Nutritionists can choose from a diverse and growing array of protein sources for their feed formulations. While this choice will be informed by a variety of factors, including cost and sustainability, one of the most important is the question of digestibility, which will have an effect on the gut health and performance of the animal.
However, according to Lallemand Animal Nutrition, an evaluation of different protein sources should not stop at digestibility, but instead should also consider how quickly proteins are absorbed. As explained by Lisa Saibi, Product Manager for Yeast Derivatives and Antioxidants, and Bruno Bertaud, Technical Manager for Yeast Derivatives and Swine Solutions, the process of hydrolysis can improve the kinetics of yeast protein digestibility. This, they argue, is the key to how Lallemand Animal Nutrition’s YELA PROSECURE can serve as a high-quality protein source for applications where rapid and complete digestibility is particularly desirable, such as in diets for young animals (like weaning piglets, puppies and kittens) or for certain specialty pet foods.
[Feedinfo] Why is it important to consider the absorption kinetics in addition to digestibility to properly assess the quality of a protein source?
[Bruno Bertaud] Protein digestibility of feed ingredients is an important piece of information for nutritionists, but it does not express the timing of absorption in the gut. Looking at the kinetics of protein absorption, in addition to protein digestibility, allows nutritionists to properly assess the quality of the protein source, as many properties and functionalities of proteins are related to their absorption kinetics.
[Feedinfo] How is the speed of protein absorption in the gut expressed?
[Bruno Bertaud] The kinetics of protein absorption helps categorize the protein fraction according to its speed of absorption. Four categories can be defined – flash, fast, slow and resistant – depending on how far along the digestive tract they reach before being digested
Flash digestion occurs under 1 hour, and refers to the fraction absorbed in the stomach. If a protein is absorbed within 1 to 3 hours, the absorption is considered fast and occurs in the small intestine. After that, we consider everything absorbed in the large intestine as slow (from 3 to 24 hours after intake).
The resistant category corresponds to the non-digested proteins that can be used as substrate for undesirable bacteria in the gut, inducing proteolytic fermentation. Ultimately, this may lead to diarrhea due to microbiota dysbiosis.
Therefore, the higher and faster the protein digestibility, the greater the protein source for animals from a digestive standpoint.
[Feedinfo] YELA PROSECURE is a specifically designed hydrolyzed yeast. Can you tell us more about that process?
[Lisa Saibi] Depending on their production process, their nutritional and functional properties, their affordability and their volume availability, different types of inactivated yeast can be found in the animal nutrition market.
For YELA PROSECURE, a hydrolysis process is applied with the addition of specifically selected enzymes to the biomass, to orient and control the lysis, ensuring a high nutrient digestibility and functionality while providing reliability in terms of product composition.
To produce YELA PROSECURE, our R&D team has long been working on the screening of different feed-grade yeast biomasses and on the optimization and standardization of the hydrolysis process.
[Feedinfo] How does that influence the protein absorption kinetics of YELA PROSECURE?
[Lisa Saibi] The bioavailability of a protein is strongly related to its amino acid composition, size, and mass range. Big proteins, protein-associated molecules and nucleic acids have lower digestibility compared to free amino acids and small peptides. Beyond that, supplying animals with a protein source that is already processed and rich in free amino acids and small peptides as it is the case for YELA PROSECURE helps ensure better absorption in the gut.
Let’s take an example by comparing the protein digestibility kinetic of YELA PROSECURE to a whole cell inactivated yeast, where no lysis process is applied, and most nutrients (including the proteins) are in the cytoplasm of the yeast cell, making them less accessible.
Whole cell inactivated yeast protein digestibility was measured at 46% right after the stomach, and increases slowly, up to 60% after 3 hours, while for YELA PROSECURE, a hydrolyzed yeast, we observed 77% protein digestibility after the stomach, and more than 90% after 3 hours of the intestinal phase.
It is then clear that the yeast lysis process strongly benefits protein digestibility kinetics and therefore nutrient bioavailability in the gut.
[Feedinfo] Lallemand claims that 90.5% of the protein content of YELA PROSECURE has “flash and fast digestibility kinetics and only 9.5% is slow and resistant.” How did you arrive at this figure? How does that compare to other feed ingredients?
[Lisa Saibi] This is correct. We measured the kinetics of protein absorption by using the Boisen method (Boisen and Fernandez, 1995 and modified by Chen, 2019), recognized as being very accurate in measuring the in-vitro protein digestibility. This is calculated from the difference between the nitrogen in the raw material sample and that in the undigested residue, measured at different time points of the intestinal phase.
With YELA PROSECURE, the maximum in vitro digestibility was observed after 3 hours of intestinal digestion meaning that 90.5% of the protein content of YELA PROSECURE has flash and fast digestibility kinetics and only 9.5% is slow and resistant. The proteins from YELA PROSECURE are, therefore, highly bioavailable for the animals.
We have also measured the protein digestibility kinetic of other feed materials which might be used as protein sources: blood plasma, whey protein concentrates and YELA PROSECURE all showed superior kinetics of protein digestibility compared to soybean meal, fish meal, soy protein concentrates and potato protein concentrate.
[Feedinfo] In light of YELA PROSECURE’s protein digestibility profile, for what applications is it most suitable, and why?
[Bruno Bertaud] YELA PROSECURE can be used in all animal species. Supplying animals with a flash and fast digestible protein source, rich in free amino acids and small peptides, will help them easily absorb and use those nutrients. It will support animal performance, digestive health and feed intake/appetite regulation while contributing to the feed protein balance. This is particularly of interest when applied to young animals or sensitive stages of an animal's development where the amino acids requirements are high, for instance around weaning. At this physiological stage, the inflammatory challenge induced by the weaning is also increasing the amino acids requirements.
Moreover, in addition to the properties we have already discussed, YELA PROSECURE contains a large proportion of functional dietary fibers, mainly insoluble, that will be used by hindgut microbial population, leading to fiber fermentation.
This fiber fermentation produces short chain fatty acids (SCFAs) that are well known to help maintain optimal gut integrity with closed tight junctions, reduce inflammation and modulate the gut microbiota, thus improving animals’ growth performance.
In addition, some free amino acids are also involved in the mechanism of taste and eating behavior including feed intake, therefore playing a role in food palatability. This is of particular interest for petfood formulation, as illustrated by some dog preference trials.
YELA PROSECURE is also a valuable source of B vitamins and minerals.
For more information, download Lallemand Animal Nutrition’s technical article about protein digestibility kinetics and the potential of a functional hydrolyzed yeast, available here.
Published in association with Lallemand Animal Nutrition