Short Communication: Conception Rates Following Detection of Estrus and Timed AI in Dairy Cows Synchronized Using GnRH and PGF2

Abstract

The objective of this study was to compare conception rates of cows exhibiting spontaneous estrus and receiving artificial insemination (AI) before completion of a timed AI protocol with cows that did not display estrus spontaneously, but were inseminated after 1 of 3 GnRH-PGF2alpha protocols. Cows (n = 432) in 2 herds were administered GnRH on d -7 and were tail-chalked daily. Cows detected in estrus before d 0 were inseminated immediately. Cows not detected in estrus by d 0 were administered PGF2alpha and were tail-chalked daily until 48 h after PGF2alpha. Cows detected in estrus from d -7 to 48 h after PGF2alpha were inseminated and designated as treatment A (n = 46). Cows not detected in estrus and not inseminated by 48 h after PGF2alpha were assigned randomly to receive either GnRH 48 h after PGF2alpha and timed AI 16 h later (treatment B; n = 132), or GnRH and timed AI 64 h after PGF2alpha (treatment C; n = 127), or timed AI 64 h after PGF2alpha (treatment D; n = 127). Pregnancy was diagnosed 38 to 45 d after AI by palpation per rectum of uterine contents. Nearly 11% of all cattle exhibited spontaneous estrus and received immediate AI. Herd did not influence the percentage of cows detected in estrus and inseminated. Conception rates did not differ among treatments. Conception rates differed between herds, but no interaction of herd x treatment was detected. No differences were detected between herds for days in milk, milk production, AI service number, or parity.

Integrating an automated activity monitor into an artificial insemination program and the associated risk factors affecting reproductive performance of dairy cows

“…venson et al, 2014). These results are in contrast to others that found no difference at first postpartum AI (Gümen et al, 2003;Dalton et al, 2005; or subsequent AI (Giordano et al, 2015;Dolecheck et al, 2016). The experimental design of our study and other similarly designed studies make it difficult to conclude the major cause for this difference (or lack thereof) in fertility between the 2 categories of inseminations, considering cows detected in estrus were bred approximately 10 d earlier than cows bred in the TAI treatment.…”

Risk factors limiting first service conception rate in dairy cows, and their economic impact

“…Our finding that cow parity does not affect FSC is consistent with those of some studies [4,19], but others have shown that FSC rate is affected by cow parity because it was lower in cows with parity ≥4 or 5 than in primiparous cows [7,10]. IDE or timed AI did not affect FSC rate in the present study, which is consistent with some previous studies [27,28]. However, other studies have shown that the FSC rate in cows undergoing AI during a detected estrus is higher than in cows undergoing timed AI following an Ovsynch protocol [17,29].…”

Comparison of Oestrous Intensity between Natural Oestrus and Oestrus Induced with Ovsynch Based Treatments in Japanese Black Cows

“…Yet, when distinct oestrous behaviour is not detected in Ovsynch based synchronization methods combined with timed artificial insemination (timed AI) protocol (Bartolome et al. 2005; Dalton et al. 2005), AI is not always performed by the AI operator.…”

“…The synchronization of oestrus or ovulation has been applied frequently to improve fertility and to achieve labour-saving at cattle farms (Pursley et al 1997;LeBlanc 2001;Gabor et al 2002). Yet, when distinct oestrous behaviour is not detected in Ovsynch based synchronization methods combined with timed artificial insemination (timed AI) protocol (Bartolome et al 2005;Dalton et al 2005), AI is not always performed by the AI operator.…”