Effects of fixed-time artificial insemination using triptorelin on the reproductive performance of pigs: a meta-analysis

Abstract

Triptorelin (TRI), a gonadotropin-releasing hormone agonist allowing ovulation synchronization in pigs, is indispensable for fixed-time artificial insemination (FTAI) protocols. However, the effect of FTAI using TRI (FTAI-TRI) on the reproductive performance is controversial. We performed a meta-analysis to determine whether FTAI-TRI affects reproductive performance of pigs, including pregnancy rate (PR), number of pigs born alive per litter (NBA), farrowing rate (FR) and total number of pigs born per litter (TNB). A total of 37 trials from 15 studies were extracted and analysed in Stata. A weighted mean difference (WMD) with 95% confidence interval (CI) was calculated for NBA and TNB, and risk ratio (RR) with 95% CI was calculated for PR and FR. Pregnancy rate, TNB and NBA data were applied to a fixed-effect protocol, and FR data were applied to a random-effect protocol. We found that for weaned sows, the FTAI-TRI group had comparable reproductive performance to the artificial insemination (AI) following oestrus detection (EDAI) group. Fixed-time AI has many advantages, including the elimination of the need to heat-check twice daily, so that FTAI-TRI is a good substitute for EDAI. Subgroup analysis indicated that the optimal timing of triptorelin treatment was 96 h after weaning, which gave significant positive effects on PR (RR = 1.08, P = 0.000) and non-significant positive effects on TNB (WMD = 0.12, P = 0.452). Triptorelin at a dose of 100 μg showed better effects than 200 μg, with significant positive effects on PR (RR = 1.09, P = 0.005) and FR (RR = 1.06, P = 0.036). So a single dose of 100 μg was recommended. The optimal protocol was insemination at 24 h and again at 48 h after triptorelin administration if they remained in standing oestrus, and this provided a significantly higher NBA (WMD = 0.59, P = 0.013) that increased by 0.59. For gilts, the FTAI-TRI group showed decreased (not significant) PR (RR = 0.96, P = 0.127) and significantly decreased FR (RR = 0.93, P = 0.013), TNB (WMD = −0.85, P = 0.006) and NBA (WMD = −0.98, P = 0.000), which were inferior to those in the EDAI group. In conclusion, the effects of FTAI-TRI on the reproductive performance of pigs were parity-, treatment timing-, insemination timing-, and dosage-dependent. Fixed-time AI using triptorelin could effectively replace the EDAI protocol for sows, but not for gilts.

Weaned Sows with Small Ovarian Follicles Respond Poorly to the GnRH Agonist Buserelin

“…The lack of response of sows not showing post-weaning estrus to GnRH agonist treatment also raises the question whether weaned sows not showing estrus should be treated and further inseminated. Accordingly, administering GnRH agonists only to sows showing signs of estrus instead to all sows at a fixed time after weaning is claimed to be an alternative approach to improve fertility results [30]. Indeed, excellent fertility results have been reported following this approach [8,21].…”

“…Indeed, excellent fertility results have been reported following this approach [8,21]. However, estrus detection does not fit into the concept of a management-efficient single fixed-time AI because it detracts the important benefits planned [30]. Indeed, the administration of GnRH agonists at a fixed time after weaning to synchronize ovulation seeks precisely to eliminate the need of estrus detection, one of the most laborious, exigent and time-consuming farm activities.…”

GnRH agonists: Updating fixed‐time artificial insemination protocols in sows

“…AI. Wang et al (2020) performed a meta-analysis based on a total of 37 trials from 15 studies, carried out between 2004 and 2018. This meta-analysis included randomized controlled trials and clinically controlled trials that studied gilts or sows with all data (except for total born and born alive piglets' data) expressed as either mean ± SE or mean ± SD.…”

“…Sows treated with triptorelin displayed similar reproductive performances as the control sows because the ovulation timing was accurately predicted by assuming that the two FTAI should be performed when estrus has been detected (Knox et al, 2014; Ulguim et al, 2016). On the other hand, Knox et al (2018) and Wang et al (2020) determined in their research (experimental and meta‐analysis, respectively) that administering 100 μg triptorelin at 96 h to weaned sows results in improved reproductive parameters compared to triptorelin treatments on gilts synchronized with altrenogest.…”

“…Some research observed inWang et al (2020) meta-analysis, which was conducted by applying different doses of triptorelin (25, 100, and 200 μg) to gilts, presented low reproductive parameters (i.e., fertility rate, farrowing rates, total births, and still births)…”