Pulse-based Vegan Dog Food: Examination of Digestibility with or without Added  Enzymes in Adult Dogs and Ileal Cannulated Pigs as a Model
Creators: Van Straten, Whitney
Publisher: name: University of Alberta Library
Year: 2023

<p>Demand for vegan dog foods is growing, yet little research has been conducted <br>
concerning the digestibility of these foods for dogs. The pulses and pulse protein concentrates<br>
that provide protein in these foods contain anti-nutritional factors (ANF), which may reduce <br>
nutrient digestibility. Addition of exogenous enzymes may help increase the digestibility of these <br>
foods, however, due to constraints on companion animal research, studies using dogs alone may <br>
not be able to accurately determine enzyme effectiveness. <br>
For the present study two diets were formulated: a low protein diet (L) including mainly <br>
field pea and lentil flours, and a high protein diet (H) including mainly field pea and lentil <br>
protein concentrates. In chapter 2, ileal cannulated pigs were fed these diets either raw (R), <br>
extruded (E), extruded with enzyme added before extrusion (E+P), or enzymes added after <br>
extrusion (E+A). The enzyme blend included protease, phytase, cellulase and xylanase. Feces <br>
and digesta were collected to determine apparent total tract digestibility (ATTD) and <br>
standardized ileal digestibility (SID) of the diets. Extrusion alone increased ATTD of gross <br>
energy (GE) by 1% and SID total AA by 4% compared to R (P &lt; 0.05). The addition of the <br>
enzyme blend after extrusion increased ATTD of crude protein (CP) and GE by 1%, ATTD of <br>
ash by 11-19% (P &lt; 0.05), and increased SID of total AA by 2% (P &lt; 0.05) compared to E. <br>
However, the addition of the enzyme blend before extrusion resulted in lower ATTD of organic <br>
matter (OM), CP, and GE, and lower SID of AA compared to E (P &lt; 0.05), likely due to <br>
overheating during processing.<br>
In chapter 3, dogs were fed the same formulations as controls which were extruded <br>
without enzymes (C), extruded with enzyme added before extrusion (P), or enzyme added after <br>
extrusion (A). Fecal samples were collected to measure ATTD, fecal metabolites and fecal<br>
consistency. Unlike for pigs, ATTD of OM, CP, crude fat (EE), GE, or ash did not increase for <br>
dogs when enzymes were added after extrusion. However, the addition of enzymes after <br>
extrusion did increase concentrations of glucose, xylose, propionic and acetic acids in dog feces <br>
compared to C (P &lt; 0.05), indicating the enzymes did hydrolyze some of the insoluble fiber in <br>
the diets leading to increased bacterial fermentation. The addition of the enzymes after extrusion <br>
also resulted in feces with higher moisture content than for C (P &lt; 0.05), causing loose stools for <br>
the dogs. Addition of enzymes prior to extrusion resulted in ATTD of CP lower than C (P &lt; <br>
0.05). Although the ATTD values from pigs were greater than from the dogs, their results <br>
followed similar trends and comparison by regression analysis resulted in high R2<br>
values for GE, <br>
OM and CP (R<br>
2 &gt; 0.7). <br>
In conclusion, extrusion and the addition of enzymes after extrusion increased the <br>
digestibility of pulse flour and protein concentrate based diets for growing pigs. The addition of <br>
enzymes after extrusion did not increase the digestibility of pulse flour and protein concentrate <br>
based diets for adult dogs, but did increase the concentrations of fecal metabolites indicating that <br>
the enzymes hydrolyzed some insoluble fiber. However, enzyme addition after extrusion also <br>
resulted in loose stools. Addition of enzymes before extrusion resulted in lower digestibility of <br>
the diets for both pigs and dogs. Overall, the addition of enzyme after extrusion can be used to <br>
increase the digestibility of pulse-based diets for growing pigs, and has some effect on dog <br>
intestinal microbiome and fecal quality. Comparison of digestibility values from the pigs and <br>
dogs resulted in high R2 values, indicating that pigs can be used as a model for dog food <br>
digestibility studies.</p>