Objective.

Compare the fertility of Brown Swiss x Zebu and Simmental x Zebu crossbred cows reared in a tropical environment.

Materials and methods.

Reproductive traits of 185 Brown Swiss x Zebu and Simmental x Zebu crossbred cows with diverse percentages of European breed were evaluated. Grazing of cows was rotational. The milking was twice daily with the help (suckling) of the calf, which was kept tied next to the dam while she was milked. Traits were evaluated fitting a repeated measures model (except for age at first calving). Calving interval, age at first calving, days open, interval from calving to first service, and weight at calving were analyzed with PROC MIXED of SAS. Pregnancy rate at first service and services per conception were analyzed with PROC GENMOD of the same software.

Results.

Simmental x Zebu cows started to re-bred 39 days earlier after calving (p<0.05) and had 47 fewer days open (p<0.05) than Brown Swiss x Zebu cows. The calving interval of the Simmental x Zebu cows was 45 days shorter (p<0.05) than that of the Brown Swiss x Zebu cows. Simmental x Zebu cows were 34 kg heavier at calving (p<0.05) than Brown Swiss x Zebu cows.

Conclusions.

Simmental x Zebu cows had better fertility than Brown Swiss x Zebu cows.

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