Influence of nutritional and ovarian parameters on pregnancy rates of Nelore cows artificially inseminated at fixed time

Abstract

This experiment aimed to evaluate the effect of weight gain, body condition score and antral follicle count on the fertility of cows subjected to fixed-time artificial insemination. To this study, it was used 194 Nelore, pluriparous cows, between the 30th and the 45th day of the postpartum period. The cows were weighed, was classified by the body condition score and a transrectal ultrasound was performed in the ovaries to identify the corpus luteum and for counting the antral follicles. Then, the females were submitted to a hormonal protocol to perform the artificial insemination in fixed time. Thirty days after the artificial insemination, the cows were weighed again and the pregnancy was diagnosed by transrectal ultrasound. The pregnancy rate did not interact (P>0.05) with the body score condition, nor the presence of the corpus luteum, neither with the antral follicles count. The weight gain between the artificial insemination moment and the pregnancy diagnosis showed an interaction (P = 0.02) with the pregnancy rate. The weight gain average between the FTAI and the pregnancy diagnosis was 9.0 kg. The animals that gained up to 73 kg, showed higher pregnancy rate. In conclusion, the weight gain between the artificial insemination in fixed time and the pregnancy diagnosis influenced the pregnancy rate.

Estratégia de protocolo hormonal baseado na antecipação de PGF2α para melhorar a eficiência reprodutiva em vacas leiteiras submetidas a transferência de embriões em tempo fixo (TETF)

“…A seleção desses animais foi baseada no peso, escore de condição corporal adequado (ECC), período pós-parto, ciclos estrais normais e estado de saúde normal. As vacas em lactação foram utilizadas após um período de espera voluntário (PEV) médio de 45 dias (30 a 70 dias após o parto), e apenas as fêmeas com um ECC entre 2,5 e 3,5 em uma escala de 1 a 5 (Negreiros et al, 2020) foram selecionadas para receber os protocolos Convencional ou o protocolo MMSINCRO (tratamento teste) de sincronização de ovulação para transferência de embrião em tempo fixo (TETF).…”

Pulsed-wave doppler ultrasound in canine reproductive system – Part 1: technical aspects

“…There are several applications for the combined use of B-mode and Doppler in the veterinary clinical routine, including detection of shunts, arteriovenous malformations, thrombus research, etc. In addition to providing quantitative data that yields important information for a more accurate diagnosis, the PW ultrasound is recommended as the first option for imaging analysis of various diseases, including those related to the reproductive system, because it can be better than invasive and complex technologies that use ionizing radiation (Holen, 2014;Lee, 2014;Benacerraf et al, 2015;Negreiros et al, 2020).…”

Relationship between viability of thawed semen and pregnancy rate of Nelore cows subjected to fixed-time artificial insemination

“…Fixed-time artificial insemination (FTAI) is a biotechnique that occupies a prominent position as it allows AI of large numbers of females in a fixed-time, without the need for estrus observation, and so optimizes the reproductive management (Bó et al, 2018;Negreiros et al, 2020;Tortorella et al, 2016). Due to the evolution of FTAI in Brazil, in the last 15 years, semen commercialization has presented an expressive increase, with more than 12 million straws commercialized, almost double the number of straws sold in the year 2000, (ASBIA, 2015; P Baruselli et al, 2012;Meneghetti et al, 2009).…”

“…Due to the evolution of FTAI in Brazil, in the last 15 years, semen commercialization has presented an expressive increase, with more than 12 million straws commercialized, almost double the number of straws sold in the year 2000, (ASBIA, 2015; P Baruselli et al, 2012;Meneghetti et al, 2009). The Artificial insemination (AI) is a breeding biotechnology intended to providing greater genetic development and economic return for livestock (Fontes et al, 2020;Negreiros et al, 2020). However, there are reports of low pregnancy rates in AI animals, due to failures in estrus detection and a high incidence of postpartum anestrus.…”

“…Among the factors that interfere in the pregnancy rate of FTAI program in cattle, the body condition score, equine chorionic gonadotropin use, and semen quality are the most important (Marques et al, 2018;Negreiros et al, 2020).…”