Genetic improvement is generally associated to large breeds and management of local small breeds is seen as maintenance of the current genetic profùe, however, selection programmes may increase sustainability oflocal breeds. The paper discusses some issues associated to selection in local breeds. First, in generai farm animal populations are under some mass selection: in these cases the commonly used formula of S. Wright to compute effective size is inappropriate and its use results in considerably lower estimates of inbreeding rates. Secondly, research has been developed in the last years to design breeding schemes which maximise genetic gain while lirnitingthe rate of inbreeding. Although these investigations generally refer to intensively selected nuclei, they set a useful framework for selection in local breeds of small size, but its implementation needs further research. As an example it is shown that index selection adjusted for average relationship can produce appreciable genetic progress in a breed as small as 750 cows with acceptable inbreeding increments: compared to the Italian Friesian, expected response per year was 0.29,0.27 and 0.29 respectively for rnilk kg, fat kg and protein kg. Thirdly, which traits should be considered? It is suggested that genetic improvement should maintain ali characteristicscontributing to low production costs, the environrnental and cultural values of their farming systems and the links between breeds and their farming areas, that can add value to their products within the European certification system~of agricultural products.

Local breeds and genetic improvement

Flavia Pizzi;
2006

Abstract

Genetic improvement is generally associated to large breeds and management of local small breeds is seen as maintenance of the current genetic profùe, however, selection programmes may increase sustainability oflocal breeds. The paper discusses some issues associated to selection in local breeds. First, in generai farm animal populations are under some mass selection: in these cases the commonly used formula of S. Wright to compute effective size is inappropriate and its use results in considerably lower estimates of inbreeding rates. Secondly, research has been developed in the last years to design breeding schemes which maximise genetic gain while lirnitingthe rate of inbreeding. Although these investigations generally refer to intensively selected nuclei, they set a useful framework for selection in local breeds of small size, but its implementation needs further research. As an example it is shown that index selection adjusted for average relationship can produce appreciable genetic progress in a breed as small as 750 cows with acceptable inbreeding increments: compared to the Italian Friesian, expected response per year was 0.29,0.27 and 0.29 respectively for rnilk kg, fat kg and protein kg. Thirdly, which traits should be considered? It is suggested that genetic improvement should maintain ali characteristicscontributing to low production costs, the environrnental and cultural values of their farming systems and the links between breeds and their farming areas, that can add value to their products within the European certification system~of agricultural products.
2006
BIOLOGIA E BIOTECNOLOGIA AGRARIA
978-90-8686-177-4
seleetion
inbreeding
loeal breeds
eonservation
animaI genetie resourees.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.14243/90168
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