Effects of Dinoprost-Tromethamine and Collection Method on Semen Quality of Commercial Boars

Semen quality is a critical factor for the success of artificial insemination programs in swine production, and is influenced by collection method, genetic lineage, collection interval and pharmacological interventions. This study evaluated the effects of Dinoprost-tromethamine (DP; Lutalyse^®, Zoetis, Parsippany, NJ, USA), a prostaglandin F₂α analog, on boar semen quality in a commercial stud, considering manual versus semi-automatic collection systems, four genetic lines and resting time between collections. A total of 653 boars (146 Large White, 210 Landrace, 282 Duroc and 15 Hybrid [Duroc × Pietrain]) were monitored over 12 months, resulting in 22,977 semen collections. DP was administered intramuscularly as a single dose of 1 mL per boar (6.71 mg of active compound; approximately 0.028 mg/kg body weight), 20 min before semen collection, exclusively to animals classified with low libido (scores 1-3), whereas boars with normal libido (scores 4-6) remained untreated. Semen parameters (ejaculate volume, sperm concentration, total motility and kinematic traits assessed by CASA) were analyzed using mixed-effects models including collection method, DP treatment, genetic line and their interactions. Semi-automatic collection increased ejaculate volume and total motility but resulted in lower sperm concentration compared with manual collection. DP administration increased sperm motility and sperm concentration while reducing ejaculate volume, with the greatest improvement in motility observed in Hybrid boars and more modest or nonsignificant responses in the other genetic lines. Longer collection intervals were associated with higher sperm concentration, whereas ejaculate volume and motility were not affected by resting time. These findings indicate that the impact of DP, collection method and collection interval on semen quality is breed-dependent and highlight the need to tailor reproductive management protocols according to boar genetics, libido and collection technology.