Expected genetic gain in milk yield in a hypothetical population of 50 000 ewes was studied. Three selection schemes were investigated. The first scheme used natural service (1250 rams), rams with a breeding value of 14.9 kg milk above the mean breeding value being selected on a pedigree index with an accuracy of 0.4. Ewes selected had a superiority of 4.1 kg (accuracy = 0.55). The second scheme used conventional progeny testing with 2 levels of AI usage (20 and 60%) and 4 selection intensities of rams. The 3rd scheme used the best 2600 of the 50 000 ewes to breed by AI the 1250 rams required for natural matings, progeny testing being used to evaluate the sires of the natural service rams. The 3rd scheme was considered to be the best, and would result in an annual genetic gain of 3.0-3.5 kg milk per lactation.
Schemi di selezione per il latte negli ovini.
Pizzi F
1988
Abstract
Expected genetic gain in milk yield in a hypothetical population of 50 000 ewes was studied. Three selection schemes were investigated. The first scheme used natural service (1250 rams), rams with a breeding value of 14.9 kg milk above the mean breeding value being selected on a pedigree index with an accuracy of 0.4. Ewes selected had a superiority of 4.1 kg (accuracy = 0.55). The second scheme used conventional progeny testing with 2 levels of AI usage (20 and 60%) and 4 selection intensities of rams. The 3rd scheme used the best 2600 of the 50 000 ewes to breed by AI the 1250 rams required for natural matings, progeny testing being used to evaluate the sires of the natural service rams. The 3rd scheme was considered to be the best, and would result in an annual genetic gain of 3.0-3.5 kg milk per lactation.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
