Goats are known for their selective feeding behavior, inquisitive nature and ability to adapt to challenging environments. The oft-quoted fable that goats eat anything and can survive on unconventional diets is somewhat misguided. Yes, they will nibble on virtually anything, including clothing and plastic, to investigate the nutritive value of such objects. In reality, goats still require adequate protein and energy nutrition and will quickly fall ill when diets are lacking.
Dairy goats producing over 1 gallon of milk per day have a large range of energy and protein requirements during their lactation. The more that’s expected from them in either milk production or activity, the more critical the need for well-balanced diets. Energy is often the limiting nutrient, especially during late pregnancy and early lactation.
Common metabolic condition
The most common metabolic disorder associated with reduced dietary energy experienced by goats is ketosis, followed by two other challenges also related to nutrition – hypocalcemia and rumen acidosis. Ketosis in pregnant goats is often referred to as pregnancy toxemia.
Ketosis is caused by a buildup of ketones, which are chemical byproducts produced by the liver during excessive mobilization of body fat. When goats need extra energy during the last weeks of pregnancy or when they are producing high levels of milk, they will mobilize and burn their body fat for the needed energy. The livers in ruminants cannot process this body fat quickly enough into glucose and, as a result, ketones are produced. When glucose is in short supply the cells are fooled into binding with ketones, which then prevents any further binding of glucose. The best way to prevent ketosis is to limit the mobilization of body fat by maintaining energy-dense diets of carbohydrates and fats.
Energy density of diets must be increased during the two most critical time periods of late gestation and early lactation so that there are more calories per pound of feed consumed. This is most easily accomplished by feeding 1 to 2 pounds of corn meal in the last few weeks of gestation. If more energy is needed, adding 1/2 to 1 ounce of fat will add more energy to the diet.
Goats that become ketotic soon become too weak to eat, which only exacerbates the problem. Advanced ketosis is difficult to reverse and many goats will not survive as their organs shut down. If and when ketosis is suspected, it is critical that the goat gets glucose back into her system as quickly as possible. The oral administration of propylene glycol is an option to treat ketosis in the early stage. For later stages when the goat is no longer ambulatory, intravenous glucose is required. Goats with advanced ketosis will also experience dehydration and it’s important to administer large volumes of electrolytes and water to keep the goat hydrated and supplied with enough minerals.
Read more: Dairy goat nutrition
High risk for ketosis
Pregnant goats are at especially high risk for ketosis – pregnancy toxemia – because the majority of goats have twins and triplets, which take up considerable space in the abdominal cavity. The growing fetuses tend to push up against the rumen, preventing the goat from eating as much as she should and reducing rumination and digestion, which leads to inadequate nutrient absorption. Keeping the energy density of the diet elevated is critical at this point.
At the time of birthing, does may already be experiencing subclinical ketosis and their appetites may not be what they should be. Ketosis can still advance to critical levels as the doe begins lactation and more energy is needed for milk production. Once again, goats in early lactation must be monitored for behavioral issues or refusal of feeds. Does will rapidly lose body condition during early lactation as feed intakes decrease and they metabolize their body fat. As with late gestational ketosis, early lactation ketosis must be treated aggressively to prevent hypoglycemia and the progression to ketosis. For the prevention and curing of ketosis, goats must always have high-quality forage available to maintain proper rumen function.
Read more: Good goats’ milk
Is hypocalcemia a concern?
Hypocalcemia (low blood calcium) appears to be much less of a challenge for dairy goats compared with dairy cows. Goats seem to metabolize calcium more efficiently during early lactation when milk production requires higher levels of calcium. Commonly known as milk fever, hypocalcemia affects proper muscle function and causes paralysis in a goat. Subclinical milk fever presents with mild nervousness and hyperactivity. Goats with advanced milk fever will not be able to stand or walk and, left untreated, the lungs and heart muscles will fail. Intravenous calcium administration is the treatment of choice for all levels of milk fever.
Prevention of milk fever is again dependent on proper nutrition. Goats seem to be more sensitive to dietary calcium-phosphorus ratios and it’s important that diets always contain more calcium than phosphorus. The dietary calcium-to-phosphorus ratio should be kept at approximately to 2:1. Too much phosphorus in a diet will prevent calcium from being properly metabolized. Adding limestone to a diet will keep calcium levels above phosphorus levels. Forages are also a preferred source of calcium. Diets high in grains or commodity byproducts generally have low levels of calcium. When pre-kidding and early lactation diets are formulated with increased levels of corn or barley to elevate dietary energy, care must be taken to not allow calcium to become deficient.
Rumen acidosis, also known as lactic acidosis, can become a problem when goats consume too much grain or other low fiber feedstuffs. Rumen ecosystems must have a high percentage of cellulose-based fiber and a stable acid-base (pH) level to function properly. Excessive levels of grains in a diet will lower rumen pH to levels that will not support the fiber-digesting bacteria. This excessive rise in acidity comes from overproduction of lactic acid, which is toxic to the fiber-digesting bacteria.
Preventing rumen acidosis requires having enough forage available for proper fermentation as well as a consistent dietary regimen. Dramatic changes in diet, reducing forage intake or quality and feeding high levels of grains must be avoided.
Goats have the innate ability to be very selective in what they eat and in preventing metabolic issues. However, in environments where goats are exposed to extreme cold or when higher levels of milk production are expected, care must be taken in formulating diets to prevent metabolic challenges that will significantly impact health and production.
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