Minimum dietary methionine requirements in Miniature Dachshund, Beagle, and Labrador Retriever adult dogs using the indicator amino acid oxidation technique

Abstract

The objective of this study was to determine the minimum requirement (MR) for methionine (Met), when cyst(e)ine (Cys) is provided in excess, in adult dogs of 3 different breed sizes using the indicator AA oxidation (IAAO) technique. In total, 12 adult dogs were used: 1 neutered and 3 spayed Miniature Dachshunds (4.8 ± 0.4 kg body weight (BW), mean ± SD), 4 spayed Beagles (9.5 ± 0.7 kg BW, mean ± SD), and 4 neutered Labrador Retrievers (31.8 ± 1.7 kg BW, mean ± SD). A deficient Met basal diet with excess Cys was formulated. Dogs were fed the basal diet randomly supplemented with different Met-Alanine (Ala) solutions to achieve final Met concentrations in experimental diets of 0.21, 0.26, 0.31, 0.36, 0.41, 0.46, and 0.66% (as fed basis). After 2 d of adaptation to the experimental diets, dogs underwent individual IAAO studies. During the IAAO study day, total feed was divided in 13 equal meals; at the sixth meal, dogs were fed a bolus of L-[1- 13C]-Phenylalanine (Phe), and thereafter, L-[1- 13C]-Phe was supplied with every meal. Total production of 13CO2 during isotopic steady state was determined by enrichment of 13CO2 in breath samples, and total production of CO2 measured using indirect calorimetry. The mean maintenance requirement (MR) for Met and the upper 95% confidence limit (CL) were determined using a 2-phase linear mixed-effects regression model. For Miniature Dachshunds, the MR for Met was between the first 2 dietary Met concentrations and is therefore between 35.7 and 44.1 mg.kg BW -1.d -1 (0.21-0.26%, as fed basis; no requirement could be determined on a metabolic BW basis). For Beagles and Labrador Retrievers, the MR for Met was 57.5 and 50.4 mg.kg BW -1.d -1, 107.7 and 121.8 mg/kg BW ^0.75 as fed basis, and 0.338 and 0.360%, as fed basis, respectively. The upper 95% CL of Met requirements were 77.9, and 72.4 mg.kg BW -1.d -1 or 147.8 and 159.6 mg/kg BW ^0.75 or 0.458, and 0.517%, (as fed basis) for Beagles, and Labradors, respectively. When pooling data from Beagles and Labrador Retrievers, the MR and upper 95% CL were 56.0 and 75.8 mg.kg BW -1.d -1 or 118.4 and 150.5 mg/kg BW ^0.75 or 0.360 and 0.482% (as fed basis). In conclusion, the MR and the upper 95% CL for Met is different for Dachshunds when compared to Beagles and Labrador Retrievers. Using this low protein diet, the estimated upper 95% CL Met requirement for Beagles and Labrador are higher than those recommended in the NRC (2006), but NRC is similar to the estimated upper 95% CL for Dachshunds.

Plasma and Whole Blood Taurine Concentrations in Dogs May Not Be Sensitive Indicators of Taurine Deficiency When Dietary Sulfur Amino Acid Content Is Reduced

“…To explain the low taurine concentrations that we observed in the LD when given Diet 4, we suggest that dietary SAA requirement of dogs may not scale in parallel with maintenance energy requirement. Supportive of this is recent research indicating the AAFCO minimum for dietary methionine maybe be too low for large dogs ( 43 ). Methionine minimum requirements for Labrador Retrievers were estimated with indicator amino acid oxidation methods to be 0.52 and 0.60% when dietary cystine concentration was greater than that of the methionine ( 43 , 44 ).…”

“…Supportive of this is recent research indicating the AAFCO minimum for dietary methionine maybe be too low for large dogs ( 43 ). Methionine minimum requirements for Labrador Retrievers were estimated with indicator amino acid oxidation methods to be 0.52 and 0.60% when dietary cystine concentration was greater than that of the methionine ( 43 , 44 ). In our research, true digestibility of the SAA could also have differed between the dog groups.…”

Short-term amino acid, clinicopathologic, and echocardiographic findings in healthy dogs fed a commercial plant-based diet

“…However, taurine deficiency has been documented in dogs fed commercial diets that have been formulated to meet the requirements of Association of American Feed Control Officials (AAFCO) Dog Food Nutrient Profiles [ 19 – 22 ]. Potential explanations include breed-related differences in minimum methionine requirements [ 24 ], which are not accounted for by AAFCO, and non-nutrient factors, such as feeding protocols of pet owners, which directly impact caloric intake and nutritional status of pets. More recently, concerns surrounding a possible association between certain commercial diets and dilated cardiomyopathy (DCM)-like disease in dogs have been accumulating [ 22 , 23 , 25 – 27 ], and many of the implicated diets have a nutritional adequacy claim stating the diet has been formulated to meet the requirements of AAFCO Dog Food Nutrient Profiles.…”

Determination of a steady-state isotope dilution protocol for carbon oxidation studies in the domestic cat

“…In pilot trial 1, increasing the priming dose (9⋅4 mg/kg) of L-[1-13 C]-Phe or increasing the priming (9⋅4 mg/kg) together with the constant dose (2⋅4 mg/kg) did not result in steady state of 13 CO 2 in breath samples. Although the latter isotope protocol was successful in producing a steady-state condition of 13 CO 2 in breath of dogs during IAAO studies (15,24,(36)(37)(38)(39) , the enrichment of 13 CO 2 indicates that the Phe pool was overprimed in the present study. Over-priming results in a negative slope following the initial rise in enrichment.…”