Mature weight of Nellore cows from selection herds in Brazil

Revista Brasileira de Zootecnia

Bezerra, Luiz Antonio Framartino³  Lôbo, Raysildo Barbosa³  Reyes Borjas, Arcádio de los¹  Oliveira, Henrique Nunes de¹  Rosa, Antonio do Nascimento² 

[1] Universidade Estadual Paulista;Empresa Brasileira de Pesquisa Agropecuária;Universidade de São Paulo

关键词: animal breeding;    beef cattle;    body weight;    cow;    maturity;    zebu cattle   IntroduçãoO peso adulto das matrizes vem despertando atenção e discussões;    nos últimos anos;    em função da globalização da economia que exige;    a cada dia;    além da qualidade;    baixos custos de produção;    como forma de se enfrentar um mercado de alta competitividade (ANUALPEC;    1998;    HOHENBOKEN;    1998;    LANNA e PACKER;    1998);   

DOI  :  10.1590/S1516-35982001000400017

学科分类：兽医学

来源: Universidade Federal de Vicosa

【 摘 要 】

- The main objective of this work was to evaluate the Nellore breed in Brazil with respect to the phenotypic and genetic variation of the mature size of cows. The observations were taken from 34 herds of eleven different beef cattle production regions in the country. There were considered cows of the horned and polled varieties, raised on pastures, from herds that had at least 50 cows. With these restrictions it was formed a general file with 6,867 cows with valid observations on mature weight (MW) and a genetic relationship matrix with 17,039 animals. Body weight, as indicator of the mature size, was defined as the first weight (kg) observed since the cows were from four through twelve years old. This weight was taken under one of three different conditions: normal, at the routine weighing, in April and October, according to the established schedule of the program, at parturition or at weaning of the calf. Data management and statistical analyses were carried out through the utilization of the Statistical Analysis System (SAS). Herd, year of birth, year of weighing, condition at weighing, season of weighing and the interactions year*season of birth and year*season of weighing were the most important sources of variation for MW. The overall mean for mature weight was 447 kg, with a coefficient of variation of 11%. The genetic analysis was carried out by the use of the Multiple Trait Derivative-Free Restricted Maximum Likelihood (MTDFREML) algorithm under an animal model. The 1,126 contemporary groups included cows from the same herd, born at the same year, weighted at the same year and season and at the same condition at weighing. The additive genetic (537.78 kg2), residual (1,553.22 kg2) and phenotypic (2,090.59 kg2) variance components provided a heritability estimate of 0.26, for MW. The predicted genetic breeding values varied from -41.9 through +61.4 kg, with accuracy ranging from 0 to 0.95.

【 授权许可】

CC BY-NC