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In utero stress has been shown to negatively affect intact male rats and mice, though very little research has been conducted in boars. The objectives of the present studies were to determine the effects of in utero heat stress (IUHS) on postnatal development and the response to postnatal heat stress of boars. Ten boars were selected at weaning from litters subjected to IUHS or in utero thermoneutral (IUTN) during 30-60 days of gestation. The boars were evaluated for reproductive performance from birth through 57 weeks of age (WOA). Testicular area tended to be smaller for IUHS boars compared to IUTN boars at 24 WOA (P = 0.080). Libido did not differ for IUHS or IUTN (P = 0.818). Total sperm production was reduced in IUHS boars compared to IUTN boars (P ≤ 0.038). Semen volume and semen concentration did not differ (P ≥ 0.469 and P ≥ 0.664, respectively). Total motility and progressive motility did not differ for IUHS and IUTN boars (P ≥ 0.430 and P ≥ 0.652, respectively). In utero heat stressed boars had a greater incidence of sperm with tail abnormalities than IUTN (P ≤ 0.042). In utero heat stressed boars had a lower incidence of sperm with proximal droplets following mild, postnatal heat stress compared with IUTN (P = 0.005). In utero heat stress resulted in significant reductions in sperm production and increased sperm abnormalities in boars. The IUHS boars may be slightly more tolerant to postnatal heat stress, though more research is needed., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The objective of this study was to evaluate relationships between common semen quality estimates including sperm motility, sperm morphology, spontaneous capacitation status and seminal plasma proteins and boar fertility using heterospermic inseminations and subsequent paternity testing. All boars (n=12) used in the study had excellent semen quality (≥70% normal sperm) that resulted in average farrowing rates and litter sizes of 88.9±0.7% and 11.7±0.1 pigs, respectively. Their ejaculates were combined to make heterospermic insemination doses in such a way that each boar was tested against all of his contemporaries. The proportion of piglets sired by each individual was used to separate boars into three fertility groups: High (71.6±4.8%; n=3); Medium (51.6±3.8%; n=6); and Low (25.2%±5.3%; n=3). Ejaculates from High fertility boars had more motile sperm with normal acrosomes that moved faster in a straight-line and were more likely to undergo an acrosome reaction (p≤0.05) compared with their counterparts in the Low fertility group. Ejaculates from High fertility boars contained the greatest concentrations of three seminal plasma proteins (25.9kD/5.9pI; 55.1kD/4.8pI; and 70.1kD/5.2pI; p≤0.05), whereas concentrations of a 19.1kD/6.8pI were highest in semen from Low fertility boars (p≤0.05). Multiple regression analyses indicated that concentrations of the 25.9kD/5.9pI seminal plasma protein explained 66% of the variation observed in the proportion of pigs sired within a litter among boars (p≤0.00001). These results demonstrate that heterospermic inseminations and subsequent paternity testing is an effective technique for defining relationships between common semen quality tests and fertility, especially in situations where reproductive performance of all the boars is high. Motility, normal acrosome morphology, average linear velocity of motile sperm, and the proportion of sperm capable of an acrosome reaction were all positively associated with boar fertility. However, concentrations of a 25.9kD/5.9pI seminal plasma protein were the best single semen characteristic for ranking boars in terms of their fertility., (Copyright © 2016 Elsevier B.V. All rights reserved.)

