Breeding to improve animal production entails the upgrading or improvement of a breed in respect of specific characteristics. An expert explains how to do this.

Animals that have poor characteristics shouldn’t be used for breeding, but those that have good characteristics should be retained as parents for the next generation of livestock.

Improvement which results from breeding is not always immediately obvious, but is permanent.

• Improvement is best achieved by using superior rams.
• The ram contributes half of the production characteristics of each lamb (progeny).
• Because one ram services 30 to 50 ewes a season, his contribution to the total progeny is considerable.
• The ram’s contribution to the total progeny of 50 ewes is 50% and that of one ewe (out of a total of 30 to 50 ewes) is only 1%.

Also read: Taking care of your rams

If one mates poor ewes with good rams every year, the progeny will, after 4 generations, have virtually all the characteristics of the ram. The generation interval for sheep is between 4 and 5 years.

ENSURE PROGRESS THROUGH BREEDING

It cannot be stressed enough that you should use only the best animals for breeding. It is, however, not possible to select for several characteristics at the same time, so choose a specific characteristic and select the animals accordingly. Animals that do not display this characteristic must be culled, slaughtered or sold.

About half the ewe lambs should be kept for breeding each year. Weaning age is the right time to select the animals in terms of body mass. Old ewes (8 years, or after 6 lambing seasons), as well as those that have udder problems or other obvious defects, must be culled.

Also read: Advice on culling ewes and does

Select characteristics for their economic value:

• In mutton sheep and Boer goats, meat production and reproduction are important.
• In milk goats, milk production and reproduction are important.
• In wool sheep the most important characteristics are wool production, wool quality (fibre thickness) and reproduction.

It must be possible to measure the characteristic for which selection is being done. A producer who wishes to breed good mutton sheep should, therefore, have a scale to determine the mass of the animals during selection.

TRANSFER OF CHARACTERISTICS TO PROGENY

Not all characteristics for which the farmer selects, are passed on to the progeny with equal success. Certain characteristics such as the production of meat, wool and milk have a high inheritance rate, but fertility has a low one.

Animals to be used for breeding should be selected according to strong inherited characteristics.

During selection those animals with serious defects such as too few teats, inverted teats, weak mouth, back or legs are culled first. Animals that have good characteristics are then selected from the remaining ones.

INBREEDING

Inbreeding occurs when animals which are too closely related (family) are used for breeding. Inbreeding often results in weak progeny.

• When animals of non-related lines are used, it is called hybrid vigour and the progeny usually have better production characteristics.
• The hybrid vigour, however, only applies to the hybrid generation and will not be transferred to their progeny.
• To limit inbreeding, rams should not be used in the same free-ranging flock for more than 2 breeding seasons.
• After 2 breeding seasons the ram usually interacts with its own progeny.
• Newly-bought rams should replace one-third of the rams every year.

The general principle with regard to selection and breeding is that the progeny of animals usually give an average performance. A few perform exceptionally well or exceptionally poor. The exceptionally good animals are selected for breeding.

• This article was written by Prof. Tertius Brand and first appeared in Farming SA.