Frozen Soil Lateral Resistance for the Seismic Design of Highway Bridge Foundations

INE/AUTC 12.3

Antioxidant therapy improves sperm DNA integrity in boars during summer

Background: Summer infertility due to heat stress significantly affects the reproductive potential of pigs causing over $300 million per year in lost productivity to the US pig industry and billions worldwide. The boar's inefficient capacity to sweat; non-pendulous scrotum, and the high susceptibility of boar sperm to temperature shock appears to correlate with higher sperm DNA damage during summer. Heat stress-induced sperm DNA damage can result in early embryo loss, as demonstrated in mice. This study investigated whether supplementing boars with antioxidants during summer could improve boar sperm DNA integrity. Method: Motility of sperm obtained from n=5 Large White boars housed in the dry tropics of Townsville, Queensland, Australia were analysed using Computer-Assisted Sperm Analysis. Sperm DNA integrity during summer was compared without or after 42 and 84 days antioxidant supplementation, by Terminal deoxynucleotidyl transferase dUTP Nick-End Labelling and flow cytometry. Paired T-tests were used to determine significant differences between treatments (P ≤ 0.05). Results and Discussion: Total and progressive motility of sperm did not differ between treatments (P ≥ 0.05). However, antioxidant supplementation of boars during summer resulted in a 38% and 55% reduction of DNA-damaged spermatozoa after 42 and 84 days treatment respectively (16.1 ± 4.8% untreated vs 9.9 ± 4.5% vs 7.2 ± 1.6%; P ≤ 0.05). Conclusions: Supplementing boars with antioxidants during summer improves boar sperm DNA integrity which could potentially mitigate the negative impact of heat stress on male fertility. Such improvements may also increase downstream fertilisation rates and early embryo survival in the sow

Summer induces DNA damage in boar sperm: implications for the management of seasonal infertility

At 40% share, pork is the most widely eaten meat globally. As such, research efforts must improve production and efficiency in the pig industry to meet growing demand. However, summer heat stress has a significant negative impact on pig fertility; causing embryonic death and decreased litter size that cost the industry millions in productivity losses. This problem is particularly prevalent in the tropics where ambient temperatures rise beyond the animal’s zone of thermal comfort. Boars are particularly vulnerable to the effects of heat stress due to their inefficient capacity to sweat; non-pendulous scrotum; and the high susceptibility of boar sperm to temperature shock. Moreover, due to limited endogenous antioxidant systems inherent in mammalian spermatozoa and the loss of cytosolic repair mechanisms during spermatogenesis, the DNA in these cells are particularly susceptible to oxidative damage. While a seemingly healthy looking sperm may swim and fertilize an oocyte normally, studies in mice demonstrate that heat stress-induced DNA damage can disrupt expression of key developmental genes in early embryos after fertilization and distort the formation of the blastocyst; resulting in implantation failure and pregnancy loss. The aim or our study is to determine whether heat stress induces DNA damage to boar sperm that could significantly contribute to the high rates of embryo loss and pregnancy failure observed in sows during summer infertility. The quality of sperm obtained from n=6 Large White boars housed in the dry tropics of Townsville, North Queensland, Australia was evaluated across different seasons (summer, winter and spring) during 2014 - 2015. Sperm motility was characterised by Computer-Assisted Sperm Analysis (CASA; IVOS version 10: Hamilton Thorne, USA), and sperm DNA integrity evaluated by Terminal deoxynucleotidyl transferase dUTP Nick-End Labelling (TUNEL; In situ cell death detection kit, fluorescein: Roche, Germany). Twenty-thousand spermatozoa per boar per treatment were analysed using flow cytometry (CyAn ADP analyser: Beckman Coulter, USA). Sperm had equal motility across all seasons (total motility: 70.8 ± 5.5% vs. 71.3 ± 8.1% vs. 90.2 ± 4.2%, P ≥ 0.05; progressive motility: 41.7 ± 2.8% vs. 35.4 ± 7.0% vs. 46.6 ± 4.0%, P ≥ 0.05 for spring, summer and winter respectively). However, sperm in summer exhibited ~9-fold higher DNA damage than that in winter and spring (16.1 ± 4.8% vs. 1.1 ± 0.2% and 1.8 ± 0.4% respectively; P ≤ 0.05). These results demonstrate that summer negatively affects sperm DNA integrity in boars without depressing sperm motility. This means traditional methods of evaluating semen quality may not detect inherently compromised spermatozoa. We are currently evaluating the effect of this DNA-damaged sperm on rates of fertilization, development and survival in pig embryos. Our study emphasizes the need for improved management practices and development of strategies to mitigate heat stress in boars during summer

