Feeds & Feeding:
Feeding Goats for Improved Milk and Meat Production
By George Haenlein
GOAT MANAGEMENT
Feeding Goats for Improved Milk and Meat Production
By
George F. W. Haenlein
Department of Animal and Food Sciences
University of Delaware
Newark, Delaware 19717-1303 USA
INTRODUCTION
Many factors can have major or minor effects on the goal of improving milk and meat production of goats. Computer programs are available (at least for cow) that will solve by least-cost formulation the maximization or the optimization of production. In either case it is important to focus on net return as the ultimate goal. Maximization of production is not guaranteeing maximization of net return. The reason is that the law of diminishing returns governs much of animal production, especially feeding and the relationship to reproduction. It means that for additional units of input, such as feed, there is an ever-decreasing increment of benefits in units of milk and meat dollars or other output, until certain general bases and levels are lifted for a new set of overall conditions. It also means that additional feed will produce additional pounds of milk and meat up to a certain biological limit, but in the meantime may already produce negative income dollars from a certain point on.
FACTORS INFLUENCING PRODUCTION IMPROVEMENT
Other important factors influencing production output and income from goats are genetic merit, udder quality, health and marketing, besides feeding. Genetic merit comes from:
selection of native goats,
crossbreeding with improver breeds.
Selection of native goats can be very effective, because of the inherent adaptation to the climate, especially if it is tropical, hot and humid, and the resistance to native diseases, insects and parasites. Selection requires regular record keeping of each herd animal in terms of production traits, milk, composition, meat, growth. In the USA this is done through the Dairy Herd Improvement Association (DHIA) record keeping system, which provides monthly individual data on management efficiency (Table 1). If it is done on an official, non-biased basis, it provides also regular data for sire proving with a certain degree of reliability, which when published annually allows selection of buck semen and doe ova from proven individuals for superior herd selection by anyone domestically or for import by foreign interests.
Crossbreeding has the advantage of selecting presumably superior genetic producing ability, but adaptation to climate, diseases, insects and parasites is usually a big, often insurmountable or at least very expensive problem, which may only be solved by using for continued breeding crossbred offspring rather than purebred parents. In either case it is necessary to realize that improved feeding is wasted if there is no simultaneous genetic improvement of the basic producing ability, because
heritability of milk yield by goats is about 25 percent,
heritability of goat milk composition about 50%, and
heritability of goat weight gain about 40%.
Heritability values can be used to predict the expected average progress from selection, assuming that environment, management, feeds and feeding, and climate is not changed between generations. Improvement in milk yield is often the most profitable choice and the predicted progress would be per generation:
heritability X selection differential or
25% X (milk yield of selected sire - milk yield of dam).
For example, if the selection differential from the buck proof is + 400 lb and the milk yield of the doe is 1,500 lb, then the expected average genetic improvement in the performance of the offspring in the next generation would be
(25% X 400 lb) + 1,500 lb = 1,600 lb
indicating that genetic selection is important, but 75% of milk yield performance progress is due to management, environment, diseases, climate and especially feeds and feeding.
The udder is the most important part among the inherited physical capabilities of the animal in its body parts and constitution (Haenlein, 1981). For centuries, this was one of the principal goals of attention of Swiss goat breeders, to improve the udder quality and conformation, and they accomplished this without parallel, making the Swiss dairy goat breeds the milk production leaders in the world. Today type evaluation is available, called the Linear Appraisal System, which can effectively aid in the selection for and improvement of goat milk production. Other programs like type judging competitions in the field and in goat magazines, county and state shows and fairs for 4-H, FFA and adults, milk-out programs for champion competitions and star milker recognitions on pedigrees all aim towards improvement of the inherited physical capability of the milking animal.
Health is the other important factor for success in goat management. Elevated, slotted floor barns have become popular in humid and hot climates for better health of goats, especially for internal parasite control. Such barns are easily and cheaply constructed, provide cool shade and dry areas for feeding and rest, they keep udders clean and free from contaminations and infections, and they prevent reinfestation from internal parasite eggs in feces, because the goats are resting on the slotted floors away from their feces. Without such basic provisions for optimum health of goats any attempts in feeding improvement are wasted.
FEEDING FOR HEALTH
The feeding program needs to aim for more than just higher milk yield or weight gain; it needs to provide the best possible health also through feeding, because this will directly affect readiness and success in reproduction. It has been said often that the goat has been neglected in research and numbers of publications, but this was true only until 30 years ago. Meanwhile there has been a ground swell of efforts recognizing the goat as an important part of agriculture, especially small holder agriculture, and in the production of valuable food for human needs for selfsufficiency, diversification, risk stabilization, natural resource utilization like no other animal, gourmet foods and for people with medical needs like cow milk allergy, digestive malabsorption and cholesterol problems. There have been new research stations and funding for goats, many national and international seminars, symposia and conferences with their voluminous proceedings, nutrient requirement bulletins from the US, British and French national research councils, the USDA Extension Goat Handbook, the monthly international Small Ruminant Research journal besides many new books, videos and trade magazines, and the standard cow research journals, which now also carry articles on dairy and meat goat topics.
