Breeding Angora Goats
Traditionally, breeding has used visual appraisal and line breeding to recognised superior ancestors. The pedigree therefore is of considerable importance. The method uses the basic assumption that visual merit is the desired objective for selective breeding.
Modern breeding tries to quantify the breeding objective in terms of productivity or economic return as a measure of quality. This method relies less on ancestor's identity and more on individual measured performance. While recent developments in statistics has revived the pedigree as an important part of evaluation, it is the performance of close relatives, rather than the identity of ancestors, which is used to increase the accuracy of selection.
Because close breeding increases the level of inbreeding, reduces vigour and increases the incidence of single recessive genes being displayed, less emphasis is placed on line breeding in selection programs and attempts are made to keep inbreeding levels down.
Genetic gain is governed by the heritability of the character, the variation in the population, the proportion of parents selected and the time taken to complete each generation. Fertility or replacement rate is therefore critical to efficient selection. It is also important to have a clear and consistent goal, a large group of animals and a long-term approach. Gains are unlikely to be greater than about 3% per year but once achieved are permanent and compound with time.
The relatively slow rate of gain makes it important to start at the highest level of production available. Avenues such as upgrading and importation of known superior stock are potentially more effective at increasing productivity of the flock. However, once these have been exhausted, selective breeding is the only genetic method for increasing performance.
Angora goats are run for their mohair fleece. While meat is of some importance, the returns from this by-product are small, particularly as most of the meat comes from cast for age does. Body weight or growth rate are therefore not of great importance though larger animals may produce more offspring.
Mohair quality and body soundness are the major areas of concern for selective breeding. Fleece weight, freedom from kemp, fineness, length and style (in that order) would seem the most important aspects of fleece quality. These can be selected independently or combined to form an Index or Breeding Value. Using economic weightings is important because the objective is to increase overall returns, not just change the components.
The balance of quality characteristics can be altered to reflect the breeding objectives of the breeder. If the breeder regards fineness as the most important character, for example, the economic weighting for fineness can be increased. It may be that this results in a lower rate of gain or even a loss in fleece weight, but that is the result of an emphasis on fineness.
There is little doubt that visual excellence and show success is a major factor in sale prices so the traditional form of selection might be favoured in the current environment. Nevertheless, direct selection for production would seem more logical if the breeder is serious in supporting the development of a commercial mohair industry based on mohair fleece sales.
MOPLAN is the performance recording system developed for the mohair industry. This system is administered by ABRI at the University of New England and follows a system similar to that used in the cattle (BreedPlan) industry. MOPLAN uses an advanced statistical technique to incorporate performance information of close relatives (parents, half sibs and progeny) in assessing the Breeding Value of each individual in the flock.
MOPLAN uses Mohair Magic (Saltbush) to collate performance data but ABRI operates a paper recording system for breeders who do not have computing skills or access to Mohair Magic.
Performance recording requires groups of at least 20 animals run under the same conditions. The power of MOPLAN is in the use of sire groups, so 3 or more sires need to be used, each producing about 20 kids. A kid drop of about 60 animals is probably the minimum number to make real use of the system. At least one sire should overlap each year to provide a link between years. The system could be expanded to make comparisons between properties but again, there would be the need for sire links so all flocks would need to use some common sires.
MOPLAN uses 4 body weights (birth, weaning, 6m and 1y), scrotal circumference, and the first two fleeces (fleece weight, fineness class, kemp score and measured length) to evaluate animals. Estimated Breeding Values (EBV's) are calculated for each character in the units of measurement (eg. An animal may have a fineness EBV of +0.5 microns indicating that its progeny are likely to be 0.5 microns stronger than average).
A combined Index is calculated using standard Relative Economic Values (REV's) but these values can be changed to match a breeder's own objectives. The Index gives the average animal a value of 100. An Index of 120 indicated the animal is 20% above average for overall returns.
Once a kid drop has been recorded, all parents are give EBV's and Index values based on the performance of their kids. Each year this information is updated as more kids provide information and the accuracy of the values improves. After 3 or 4 drops, and the use of high index sires begins, gains start to be obvious and the system can be used to select superior stock for use and for sales. Because there are no links between flocks at present, value cannot be compared between flocks.
While it is extremely important to breed superior animals for mohair production and quality, other factors such as fertility, vigour, survivability, size, horn shape, overall conformation and freedom from single gene faults should be considered. Each of these characters has its own genetic component and each requires consideration. Fortunately size, vigour and fertility seem to be linked so body weight, and scrotal circumference is likely to produce gains in this area. Additional selection might still be necessary and other areas are left to the breeder to evaluate.
MOPLAN should be seen as a base line system to select high producing candidates from which stud animals can be selected. Further development is required to include fertility measures, and second stage selection of sires using measured fibre diameter and CV at the third fleece stage. Such developments depend on the level of demand and use of MOPLAN and breeders are urged to adopt MOPLAN in its current form. Not only is it a remarkably powerful tool, but it provides the only available method for combining performance data into a single selection index.
Cost. MOPLAN costs $30 per annum and $1.00 per kid processed. A full report on all animals is supplied with each drop processed. This includes an updated list of Breeding Values for all animals present in the flock.
Further information and MOPLAN membership from:-
Mohair Australia Limited, ABRI, University of New England NSW 2351
(Phone 02 6773 3557).
© 2000 Mohair Aust Ltd