Cryoprotective effect of glycerol against sperm DNA damage in frozen-thawed boar spermatozoa.

The use of frozen-thawed boar sperm still lags behind chilled boar semen in artificial insemination (AI) operations despite its advantages [1]. Freezing however, may damage the structure and function of sperm, leading to reduced fertilization success. Moreover, glycerol, which is a critical cryoprotectant in most sperm freezing protocols, can be toxic to cells in high concentrations [2]; affecting sperm motility and acrosomal integrity. This study was conducted to determine the cryoprotective effect of glycerol on sperm DNA integrity and motility in frozen-thawed boar sperm

Antioxidant supplementation alleviates DNA damage in boar spermatozoa induced by tropical heat stress

Seasonal heat stress is known to significantly diminish reproductive performance in pigs, particularly in the tropics, costing the industry millions in annual loses. The boar’s reduced capacity to sweat, non-pendulous scrotum, and widespread use of European breeds in the tropics, makes this species particularly vulnerable to heat stress. While traditionally considered a sow problem, recent mouse studies demonstrate that heat stress-induced sperm DNA damage can result in arrested development and loss of early embryos. Our study investigated the impact of tropical summer heat stress on the quality and DNA integrity of boar sperm, and trialled antioxidant supplementation to alleviate the problem. Data, expressed as mean ± SEM, were analysed by one-way repeated measures ANOVA with pairwise Bonferroni tests. Motility of sperm obtained from n = 5 Large White boars housed in the dry tropics of Townsville, North Queensland, Australia was characterized by Computer-Assisted Sperm Analysis but did not differ between summer, winter or spring (total motility: 71.3 ± 8.1 vs. 90.2 ± 4.2 vs. 70.8 ± 5.5% respectively, P > 0.05; progressive motility: 35.4 ± 7.0 vs. 46.6 ± 4.0 vs. 41.7 ± 2.8% respectively, P > 0.05). Sperm DNA integrity in 20,000 sperm/boar/season, evaluated using TUNEL and flow cytometry, revealed 16-fold more DNA damaged sperm in summer than winter, and nearly 9-fold more than spring (16.1 ± 4.8 vs. 1.0 ± 0.2 vs. 1.9 ± 0.5% respectively, P ≤ 0.05). However, boar feed supplemented with 100g/boar/day of proprietary custom-made antioxidants during summer significantly reduced sperm DNA damage to 9.9 ± 4.5% and 7.2 ± 1.6% (P ≤ 0.05) after 42 and 84 days treatment respectively. Total and progressive motility were not altered by the supplement. In summary, sperm DNA integrity is compromised in boars during summer, suggesting boar factors may contribute to seasonal embryo loss in sows. Moreover, such damage appears undetectable using traditional measures of sperm motility. Antioxidant supplementation during summer appears to mitigate the negative impact of heat stress on sperm DNA integrity

Revisiting summer infertility in the pig: could heat stress-induced sperm DNA damage negatively affect early embryo development?

