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vol.18PRODUCTIVITY OF PEARL MILLET THREE SOWING DENSITIES AND TWO CUTTING HEIGHTSETHOLOGICAL ANALYSIS RELATED TO THE PROCEDURE OF WEARING OR NOT THE TEETH OF PIGLETS IN MATERNITY author indexsubject indexarticles search
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Ciência Animal Brasileira

Print version ISSN 1518-2797On-line version ISSN 1809-6891

Abstract

REZENDE, Marcos Paulo Gonçalves et al. POPULATION STRUCTURE OF THE NELLORE HERD REARED IN THE BRAZILIAN NORTHEAST SEMI-ARID. Ciênc. anim. bras. [online]. 2017, vol.18, e38048.  Epub Oct 02, 2017. ISSN 1809-6891.  https://doi.org/10.1590/1089-6891v18e-38048.

The objective of this study was to evaluate the population structure of 91,579 Nellore cattle reared in the Northeast semi-arid, born between 1965 and 2011. We analyzed the pedigree and the estimation of population parameters based on the probability of gene origin. In the early years, a higher number of female births occured, tending to gender balance over the years. The number of founder animals (fe) and ancestors (fa) indicated the reduced use of animals in the genetic formation of the herd. Among 2,4676 ancestors, 450 were responsible for 50% of the genetic variability of the population. Of the 10 most important founders, 8 were among the 10 ancestors. The individual with the highest expression presented a mean coefficient of relationship (CR) of 1.31%, explaining 1.81% of the variability.72% of animals have identified fathers and mothers, revealing loss of information between generations. 100% of the herds use external bulls and 61% of them sell bulls, with no core classification or isolate. Inbreeding ranged from 0.14% in the second generation to 0.73% in the eighth, while the CR ranged from 0.8% to 0.35% between the first and fourth generations, decreasing from the fifth on. The average generation interval observed was of 8.3 years. The herd has a small number of animals in the genetic make-up, and small completeness of pedigree, making it difficult to estimate some population parameters.

Keywords : generation interval; genetic variability; inbreeding; Zebu.

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