In the post-weaning period, the pigs’ microbiological ecosystem is subject to massive fluctuations and they experience significant changes in their gut physiology, microbiology and immunology. Therefore, post-weaning pigs are more susceptible to intestinal and immunological disorders than older pigs.
One of the most common beneficial bacterial groups in pig intestines that are reduced after weaning is the genus Lactobacillus. The absence of these beneficial bacteria associated with the mucous membrane allows harmful bacteria to attach to intestinal cells and multiply, with negative consequences for gut health.
Consumer pressure to reduce antibiotics
Due to public demand to reduce the use of antibiotics in pig production, dietary intervention is recognized as an important factor in improving post-weaning gut health. Studies suggest that dietary calcium supplementation is a possible strategy for modulating the gut microbiota in pigs, reducing the number of harmful bacteria and increasing the number of lactobacilli. Therefore, regulation of dietary calcium levels is essential to improve pig health and performance.
Calcium is the main mineral component of the skeletal system and is an essential nutrient needed for blood clotting, nerve conduction, muscle contraction, endocrine and hormone secretion at all stages of growth, pregnancy and lactation.
Calcium requirement in pigs
The National Research Council estimates the requirement of 0.66% calcium for breeding pigs weighing 25-50 kg. The requirements are higher for younger pigs and lower for fattening pigs. In pregnant and lactating sows, calcium requirements are influenced by gestation stage, mating and milk production. The higher calcium requirement during late pregnancy is due to the rapid development of the fetus.
Factors affecting the gut microbiota in pigs
Gut microbiota composition and distribution can coevolve with the host and can be subtly influenced by various factors such as host factors, diet, feeding management and environment, and feed additives. Host factors consist of gut region, age and growth stage, breed, sex, and production capacity. The diet includes feed type, feed ingredients, energy source, protein limitation and amino acid balance. Feeding management and environment includes weaning, altitude, region, feeding mood and maternal factors. Feed additives include antibiotics, probiotics, prebiotics, essential oils and organic acids.
Gut Microbiota and Gut Integrity: How Does Dietary Calcium Work?
Calcium levels in the feed above requirements are considered to be detrimental to the health of pigs after weaning, as it may impair intestinal barrier function. However, there is evidence that adequate intake of dietary calcium can regulate the gut microbiota of pigs and also promote gut integrity. Diets high in calcium, containing 10-15 g calcium per kg, increase the growth of Lactobacillus species in the gut of growing or weaning pigs. In general, calcium intake over 14 days increases Clostridium clusters in the ilea, caeca, and colon of weaned pigs. Several types of Clostridium clusters produce butyrate, which is an important source of energy for intestinal cells. The stage of intestinal maturation is another factor affecting the composition of the gut microbiota. For example, Enterococcus species decrease and increase in the ileum in growing and weaned pigs after calcium supplementation.
The composition of the feed has a major impact on the pig gut microbiota and represents a useful preventive tool against gut disorders in post-weaning pigs. The gut microbiota communities of pigs are subtle to several internal and external factors. In relation to the public demand to reduce the use of antibiotics in pig production, dietary intervention to promote gut health and integrity is now receiving more attention. Therefore, information on the selective stimulation of certain beneficial bacterial groups in the feed formulation for pigs in the post-weaning period may be useful.