Temperature is a crucial factor in mammalian spermatogenesis. The scrotum, pampiniform plexus, and cremaster and dartos muscles in mammals are specific adaptations to ensure sperm production in a regulated environment 4-6°C below internal body temperature. However, the limited endogenous antioxidant systems inherent in mammalian spermatozoa compounded by the loss of cytosolic repair mechanisms during spermatogenesis, make the DNA in these cells particularly vulnerable to oxidative damage. Boar sperm is likely to be more susceptible to the effects of heat stress and thus oxidative damage due to the relatively high unsaturated fatty acids in the plasma membrane, low antioxidant capacity in boar seminal plasma, and the boar’s non-pendulous scrotum. Heat stress has a significant negative impact on reproductive performance in piggeries, which manifests as summer infertility and results in productivity losses that amount to millions of dollars. This problem is particularly prevalent in tropical and subtropical regions where ambient temperatures rise beyond the animal’s zone of thermal comfort. Based on preliminary studies in the pig and other species, this article discusses whether heat stress could induce sufficient DNA damage in boar sperm to significantly contribute to the high rates of embryo loss and pregnancy failure observed in the sow during summer infertility. Heat stress-induced damage to sperm DNA can lead to disrupted expression of key developmental genes essential for the differentiation of early cell lineages, such as the trophectoderm, and can distort the timely formation of the blastocyst; resulting in a failure of implantation and ultimately pregnancy loss. Confirming such a link would prompt greater emphasis on boar management and strategies to mitigate summer infertility during periods of heat stress

Tropical summer induces sperm DNA damage in boars which can be mitigated by antioxidant therapy

Summer infertility due to heat stress grossly affects reproductive performance in pigs, particularly in the tropics, and causes over $300 million in annual losses to the US swine industry. Boar's inefficient capacity to sweat; non-pendulous scrotum and the high susceptibility of boar sperm to temperature shock makes this species particularly vulnerable to heat stress. While traditionally considered a sow problem, recent studies demonstrate that heat stress-induced sperm DNA damage can result in early embryo loss in mice. Our study aimed to demonstrate higher sperm DNA damage during summer in boars and trial antioxidant therapy to alleviate the problem. Motility of sperm obtained from n=5 Large White boars housed in the dry tropics of Townsville, North Queensland, Australia was characterized by Computer-Assisted Sperm Analysis (CASA), but did not differ between spring, summer and winter (total motility: 70.8 ± 5.5% vs. 71.3 ± 8.1% vs. 90.2 ± 4.2%; progressive motility: 41.7 ± 2.8% vs. 35.4 ± 7.0% vs. 46.6 ± 4.0% respectively, both P ≥ 0.05). However, sperm DNA integrity in twenty-thousand spermatozoa per boar per treatment, evaluated using TUNEL staining and flow cytometry, revealed nearly 9-fold higher DNA damage in summer than spring and winter (16.1 ± 4.8% vs. 1.8 ± 0.5% vs 1.1 ± 0.2% respectively; P ≤ 0.05). However, boar feed supplemented with antioxidants during summer significantly reduced sperm DNA damage to 9.9 ± 4.5% and 7.2 ± 1.6% (P ≤ 0.05) after 42 and 84 days treatment respectively. Total and progressive motility were not altered by the supplement. Our results show sperm DNA integrity is compromised in boars during summer, suggesting boar factors may contribute to embryo loss in sows. Moreover, such damage may go undetected using traditional measures of sperm motility. Antioxidant supplementation during summer alleviates the negative impact of heat stress on sperm DNA integrity

