Estimation of reproductive, production, and progeny growth differences among f1 boer-spanish and spanish females
Rhone, Jeffrey Andrew
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The study was performed in the Edwards Plateau region of West Texas from the years of 1994 through 2004 and involved data collected on 291 F1 Boer-Spanish and Spanish does and their 1,941 kids. Differences were estimated between dam types for growth traits, fertility traits, prolificacy, kid growth traits, survivability, longevity, and progeny growth. The mixed model analysis of variance procedure was used for all traits, except doe survivability where chi-square analysis was used. The F1 Boer-Spanish does were significantly heavier at birth than Spanish does, but there was no significant difference between the F1 Boer-Spanish and Spanish does for weaning weight. The F1 Boer-Spanish does had a significantly heavier body weight at breeding than the Spanish does (46 vs. 43 kg). No significant differences were found between breed types for fertility traits. Age of doe was a significant source of variation for fertility. There was no significant difference between the two doe breed types for number of kids born or number of kids weaned. Age of doe significantly affected both number of kids born and number of kids weaned. There was no significant differencebetween breed for total litter weight at weaning. For kid birth weight there was no significant difference between dam breed types. Kid weaning weight and pre-weaning average daily gain were not significantly different between dam breed types. Age at time of leaving the herd for all causes was 6.15 years for F1 Boer-Spanish does and 5.56 years for Spanish does (P = 0.06). There was no significant difference between breeds for proportions of does leaving the herd for the three main reasons. Although F1 Boer-Spanish does were significantly heavier for birth weight and body weight at breeding, there were no significant differences for weaning weights, reproduction, production, and progeny growth differences at weaning between F1 Boer- Spanish and Spanish does. When kid production was measured at weaning there was no difference between breeds. However the greater body weight of the F1 Boer-Spanish does at breeding suggests that if kid production was measured at a later endpoint, a significant difference may be realized.