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 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 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, 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.
Flushing is an effective practice of temporarily increased energy and protein supplies in sheep feeding to stimulate estrus in ewes and synchronize pregnancies. This has not been studied much in goats, but practical experience has shown that the principle works in goats as well, making out-of-season estrus, kidding and milk production possible, in addition to increasing litter size.
Practical feeding of goats can be grouped into three types:
- free grazing and no supplementary feeding,
- limited grazing and supplementary feding, and
- confinement feeding with no grazing.
Effects and expectations in meat and milk production obviously differ with these types of feeding under extensive or intensive management. Proper rations must then be calculated differently, depending on the degree of nutrient supply expected from the amount of grazing provided.