Poor welfare compromises testicle physiology in breeding boars

Abstract

In commercial pig breeding farms, boars are often exposed to stressful situations, such as confined housing conditions, inadequate environmental temperature, food restriction, lameness, diseases, among other challenges. Confined housing conditions, such as crates, are reported as a major source of stress for pregnant sows, and were banned in the UK and in Europe, however there is limited information about the impact of this housing system for boars. The goal of this study was to investigate the impact of three different housing conditions for boars and the consequence on the testicles. We studied 27 crossbred boars (F1 large white and landrace), housed in crates (n = 9), pens (n = 9), or enriched pens (n = 9), during 10 weeks. We collected data of scrotal superficies mean temperature (SSMT) with a thermal camera; we measured testicular parenchyma perfusion (ultrasound evaluation); and we measured sperm characteristics. We found that boars housed in crates had a higher SSMT (p < 0.05) and higher testicular parenchyma perfusion than boars housed in pens and enriched pens (p = 0.01). Regarding the semen features, we found that boars housed in crates showed more agglutinated semen, and higher values of linear curved linear velocity (VCL) than boars housed in pens and enriched pens, both indicators of reduced fertility. These results indicates that boars housed in pens and in enriched pens showed better indicators of testicular health, better sperm motility features (VCL, p = 0.046), and less agglutinated sperm (p < 0;05) than that observed in boars kept in crates.

Life experiences of boars can shape the survival, aggression, and nociception responses of their offspring

“…As reported by Bernardino et al (2022), boars housed in crates had greater perfusion of the testicular parenchyma and higher velocity linear curve values in sperm, which can contribute to reduced fertility. The review by Nätt et al (Nätt and Öst, 2020).…”

“…In a sequence of events per enrichment exposure, boars were brushed for two minutes using a broom, showered with water for 30 seconds, and provided with 500 grams of hay as rooting material for the pen floor. Water was supplied ad libitum by a nipple drinker, and the animals were fed a concentrate diet of approximately 2.8 kg/day/boar in troughs daily, proportioned into two meals at 07 h and 13 h. Further details on housing features can be found in Bernardino et al (2022).…”

“…According to the treatment distribution, the animals were classified as having high, medium, or low semen quality and equally distributed among treatment groups. Details about semen quality were previously reported by Bernardino et al (2022).…”

“…Conversely, few scientific studies evaluating the welfare of boars and the consequences on their offspring have been carried out. The scientific literature showed that when boars were exposed to positive environmental conditions, they produced better quality semen (Bernardino et al, 2022). Other studies have shown that piglets born from boars from different genetic lines that received or did not receive herbal diets have different levels of aggressiveness (Aikins-Wilson et al, 2022).…”

Investigating Visual Monitoring of the Scrotum as a Supplementary Tool for Boar Semen Quality Evaluation

“…The lengthy mounting of a boar on a dummy allows thorough visual recording of its visible genital system. On the other hand, the supporting role of the scrotum on the normal spermatogenesis by testicular thermoregulation is well known [ 9 ], while any factor affecting testis reflects semen quality. Artificially induced heat shock environmental conditions, as well as ultrasonographical and thermographic techniques, have been used to study boar scrotum function and sperm susceptibility [ 10 , 11 ].…”