Effect of dietary processing on the gut microbiome of dogs (Canis lupus familiaris) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Animal Science at Massey University, Palmerston North, New Zealand
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Date
2024
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Massey University
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Abstract
The gastrointestinal microbiome of the dog plays important roles in the overall health of the dog. Generally, a greater microbiome diversity is indicative of better gastrointestinal health. The microflora in the gastrointestinal tract can be altered by the diet that the dog is consuming. Therefore, it is important to understand how the diet interacts with the dog’s microbiome, to further expand our knowledge of the overall health of dogs. This study investigated the effects of processing of a series of high meat diets on the gastrointestinal microbiome of dogs. A literature review was carried out to establish the current base of knowledge of the microbiome of the dog, and how the diet may affect it. The nutritional requirements of dogs, as well as how diets are assessed for suitability were also reviewed. To assess the impact of diet changes on the microbiome, a series of standard digestibility trials were run. To do this, a raw version, and a processed version of two diets were fed to a group of dogs over two-week blocks, as well as two high meat kibble diets in subsequent blocks. The faeces were collected over a period of five days, with a final faecal sample taken on the final day. This enabled a digestibility analysis to be completed, and the microbiome to be analysed using 16S sequencing which allowed comparisons to be made between the microbiota present in the gut while the dogs were consuming a raw and processed version of two of the diets and two other high meat diets. A high number of reads were present in all samples after the 16S sequencing was completed, and Bacteroidetes, Firmicutes, Fusobacteria and Proteobacteria were the phyla present in the largest proportions on average across all the samples. Phascolarctobacterium, Prevotella, Bacteroides and Fusobacterium were the most prominent genera. The diet with the highest microbial diversity was Blackhawk (BH) and the diets with the least were steamed and dried raw (SDR) and Orijen (OR). The two unprocessed diets had lower diversity present in the gut microbiome than their processed counterparts. This suggests that the processing those diets went through did result in positive changes in the microbiota compared to the raw versions. Microbiomes that are more diverse are generally thought of to be healthier than ones with less diversity present.