Avaliação da reutilização de implantes contendo progestágenos para controle farmacológico do ciclo estral e ovulação em vacas de corte. / Evaluation of progestagen implants reutilization on pharmacological control of estrus cycle and ovulation in beef cows.

AUTOR(ES)

Décio Zuliani Maluf

DATA DE PUBLICAÇÃO

2002

RESUMO

Two-hundred and twenty-one (78 suckling– 40 to 90 days) Nelore (Bos taurus indicus) X Charolais (Bos taurus taurus) cows were used to evaluate the reutilization of progestagen implants to control pharmacologically the estrus cycle and ovulation. Cows were randomly assigned to one of three protocols for estrous synchronization and artificial insemination in pre-fixed time. In treatment 1 (T1; n=73) cows were implanted with Crestar® (3 mg de norgestomet); in treatment 2 (T2; n= 75) cows were implanted with Crestar®, already used in a previous synchronization; and in treatment 3 (T3; n=73) cows received two Crestar® implants, also previously used, both placed side by side in the same ear. All cows were injected with an intra muscular (i.m.) dose of 2 mL of progesterone (25mg/mL) + estradiol benzoate (1mg/mL) at the time of implants insertion (D0). Implants were removed after 8 days (D7) and an i.m. dose of Preloban® (150mg de D-cloprostenol) was administered. Twenty-four hours after implants removal, cows were i.m. injected with a dose of Estrogin® (1mg of estradiol benzoate). All cows were artificially inseminated at 54-56 h after implants removal. Ninety percent of semen used in the experiment was from only one bull, the remaining 10% were equally distributed among treatments. Artificial insemination was performed by only one technician. Suckling cows had a body condition score of 5–6, in a scale of 1-9, and the non-suckling cows were 6-7. Pregnancy rate was the variable studied. Statistical analysis was accomplished by using "Statistical Analysis System 8.0", and logistic regression. There was no difference (P>0.05) on cow’s pregnancy rate among treatments. Pregnancy rates were 39.72, 34.21 and 36.98% for T1, T2 and T3, respectively. Progestagen implants reutilization did not affected pregnancy rate in beef cows ready for reproduction.

ASSUNTO(S)

beef cattle animal hormone ciclo estral bovinos de corte ovulação ovulation animal reproduction hormônio animal estrous cycle vacas reprodução animal cows

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