When asked if Icelandic sheep are more or less prone to stress during the heat of summer, I would have to say I don't think so if they are acclimated to their climate. All sheep must have certain basics met in order to survive summer safely and in good health (the same goes for all animals and people too). I will share here some tips for managing the flock during the hottest parts of the summer.
WATER: It may seem redundant to mention water, but providing FRESH, CLEAN, COLD water during the summer is very important. You can freeze ice in plastic bottles to place in the water troughs to help keep the water colder, longer. Be sure that your sheep always have access to fresh, cold water at all times, especially during the summer.
Apple Cider Vinegar - we believe in the health benefits of using apple cider vinegar and we add it to our flock's water trough. The rate is 1/4 gallon of cider vinegar to 30 gallons of water.
Soluble Vitamin E - we purchase this product from Pipestone Veterinary Supply and keep a dilute mixture ready to add to the drinking water. During very hot days of 85 degrees and higher, I add it almost daily.
MINERALS and KELP: Be sure that your sheep have access to DRY free choice, loose minerals (the minerals should be stored where they cannot get soaked by rain). We mix ours 50/50 with kelp year 'round, but during the worse heat of summer, I make a mixture of about 1/3 each of minerals, kelp and soybean meal. This gives them added protein during the hottest time of the summer, when the dry summer grasses are most depleted of protein.
PROTEIN BLOCKS: When parasites are especially problematic due to wetter than normal conditions, combined with temperatures that fluctuate, we have found the sheeps' protein needs are higher. We have started providing Sheep and Goat mineral/protein blocks in addition to the loose minerals mentioned above. An excess of internal parasites can cause anemia in sheep and in order to combat that the red blood cells need to be built up. Providing extra, readily available protein with the extra minerals is important. Because we cannot always depend upon the pasture grasses to provide consistent good levels of protein due to fluctuating weather, this is a way to help supplement their protein needs, especially during the stress of summer heat. WARNING: Watch ram lambs and wethers to make sure they are urinating properly. Sometimes an imbalance in protein, salts or calcium can cause either "urinary calculii" or "pizzle rot."
SHELTER: It is imperative that your sheep have shelter from the hot sun. If you do not have stands of trees that offer shade, there must be some sort of lean to or building for them to go into for relief from the sun and heat. During the summer's heat we run several large industrial fans in the barn, and I often find the sheep clustered in front of the fans, cooling off.
FOOD: Sheep will often eat less if they are too hot. If they are standing inside the barn or shelter to avoid heat, then make sure there is free choice hay near them so they can eat while seeking shade. If they go to pasture, make sure they can go out early in the morning to graze when it is cooler and that they can go back out in the evening or even allow them to graze at night. Lambs and wool growth will both be compromised during the hottest parts of the summer, so making sure the sheep still consume enough energy to maintain their own weight and wool growth is important. This may entail some management changes on the part of the shepherd to help them through the worse heat of summer. We were surprised to find some our lambs lost weight during August when it was a particularly bad summer. Some of them lost as much as 5 lbs. in a two week period because they were too hot to eat.
HORNS: I am told that sheep with horns handle heat better than polled sheep because the horns help to dissipate the heat.
RAMS: Rams handle heat less well than ewes do, so pay particular attention to your rams during the summer heat.
SELENIUM: Sheep will deplete their selenium reserves faster during the worse heat of summer. Fast growing lambs are at highest risk. Be sure to work with your veterinarian if you know your soils are depleted of selenium. Bo-SE shots can help sheep avoid the devestating effects of White Muscle Disease.
GENETICS: Just as people are prone to handle heat differently than each other, so will sheep have differing levels of heat tolerance. If you live in a hot climate, seek out shepherds in your area to see how they manage their flocks during the heat. What breeds are being raised in your area? If possible buy your starter stock from flocks that have acclimated to similar climates. Sheep born and raised in a particular climate will be more adaptable to that climate than bringing in stock from a different part of the country that may have a vastly different climate. If you have sheep showing signs of heat stress, or if you lose sheep during the heat, realize it is partly nature's way of culling. Eventually you will have a flock that is very hardy for your climate as your more hardy animals survive the climate that you are raising them in. Ron Parker in "The Sheep Book" discusses a program wherein a Professor Leroy Boyd of Mississippi State University attempted to develop sheep that would be adapted to the hot and humid conditions of the deep South. He noted that "animals with greater development in the loin and rump, thicker skin, and deep rather than wide bodies tended to have a greater heat tolerance." (pg 87)
If you are unsure whether Icelandic sheep (or any breed) will do well in a warmer climate, consider buying a couple of castrated rams (wethers) and seeing how they do for a season before you invest in breeding stock.
DEWORMING: Any time that your sheep are stressed, their immune system will be compromised. Be sure to stay on top of parasite overload by making sure y our flock is dewormed appropriately. Keeping your sheep in top condition during the summer, with a high plane of nutrition, will allow them to tolerate parasite loads better. Even though it may look like your sheep are grazing all day, be sure to understand and learn about pastures and to evaluate what a productive, healthy pasture is. We keep high quality alfalfa hay in our feeders all summer (for the ewes and lambs), in addition to their pasture grazing. This insures that the sheep can eat at any time and also helps to conserve our pastures when grass growth slows down during the heat of summer.
SHEARING: You may need to schedule your shearing differently to work within a warmer climate (and conversely for a colder climate). It is very important that Icelandic sheep be sheared at some point during the spring before summer heat begins. This will help them get through the summer months, and then as autumn approaches, and cooler weather with it, they will begin to grow their wool out fuller. If you raise Icelandic sheep in a warmer climate, you may never have the fullest, heaviest fleece yield as the sheep will when they are in colder climates.