FIBER
A major concern in feeding for better health is the problem of enterotoxemia or overeating disease (Haenlein, 1982). Many goat managers vaccinate against it successfully, to prevent the associated toxin produced by Clostridium perfringens. Actually, enterotoxemia is caused primarily by acidosis in the rumen due to faulty feeding. At any age, symptoms of diarrhea, depression, incoordination, digestive upsets, coma and death are observed after excessive feeding of kids or mature goats, when sudden changes of feeds occur, when goats are hungry and had free access to palatable, readily fermentable feeds, when goats are fed too little calcium supplement and when too little roughage with too short fiber is fed. The best prevention for nursing kids is to have frequent feeding or nursing immediately starting after birth, so that kids are never hungry. Large meals, once a day and of little variety should be avoided. Goats are by nature browsers and like to select various feeds. High levels of grain feeding relative to roughage in the ration (> 60%), especially in early lactation lead to rumen acidosis, followed by inappetence and indigestion. Feeding buffers like sodium bicarbonate and magnesium oxide and stemmy hay will help alleviate the early symptoms and prevent enterotoxemia. Other effective feeds are sunflower seeds, cottonseed, oats, dry brewers grain.
Fiber is a feeding requirement unique to ruminants, because:
it maintains a beneficial rumen flora, that produces mainly acetate, the important energy source for all ruminants, rather than propionate from starch fermentation; and
it causes extensive regurgitation for rumination and plentiful salivation for rumen buffering, rather than fast passage through the rumen and incomplete digestion.
Fiber is rarely stated in nutrient requirement tables, but from dairy cattle research it is recognized, that at least 17percent of the daily dry matter intake is needed. However, it makes a difference whether this fiber is shorter than 1 inch or longer. Effective fiber needs length to stimulate chewing and rumination. Feeds and diets, which cause significantly less chewing are potential problems leading to acidosis and enterotoxemia. When less frequent chewing is observed and before other more serious symptoms occur, a drop in milk fat content of 1 to 2 percentage units will be noted in a few days, the socalled low fat syndrome. Feeding of buffers should immediately commence, besides a reexamination of the ration formulation. Table 2 lists some feeds like sunflower and cotton seed, which are very high in fiber contents, but also have high fat and protein contents, so they are ideal for maintaining the high energy and protein supply needed for early lactation high milking goats, besides providing the extra protective fiber content to avoid low fat syndrome, acidosis and enterotoxemia (Haenlein, 1982).
VITAMINS
Feeding ruminants and their rumen microflora correctly should result in sufficient amounts of rumen synthesized B vitamins (Haenlein, 1981). However, any change and upset in feed intake may reduce the amounts significantly.
Niacin is a water-soluble B vitamin functioning as coenzyme in energy metabolism and is needed by high performing dairy animals, especially in early lactation when ketosis or acetonemia may be a problem. Some supplementation has been beneficial, especially when there is much corn in the ration, since corn is low in the amino acid precursor for niacin, and niacin deficiency may develop.
Thiamine deficiency may occur after heavy grain feeding or if certain feeds with antithiamine activity are ingested. Blindness can result and thiamine supplementation may be needed.
Pyridoxine is another B vitamin synthesized in the rumen and is required for biosynthesis of fatty acids, transport of amino acids and minerals. Upset rumen metabolism can lead to deficiency in pyridoxine synthesis and symptoms of anemia in the dairy goat. Not all anemia in goats is necessarily due only to internal parasites, but not much research into vitamin requirements and metabolism of goats has been done in recent years.
There are other feeding related disorders in goats, which are preventable (Naylor and Ralston, 1991). When goats are becoming fat at the end of lactation, they risk getting acetonemia, pregnancy toxemia or ketosis problems at or soon after kidding. Bearing triplets or quadruplets can aggravate the condition triggered by hypoglycemia. Prevention of undue weight gain in the dry period is often easier than treatment and correction when symptoms of dullness, depression, acetone odor in the breath, recumbency occur, which can lead to death. Gradually increasing feeding of 1 to 1.5 lb of concentrates 3 to 4 weeks prior to kidding is usually a best practice. Calcium deficiency soon after kidding in the form of milk fever or parturient paresis is not frequent in dairy goats as it is in certain breeds of cows. A reduction of calcium supplementation and replacement of alfalfa hay with grass hay during the dry period can prevent the problem.
MINERALS
Several minerals besides calcium require particular attention in proper goat feeding: phosphorus, magnesium, selenium, iron, copper (Haenlein, 1992).
Urinary calculi or urolithiasis in male goats are due to nutritional imbalance, especially on high grain feeding with too much phosphorus in relation to calcium and potassium, and more in confinement management than on pasture. Calcium to phosphorus ratio should be 2:1, but grass hay feeding is preferred to alfalfa. Increasing salt in the ration to 4 to 5 percent promotes higher water intake and diuresis. Acidifying the urine with 2 percent addition of ammonium chloride or potassium chloride to the ration also helps (NRC, 1981).
