Using Nutritional Strategies to Shape the Gastro-Intestinal Tracts of Suckling and Weaned Piglets

Abstract

This is a comprehensive review on the use of nutritional strategies to shape the functioning of the gastro-intestinal tract in suckling and weaned piglets. The progressive development of a piglet's gut and the associated microbiota and immune system offers a unique window of opportunity for supporting gut health through dietary modulation. This is particularly relevant for large litters, for which sow colostrum and milk are insufficient. The authors have therefore proposed the use of supplemental milk and creep feed with a dual purpose. In addition to providing nutrients to piglets, supplemental milk can also serve as a gut modulator in early life by incorporating functional ingredients with potential long-term benefits. To prepare piglets for weaning, it is important to stimulate the intake of solid feed before weaning, in addition to stimulating the number of piglets eating. The use of functional ingredients in creep feed and a transition diet around the time of weaning helps to habituate piglets to solid feed in general, while also preparing the gut for the digestion and fermentation of specific ingredients. In the first days after weaning (i.e., the acute phase), it is important to maintain high levels of feed intake and focus on nutritional strategies that support good gastric (barrier) function and that avoid overloading the impaired digestion and fermentation capacity of the piglets. In the subsequent maturation phase, the ratio of lysine to energy can be increased gradually in order to stimulate piglet growth. This is because the digestive and fermentation capacity of the piglets is more mature at this stage, thus allowing the inclusion of more fermentable fibres. Taken together, the nutritional strategies addressed in this review provide a structured approach to preparing piglets for success during weaning and the period that follows. The implementation of this approach and the insights to be developed through future research can help to achieve some of the most important goals in pig production: reducing piglet mortality, morbidity and antimicrobial use.

Keywords: creep feed; early life; feed intake; gut function; health; nutrition; pig; post-weaning; pre-weaning; supplemental milk.

Figure 4

Interactions between the passage rate of digesta and feed intake. AA = amino acids, CCK = cholecystokinin, GLP-1 = glucagon-like peptide 1, GIP = glucose-dependent insulinotropic polypeptide, HCl = hydrochloric acid, PYY = peptide YY, SCFA = short-chain fatty acids. The figure is adapted from Giger-Reverdin et al. [152] and Lee et al. [167].

Figure 1

Effect of litter size on birth-weight distribution. The data were collected at Schothorst Feed Research B.V. (Lelystad, The Netherlands) from 2011 to 2019, based on 97,552 piglets born alive from 7888 litters.

Figure 2

Box plots representing individual variation in digesta pH of the stomach and the ileum 4 h after the piglet’s last meal. Piglets were ± 47 days of age (3 weeks post-weaning). Average stomach pH was 4.04 (SD = 0.991) and average ileal pH was 7.03 (SD = 0.323). The data represent 213 individual piglets that were fed one of 31 experimental diets containing protein-rich feedstuffs (6–8 piglets/experimental treatment; between 2017 and 2020 at Schothorst Feed Research B.V., Lelystad, The Netherlands). The pH of the stomach was measured in the stomach content after thorough mixing. Ileal digesta were taken from the last 2 m of the small intestine and mixed before measuring the pH value.

Figure 3

Relationship between the acid-binding capacity (ABC)-4 value of the complete diet and stomach pH. (A) shows the correlation between the ABC-4 value of the complete diet and stomach pH. The data represent the ABC-4 value of 31 experimental diets containing protein-rich feedstuffs (6–8 piglets/experimental treatment) (between 2017 and 2019; Schothorst Feed Research B.V., Lelystad, The Netherlands). The ABC-4 value was measured in meq/kg using the methodology described by Lawlor et al. [151]. Each dot represents the average stomach pH per dietary treatment. (B) shows the effect of acidifying the complete diet on individual stomach pH. The experimental diets contained one of three different protein-rich feedstuffs that are known for their high (i.e., fish meal), intermediate (i.e., Hi-Pro Soybean Meal) and low ABC-4 value (i.e., maize gluten). The values displayed in (B) represent the stomach pH from all protein-rich feedstuffs together. The low ABC-4 diets were acidified by replacing limestone with calcium formate (either completely or partially) and adding citric acid. The unaffected diets did not contain organic acids. The average ABC-4 values of the unaffected diet were 308 meq/kg (SD = 26), with a value of 243 meq/kg (SD = 95) for the low ABC-4 diets. The average stomach pH of the unaffected diet was 4.22 (SD = 0.997), with a value of 3.57 (SD = 1.075) for the low ABC-4 diet.

Figure 5

Differences in the viscosity of diets based on wheat, barley and maize under different heat-processing conditions. The data were collected at Schothorst Feed Research B.V. (Lelystad, The Netherlands). The respective diets consisted of 60% maize, 60% wheat or 60% barley, and they were pelleted at 70 °C, pelleted at 90 °C or expander pelleted at 120 °C. Viscosity was measured after 15 min according to the method developed by Bedford and Classen [177].

Scheme 1

Summary of physiological changes and nutritional strategies for weaned piglets during the acute (Week 1 post-weaning) and maturation (from Week 1 to Weeks 5–6 post-weaning) phases.