The Suinfort® Semen Supplement Counters Seasonal Infertility in Iberian Sows

Suinfort®, a commercial semen supplement demonstrated to increase fertility and litter size in commercial sows, was tested to improve reproductive performance in Iberian sows. A total of 1430 Iberian sows were artificially inseminated (AI) with semen from Duroc boars and assigned by parity to receive the seminal additive Suinfort® containing 2 IU oxytocin, 5 µg lecirelin, and 2 mM caffeine (SF; n = 1713 AI), or to serve as non-supplemented controls (CON; n = 2625 AI). CON showed a lower fertility comparing to winter for spring (p = 0.001) and summer (p < 0.001); summer was lower than autumn (p = 0.012). SF removed this seasonal effect (p > 0.05). Fertility was significantly higher for SF sows during summer (p = 0.025) and autumn (p = 0.004). Total born, live-born, stillborn, and mummified piglets did not differ between CON and SF but were impacted by the season, with total and live-born decreasing in summer compared with autumn (p < 0.001) and winter (p = 0.005). In conclusion, seminal supplementation with Suinfort® improved the fertility of Iberian sows during periods of seasonal infertility.

Latest Advances in Sow Nutrition during Early Gestation

In the pig, the establishment and maintenance of luteal function in early gestation is crucial to endometrial function, embryo development, and survival. The level of feed intake has a positive effect on formation of luteal tissue and progesterone secretion by the ovaries in the pre-implantation period, which is important for endometrial remodeling and secretion. These effects are independent of luteinising hormone (LH) and probably driven by metabolic cues, such as insulin and insulin-like growth factor (IGF-1), and seem to support progesterone secretion and delivery to the endometrium, the latter which occurs directly, bypassing the systemic circulation. Even after implantation, a high feed intake seems to improve embryo survival and the maintenance of pregnancy. In this stage, luteal function is LH-dependent, although normal variations in energy intake may not result in pregnancy failure, but may contribute to nutrient supply to the embryos, since in this phase uterine capacity becomes limiting. Feed incidents, however, such as unintended fasting of animals or severe competition for feed, may result in embryo or even pregnancy loss, especially in periods of seasonal infertility. Specific nutrients such as arginine have a role in the vascularisation of the placenta and can improve the uterine capacity in the period after implantation.

81 Zearalenone Affects the Ovarian Proteome During Heat Stress in Prepubertal Gilts

Zearalenone (ZEA), an estrogenic mycotoxin, causes hormonal disruption and reproductive dysfunction in pigs. Heat stress (HS) occurs when exogenous and metabolic heat accumulation exceeds heat dissipation; a scenario negatively impacting gilt reproduction. Our objective was to identify differentially abundant ovarian proteins in gilts exposed to HS +/- ZEA. We hypothesized that ZEA exposure would negatively impact the prepubertal gilt ovarian proteome and HS would be additive to ZEA-induced toxicity. Prepubertal gilts (n = 38) were assigned to one of six treatment groups: thermoneutral (TN) ad libitum control (TNCtl; n = 6); TN + ZEA (TNZea; 2 ppm; n = 6); pair-fed (PF) control (PFCtl; n = 6); PF+ ZEA (PFZea; 2 ppm; n = 6); cyclical HS control (HSCtl; n = 7); and HS + ZEA (HSZea; 2 ppm; n = 7). Gilts were subjected to TN (20 ± 1°C) or cyclic HS (35 ± 1°C for 12 h/31.6° for 12 h) conditions for 7 d. Liquid chromatography-mass spectrometry (LC-MS/MS) was performed on ovarian protein homogenates. Exposure to ZEA altered (P &lt; 0.05) abundance of 93 proteins in TN gilts (48 increased and 45 decreased). In PF gilts, ZEA increased 50 and decreased 47 proteins (P &lt; 0.05). During HS, ZEA differentially affected (P &lt; 0.05) 126 proteins: 58 increased and 68 increased. Pathways impacted by either HS or ZEA alone or in combination included cellular stress, metabolic pathways, and estrogenic pathways. Thus, ZEA and HS, either alone or in combination, impact the ovarian proteome in prepubertal gilts in ways that could contribute to seasonal infertility. This project was supported by the Iowa Pork Producers Association.

Effect of seasonal infertility period on boar sperm proteins and quality characteristics

Swine seasonal infertility reduces the productivity and profitability of a pig farm. The main causes of this condition are elevated environmental temperatures and long photoperiod during the summer season. The aim of this study was to investigate which sperm proteins and parameters are affected during the period of seasonal infertility. Depending on the environmental temperatures, the period from October to June was considered as cold and the period from July to September as warm season. A total of 65 ejaculates from 18 boars were collected over a year. Each semen sample was evaluated for kinetics (Computer Assisted Semen Analyzer), morphology (Sperm Blue stain), viability (Propidium Iodide - Calcein AM stain), mitochondrial membrane potential (Rhodamine 123 – Propidium Iodide stain), membrane integrity and functionality (Hypo-osmotic swelling test) and sperm DNA integrity (Acridine Orange Test). Moreover, selected proteins (HSP90, GPX5, OPN) were detected and quantified. The kinetic parameters VSL, LIN and the midpiece abnormalities were significantly higher in the warm compared to the cold season (p<0.05), while a strong tendency towards higher values for HSP90 and GPX5 was observed in warm compared to cold season (p=0.07and p=0.06, respectively). In conclusion, among the boar sperm characteristics tested in our study, seasonal infertility period negatively affected VSL and LIN kinetics, while GPX5 seminal plasma enzyme and HSP90 sperm surface protein increased their sperm protective effects.

