Lignocellulose (LC) might be used as a substitute fiber source for dogs as a strategy to decrease energy density and enhance gastrointestinal functionality. The objective of the present study was to compare the effects of including different levels of LC on apparent nutrient digestibility and fecal parameters (dry matter (DM), fecal score, and daily fecal output), as well as fecal fatty acid concentrations. Four diets were tested: control diet (no supplementation of LC; LC0), and three control diets diluted with increasing levels of LC: 1, 2, and 4% (LC1, LC2, and LC4). Six Beagle dogs (BW 17.1 kg ± 1.22) participated in a crossover experimental design. Before each experimental period, five days were used as a wash-out period. The fecal consistency was scored based on a 5-point scale (1 = very hard; 2 = solid, well-formed “optimum”; 3 = soft, still formed; 4 = pasty, slushy; and 5 = watery diarrhea). The results demonstrated that the organic matter apparent digestibility (p = 0.01) and nitrogen-free extract (NFE) (p < 0.01) was significantly lower for dogs fed LC4 compared to those fed LC0. Dogs fed LC2 and LC4 had a lower fecal consistency score (2.39 and 2.18, respectively; p < 0.05). The fecal DM was significantly the highest (p < 0.01), and the daily fecal output on fresh matter was lower (p < 0.05) when dogs were fed the LC4 diet compared with the LC0 diet. Including LC at 1% in the diet resulted in significantly higher fecal acidic pH levels. However, no differences among treatments were noted regarding fecal fatty acid concentrations.

In animal feeds and pet food, meat industry rendered by-products as a source of high-quality protein are commonly used. Among all rendered protein sources, poultry carcasses and neck meal are frequently used as ingredients in commercial pet foods due to their agreeable fatty acid and amino acid profiles, and they have no impact on the palatability of the diet. Nonetheless, it is unclear how poultry by-product meal affects companion animals regarding diet digestibility and fecal quality. This study either aimed to provide information on poultry by-product meal, including coarsely, finely, or very finely ground varieties, regarding their nutrient digestibility and characteristics of feces in dogs. One type of animal by-product meal was used in the three aforementioned particle sizes. Beagle dogs (n = 6; body weight, 16.6 kg ± 2.03) participated in a crossover experiment design. Each trial consisted of a five day adaptation period to the diet, and five days of fecal samples were collected and measured for individual apparent nutritional digestibility and fecal scores. The animal by-product supplementation in the diet of dogs was well accepted, with an acceptable percentage of apparent nutrient digestibility. Different particle sizes had no significant effect on the organic matter, crude protein, and crude fat digestibility as well as the fecal fatty acid concentrations. In addition, feces remained firm and well-formed and increased fecal dry matter. This indicates that poultry by-products should be taken into account as a potential dietary protein source in dog food.