WINTER BONUS MAGAZINE 2026

Gestation phase-specific requirements The gestation period in a sow can be divided into three distinct physiological phases, each characterised by different nutrient demands: • Early gestation (day 0–42): Embryo implantation and maternal recognition of pregnancy occur during this period. Nutritional stability and low stress are critical, as disruptions can result in early embryonic loss. Feeding should support recovery from lactational body reserve losses, particularly in young sows. • Mid-gestation (day 43–84): Foetal growth is limited, and nutrient requirements are relatively low. This phase is well suited for step-down feeding once body condition recovery is achieved. • Late gestation (day 85–115): Foetal growth accelerates exponentially, with rapid increases in foetal weight and nutrient demand. Udder development and colostrum synthesis also intensify, necessitating step- up feeding with adequate energy and amino acid supply. Step-up feeding strategies Gilt development and first gestation Proper gilt development is a prerequisite for successful step-up feeding during the first gestation. Target growth rates of approximately 600–650 g/day result in optimal body weight (140–170 kg) and age at first insemination. Adequate backfat at insemination (12–15 mm) is essential, as body fat serves as a critical energy reserve during lactation. Following insemination, gilts benefit from a step-up gestation feeding programme that supports continued maternal growth and litter development. Compared with multiparous sows, gilts require higher nutrient density, particularly for amino acids, minerals, and vitamins that support skeletal development and reproductive function. Late gestation step-up feeding During late gestation, foetal weight increases from approximately 400 g on day 85 to more than 1 400 g on day 115. Growth during this phase is predominantly lean tissue accretion, making adequate protein and amino acid supply critical. Insufficient nutrient provision during late gestation is associated with reduced piglet birth weight, impaired colostrum production, and increased pre-weaning mortality. Figure 1: An example of a step-up feeding schedule focused on gilts. Values are dependent on feed type and animal conditions. www.agribonus.co.za Winter 2026 BONUS 39