Contribution of boars to reproductive performance and paternity after homospermic and heterospermic artificial insemination

Abstract

Heterospermic AI is commonly used in swine despite preventing precise evaluation of individual boar fertility. The present study compared the contribution of four boars (A, B, C and D) for reproductive performance and for paternity using homospermic and heterospermic (AB, AC, AD, BC, BD and CD) AI (n=204 for homospermic AI; n=307 for heterospermic AI). Blood samples from the four boars, from all sows inseminated with heterospermic doses and from the umbilical cords of their piglets, as well as tissue smears from mummified fetuses, were genotyped using single nucleotide polymorphisms (SNPs). Differences among boars were detected for the in vitro oocyte penetration rate and for the number of spermatozoa per oocyte (P<0.05), but not for sperm motility, mitochondrial functionality and integrity of the membrane, acrosome and DNA (P>0.05). Homospermic and heterospermic AI resulted in similar (P>0.05) farrowing rates (90.5% and 89.9%, respectively) and total litter size (12.4±0.4 and 12.7±0.7, respectively). Farrowing rate was lower for Boar B than for Boar C (P<0.05), but no other differences in reproductive performance among boars were observed with homospermic AI. The SNPs determined the paternity of 94.2% of the piglets sired by heterospermic AI. In the AC pool, paternity contribution per boar was similar (P>0.05), but differences between boars occurred in all other pools (P<0.05). Boar D achieved the greatest paternity contribution in all pools and parity categories (nearly 60%), whereas Boar B sired the fewest piglets (at most 40%). Reproductive performance was similar with homospermic and heterospermic AI, but differences in performance among boars undetected with homospermic AI were only evident after genotyping the piglets sired through heterospermic AI.

The effect of dietary supplementation of algae rich in docosahexaenoic acid on boar fertility

“…In this study, overall farrowing rate (~75%) was marginally lower, in comparison to the average farrowing rate recorded within the pig industry for liquid semen (80-85%; [50]). This lower farrowing rate is likely to be due to the use of homospermic semen in the current study compared to the routine practise, of the use of heterospermic semen [51], which has been shown to enhance reproductive performance [52]. Results in the current study correspond to Alm et al [53] who reported a farrowing rate of 75.8% using homospermic inseminations.…”

“…It should also be noted that inseminations were conducted mainly on purebred sows of both maternal and terminal lines and therefore, lower farrowing rates would be expect due to the lack of heterosis in sow fertility traits. The average litter size of ~14 piglets is comparable to the industry norm [55] and is greater than the homospermic litter size of 12.4 ± 0.4 piglets reported by Ferreira et al [51].…”

Boar Differences In Artificial Insemination Outcomes: Can They Be Minimized?

“…), logically hiding individual boar variation in fertility (Ferreira et al. ). This scenario would explain the few studies dealing with this important matter found in the literature.…”

“…The existence of variability in fertility between current highly selected breeding boars is a proven issue, however, considered more of individual nature that an event related to breed or to genetic lines (see reviews of Foxcroft et al 2010 andFlowers 2013). Yet, highlighting this individual variation has not been an easy task because semen doses used in most commercial swine AIprogrammes for industry production are 'pooled' doses, for example they include aliquots of ejaculates from three or more boars (Knox et al 2008), logically hiding individual boar variation in fertility (Ferreira et al 2014). This scenario would explain the few studies dealing with this important matter found in the literature.…”

Importance of sperm morphology during sperm transport and fertilization in mammals

“…When females are artificially inseminated with spermatozoa from two or more males (heterospermic insemination dosages), spermatozoa from specific males are consistently favored in their ability to fertilize oocytes and produce offspring 45464748. This indicates either a significant female selection of spermatozoa or sperm traits per se , and in both cases, morphological characteristics could be involved.…”