Nutrient digestion kinetics is a crucial aspect of pig nutrition, focusing on the rate and location of nutrient digestion and absorption within the gastrointestinal tract. This approach goes beyond traditional nutrient digestibility, which only provide static coefficients for nutrient absorption without considering the dynamics of digestion.

Techniques such as in vitro and in vivo models are used to determine the digestion kinetics of various feed ingredients. This information is crucial for developing diets that meet the dynamic nutrient needs of pigs. Protein digestion kinetics is the rate at which proteins are broken down and absorbed in the small intestine. Fast proteins are quickly digested and absorbed, supporting rapid growth in young pigs. Slow and resistant proteins lead to post-weaning diarrhea (PWD) if not managed properly in weaned pigs. In lactating sows on the other hand, slow protein increased milk production. Dietary fiber kinetics involves the fermentation rate of dietary fiber in the gastrointestinal tract. Fast fibers promote beneficial gut bacteria and short-chain fatty acids, while resistant fibers, though not fermented, play a role in gut health by reducing transit time and limiting fermentation. A global feeding system was thus created by quantifying the protein digestion kinetics and fiber fermentation kinetics of feed ingredients. The ingredient matrixes for protein and fiber kinetics was also determined to be additive in mixed diets. Finally, nursery pig and sow feeding recommendations were determined by observing the response of pigs and sows fed diets differing in protein and fiber kinetics. This allowed nutritionists and formulators to steer formulations towards different rates and combinations of protein and fiber fermentation and releasing ingredient constraints. This led to greater formulation flexibility and cost reduction potential. It was also observed that a stronger understanding of the interaction between protein and fiber kinetics within this feed system allowed feed formulations to be tailored to enhance nutrient utilization, leading to better growth performance and reduced nutrient excretion. Further, this interaction between protein digestion kinetics and fiber fermentation kinetics helps in maintaining gut health by ensuring that nutrients are available at the right locations in the digestive tract, supporting the gut microbiome and preventing digestive issues. In summary, nutrient digestion kinetics provides a more comprehensive understanding of the rate and location at which nutrients are processed in the pig’s digestive system. This knowledge allows for the formulation of more effective and health-promoting diets, ultimately enhancing the overall productivity and well-being of pigs.

Jaworski, N. 2025. Importance of the kinetics of protein digestion to the practical formulation of swine diets. 2025 American Society of Animal Science Midwest Section meeting, Abstract 256.