A study published in Animal Feed Science and Technology in 2003 examined the effects of increasing levels of soluble non-starch polysaccharides (NSP) and the addition of feed enzymes on faecal quality and digestibility in dogs. The research, conducted by L.N. Twomey and colleagues from Murdoch University and the University of New England in Australia, aimed to investigate potential benefits of using higher cereal content and enzymes in dog food formulations.
The experiment utilised 36 mixed-breed dogs in a 3×2 factorial design. Three diets with varying levels of soluble NSP (11, 16, and 20 g/kg) were tested, with and without the addition of an enzyme mixture containing xylanase, β-glucanase, and amylase. The trial lasted 13 days, with faecal collections occurring during the final five days.
Key findings of the study include:
- Digestibility: Increasing levels of soluble NSP decreased the coefficient of total tract apparent digestibility (CTTAD) for starch, fat, protein, and energy. However, the addition of enzymes reversed these effects in diets with higher soluble NSP content (16 and 20 g/kg), improving digestibility to levels comparable with the low NSP diet.
- Faecal Quality: Higher soluble NSP levels led to deterioration in faecal quality, with scores increasing from 2.2 to 3.0 as NSP levels rose. The addition of enzymes improved faecal scores across all diets, with the effect being most pronounced in the high NSP diet.
- Faecal Characteristics: Increased soluble NSP levels resulted in lower faecal pH and dry matter content. The enzyme addition did not significantly affect these parameters.
- Faecal Acids: Higher soluble NSP levels decreased faecal volatile fatty acid (VFA) concentrations and increased lactate concentrations. Total acid concentrations in faeces increased with higher soluble NSP content. Enzyme addition did not significantly affect these measurements.
- VFA Proportions: The addition of enzymes decreased the proportion of propionate and increased isobutyrate in faecal VFA.
The researchers found significant correlations between faecal lactate concentration and both faecal pH and faecal score. As lactate concentration increased, faecal pH decreased and faecal scores worsened, indicating softer stools.
The study suggests that increasing levels of soluble NSP in dog diets can have anti-nutritive effects and deteriorate faecal quality. However, the addition of enzymes can alleviate some of these negative impacts, particularly at moderate levels of soluble NSP inclusion.
The authors concluded that a balance can be achieved between increased fermentation and maintenance of acceptable stool quality and overall digestion at moderate levels of NSP. They proposed that the enzyme mixture likely hydrolysed the soluble NSP into smaller, more readily fermentable molecules, leading to increased fermentation in the large intestine.
This research has potential implications for the dog food industry, suggesting that moderate increases in dietary soluble NSP can be tolerated by dogs when enzymes are added. This finding could allow for more flexible and potentially more cost-effective formulations in commercial dog foods.
The study highlights the complex interactions between dietary components, digestive processes, and gut microbiota in dogs. It also underscores the potential benefits of using feed enzymes to improve nutrient utilisation and maintain faecal quality in diets with higher cereal content.
Further research may be warranted to explore long-term effects of such dietary modifications and to optimise enzyme formulations for different dog food compositions. Additionally, investigations into the impact on gut health and the dog’s overall well-being could provide valuable insights for both pet food manufacturers and veterinary professionals.