Culling Practices in Leicester Longwools
D. P. Sponenberg
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Questions always seem to come up concerning culling in rare breeds, and especially in Leicester Longwools. Culling is an
Culling Practices in Leicester Longwools
D. P. Sponenberg
Click Here to Download this Article
Questions always seem to come up concerning culling in rare breeds, and especially in Leicester Longwools. Culling is an essential component of breed management, and has a role in all breeds. Unless done carefully, though, it can damage rare breeds beyond their capacity to survive as the useful entities they are. All breeds need to have some culling, but in all breeds that culling must be wise in order to not jeopardize the breed’s future genetic structure and viability.
Culling serves various purposes in breed maintenance, and all of these are related to the removal of animals from the reproducing population. Culling, essentially, is the downside of selection. Selection sounds so wonderfully positive, because certain animals are recruited for reproducing the next generation. Culling is the other side of that coin, and represents those animals that are not destined to reproduce the breed. Reasons for culling vary, and can usually be split into two main categories: low production potential, or deviation from the breed standard. These two are very different, and breeders need to reflect on those differences in order to use culling most effectively for breed improvement, survival, and conservation.
In all breeds it is important to breed “to the standard,” and to work to assure that the animals produced do indeed meet that standard. However, the standard can become a very harsh dictator, and in some cases can impede breed survival if breeders impose culling levels that are too high. Depending on the specific factor that is used to cull animals, the breed standard can itself become a huge problem in breed survival. Some points in a breed standard are more important than others (usually these relate to soundness and production) and others have less importance (usually these are the details of appearance that contribute to “breed type” and set one breed off as unique from other related breeds).
The differences in importance of characters in the breed standard are not trivial, and if each character is used as an independent and absolute “veto” of an animal’s future in the breed, then many breeds will have so few animals remaining that they will cease to be viable as genetic units. This means that breeders need to be wise in using the breed standard as a tool for culling. The breed standard is a useful tool, but needs to be used constructively and usefully.
One approach to using the breed standard as a tool in culling animals is to mimic “card grading” as a process for evaluating animals. In card grading, each animal is compared to the breed standard, rather than comparing the animals to one another. This is a useful alternative to competitive showing, and the same procedure can be useful in individual flocks and herds of animals as young candidates for inclusion in the breeding population are considered.
Card grading has been done on several occasions by Leicester Longwool sheep breeders, and the results are interesting and useful for all breeds. The top “blue card” animals are obvious choices for retention into the breeding population. Likewise, the “red card” animals usually are good choices, despite having a weakness or two in meeting the ideal breed standard. The “yellow card” animals are a very fascinating group, because some of these have a single signficant flaw, while others are more generally more moderately weak in several different characteristics. The “single signficant flaw” animals are actually pretty useful in the breed, because they can be mated to animals that are strong in whatever one characteristic is weak, and the other strengths in the “yellow card” animal can therefore benefit the breed. The key here is that these “single signficant flaw” animals may indeed have a role, and an important one at that, in the breed’s future despite their flaw. The key is that they must be used wisely. If the breed standard is used as a sequence of absolutes to require culling, then these animals would be removed and their positive contribution would be lost.
The “overall weak animals” have less to offer a breed, and if used at all must be used carefully, although certainly could be mated to uniformly strong animals to improve the next generation. At the bottom of the heap are “white card” animals, which deviate from breed standard in signficant ways. Some of these still only have one very serious flaw, and even in this case such animals might have a role in the breed’s future, but only with wise and limited use.
The key point is to not let a single flaw eliminat