Replacing traditional poultry byproduct meal with hydrolyzed chicken liver in adult cat diets may improve digestibility and palatability. A study published in the Journal of Animal Science evaluated six extruded diets formulated with either poultry byproduct meal or hydrolyzed chicken liver, with protein levels adjusted to 24%, 32% or 40% of crude protein by weight.
“Feeding cats with hydrolyzed chicken liver promoted an increase in palatability, as well as in combination with higher concentrations of protein in the diets,” the study’s authors wrote.
Hydrolyzed chicken liver is chicken liver that has been broken down into smaller parts using water and enzymes. This process makes it easier for cats to digest and absorb the nutrients. It also creates strong smells and tastes that many cats find appealing, making their food more enjoyable to eat.
Researchers aimed to assess the impact of hydrolyzed proteins on nutrient utilization and gut health. Hydrolyzed chicken liver was used to replace carbohydrates from brewers rice in three formulations, allowing for comparison with corresponding poultry byproduct meal diets at matched protein levels.
Cats fed diets with higher protein concentrations showed increased crude protein digestibility. However, fat digestibility declined in the highest hydrolyzed liver formulation. Carbohydrate digestibility also decreased as protein levels rose, reflecting the substitution of carbohydrates with protein sources.
Gross energy digestibility was lower in cats fed the 32% diet, and metabolizable energy values declined in all hydrolyzed liver diets compared to those with poultry byproduct meal. Fecal dry matter content and fecal scores also decreased with hydrolyzed chicken liver inclusion, respectively, indicating looser stools, though still within acceptable physiological limits. In particular, the 32% group showed the softest feces.
Urinary pH increased with higher dietary protein levels and with hydrolyzed chicken liver inclusion, potentially relevant for urinary tract health. Moreover, cats fed hydrolyzed chicken liver exhibited significantly elevated levels of fecal short-chain fatty acids and volatile fatty acids (P < 0.05), including acetate, propionate, and valerate. These fermentation end products are considered beneficial markers of gut microbiota activity and intestinal health.
Palatability trials demonstrated a clear preference for hydrolyzed liver-based diets, particularly those with higher protein inclusion. Cats favored the 40% formulation over all other diets, suggesting that hydrolyzed ingredients may improve voluntary consumption.
Overall, substituting poultry byproduct meal with hydrolyzed chicken liver improved nutrient digestibility and fermentation profiles while maintaining acceptable stool quality and enhancing palatability. These findings may inform future formulation strategies aimed at optimizing health and acceptance in feline diets.
