Practical approach to determine apparent digestibility of canine diets

Abstract

A practical approach to determine apparent faecal digestibility using privately owned dogs may be a useful tool in evaluating differences in nutrient digestibility between dogs with various life stages. The aim was to develop a simple method that would suit such studies using the whitening agent titanium oxide (TiO2) as an indigestible marker. Forty privately owned, healthy male and female dogs of various breeds were included. Selection was based on an owner questionnaire. Means with their standard errors age and body weight (BW) of the dogs were 6·2 (0·6) years (range 1·0–13·0 years) and 22·3 (2·5) kg (range 5·0–43·2 kg), respectively. Owners were provided a commercial dry extruded diet supplemented with a commercially available TiO2 containing kibble (final dietary TiO2 content: 0·77 g/kg). Dogs were fed the diet for seven consecutive days at 480 kJ × BW0·75. On day 7, owners were asked to collect all faeces during 24 h and store faeces at −20°C. Faecal samples were analysed for DM, ash, N, crude fat (CF), crude fibre and Ti and gross energy (GE) and organic matter were calculated. Means with their standard errors apparent faecal digestibility of GE, DM, organic matter, N, CF and crude fibre was 83·7 (0·71), 77·4 (0·79), 83·0 (0·61), 77·7 (0·81), 94·3 (0·51) and 30·3 (4·85), respectively. No significant differences were observed in nutrient digestibility due to weight, age, sex or neuter status. The digestibility assay using a practical approach described here may be a promising tool to determine digestibility of dietary nutrients under free-living conditions. Owner compliance, however, is a potentially limiting factor.

Determining the protocol requirements of in-home dog food digestibility testing

“…The present variation in digestibility values could be partly explained by individual dog characteristics [4][5][6][7]9 , including sex, neuter status and age, but not body size. Male dogs tended to have higher digestibility values for OM, Cfat and GE, which might need further validation as this is contradictory to an earlier finding by Hagen-Plantinga et al 12 who reported no differences in GE digestibility between male and female dogs (overall n=39). Compared to intact dogs in the present study, neutered dogs showed higher digestibility values for N and lower values for crude ash, with no differences observed for DM, OM, Cfat, starch, and GE.…”

“…The digestibility values obtained in the present study could have been compared to values obtained using a digestibility study with kennelled dogs in a laboratory setting, as suggested by Plantinga et al 12 . In case such comparison would be made, one would then attribute potential significant differences in digestibility values between the two approaches to differences in factors such as the dog population (e.g.…”

“…The use of an indigestible marker is a practical method for digestibility measurements in a relatively un-controlled environment (12) . Titanium dioxide (TiO 2 ) has been approved as a colouring agent and feed additive (15) , validated as a digestibility marker for multiple animal species (12,(53)(54)(55)(56)(57)(58)(59) and used extensively in the past. However, recently the safety of TiO 2 as a food additive has been questioned (60,61) , given the body's potential to absorb nanoparticles.…”

“…The population of pet dogs differs from kennel dogs by a greater variability in factors that impact nutrient digestibility, like age, breed, body size, neuter status, body condition and physical activity [4][5][6][7][8][9][10][11] . The home environment of dogs and involvement of the owner ('inhome' 12,13 ) may cause further variability due to owner (non)compliance, environmental conditions (e.g. feeding schedule, ambient conditions, presence of other pets in the household) and the dogs' food history.…”

“…In addition to the required length of the adaptation period, it is unclear how many faecal collection days are sufficient. Hagen-Plantinga et al ( 12 ) developed an in-home digestibility study using titanium (Ti) dioxide as a marker, a 7 d adaptation and 24-h faeces collection period. The authors reported that it could be questioned whether the 24-h collection period was sufficient to cover day-to-day variation in faecal marker and nutrient excretions.…”