Piglet Management and Feeding Strategies to Protect Post-Weaning Health and Improve Performance

Weaning is a stressful phase for piglets as the maternal bond is lost, there is an abrupt change in the conditions of the environment, breastfeeding is replaced with dry feed, and intestinal adaptation to the new diet is required (Boston et al., 2022; Cera et al., 1988; van Beers-Schreurs et al., 1998). This phase can, therefore, negatively impact the growth and productive performance of piglets, since there is a reduction in food intake and an increased chance of gastrointestinal disorders (Jayaraman & Nyachoti, 2017; Leibbrandt et al., 1975). To minimize the deleterious effects caused by post-weaning stress, some strategies during the pre-weaning phase can be implemented, such as supplemental feeding, socialization, providing toys in the farrowing crate, and the proper sizing or placement of pigs during cross-fostering. These strategies aim to increase the survival rate, improve intestinal health, and enhance the overall growth performance of the piglets.

In industrial pig farming, the piglets are weaned at early ages to increase pigs/sow/year production. The weaning period was gradually reduced from 40 to 50 days (late weaning), to 35, 28, or 21 days (early weaning), and may even occur when piglets are less than 21 days old (super early weaning) (Valentim et al., 2021). When very young, the physiological metabolism of piglets is still immature — which contributes to post-weaning issues such as gastrointestinal dysfunction, low immunity, and stress. Studies have shown that increasing the weaning age from 19 to 22, 25, or 28 days improved overall performance, produced positive effects in the nursery, and increased the number of pigs reaching market weight (Faccin et al., 2020). Coincidentally, weaning piglets at 21 days had more negative impacts on growth rate and stress endocrine responses than weaning at 28 days (Colson et al., 2006). According to a meta-analysis of the relationship between weaning age and daily weight gain of piglets in the farrowing and nursery phases, results suggest that the optimal age of weaning piglets appears to be between 26 and 32 days, at which point piglets are physiologically ready to switch from milk to a dry diet and are able to use other complex carbohydrates as their main sources of energy (Valentim et al., 2021). Therefore, the age that piglets are weaned is closely correlated to the level of adaptation in the nursery, as well as future performance.

Some farms do split suckling during the colostrum phase and/or milk phase. This practice consists of separating, soon after farrowing, the heaviest half of piglets born from the sow and placing them under a heat lamp for a couple of hours to allow the smaller piglets to suckle more milk and keep up with the weight of their larger siblings (Morton et al., 2019). According to Morton et al. (2019) both litter order and piglet birth weight affect access to colostrum and maternal IgG, with birth weight more strongly affecting colostrum intake, and birth order having a greater effect on immunocrit. On the other hand, Vandaele et al. (2020) reported that when split-suckling was applied on the first day of life, piglet performance was neither improved nor impaired, but growth was impaired when litters were intensively split-suckled during the first three days of life.

Another strategy used to equalize litter size is cross-fostering. In this approach, the heaviest or the smallest piglets can be moved to a foster sow, after colostrum intake, matching the litter size to the number of functional teats on the sow. Vande Pol et al. (2021) observed that cross-fostering was beneficial for light piglets, detrimental for heavy ones, and neutral for medium-sized piglets. Similarly, Zhang et al. (2021) reported that cross-fostering within 24 hours of birth has adverse influences on the average daily gain of high birth weight piglets, while having no negative effect on the average daily gain of low birth weight and intermediate birth weight piglets. Moreover, late cross-fostering (day 7 after farrowing) of intermediate birth weight piglets has a negative impact on the growth performance and teat order of piglets, and it increases the stress level of the piglets (Zhang et al., 2021).

Creep feed is especially important for sows with large litters and needs to be provided early in life to stimulate the development and maturation of piglets’ gut microbiome. It also stimulates feed intake and contributes to a reduction of pig body weight variability from weaning onwards (Solà-Oriol & Gasa, 2017). Besides creep feed, the sire line growth pattern seems to result in growth performance differences of early and late maturing progeny according to Wensley et al. (2022). Early maturing pigs had improved growth performance and decreased stress immediately after weaning until 136 days of age, with little impact of creep feed on these pigs. On the other hand, creep feeding resulted in improved post-weaning growth performance of late maturing pigs, when compared to late maturing pigs that were not offered creep feed. In addition, late maturing pigs without creep feed had increased intestinal permeability which may have contributed to their poorer growth performance (Wensley et al., 2022).

Supplemental liquid milk can be offered with a solid starter diet to newly weaned piglets, so the piglets get used to a solid diet (DeRouchey et al., 2010). It has been reported that piglets fed liquid creep-feed have faster growth (Toplis et al., 1999) and increased villi length after weaning (Deprez et al., 1987), although Lawlor et al. (2002) reported no consistent effects of feeding liquid diet to suckling piglets. Just like creep feeding, milk replacer supplementation has beneficial effects on piglets’ weaning body weight and survival (Wolter et al., 2002; Zijlstra et al., 1996).

The spray-dried plasma from bovine, porcine, or mixed animal species has also been widely used as a highly digestible protein source that can improve the average daily weight gain of piglets (reviewed by Balan et al., 2021). It can also modulate their immune response, since it has immunoglobulins, growth factors, and other biological compounds that can positively affect the immune response of the urogenital system, bronchoalveolar tissue, and gut-associated lymphoid tissue, reducing the incidence of post-weaning diarrhea (Solà-Oriol & Gasa, 2017). Because it is an expensive product, it is recommended to only provide it during the first 7 to 10 days after weaning.

Familiarizing non-littermate piglets during lactation by creating piglet doors between adjacent farrowing pens, providing access to an additional piglet area, and allowing piglets and sows to interact freely in group-housing systems can reduce fighting at weaning and enhance socio-cognitive development, which enables them to form stable dominance hierarchies more rapidly, and contributes to greater familiarization with creep feed (D’Eath, 2005; Salazar et al., 2018). Furthermore, some recent research findings demonstrate that early socialization and neonatal environmental enrichment with toys impacts piglets’ caecal microbiota positively, affects their fecal microbe composition, changes intestinal mucosal gene expression related to nutrient metabolism and absorption, and reduces energetic metabolism – all of which are consistent with reductions in aggression and social stress (Bi et al., 2022; Saladrigas-García et al., 2021).

Because of the behavioral, biological, and immunological changes that are occurring simultaneously at the time of weaning, proper attention to nutrition, management, and the environment are all essential for the newly weaned pig to start out well. A lapse in just one of these areas can cause problems in the nursery and in subsequent growing periods. Their survival depends on the early intervention and management strategies used by production staff.