The most important goal of any breeding program should be to create future goats with the greatest possible genetic capability to make a profit. This may sound unrealistic, or even materialistic, to some, but it is a good place to start. This goal may be based on milk yield for selling milk in a commercial dairy, on type for selling breeding stock and for success in the show ring, or on both. It doesn't matter if the emphasis is more on production or type, as each requires strong, healthy does that can withstand the stresses of many high production lactations or rigorous show circuits without special management.
Determining the goals of a herd's breeding program is a personal decision for each breeder. The ideal for which to strive varies from herd to herd, depending on the breeder's objectives; therefore, breeding goals can vary widely from herd to herd and receive much different emphasis in different herds. Short term goals may be considerably different from long-term goals. Once goals have been established, they should be followed. Frequent changing from one set of herd breeding goals to another will surely decrease a herd's genetic progress.
The first and most important factor for making genetic improvement is selecting the group of bucks that will be used in the herd. In most herds genetic progress will be determined largely by the effectiveness with which this selection is carried out. Commercial dairies may be selecting matings primarily on milk yield and milk components and may only make occasional corrective matings to improve functional type. Hobbyists may be selecting mainly for type. Continued selection for a single trait without attention to others is the least effective method of selection and can cause many problems. For example, continued selection for superior udder traits without concern for milk yield could lead eventually to beautiful show udders without enough milk to fill them on show day. Likewise, selection based solely on milk yield could lead to high producing does with structural problems, such as poorly attached udders, bad feet and legs, or lack of body capacity, that will eventually limit milk yield and longevity.
Breeders sometimes make the mistake of judging a buck's genetic merit for a trait on the basis of one or two daughters (good or bad) they see or hear of somewhere, possibly even a couple of daughters in their own herd. Judgment of a buck's genetic merit on so little information can be misleading and cause a breeder to use an inferior buck or hesitate to use a superior buck. Most traits vary considerably among a buck's daughters. Some of the best bucks have some very poor daughters and vice versa.
The most reliable sources of superior germ plasm for a herd's breeding program are bucks that have been accurately evaluated for a large number of traits, including milk yield and type. Older bucks will have Sire Summaries for Production and Type calculated by the Animal Improvement Programs Laboratory of the USDA. Young bucks will have predictions of their genetic merit calculated by the ADGA Sire Development Program. USDA Sire Summaries for bucks are incorporated into the Production and Linear Appraisal Summaries published by the American Dairy Goat Association. In addition, lists of the top 15% of bucks on the Production Sire Summary and young bucks that have qualified for the ADGA Sire Development Program are published in the leading dairy goat publications.
Reliability is a measure of the accuracy of the genetic evaluation. High reliability does not necessarily mean genetic superiority. As reliability increases, it means the breeder may have more confidence that the genetic evaluation approaches the true transmitting ability of the sire. Reliability should not be used to determine whether or not to use a buck, but should be used to determine how heavily to use each buck in a herd. Bucks with high reliabilities may be used heavily in a herd, and bucks with low reliabilities should be used cautiously. Groups of bucks with high genetic evaluations but low reliabilities may be used for genetic improvement as long as no single buck is used heavily in a herd. The latest genetic evaluation is the best estimate of an animal's transmitting ability with reliability indicating how reliable that estimate is. The percentile ranking tells how a buck ranks in relationship to all other bucks on that Sire Summary.
When planning matings, breeders must decide what are the most important traits they want to correct in their herds and in each doe, and rank these traits in the order of their importance. Then they can select bucks that will correct those traits.
Selection should be on a multiple trait basis. A minimum acceptable phenotypic level is set for each trait. When a buck falls below the minimum phenotypic value in any trait he is eliminated regardless of his phenotypic merit in other traits. Breeders should look for a group of bucks that are particularly strong in the trait they feel is the most important to correct. Then, from, among that group of bucks they can pick the charge upon request from the ADGA office.
The second index available to dairy goat breeders is the index used for the ADGA Sire Development Program evaluations, called the Estimated Transmitting Ability (ETA). This also occurs in two forms - ETA 2:1 and ETA 1:2, where the numbers refer again to the respective weightings of production and type. The ETAs on a young sire are based on the PTIs of his parents or the PTIs of his sire and maternal grandsire. The animals chosen for breeding with the index selection method are those with the highest composite scores based on all the traits for which they are being selected. Those with the lowest composite scores are eliminated.
Bucks should be selected for use in the herd with the goal of improving the herd as a whole, not only individual does. This can be done most effectively by selecting a group of bucks according to a set of average minimum and maximum standards for the group rather than selecting individual bucks according to a set of minimum or maximum standards. This is called complementary sire selection. It is more successful than individual buck selection because, when bucks are evaluated against a set of standards individually, each buck is eliminated if he falls outside the acceptable range for any single standard. The best buck in one trait might be eliminated because he is just outside the acceptable range for another trait. However, when a group of bucks is selected against a set of average standards for the group, bucks just outside the acceptable range for one or even a few traits can be selected for breeding if they are sufficiently superior for other traits, as long as the average minimum or maximum standards are met for the group of bucks as a whole. Use of this group selection concept will almost certainly re-sult in selection of a group of bucks that will have higher genetic and economic merit for most traits than will selection of individual bucks one at a time.
Once the bucks are selected for use in the herd, the breeder may plan individual matings between each buck and doe. Keep the doe and others in her family in mind during this process of sire selection. You may want to eliminate a sire that appears best for a doe if he is low where the doe's family is weak. You also need to keep in mind the sire of the doe for whom you are planning the mating. The data on him is an excellent indicator of his daughter's transmitting ability. If you have a doe which is strong in a certain trait, remember she may not transmit that desirable trait if her sire is ranked low in that trait.
When you are choosing a buck to correct a specific fault, it is important to choose a buck known to consistently sire the correct trait. Although there are a few examples in genetics where the average of a trait is created by mating parents showing the opposite extremes of the trait, such is not the usual result. Therefore, do not choose a buck that sires the opposite extreme of the fault you are trying to correct, for by doing so you will usually be adding another fault to your herd, the fault opposite of the one you are trying to correct. An example of this would be correcting posty back legs (too straight) in a doe. This doe should be bred to a buck known to sire correct angulation of back legs. Do not breed her to a buck that is overangulated (sickle hocked) hoping to get offspring with legs set intermediary between their two parents. Likewise, do not breed a small, overly refined doe to a large, long, big-boned buck. You may very well get a small, compact, but heavy boned and coarse offspring.
Breeders should always keep in mind that the genetic progress in their herds depends much more on the average merit of the group of bucks selected for use in the herd than on corrective matings. Gambling that any individual buck is superior through heavy use in one herd is not a wise gamble.
Application of these principles in a manner that is most effective for a particular herd situation is the essence of success in making rapid genetic improvement and breeding goats for greater profitability.
Many thanks to the author and publishers of Dairy Cattle: Principles, Practices, Problems, Profits for permission to use some material from their book. Bath, Donald L. et al : Dairy Cattle: Principles, Practices, Problems, Profits. Lea & Febiger, Philadelphia, 1985.