Extruded feline diets formulated with high inclusion of soybean hulls: effects on apparent total tract macronutrient digestibility, and fecal quality and metabolites

Abstract

Dietary fibers have gained renewed interest in companion animal nutrition as a means to manage pet obesity and improve gut and host health. Soybean hulls (SBH), a coproduct of the soybean oil extraction process, is an accessible and economical fiber source. However, limited research is available on the use of SBH in feline nutrition. Thus, the aim of this study was to determine the effects of a high SBH inclusion level on daily food intake, apparent total tract (ATT) macronutrient digestibility, fecal quality, and fecal fermentative end products in diets of adult cats. Four diets were formulated with either SBH, beet pulp (BP), or cellulose (CL) as the main source of dietary fiber, with the control diet formulated with no added fiber (NF). The fiber treatments were formulated to achieve approximately 15% total dietary fiber (TDF). Eight adult male cats (mean age = 10.5 yr ± 0.1; mean BW = 6.1 ± 0.8 kg) were used in a replicated 4 × 4 Latin square design. Each period consisted of 14 d, with 10 d of diet adaptation followed by 4 d of total fecal and urine collections. Food was offered twice daily and cats were fed to maintain BW. Food intake on a DM basis (DMB) was lower (P < 0.05) in cats fed BP (55.2 g/d) when compared with SBH (70.8 g/d). As-is fecal output did not differ in cats fed BP or SBH, and when expressed on a DMB, fecal output did not differ among fiber treatments. The ATT digestibility of DM, OM, and GE was greater (P < 0.05) in cats fed NF when compared with those fed BP, CL, or SBH. Cats fed CL had the greatest (P < 0.05) ATT CP digestibility (88.5%), followed by cats fed NF (84.9) and SBH (81.7%) with the lowest values (77%) noted for cats fed BP. Acid-hydrolyzed fat (AHF) digestibility was greater for cats fed CL (92.9%) than for cats fed BP (86.9%) and SBH (88.6%). The TDF ATT digestibility was lowest for cats fed NF and CL (8.5% and 15.1%, respectively), followed by SBH (18.0%), with BP having the highest digestibility (33.7%). Total short-chain fatty acid concentration was greatest (P < 0.05) in cats fed BP (699.7 μmole/g) when compared with the other 3 treatments, whereas phenol and indole concentrations did not differ among treatments. In conclusion, a high inclusion level (15% TDF) of SBH appears acceptable in diets for adult cats, resulting in no negative effects on daily food intake, fecal scores, and similar ATT digestibility for most macronutrients when compared with BP and CL.

Miscanthus Grass as a Novel Functional Fiber Source in Extruded Feline Diets

“…This is due to the higher soluble fiber content of beet pulp that has a higher water-holding capacity, therefore increasing fecal water content and overall fecal mass. A similar effect was reported in felines by Detweiler et al and in other studies across multiple species including canines and swine (21)(22)(23).…”

“…In contrast, in this study, while not significant, the CP digestibility of the BP treatment was reported to be numerically lower than for all the other treatments. Many similar effects have been reported due to beet pulp's moderate level of fermentability compared with cellulose and other fiber sources with greater concentrations of insoluble fiber (10,21,25). Providing greater amounts of substrate for saccharolytic fermentation may result in increased microbial proliferation causing more microbial protein to be present in the feces.…”

“…Similarly, Donadelli and Aldrich saw no effect on food intake when cellulose, beet pulp, and Miscanthus grass were added to the formula at a 10% inclusion rate (20). Detweiler et al evaluated diets including either 15.5% beet pulp (17.1% TDF), 9.6% cellulose (15.1% TDF), or 14% soybean hulls (16.6% TDF) and observed that cats fed the diet containing beet pulp had lower intake than the diet containing soybean hulls due to feed refusals (21). This indicates that although no effect on palatability was observed in this study with an inclusion level up to 9% Miscanthus grass (15.0% TDF), or up to 10% inclusion (13.8% TDF), higher inclusion levels and, subsequently, higher TDF contents may impact palatability and must be considered in the practical utilization of this ingredient (20).…”

Evaluation of dried apple pomace on digestibility and palatability of diets for cats

“…According to Godoy et al (2013), fiber may dilute dietary energy density. Therefore, the inclusion of fiber-rich feedstuffs that considerably dilute the energy content of dog and cat foods may be particularly interesting for weight loss purposes (Sabchuk et al, 2017;Detweiler et al, 2019).…”

“…The benefits include hairball control, maintenance of intestinal peristalsis, good functionality of the immunological system, and modulation of intestinal microbiota. Dieyary fiber may also regulate glycemia, reducing the incidence of diseases, such as obesity and diabetes mellitus (Rochus et al, 2014;Loureiro et al, 2017;Detweiler et al, 2019;Donadelli and Aldrich et al, 2020). Therefore, the physiological importance of fiber for cats is documented, attracting the interest of the pet food industry about dietary fiber sources.…”