Genetic analysis of a crossbreeding experiment using improved dairy goat breds and native goats in a dry tropical environment
Mixed model techniques were used to analyze growth traits of crossbred kids and reproductive and productive traits of Native and crossbred dams from 1969 to 1978 in an experiment at Loma de León Field Station in Venezuela. Three contemporary groups were formed for the analysis of body weights (kg) at successive ages of 1468 kids born in the Station during the above period. Group I (1969-1974) included: ½ Nubian, ½ Native; ½ Alpine, ½ Native; ½ Toggenburg, ½ Native; 3/4 Nubian, ¼ Native, and 3/4 Alpine, ¼ Native. Group II (1971-1978): 3/4 Nubian, ¼ Native, and 7/8 Nubian, 1/8 Native. Group III (1975-1978): ½ Alpine, ¼ Nubian, ¼ Native; ½ Nubian, ¼ Alpine, ¼ Native, and ½ Nubian, ¼ Toggenburg, ¼ Native. Birth, weaning (4 mo.), 6 month weights, and first year mortality rate for above breed groups are presented. Phenotypic correlations and heretabilities were calculated. All correlations were highly significant. Multiple births increased with parity. Close relationship between rain during the dry season and estrus presentation was observed as well as seasonality in estrus presentation. No significant differences were found between breed groups on litter size, gestation length, services per conception, or age at 1st kidding. Milk yield and lactation length were both positively related to postkidding weight of dam. It is concluded that the use of Alpine and Toggenburg breeds is more advisable than the use of Nubian in future programs for genetic improvement of Native goats under environmental conditions similar to those in this experiment
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| Format: | biblioteca |
| Published: |
1982
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| Subjects: | CAPRINOS, MEJORAMIENTO ANIMAL, CRUZAMIENTO, GENETICA, CORRELACION GENETICA, REPRODUCCION, CRECIMIENTO, PESO, INDICES REPRODUCTIVOS, PRODUCCION DE LECHE, VENEZUELA, |
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