Antioxidant therapy mitigates summer-induced DNA damage in boar spermatozoa

Introduction: While pork is the most widely eaten meat in the world, pig production is continually threatened by changing climate conditions resulting in poor reproductive performance, particularly in the tropics. The boar's inefficient capacity to sweat; non-pendulous scrotum and high susceptibility of boar sperm to temperature shock makes this species particularly vulnerable to the effects of heat stress. While DNA-damaged sperm may fertilize normally, key genes involved in early embryo development may be severely affected inducing early embryo loss as shown in the mice. Our study demonstrates that tropical summer significantly increases DNA damage in populations of sperm within the ejaculate without necessarily affecting sperm motility. Moreover, supplementing boars with antioxidants during summer could potentially reduce the negative impact of heat stress on sperm DNA integrity. Materials and Methods: Five mature Large White boars were housed individually in open gable pens at JCU in the dry tropics of Townsville, Queensland, Australia. Semen was collected by the gloved-hand technique using a dummy sow during spring (Oct 2014), summer (Feb 2015) & early winter (end May 2015) and diluted 1:3 in BTS media. Boar feed was supplemented with 100g/boar/day custom-made antioxidant formulation during summer (Jan - Apr 2016) and semen was collected after 42 & 84 days treatment. Sperm concentration was determined by haemocytometer and motility of 20 x 106 sperm/ml at 38°C was analyzed using CASA (Hamilton Thorne). Sperm DNA damage in 20,000 Percoll-purified sperm per boar per treatment was evaluated using TUNEL (Roche) & flow cytometry (Dako Cytomation; Fig. 1). Results: Sperm motility was similar in summer to winter & spring (P > 0.05) but total motility was lower in spring than winter (P ≤ 0.05). Antioxidant supplementation for 42 & 84 days during summer did not affect motility of spermatozoa (P > 0.05). Sperm DNA damage was more than 16-fold higher in summer than winter & nearly 9-fold higher than spring (P ≤ 0.05; Fig. 2). Antioxidant supplementation during summer reduced sperm DNA damage after 42 & 84 days antioxidant treatment (P ≤ 0.05; Fig. 3). Conclusions and discussion: Sperm DNA integrity is compromised in boars during summer, suggesting boar factors may contribute to embryo loss in sows. Moreover, such damage appears undetectable using traditional measures of sperm motility. Antioxidant therapy during summer appears to significantly alleviate heat stress-induced DNA damage in boar sperm, which may provide one solution to the problem of summer infertility in the pig

Boar sperm DNA damage induced by tropical heat stress can be alleviated using antioxidants

Seasonal heat stress is known to significantly diminish reproductive performance in pigs, particularly in the tropics, costing the industry millions in annual loses. The boar's reduced capacity to sweat, non-pendulous scrotum, and widespread use of European breeds in the tropics, makes this species particularly vulnerable to heat stress. While traditionally considered a sow problem, recent mouse studies demonstrate that heat stress-induced sperm DNA damage can result in arrested development and loss of early embryos. Our study investigated the impact of tropical summer heat stress on the quality and DNA integrity of boar sperm, and trialled antioxidant supplementation to alleviate the problem. Motility of sperm obtained from n = 5 Large White boars housed in the dry tropics of Townsville, North Queensland, Australia was characterized by Computer-Assisted Sperm Analysis but did not differ between summer, winter or spring (total motility: 71.3 ± 8.1 vs. 90.2 ± 4.2 vs. 70.8 ± 5.5% respectively, P > 0.05; progressive motility: 35.4 ± 7.0 vs. 46.6 ± 4.0 vs. 41.7 ± 2.8% respectively, P > 0.05). Sperm DNA integrity in 20,000 sperm/boar/season, evaluated using TUNEL and flow cytometry, revealed 16-fold more DNA damaged sperm in summer than winter, and nearly 9-fold more than spring (16.1 ± 4.8 vs. 1.0 ± 0.2 vs. 1.9 ± 0.5% respectively, P ≤ 0.05). However, boar feed supplemented with 100g/boar/day of proprietary custom-made antioxidants during summer significantly reduced sperm DNA damage to 9.9 ± 4.5% and 7.2 ± 1.6% (P ≤ 0.05) after 42 and 84 days treatment respectively. Total and progressive motility were not altered by the supplement. In summary, sperm DNA integrity is compromised in boars during summer, suggesting boar factors may contribute to seasonal embryo loss in sows. Moreover, such damage appears undetectable using traditional measures of sperm motility. Antioxidant supplementation during summer appears to mitigate the negative impact of heat stress on sperm DNA integrity

Effects of mass transfers and heating rates during bark and wood hydrothermal treatment

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