Development of fixed-time artificial insemination protocols for locally adapted Curraleiro Pé-Duro cows

Rodrigo Dorneles Tortorella ,Jairo Pereira Neves ,Mairon Rocha Modesto ,A F Ramos

doi:10.1590/1678-4162-8555

Abstract

ABSTRACT Two experiments were conducted aiming to evaluate the effects of two ovulatory inducers (Exp.1) and equine chorionic gonadotropin (eCG; Exp.2) on follicular and luteal dynamics in a fixed-time AI (FTAI) protocol in locally adapted Curraleiro Pé-Duro cows. In Exp. 1 multiparous cows (n=12) received an intravaginal device containing 1g of progesterone (P4) for 8 days and 2mg of estradiol benzoate (EB) intramuscularly (IM) at device insertion (Day 0). At device removal (Day 8) 0.150mg of Sodium D-Cloprostenol was administered IM and the cows were randomly assigned to receive 1mg of EB (EB8) or 1mg of estradiol cypionate (EC8) IM, or to not receive any ovulatory inducer (Control). All the animals participated in all treatments (crossover). The interval from P4 removal to ovulation was shorter and less variable in the EB8 treatment group (P≤0.05). In Exp. 2 (crossover), multiparous cows (n=12) received the same hormonal treatment as the EB8 group in Exp.1. At device removal (Day 8) cows were randomly assigned to receive 300UI of eCG IM or to not receive eCG (Control). No difference was ascertained on follicular and luteal parameters in Exp. 2 (P>0.05). We concluded that EB can be used as the ovulatory inducer (Exp. 1) in a FTAI protocol in Curraleiro Pé-Duro cows. However, eCG (Exp. 2) was not able to stimulate follicular and luteal development. This result is probably due to the adaptive capacity of Curraleiro Pé-Duro cows that maintained a satisfactory body condition score even in dry and hot environments.

Highlights

The global growth of the human population has led to an increased demand for animal protein
In Exp. 1, the presence of a dominant follicle (DF) > 8mm at P4 device removal was observed in 83.33% (10/12) of cows in Control, EB8 and EC8 treatment groups (P>0.05)
The main findings of this study were that the ovulatory inducer estradiol benzoate (EB) allowed better ovulation synchronization, but equine chorionic gonadotropin (eCG) was not able to improve DF and corpus luteum (CL) development

Summary

Introduction

The global growth of the human population has led to an increased demand for animal protein. Raised extensively with little or no attention paid to nutritional, health, or reproductive management, locally adapted breeds, such as the Curraleiro Pé-Duro, became extremely hardy and resistant to diseases and parasites, as well as dry and hot climates (Egito et al, 2002; Bianchini et al, 2006). Despite these desirable characteristics, locally adapted breeds began to decrease in numbers due to cross-breeding with exotic Bos taurus and Bos indicus breeds (Fioravanti et al, 2011)

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Discussion

Conclusion