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:
1. selection of native goats,
2. 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.