While debates about dog food tend to focus on the recipes, dog breed also may have a significant effect on how one formulation or another influences a particular pet’s health. High protein dog foods have been a strong trend in the pet food industry for years, following similar trends in human foods. However, using livestock muscle tissue in pet food contradicts drives towards lower environmental impacts and attracts criticism from animal welfare advocates. The use of grains in dog foods has been contentious, although for different reasons. While dogs have a greater capacity to digest carbohydrates than their wolf ancestors, some question the biological appropriateness of grain-based pet foods, and raw meat dog food has grown in popularity. Fears of canine dilated cardiomyopathy (DCM) further muddled the waters after the U.S. Food and Drug Administration launched an investigation into correlations among certain grain-free formulations and DCM.
Research on dog breed and formulation
In this maelstrom of consumer demands and formulation necessities, scientists work to build evidence-based knowledge of how various combinations of animal protein and grains influence dogs’ health. In the Journal of Animal Science, a team of researchers published the results of their experiment on the effect of animal protein inclusion rate and grain-free or grain-inclusive diets on macronutrient digestibility, fecal characteristics, metabolites, and microbiota in mixed-breed hounds and Beagles. While formulation influenced some aspects of the dogs’ physiology, the animals’ ancestry played a role too.
The study involved four specially formulated extruded kibble diets, each differing in their animal protein and carbohydrate content. These diets were classified:
- HA-GI: high animal protein, grain-inclusive
- LA-GF: low animal protein, grain-free
- LA-GI: low animal protein, grain-inclusive
- HA-GF: high animal protein, grain-free
In the experiment, 32 Beagles and 33 mixed-breed hounds were randomly assigned to these dietary regimens for a period of 180 days. Despite the recipe differences, all the diets had similar chemical compositions and were well-tolerated by the test subjects.
The mixed-breed dogs differed in fecal metabolites from the Beagles. Mixed-breed hounds exhibited a higher concentration of total short-chain fatty acids and ammonia, while their indole levels were lower compared to Beagles. In particular, the LA-GF diet induced a notable increase in short-chain fatty acid concentrations in mixed-breed hounds but not in Beagles. Additionally, the HA-GI diet was associated with greater concentrations of ammonia, phenol, and indole compared to LA-GF.
The impact of breed on fecal primary bile acid concentrations was also apparent, with mixed-breed hounds displaying a higher concentration of cholic acid than Beagles. Interestingly, mixed-breed hounds fed the LA-GF diet exhibited greater cholic acid concentrations than those on the HA-GI and LA-GI diets. Furthermore, dogs consuming LA-GF exhibited lower fecal secondary bile acid content than the other groups.
The researchers examined the composition of fecal microbiota, revealing distinctive differences in the LA-GF diet group, with lower α-diversity. Despite this reduction in diversity, all dogs remained in good health. Dogs on the LA-GF diet exhibited a notable shift in their microbiota composition, with increased abundance of Selenomonadaceae, Veillonellaceae, Lactobacillaceae, Streptococcus, Ligilactobacillus, Megamonas, Collinsella aerofaciens and Bifidobacterium sp.
These results from this study exemplified how both breed and diet choice influenced nutrient digestibility, fermentative end products and fecal microbiota. Mixed-breed hounds displayed higher macronutrient apparent total tract digestibility, a greater fecal total short-chain fatty acid concentration, and a higher fecal bile acid concentration. The LA-GF diet stood out for its unique effects, including lower fecal ammonia and indole concentrations but higher total short-chain fatty acid, acetate, propionate and primary bile acid concentrations.
