Pregnancy rate evaluation in lactating and non-lactating Nelore cows subjected to fixed-time artificial insemination using injectable progesterone

Abstract

Most fixed-time artificial insemination (FTAI) protocols utilize progesterone (P4) as a hormonal source to achieve synchronization of estrus in cattle. The use of an injectable P4 source to control estrus would be an interesting pharmacological strategy owing to the practicality of parenteral application. However, the effects of injectable P4 on estrus cycle control in cattle remain poorly studied. In particular, no existing studies have investigated the effect of injectable P4 on the fertility of cows subjected to FTAI. The aim of this study was to evaluate the pregnancy rate of lactating and non-lactating Nelore cows subjected to FTAI with injectable P4. Of the 422 non-lactating cows in this study, 162 (38.3%) became pregnant by 60 days post-FTAI. In the lactating group (n = 516), 166 (32.1%) were pregnant by 60 days after treatment with injectable P4. The proportions of lactating and non-lactating cows becoming pregnant were compared using the chi-square test, adopting a significance level of P < 0.05. It was found that the pregnancy rate of the cows subjected to FTAI with injectable P4 was influenced by lactation status. Lactating cows had lower reproductive performance, possibly because of their higher nutritional requirements. However, the use of injectable P4 shows promising results and may prove to be a useful strategy in large-scale livestock production. Key words: Injectable progesterone. Lactating cow. Non-lactating cows Synchronization of ovulation. Pregnancy rate. ResumoEm bovinos a maioria dos protocolos de inseminação artificial em tempo-fixo (IATF) utiliza a progesterona (P4) como base hormonal para a sincronização do estro. A utilização de uma fonte de P4 injetável para este controle do ciclo estral poderia ser uma estratégia farmacológica interessante, devido à praticidade de uma aplicação parenteral. O efeito da P4 injetável no controle da dinâmica folicular em bovinos tem sido pouco estudado, e até o momento, não há estudos que investigaram o efeito da P4 injetável na fertilidade de vacas submetidas à IATF. O objetivo do presente estudo foi avaliar a taxa de prenhez de vacas Nelore em lactação e não lactantes, submetidas a um protocolo de IATF a base de

Injectable progesterone in timed artificial insemination programs in beef cows

“…Therefore, considering the use of injectable P4 for TAI, the design of this study did not provide favorable efficiency to commercial use, but it is valid to highlight advances in this pharmacological strategy to timed insemination. The pregnancy rate in this study (34%) was higher than observed in our previous study (18%) with an injectable P4 ( Morotti et al ., 2013b ) and very similar (35.2%, 328/938) to a more recent study ( Campos et al ., 2016a ).…”

“…Some reproductive parameters remain critical for the fertility of females synchronized with P4 injectable, such as the ovulation and pregnancy rates, but it is valid to highlight important aspects of this pharmacological strategy for reproductive management in cattle. In the present and other studies (Morotti et al, 2013a;Morotti et al, 2013b;Campos et al, 2016a), greater convenience in managing animal synchronization was observed using P4 injectable. Such benefits are due to the convenience of a parenteral application in addition to the hygienic and sanitary advantages of injectable solution compared to intravaginal devices.…”

“…To assist reproductive biotechnology, several pharmacological strategies have been proposed ( Sales et al ., 2012 ; Campos et al ., 2013 ; Barreiros et al ., 2014 ; Torres et al ., 2014 ; Marques et al ., 2015 ; Pellegrino et al ., 2016 ) and progesterone (P4) has been the main exogenous hormonal basis for estrus synchronization in cattle; treatment can be performed through intravaginal devices ( Macmillan et al ., 1991 ; Macmillan and Peterson, 1993 ), ear implants ( Baruselli et al ., 2004 ; Sa Filho et al ., 2011), oral formulations ( Fike et al ., 1999 ) or injectable sources ( Morotti et al ., 2013a ; Morotti et al ., 2013b ; Campos et al ., 2016a ).…”

“…However, several positive aspects of injectable P4 have been encouraging new experiments. For example, injectable P4 has been related to low cost of handling, easy management of animals, hygienic benefits and no discard of devices ( Morotti et al ., 2013a ; Morotti et al ., 2013b ; Campos et al ., 2016a ; Campos et al ., 2016b ).…”

Induction of puberty in Bos indicus heifers in the western Amazon region

“…However, in both cows and heifers, the reuse of P4 devices have shown varied results depending on the breed, individual response, nutritional status, diet, and adopted hormonal combination (Pinto, Silva, Mota, & Alberton, 2009). Conversely, the use of injectable P4 in synchronization protocols has been related to low cost, easy management of animals, and hygienic benefits (Morotti, Campos, Oliveira, & Seneda, 2013a;Morotti, Campos, & Seneda, 2013b;Campos, Morotti, Bergamo, Costa, & Seneda, 2016a;Campos, Morotti, Costa, Bergamo, & Seneda, 2016b). For TAI programs, these benefits provide a reduction in the risk of health problems associated with intravaginal devices, such as loss of the device and the occurrence of vaginitis and vulvovaginitis (Morotti et al, 2013a(Morotti et al, ,b, 2018.…”