Effect of Dextrose Supplementation in the Pre-Ovulatory Sow Diet to Reduce Seasonal Influences on Litter Birth Weight Variation

In this experiment, we proposed two hypotheses: birth weight variation would increase in litters from sows bred in summer, and dextrose supplementation during the wean to mate period would ameliorate this manifestation of seasonal infertility. Five hundred and ninety-one multiparous sows were allocated to Control; standard diet, or Dextrose; control +5% dextrose diets from weaning until insemination during summer and winter. Dextrose sows farrowed 1.0 and 1.4 more total pigs born and pigs born alive than Control sows, respectively (p < 0.05). There was a tendency for a higher co-efficient of variation (CV) birth weight in summer than winter (16.6 ± 0.4 versus 15.8 ± 0.4; p = 0.1), but no effect of treatment or interaction between treatment and season was observed. Piglet average daily gain was unaffected in those born to sows bred in summer, but when born to sows bred in winter, Dextrose piglets grew 23 g per day faster than Control (p < 0.05). This experiment identified evidence for increased birth weight CV in sows bred during the summer months despite the reduced litter size, suggesting that this is another way seasonal infertility can manifest.

Heat stress during the luteal phase decreases luteal size but does not affect circulating progesterone in gilts1

Heat stress (HS) occurs when heat dissipation mechanisms are insufficient to maintain euthermia, and it is associated with seasonal infertility (SI), which manifests as smaller litters, longer wean-to-estrus interval, increased abortions, and reduced conception rates. To understand HS-induced mechanisms underlying SI, crossbred post-pubertal gilts (167 ± 10 kg; n = 14) experienced either thermal neutral (TN, 20 ± 1 °C, n = 7) or cyclical HS (35 ± 1 °C for 12 h and 31.6 °C for 12 h, n = 7) conditions from 2 to 12 d post-estrus (dpe). Estrous cycles were synchronized via altrenogest administration for 14 d, phenotypic manifestation of estrus was observed and gilts were assigned to experimental treatment. Gilts were limit fed 2.7 kg daily with ad libitum water access. Blood was collected at 0, 4, 8, and 12 dpe via jugular venipuncture and animals were humanely euthanized at 12 dpe. The corpora lutea (CL) width were measured via digital calipers on both ovaries, and CL from one ovary were excised, weighed, and protein and steroid abundance analyzed via western blotting and ELISA, respectively. Relative to TN, HS increased (P < 0.01) rectal temperature and respiration rates and reduced (P < 0.01) feed intake. The CL from HS ovaries were reduced in diameter (P < 0.05) and weight (P < 0.01) relative to those from TN animals. No difference (P = 0.38) in CL or serum progesterone concentrations between groups was observed at any time point, though at 12 dpe the serum progesterone:CL weight was increased (P < 0.10) by HS. No treatment differences (P = 0.84) in circulating insulin were observed. Luteal protein abundance of steroid acute regulatory protein, 3 beta-hydroxysteroid, or prostaglandin F2α receptor were not different between treatments (P = 0.73). Taken together, these data demonstrate that the CL mass is HS sensitive, but this phenotype does not appear to be explained by the metrics evaluated herein. Regardless, HS-induced decreased CL size may have important implications to pig SI and warrants additional attention.

208 Molecular mechanisms through which heat stress compromises reproduction in pigs

Seasonal variations in environmental temperatures impose added stress on domestic species bred for economically important production traits. These heat-mediated stressors vary on a seasonal, daily, or spatial scale, and negatively impact behavior and reduce feed intake and growth rate, which inevitably leads to reduced herd productivity. The seasonal infertility observed in domestic swine is primarily characterized by depressed reproductive performance manifesting as delayed puberty onset, reduced farrowing rates, and extended weaning-to-estrus intervals. Understanding the effects of heat stress at the organismal, cellular, and molecular level is a prerequisite to identifying mitigation strategies that could reduce the economic burden of compromised reproduction. Additionally, hyperthermia experienced in utero influences industry-relevant postnatal phenotypes. Understanding tissue-specific molecular mechanisms through which heat stress confers suppressed reproductive ability is essential to the development of mitigation focused hypothesis driven solutions. This work was supported by the National Pork Board and the Iowa Pork Producers Association.

Effect of altering the ratio of exogenous gonadotropins on reproductive performance of primiparous sows during the seasonal infertility period

At weaning, 150 primiparous sows were assigned sequentially to receive 400 IU equine chorionic gonadotropin (eCG) with 200 IU human chorionic gonadotropin (hCG) (Gn600), or 400 IU eCG with 400 IU hCG (Gn800), or served as untreated controls. Compared with control and Gn600, the Gn800 had increased estrus response by day 7 and reduced wean-to-estrus intervals (P < 0.05). Compared with controls, both Gn600 and Gn800 increased numbers of large follicles (≥6 mm) at estrus detection (P < 0.05) and the subsequent farrowing rates (P < 0.05). Litter size was unaffected. These data demonstrate the efficacy of supplemental hCG for alleviating effects of seasonal infertility in primiparous sows.