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Breeding for better production
Afrikaans | Xhosa
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When people breed for better production, the aim is the improvement of the breed with respect to specific characteristics. Practically, this means keeping the best animals as parents for the next generation, while poorer animals are not used again for breeding.
Although improvement by breeding is never as spectacular as a good year with good rain and abundant food, it is permanent. The good or better characteristics are therefore carried over from one generation to the next. Improved production by breeding is brought about by the use of better or superior rams. The ram contributes one half of the production characteristics of each lamb, that is to say, the progeny. |
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This can be pictured as following: (see left diagram)
Because one ram services 30 to 50 ewes each season, the contribution of the ram to the total progeny is considerable. In a total of 50 ewes that each gives birth to a single lamb, the contribution of the ram is 50 %, and that of each ewe only 1 %. |
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If poor ewes are annually mated with good rams, practically the total progeny will have the characteristics of the rams after four generations.
In order to make good progress with the breeding, only the best animals must be used for further breeding. However, animals cannot be selected for many characteristics simultaneously. Therefore one must decide on a specific characteristic and select the animals accordingly. Animals that do not have this characteristic are culled, slaughtered or sold. With sheep and goats, about half the ewe lambs are retained annually for further breeding. Weaning age is a good time to screen the animals for body mass. Ewes older than eight years, or those that have had six lambing seasons, ewes that have developed udder problems, or ewes that have other obvious defects, are then culled. Skip ewes can already be culled at an early age. |
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It is important to select animals for characteristics such as meat, wool and milk production that have economic value. In mutton sheep and Boer goats, meat production and reproduction are the most important characteristics to be selected for. In milch goats, it is milk production and reproduction. In woolled sheep, the most important characteristics are wool production, wool quality or fibre thickness and reproduction. The quality for which animals are selected must be measurable. A farmer who wants to breed good mutton sheep, will, for example, own a scale with which to weigh his animals when selecting them. |
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However, not all the characteristics for which animals are selected, are equally heritable.
Some characteristics such as meat, wool and milk production, are highly heritable, while fertility has a low heritability rate. Breeding animals must be selected for the highly heritable characteristics. In selection, animals that have serious defects such as too few teats, inverted teats, or a weak mouth, back or legs, are culled first. The good animals are then selected from those that remain.
The grazing environment also influences the genetic potential of the animal. |
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Under poor feeding conditions the animal cannot grow properly. Therefore the animal must also be adapted to its environment. Please note that the solution does not necessarily lie
in introducing "new blood". Local animals are adapted to their environment and usually have special characteristics. These characteristics are inherited by the progeny and usually contribute to their better production.
When closely related animals (family of each other) are used for breeding, it is called inbreeding. This often produces a weak progeny. When animals of different breeds are used, we find hybrid vigour, and a progeny with better production characteristics is usually obtained. However, hybrid vigour is carried over only to the first generation. In order to combat inbreeding , a ram must not be used for more than two successive mating seasons in the same free-grazing flock. After two mating seasons, the ram usually mates with his own progeny. Newly purchased rams usually replace one third of the rams. |
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The general principle of breeding and selection is as follows:
The progeny performance of animals is usually average. A few animals perform exceptionally well and a few exceptionally poorly. The exceptionally good animals are used for further breeding. |
TS Brand
ELSENBURG / Research
