors this summer.