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This simple shade structure was constructed using T-posts,
1-inch box tubing and an inexpensive plastic tarp with the silver side turned up. |
See the difference a little shade makes:
Temperature in the sun (left) and under the tarp (right).
This article by Dr. Dave Sparks, DVM, is reprinted from the August 2011 issue of Goat Rancher.
The widespread use of air-conditioning has made life much better for people, but little has changed for our livestock. Summer is still a high stress time. Goats, as a desert animal, handle heat better than other livestock, but they can still have serious issues when the thermometer climbs.
Dark colored goats are more affected than light colored goats by heat, although light colored goats are more susceptible to sunburn. Males are more affected than females; fat goats more than thin goats; mature more than young; and polled or disbudded goats are more likely to be affected by heat than horned goats. Goats with any compromise of the immune or respiratory systems are at serious risk.
Some advance planning and observation of your goats can make a big difference in your goats' comfort and in your profits.
Unlike humans and horses, goats do not sweat, at least not in amounts sufficient to be beneficial for body cooling. They maintain their body temperature at or near a constant, normal, level (102.5 F) by panting. This moves air across the highly vascular and moist mucous membranes of the mouth, tongue, and nasal passages, thus cooling the blood passing through these tissues much like the water in an engine is cooled as it passes through the radiator.
For this to occur, they need a lower environmental humidity and adequate water for evaporation on the surface of the membranes. The blood is also cooled as it passes through the horns.
If goats are not able to maintain their normal body temperature, they start to show signs of reproductive compromise first, followed by heat exhaustion at about 105 F, and cell breakdown and death at about 107 F.
It is normal for body temperatures to rise moderately above normal during the heat of the day and to cool off at night when environmental temperatures are less. It takes several hours, however, for this to occur.
Although air temperatures often decline in the late afternoon or evening, the goat's body temperature may not fully recover its normal level until 2 or 3 o'clock in the morning after several hours of cooler temperatures. Because of this, taking the temperature to determine if a goat is sick is best done early in the morning to get a true indication.
If you must "work" or handle goats during hot weather, do it as early as possible in the morning and be finished before their body temperature starts to rise.
The digestion of grain generates a lot of heat, so in hot weather it is best not to feed high levels of grain and to feed grain early in the morning.
In hot weather the first thing to suffer in your goat herd is reproductive efficiency. Reproductive problems can range from poor fertility to no fertility. In some male goats, high core body temperature causes suppression of libido, but that is only the beginning of the problems.
In bucks, the testicles cannot produce or maintain sperm cells at body temperature. The scrotum is designed to keep the testicles several degrees cooler than the body's core temperature by means of special muscles that lower the testicles away from the body as air temperature rises and pull them back closer as air temperatures decrease.
Also, the pampiniform plexus is a heat exchange unit that cools the blood entering the testicles. When these mechanisms are overcome by the environmental temperature, problems occur. Sperm cell formation, or spermatogenesis, starts to decrease when the testicular temperature rises as little as 1/2 degree; sperm cells start to die if the testicular temperature rises as much as 2 degrees above optimum.
This can be significant because if extremely hot weather causes the death or deformation of the sperm in the male system, it can take as long as 6 weeks for new cells to be formed and to mature. This can result in a temporary sterility in the buck.
Research has shown that in the doe, high body temperatures can result in lowered conception rates, embryonic death, and thus, reduced average litter size. Excessive heat affects embryo survival and fetal development most markedly during the first 21 to 30 days after breeding. This is part of the explanation of why does bred early in the year, in high heat conditions, have more singles than does that are bred after temperatures moderate.
Charles Dudley Warner, a friend of Mark Twain, is famous for saying "Everyone complains about the weather, but no one does anything about it." So what can we do? The simplest answer is shade and the simplest shade is the shade tree.
Closed in spaces are not very helpful because they restrict air movement. If you use a barn for shade, utilize a breezeway or fans. If natural shade is not available, a little creativity and simple materials can provide permanent or temporary shade.
The accompanying picture shows a temporary shade structure constructed of an inexpensive plastic tarp, some used T-posts, and a few sticks of 1" X 1" box tubing. Turning the silver side of the tarp up helps reflect most of the radiant heat. On an extremely hot day this shade shelter can cause a drop of 12 to 15 degrees F in environmental temperature.
Sprinklers and misters, which are often used for cooling with other species, are not very affective for goats because goats avoid the water. Wetting the ground, however, can help to reduce temperature by evaporative cooling and also helps to keep dust irritation down.
There is a theory among some goat producers that dirty, stagnant water with lots of growth in it is good for goats. Nothing could be farther from the truth. A good rule of thumb for drinking water is that if you wouldn't drink it and enjoy it, neither will your goat!
In cool temperatures, mature goats drink about 10% of their body weight per day in water. This is about 1 1/2 gallon per day for a 120-pound doe. In summer this doubles or even triples in order to meet body cooling requirements. Cleaning water tanks and supplying fresh water becomes even more critical. The question is not "does my goat drink", but "does my goat drink enough?"
Summertime temperatures also necessitate more frequent tank cleaning because as the temperature rises, bacteria and algae grow much faster. Young goats have even more critical requirements. They drink smaller amounts at a time, have a higher metabolic rate, and are more likely to be finicky drinkers.
Another hot weather water concern for all livestock is blue-green algae. This organism is not really an algae but a bacterium capable of photosynthesis. At warm temperatures, especially when fertility levels are high on adjoining fields, a paint-like scum forms on the water on the downwind side of ponds and lakes. This scum can be various shades of blue, green or even brown. It is very toxic and can cause sudden death or chronic liver damage, depending on the particular toxin present.
Dead animals of commonly found in or around the edges of the water. If you suspect a problem in your water source, ensure that clean water is available, restrict access to the suspect water source, and contact your local veterinarian or extension agent.
Excessive heat can affect your goats and your profits in several ways. Hot goats have poor appetite and growing goats that don't eat don't grow. Does that have weaned their kids and are trying to pick up body condition prior to breeding season need to eat to capacity as well.
While air conditioning is not practical, adequate shade, plenty of clean water and a moratorium on handling in the afternoon and evening can limit health problems and help ensure good reproduction rates in your herd.
(Dave Sparks, DVM, is the Oklahoma State University, Oklahoma Cooperative Extension Service, Area Extension Food-Animal Quality and Health Specialist. He can be contacted at dave.sparks@okstate.edu.)