Selenium deficiency can be suspected in areas with deficient soils, when goats have various reproduction problems, early embryonic death, repeat estrus, retained placenta after kidding, metritis, weak newborn kids. Intramuscular injection with a selenium - vitamin E preparation one month before kidding can prevent symptoms, but addition of 0.2 ppm selenium to the ration provides a more constant protection. Selenium status in goats can be tested best in milk or blood besides hair samples.
Iron stores are minimal in newborn kids in contrast to calves. Therefore anemia can be a problem that can be treated with an iron dextran injection or with iron supplementation to the ration.
Magnesium deficiency and grass tetany can occur in early spring grazing on lush pasture, which may be high in potassium, especially cereal grain pastures. Intravenous injection with a calcium - magnesium preparation may be needed to prevent death, but prevention is best by hay feeding prior to turning out to pasture and time-limited grazing of this kind of pasture. A magnesium mineral mix feeding, e.g., 15 percent magnesium oxide in the ration, is also helpful (Naylor and Ralston, 1991).
Zinc is an element that needs to be supplied continuously, since it is not stored in the body. Blood, milk or hair samples are useless in assessing zinc status of an animal; only rib contents are good indicators. Legumes contain more than grasses, but contents decrease with increasing maturity. Zinc supplementation and treatment helps reduce and cure mastitis, stimulates male reproduction, wound healing, prevents parakeratosis and lameness from foot fissures. Recommended levels are 10-50 mg/kg dry matter daily feed intake.
Copper is needed by goats at the level usually provided in dairy cattle or horse rations, in contrast to sheep, which are sensitive to such levels and will develop toxicities. Leaves and certain browse contain more copper than stems of forages, but this will decrease with maturity. Copper deficiencies can be prevented by adding 0.5 percent copper sulfate to the mineral mixture.
ENERGY
Energy is the nutrient most frequently deficient in goat management, not only of high yielding milkers. Abortions can occur, especially during the time of 90 to 110 days of pregnancy, when undernutrition stresses goats, due to hypoglycemia. Insufficient energy supplies will reduce weight gain and milk yield, but also change the fatty acid composition in the milk fat to less medium chain fatty acids, which are the most desirable fatty acids for human nutrition (Haenlein, 1995). Increasing the energy density of the ration is often necessary as the volume of feed intake is limited, especially in early lactation. Adding fat to the grain ration is increasing energy density effectively as long as it does not interfere with the normal rumen flora. Rumen unavailable or protected fat has been effective at 5 percent supplementation, increasing milk yield, milk fat and protein contents, however, the kind of fat makes a difference in results. Calcium salts of fatty acids are insoluble at normal rumen pH, and reach the abomasum unchanged, where they then can be digested (Morand-Fehr, 1991). Another means of increasing energy density of the ration is by pelleting, which improves gains and milk yield by increasing feed intake, but often reduces milk fat content, if effective fiber length is insufficient in the ration.
PROTEIN
Protein is the more expensive nutrient in feeding and therefore often limiting maximum productivity. Industry by-products often are less expensive sources besides the traditional major supplies of oilmeals. However, as forages have higher fiber and lower protein contents with increasing maturity, the least expensive sources of protein are usually forages, alfalfa, clovers, well fertilized grasses, harvested at prebloom or immature stages. Protein supplies to the rumen in the form of degradable protein are necessary for optimum growth of rumen bacteria, but they require energy at the same time, without which some proteins will be wasted into ammonia in the rumen. A minimum of 7 percent crude protein in the diet dry matter is required for normal rumen function, and forage intake will be decreased at lower protein levels. The supply of some rumen protected protein has been effective in increasing milk yield. Excess protein feeding is not only wasting money but is stressing the goat by increasing her blood urea levels, increasing urine excretion and interfering with efficient reproduction. Protein deficiencies will reduce feed intake, rumen function and retard fetal development.
NON-PROTEIN NITROGEN
Non-protein nitrogen, such as urea, can be utilized by goats very well, as long as it does not exceed one third of the total nitrogen in the daily diet or 3 percent of the grain ration . A gradual adaptation of at least three weeks is required. Urea may be a cheaper means of providing some of the required nitrogen to goats, but it must not interfere with maximum feed intake. The nitrogen content of feed grade urea is 42-45 percent in contrast to feed protein with 16 percent. Good urea use in the rumen depends on rations with at least 75 percent TDN and the availability of sufficient starch and sugars like molasses to convert the urea nitrogen into microbial protein, and when the ration protein content is below 12 percent. The addition of alfalfa meal, extra vitamin A and salt helps urea utilization. Feeding of urease containing feeds like raw beans, legume seeds, wild mustard must be avoided. A common thumb rule is that 6 lb corn plus 1 lb urea equal 7 lb soybean oilmeal nutritionally, but the economics of that relationship have to be calculated to be positive (Ensminger et al. 1990). Aside from grain mixtures, urea is effectively used as a liquid molasses-urea lick or as urea salt block.
