SPRING SUMMER BONUS MAGAZINE 2026

The weaning-to-oestrus interval (WOI) is one of themost important reproductive indicators in a commercial sow herd. It reflects howwell the sow transitions from lactation back into the next reproductive cycle. Management during this short, yet intense period, will impact farrowing rate, litter size, sow longevity, and overall farmproductivity. Porcare Maxi Flush – unlock your sows’ natural power during the weaning-to-oestrus interval Annalise Kotzé - Technical Advisor: Monogastric & Ostriches Understanding the weaning to oestrus interval A normal WOI ranges between 4 and 7 days, with 5 days being ideal. It is the period from the day of weaning up to, and including, the first day that the sow shows standing heat. Although this period is short, it is physiologically intense, and therefore, management, nutrition, and environmental conditions must all work together to support optimal reproductive performance. At weaning, the hormonal environment of the sow shifts dramatically. During lactation, follicular activity is suppressed due to the presence of piglets and milk production demands. However, once piglets are removed from the sow, a cascade of hormonal changes begins to restart the reproductive cycle. Understanding this cascade of hormonal changes is very important. Firstly, to support the animals’ changing dietary needs, but also because it creates an opportunity to help sows unlock their full potential in terms of good heat expression and optimal ovulation. Initial post-weaning physiology At weaning, follicles are small (1–2 mm) and produce only low levels of oestrogen. Oestrogen is essential for expression of oestrus; therefore, stimulation of follicle growth must occur quickly after weaning. Removing the suckling stimulus by weaning the piglets from the sow allows the hypothalamus to resume secretion of the Gonadotropin-releasing hormone (GnRH). Hormonal cascade • The hormonal cascade begins in the brain when GnRH stimulates the pituitary gland to release Follicle Stimulating Hormone (FSH) and Luteinizing hormone (LH). • FSH and LH promote follicular growth. Spring/Summer 2026 BONUS www.agribonus.co.za 86