Gestation Rate in Beef Cows with Different Calving Orders Submitted to FTAI Protocol: Effects of Body Condition, Number of Progesterone Intravaginal Device Uses and Bull

Lucas Balinhas Farias,Gabriel Weizenmann Fernandes,Matheus Gomes Lopes,Gustavo Fischer,Cássio Cassal Brauner,Ana Laura Aita Xavier,Matheus Wrege Meireles Barbosa

doi:10.5296/jas.v8i2.17002

Lucas Balinhas Farias, Gabriel Weizenmann Fernandes + Show 5 more

Open Access

https://doi.org/10.5296/jas.v8i2.17002

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Abstract

The search for better reproductive rates in beef cattle breeding must consider some important issues, such as nutrition, health, animal category, type of reproductive technique, and selection of animals. Thus, the objective of this study was to evaluate the effect of the body condition score (BCS), the number of uses of the intravaginal progesterone device and the effect of the bull on the gestation rate of lactating beef cows, with different calving orders, submitted to a fixed timed artificial insemination (FTAI) protocol. In the study, 623 Aberdeen Angus cows were used, which were categorized into three groups according to the calving order: primiparous cows, second-parity cows, and multiparous cows. On day zero of the FTAI protocol, an evaluation of the BCS of the cows was performed, using progesterone intravaginal devices (IVD) for 9 days, starting from the D0 of the protocol both for used and new IVD. Semen from three different Aberdeen Angus breeders was used. Statistical analysis was made in the NCSS 7.0 software, using the Chi-square test and a significance value of p<0.05. The calving order influenced the pregnancy rate, with the category of primiparous cows having the lowest rates (p<0.05). The BCS and the number of uses of the IVD showed significance only in the primiparous category, in which animals with BCS equal or above 3.5 obtained a higher pregnancy rate, as well as animals with second-use IVD when compared to other groups (p <0.05). Therefore, primiparous cows presented a lower pregnancy rate when compared to the other categories, as well as the BCS and the number of uses of the IVD.

Highlights

Protocols for estrus induction and ovulation synchronization have facilitated the use of artificial insemination, as a consequence, accelerate the genetic progress of herds (Lucy, 2001)
According to the results presented on table 1, the calving order is a determining factor to the gestation rate in caws submitted to fixed timed artificial insemination (FTAI) protocol, in which the primiparous category had the lower rate when compared to second-parity cows and multiparous cows, (47.1%), (67.3%) e (68.9%), respectively (P
Corroborating with Grillo et al, (2015), who evaluated the reproductive efficiency of Nellore cows submitted to FTAI protocol and demonstrated that first-calf cows obtained lower pregnancy rates when compared to heifers and multiparous cows (45.3%), (86%) e (76.8%), respectively

Summary

Introduction

Protocols for estrus induction and ovulation synchronization have facilitated the use of artificial insemination, as a consequence, accelerate the genetic progress of herds (Lucy, 2001). Several factors influence the reproductive performance of beef cattle, such as mating season, body condition, bull fertility, and nutritional management (Campos et al, 2005). The nutritional status of cows in the postpartum period affects the pregnancy rate, as it interferes with the growth of the dominant follicle, ovulation, and fertility, having a direct effect on GnRH and pituitary gonadotropins, and indirectly on the somatotropic axis (Diskin et al, 2003). The body condition score (BCS) is a visual measure used worldwide to monitor the nutritional status and the reproductive performance of dams because it is a determining coefficient in the redesign and the general productivity of the herd, besides being practical and of low cost (Lake et al, 2005)

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