Resumo

PICO, B.A.; VAN WYK, J.B.  e  NESER, F.W.C.. Inbreeding in the South African Brahman breed. S. Afr. j. anim. sci. [online]. 2006, vol.36, n.5, pp.103-106. ISSN 2221-4062.

Inbreeding levels and their possible influence on growth traits of the South African Brahman cattle were investigated. Data utilized in this study consisted of 180264 pedigree (1955 - 2002), 41509 birth weight (BWT), 37705 200-days weaning weight (200d), 22682 400-days weight (400d) and 13055 600-days weight (600d) records. Inbreeding coefficients were calculated by inverting the diagonal of the inverse relationship matrix using the MTDFNRM procedure of the MTDFREML package. Inbreeding depression was estimated as the regression of performance on animal and dam inbreeding coefficients using an animal model (ASREML) considering linear effects in the model. The mean inbreeding of the population was very low (1.31%) with an average of (3.97%) for inbred animals. Estimates of inbreeding depression on animal (dam) inbreeding were -0.016 (0.004) kg for BWT, 0.418 (-0.241) kg for 200d -0.689 (-0.120) kg for 400d and -0.957 (0.011) for 600d, respectively. The results suggest that both the level and rate of inbreeding at present are not a serious problem in the South African Brahman breed and well below the critical levels and consideration of additional methods to avoid inbreeding is not necessary at the present time.

Palavras-chave : Inbreeding depression; growth traits; linear.

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