Use of the precision-fed cecectomized rooster assay to determine standardized amino acid digestibility, true metabolizable energy content, and digestible indispensable amino acid scores of plant-based protein by-products used in canine and feline diets

Abstract

Traditionally, protein by-products from oil seeds and cereal grains have been used in pet foods as sustainable, inexpensive, and protein-rich ingredients. However, the on-going demonization of soy- and corn-based ingredients continue to hinder their use in pet food and treat formulations. Ideally, the further demonstration of their protein quality and nutrient composition may encourage their favorable return as acceptable ingredients in pet foods and treats. Therefore, the objectives of this study were to determine the macronutrient composition, indispensable amino acid profile, standardized amino acid digestibility, true metabolizable energy content corrected for nitrogen (TMEn), and digestible indispensable amino acid scores (DIAAS-like) of soy flakes (SF), peanut flour (PF), soybean meal (SBM), and corn gluten meal (CGM). Standardized amino acid digestibility was assessed using the precision-fed cecectomized rooster assay. All test ingredients demonstrated a profile of highly digestible indispensable amino acids except for lysine in PF, which was lowest (P < 0.05) at 45.5%. The SBM and CGM had the highest (P > 0.05) digestibilities of indispensable amino acids. A DIAAS-like values was calculated for each ingredient using either AAFCO (2020) recommended values or NRC (2006) recommended allowances as the reference protein pattern. For adult dogs compared to AAFCO recommended values, the first-limiting amino acid was lysine for PF and CGM but it was methionine for SF and SBM. For adult cats compared to AAFCO recommended values, the first-limiting amino acid was lysine for PF and CGM but it was threonine for SF. There was no first-limiting amino acid in SBM for cats as DIAAS-like values were over 100% for all indispensable amino acids. The TMEn values were highest (P < 0.05) for PF and CGM (4.58 and 4.31 kcal/g [dry matter basis], respectively). The protein quality of these plant-based protein by-products reflect their value as nutritional ingredients for canine and feline diets. However, the prior processing of these by-products must be considered before exposing them to additional processing methods, such as extrusion. Additionally, the inclusion of complementary proteins or supplemental amino acids will be needed to meet all indispensable amino acid requirements for a nutritionally complete and balanced pet food.

Digestible indispensable amino acid scores of animal and plant ingredients potentially used in dog diet formulation: how this protein quality metric is affected by ingredient characteristics and reference amino acid profile

“…Fundamentally, the most appropriate IAA reference patterns to apply for dogs are based on MR estimates established by the NRC (2006) for adult dogs and growing puppies, as these represent physiological IAA requirements. Though, based on the pet food industry’s reliance on practical dietary IAA recommendations presented by AAFCO and FEDIAF as well as the recent literature reporting “DIAAS-like” values for dog food ingredients calculated using reference patterns based on IAA recommendations from these regulatory bodies ( Oba et al, 2019 ; Do et al, 2020 ; Reilly et al, 2020a , 2020b , 2021 ; Gomez et al, 2021 ), we sought to assess the degree to which using these reference patterns may affect the PQ interpretation.…”

“…In brief, what this suggests is that, yes, using reference IAA patterns based on these AAFCO or FEDIAF recommendations will generate different DIAAS-like values than those determined using NRC MR estimates; however, these data must be interpreted with caution as these reference patterns no longer represent the physiological requirements of the dog, but rather account for assumed digestibility of the protein source. That being acknowledged, with the propensity of the pet food industry to rely on the recommendations presented by AAFCO and FEDIAF for commercial formulation purposes, and with the recent literature assessing PQ of ingredients intended for dog diet formulation using reference IAA patterns based on these regulatory bodies ( Oba et al, 2019 ; Do et al, 2020 ; Reilly et al, 2020a , 2020b , 2021 ; Gomez et al, 2021 ), it may be valuable to assess the extent to which using these reference patterns may affect the PQ interpretation.…”

“…In the case of dogs, this would refer to IAA reference patterns based on minimal requirement ( MR ) estimates established by the NRC (2006) for adult dogs as well as for growing puppies. However, in recent years, a number of reports have been published wherein DIAAS for protein ingredients potentially used in commercial dog diet formulation have been calculated using reference patterns based on physiological IAA requirements from the NRC as well as practical dietary IAA recommendations from pet food regulatory bodies, such as AAFCO ( Oba et al, 2019 ; Do et al, 2020 ; Reilly et al, 2020a , 2021 ; Gomez et al, 2021 ). It should be noted, though, that for each of these aforementioned reports, DIAAS values generated were referred to as “DIAAS-like” values, and the DIAAS equations utilized were adapted from the equation defined by the FAO (2013) so as to capture the fact that the IAA reference pattern utilized was generated using the “minimum protein recommendation” ( Oba et al, 2019 ) rather than a “reference protein” ( FAO, 2013 ).…”

Comparative In Vitro Digestion and Intestinal Absorption Simulation of Chicken Protein, Wheat Gluten, and Their Hydrolyzed Analogues for Canine and Feline Nutritional Supplement

“…As the pet food market continues its robust growth, the demand for novel protein sources is increasing to cater to the development of innovative products and meet specific dietary needs of animals. 1 Currently, pet food formulations primarily rely on animal-derived proteins, such as meats and meat byproducts, due to their rich amino acid profile and high nutritional value. However, with growing concerns over sustainability and cost-effectiveness, the modern pet food industry is exploring plant-based protein sources like legumes and grains.…”

“…Currently, pet food formulations primarily rely on animal-derived proteins, such as meats and meat byproducts, due to their rich amino acid profile and high nutritional value. However, with growing concerns over sustainability and cost-effectiveness, the modern pet food industry is exploring plant-based protein sources like legumes and grains . These emerging protein sources, while environmentally friendly and economical, exhibit significant differences in nutritional value, digestibility, and bioavailability compared with traditional animal proteins.…”