Evaluation of three methods of induction and jealousy grouping in heifers for meat

Abstract

Three methods of induction and syncronization of estrus in heifers for meat were evaluated, on the percentage of pregnancy achieved in a service of 21 days, 83 Hereford and polled Hereford heifers of 30 to 36 months old, weight average 380 kg divided in three lots. Evaluation of the pregnancy in the induction onf estrus with PGF2a (Group 1), implant of norgestomet and an injection of estradiol valeriate (Group 2) and biostimulation (Group 3) by means of the use of an androgenized cow with two doses of testosterone propionate. All groups were exposed to bulls of high serving capacity during 21 days. Rectal palpation were carried out 90 days later. The outputs of pregnancy were Group 1=90%, Group 2=79% and Group 3=92%. The statistical analysis for exact test of Fischer (P=/ 0.05) had not demostrate significant differences between three treatments. However it is needed to study if economical and management differences between methods exist.