Adult dogs of different breed sizes have similar threonine requirements as determined by the indicator amino acid oxidation technique

Abstract

Threonine (Thr) requirements for immature (growing) Beagles have been determined, but little knowledge is available on Thr requirements for maintenance in mature dogs. Moreover, differences of Thr requirements among different breeds or sizes of adult dogs have not been investigated. The objective of the present study was to determine Thr requirements in adult dogs of three different breeds using the indicator amino acid oxidation (IAAO) technique. In total, 13 adult dogs were used, 4 Miniature Dachshunds (5.8 ± 0.4 kg body weight [BW]; 3 spayed and 1 neutered), 4 spayed Beagles (9.3 ± 0.6 kg BW), and 5 neutered Labrador Retrievers (30.5 ± 1.7 kg BW). Dogs were fed a Thr-deficient diet (Thr = 0.23%) and randomly allocated to receiving one of seven concentrations of Thr supplementation (final Thr concentration in experimental diets was 0.23%, 0.33%, 0.43%, 0.53%, 0.63%, 0.73%, and 0.83%; as fed basis) for 2 d. After 2 d of adaptation to the experimental diets, dogs underwent individual IAAO studies. During the IAAO studies, total daily feed was divided into 13 equal meals; at the sixth meal, dogs were fed a bolus of l-[1-13C]-Phenylalanine (Phe) (9.40 mg/kg BW), and thereafter, l-[1-13C]-Phe (2.4 mg/kg BW) was supplied with every meal. Before feeding the next experimental diet, dogs were fed a Thr-adequate basal diet for 4 d (Thr = 0.80% as fed basis) in known amounts that maintained individual dog BW. 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 requirements for Thr, defined as the breakpoint, and the 95% confidence interval (CI) were determined using a two-phase linear regression model. For Miniature Dachshunds, the two-phase model was not significant, and Thr requirements could not be determined. Mean Thr requirements for Beagles and Labradors were 72.2 and 64.1 mg/kg BW on an as-fed basis, respectively. The requirement for Thr between these two dog breeds was not different (P > 0.10). Thus, the data for Beagles and Labradors were pooled and a mean requirement for Thr was determined at 66.9 mg/kg BW, and the 95% CI was estimated at 84.3 mg/kg BW. In conclusion, estimated Thr requirements for Beagles and Labradors did not differ, and these recommendations are higher than those suggested by NRC (2006) and AAFCO (2014) for adult dogs at maintenance.

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

“…Similar to other studies presented by our lab ( Mansilla et al, 2018 , 2020 ; Templeman et al, 2019 ; Sutherland et al, 2020 ), calorimetry data remained similar at all levels of Met supplementation, indicating no differences in AA or nutrient metabolism with increasing levels of Met supplementation. The animals used for the present experiment have been used for similar studies ( Mansilla et al, 2018 , 2020 ; Templeman et al, 2019 ; Sutherland et al, 2020 ); therefore, the calorimetry data are comparable to data published elsewhere. The higher REE (kcal/BW 0.75 ) in Labrador Retrievers compared with Beagles and Miniature Dachshunds is, however, not consistent with our previous results.…”

“…This study is part of a series of experiments where the requirements of Phe, Trp, Thr, and Lys for adult dogs of different breeds have been previously estimated using the IAAO technique ( Mansilla et al, 2018 , 2020 ; Templeman et al, 2019 ; Sutherland et al, 2020 ). It should be noted, though, that in all these reports (including the present study), only spayed and neutered dogs were used.…”

“…Those techniques are directly related to increments in whole-body protein mass and, therefore, are not suitable for adult dogs at maintenance. We have previously estimated phenylalanine (Phe), tryptophan (Trp), threonine (Thr), and lysine (Lys) requirements in adult dogs of different breeds using the IAAO technique and found that Phe requirements are lower ( Mansilla et al, 2018 ) and Trp, Thr, and Lys requirements are higher ( Templeman et al, 2019 ; Mansilla et al, 2020 ; Sutherland et al, 2020 ) than those recommended by NRC (2006) .…”

Lysine requirements in small, medium, and large breed adult dogs using the indicator amino acid oxidation technique1

“…The indicator AA oxidation (IAAO) technique results in requirement estimates greater than those obtained with nitrogen balance studies and is a more accurate method of determining requirement estimates, especially at maintenance ( Bross et al, 1998 ; Moehn et al, 2004 ). The IAAO method has been applied and validated in several species, including dogs ( Shoveller et al, 2017 ), and since used to measure the phenylalanine (Phe; Mansilla et al, 2018 ), tryptophan (Trp; Templeman et al, 2019 ), and threonine (Thr; Mansilla et al, 2020 ) requirements of adult dogs. Previously, we reported no differences in Phe requirements for three breeds of dog, but Beagles had a greater Trp requirement than Labrador Retrievers and Miniature Dachshunds ( Mansilla et al, 2018 ; Templeman et al, 2019 ).…”

“…Previously, we reported no differences in Phe requirements for three breeds of dog, but Beagles had a greater Trp requirement than Labrador Retrievers and Miniature Dachshunds ( Mansilla et al, 2018 ; Templeman et al, 2019 ). Beagles and Labrador Retrievers had similar Thr requirements, but a requirement could not be determined for Miniature Dachshunds ( Mansilla et al, 2020 ). All estimates of AA requirements are greater than those currently recommended by NRC (2006) and the affiliated regulatory bodies.…”