This study evaluated the effect of supplemental dietary betaine at three concentrations (0.0%, 0.63% and 1.26%) on semen characteristics, quality and quality after storage on boars. The trial was conducted between 22 July and 1 October 2014 in a boar stud located in Oklahoma. Boars were blocked by age within genetic line and randomly allotted to receive 0% (CON, n (line T)=22, n (line L)=10), 0.63% (BET-0.63%, n (line T)=21, n (line L)=6) or 1.26% (BET-1.26%, n (line T)=23, n (line L)=7). The diets containing betaine were fed over 10 weeks, to ensure supplemental betaine product (96% betaine) daily intakes of 16.34 and 32.68g, for the BET-0.63% and BET-1.26% diets, respectively. Serum homocysteine concentrations were less for animals with betaine treatments (P=0.016). Rectal temperatures of the boars were unaffected by betaine diets. Betaine tended to increase total sperm in the ejaculates when collectively compared with data of the control animals (P=0.093). Sperm morphology analysis indicated there was a greater percent of sperm with distal midpiece reflex (P=0.009) and tail (P=0.035) abnormalities in boars fed the BET-1.26% than boars fed the BET-0.63% diet. Betaine concentration in the seminal plasma was greater in boars with betaine treatments, with animals being fed the 0.63% and 1.26% diets having 59.2% and 54.5% greater betaine concentrations in seminal plasma as compared with boars of the control group (P=0.046). In conclusion, betaine supplementation at 0.63% and 1.26% tended to increase sperm concentration in the ejaculates by 6% and 13%, respectively, with no negative impacts on semen quality when 0.63% of betaine was included in the diet., (Copyright © 2016 Elsevier B.V. All rights reserved.)

The primary objective of this research was to evaluate the effect of long-term dietary selenium supplementation of commercial swine diets on semen production and sperm quality. The dietary treatments were a non-supplemented basal diet or the basal diet supplemented with 0.3ppm selenium in either an organic or inorganic form. A secondary objective was to determine if there were any beneficial effects of dietary selenium supplementation on changes in sperm quality during storage of semen post collection. Boars were fed dietary treatments from weaning at 20.97±0.18 d of age until the study was terminated when they were 382.97±0.18 d of age. Boars (n=6 per treatment) were maintained on a 1 time per week collection frequency for 5 months. Immediately after this, boars were collected six times over a 4 day period. Ejaculates were extended in a commercially available, 5-day semen extender and evaluated on day 1 and 6 of storage post-collection. Boars fed the organic selenium had higher (P<0.01) plasma levels of selenium compared to control boars and similar levels to those supplemented with the inorganic form (P=0.18). Dietary treatment did not affect (P>0.2) volume, concentration, total sperm in the ejaculate, sperm motility, progressive motility, morphology, lipid peroxidation, or glutathione peroxidase activity. These results indicate that supplementing a basal diet with organic or inorganic selenium did not affect semen quantity or sperm quality in fresh ejaculates nor did it appear to have any beneficial latent effects in extended semen stored post collection., (Copyright © 2013 Elsevier B.V. All rights reserved.)

The present study examined the effectiveness of intravaginal administration of a GnRH agonist, triptorelin, on the induction of the preovulatory LH surge; synchronization of time of ovulation; and reproductive characteristics in weaned sows. Sows were given 100microg of triptorelin in 0.9, 1.2, or 1.5% methylcellulose gel intravaginally 96h after weaning and then bred at 8 and 32h post-treatment. Untreated sows inseminated once each day of estrus served as the positive controls, while females treated with only the methyl cellulose gel and also bred once each day of estrus were negative controls. Sows treated intravaginally with triptorelin exhibited preovulatory LH surges with magnitudes comparable to those that occurred spontaneously in the negative controls. Preovulatory LH surges were initiated over a narrow and well-defined time interval that occurred 4-12h after treatment in sows receiving triptorelin in 1.2 or 1.5% methyl cellulose gel. As a result, the majority of the sows in these two treatments had ovulations within a 12h time frame 36-48h after treatment. In contrast, both the LH surge and ovulation occurred over extended periods of time after weaning in negative controls and sows given triptorelin in 0.9% methylcellulose gel. Farrowing rates and litter size were similar between untreated controls and triptorelin-treated sows that were bred with two fixed timed inseminations. Insemination of sows induced to have ovulations and bred at least once while not in estrus did not have any overt negative effects on reproductive characteristics. These results demonstrate that 100microg of triptorelin administered intravaginally in a least 1.2% methyl cellulose gel induced a normal preovulatory LH surge and synchronized time of ovulation in weaned sows. Furthermore, there were no obvious changes in reproductive performance when these sows were bred with two fixed time inseminations regardless of whether they exhibited a standing reflex., (Copyright 2010 Elsevier B.V. All rights reserved.)