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Genetic association between milk production and weight performance of Pitangueiras cattle (5/8 Red Poll:3/8 Zebu)^*

Vera Lucia Cardoso^I; Raysildo Barbosa Lôbo^II; Henrique Nunes de Oliveira^III

^IInstituto de Zootecnia, Estação Experimental de Zootecnia, Caixa Postal 206, 14030-100 Ribeirão Preto, SP, Brasil. Send correspondence to V.L.C.
^IIDepartamento de Genética, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brasil
^IIIFaculdade de Medicina Veterinária e Zootecnia, Universidade Estadual Paulista, Botucatu, SP, Brasil

ABSTRACT

Data on 1,567 first lactations and 1,776 records of steers, including body weight at time of allocation to feedlot and live-weight-for-age, of Pitangueiras cattle were used to estimate predicted differences of sires. Data were also used to compute the genetic correlation between milk and weight traits, and to calculate expected correlated responses for weight performance traits. Animals were raised in São Paulo State and males were allocated to the feedlot at an average age of 28 months. Overall means and coefficients of variation (CV) were respectively 1,930 kg (CV = 56%), for 305-day milk yield (MY305); 234 days (CV = 50%), for lactation length (LL); 28 months (CV = 17%) and 365 kg (CV = 16%), for age and body weight at allocation to the feedlots (AGEI and WAF); and 0.421 kg (CV = 13%), for live-weight-for-age (LWA). Predicted differences for MY305, WAF and LWA ranged from -521 to 612 kg; -14 kg to 22 kg; and -0.014 kg to 0.021 kg, respectively. The genetic correlation between MY305 and WAF was -0.24 + 0.15 and -0.35 + 0.14 for MY305 and LWA. The correlated responses for WAF and LWA resulting from direct selection for milk production were 1.667 kg and 0.0016 kg, respectively. Selection for milk production did not cause detrimental effects on weight of animals raised for beef.

Keywords: milk production; weight performance; Pitangueiras cattle.

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* Part of a thesis presented by V.L.C. to Universidade de São Paulo in partial fulfillment of the requirements for the Doctoral degree.