This study intended to determine in vitro DM digestibility of expanded pork skin chews and rawhide chews and apparent total tract digestibility (ATTD), gastrointestinal transit time and blood metabolite measurements in healthy adult dogs fed a weight control commercial diet and expanded pork skin chews.

An in vitro method simulated gastric and small intestinal digestion of expanded pork skin and rawhide chews. Ten intact female dogs were fed the diet plus an expanded pork skin chew (approximately 45 g) each day for 22 days.

In vitro gastric digestibility of expanded pork skin chews increased with time, with chews being 54.7, 58.6, 76.4 and 86.4% digestible after six, 12, 18 and 24 hours of gastric digestion, respectively. Gastric digestibility of rawhide chews was low at six hours (7.6%) and slowly increased over time, reaching a maximum of 41.6% at 18 hours. In vitro gastric plus small intestinal digestibility results indicated near complete digestibility of expanded pork skin chews at all time points, while rawhide chews were 50% to 85% digestible.

In vivo ATTD of DM, OM and nitrogen (N) were greater when dogs were fed expanded pork skin chews along with the base diet compared with the diet alone. However, chew intake did not change transit time; rather, motility index and contraction pattern of the colon were altered during chew feeding relative to control. Blood urea N concentrations were greater in dogs fed expanded pork skin chews compared to baseline, which was not surprising given the increased N intake and absorption from the chews.

Expanded pork skin had a greater DM digestibility than rawhide chews. In addition, expanded pork skin decreased blood cholesterol and triglyceride concentrations, which may justify further research on this area.

Source : S. Hooda et al., 2012. In vitro digestibility of expanded pork skin and rawhide chews and digestion and metabolic characteristics of expanded pork skin chews in healthy adult dogs. J Anim Sci online October 2012. doi: 10.2527/jas.2012-5333J