A new in vitro method to evaluate digestibility of commercial diets for dogs

Figures & data

Table 1. Chemical composition (% on DM basis) of the four dog foods used during the development of the in vitro digestion method.

Diet^a	Crude protein	Ether extract	Starch	Crude fibre	Ash
1	31.8	16.0	39.1	1.60	6.96
2	30.8	15.5	43.2	1.18	6.57
3	26.7	11.2	39.2	3.43	8.92
4	35.7	30.3	19.3	0.96	11.48

DM: dry matter.

^aDiets 1, 2 and 3 were dry extruded foods, diet 4 was a wet canned food.

Table 2. Chemical composition (% on DM basis) of the 16 dry dog foods used for the validation of the in vitro method.

Diet	Dry matter	Crudeprotein	Etherextract	Starch	Crudefibre	Ash	Insolubleash
1	94.5	23.8	16.4	30.0	2.37	9.67	1.68
2	93.7	24.8	18.4	34.6	1.65	8.80	1.59
3	94.9	24.0	15.5	34.7	2.57	9.47	1.28
4	94.9	25.2	12.5	38.2	2.90	8.74	0.41
5	94.2	21.5	16.4	36.1	2.86	7.35	0.92
6	93.5	24.0	14.4	37.4	2.88	10.24	0.61
7	96.3	26.3	12.7	40.0	3.15	8.92	0.84
8	96.2	26.8	15.3	43.0	2.44	5.88	1.10
9	92.5	23.2	10.4	42.0	1.99	8.44	1.03
10	91.3	23.1	11.9	37.5	2.85	6.82	1.04
11	93.6	29.4	16.1	34.1	2.73	7.53	0.93
12	91.7	22.5	13.8	34.9	2.66	8.09	1.09
13	92.9	22.9	12.0	46.4	2.04	6.61	0.56
14	93.5	30.4	14.0	36.4	2.61	8.16	0.54
15	93.8	31.6	12.4	33.8	3.01	12.28	0.55
16	94.7	24.2	16.3	39.1	1.63	7.34	0.35

Table 3. In vitro digestibility (mean values ± SD) of three dry extruded diets for adult dogs as determined using the method proposed by Vervaeke et al. (1989) and literature data.

		Digestibility, %
Diet	N	DM	CP	EE	Starch
1	3	72.4 ± 0.42	84.7 ± 1.00	28.9 ± 1.05	96.4 ± 0.19
2	3	73.2 ± 0.31	79.3 ± 0.23	45.3 ± 1.32	95.7 ± 0.24
3	3	65.7 ± 0.39	83.1 ± 0.58	33.9 ± 1.31	96.6 ± 0.16
Literature^a^,^b	10	82.2 ± 4.91	84.6 ± 3.19	94.3 ± 3.36	99.7 ± 0.14

DM: dry matter; CP: crude protein; EE: ether extract.

^a Means obtained from: Dust et al. 2005; Yamka et al. 2006; Vhile et al. 2007; Kempe and Saastamoinen, 2007; Guevara et al. 2008; Barry et al. 2009; Dobenecker et al. 2010; Brambillasca et al. 2010; Hendriks et al. 2013; Menniti et al. 2014.

^b Starch digestibility values from the literature refer to N-free extract, calculated as follows: 100 – (ash + CP + EE + crude fibre).

Figure 1. In vitro lipid digestibility of a sample of wet canned food for adult dogs as determined using different combinations of gastric lipase and emulsifiers and literature data. The dotted line indicates the mean of results drawn from the literature (Dust et al. 2005; Yamka et al. 2006; Vhile et al. 2007; Kempe and Saastamoinen, 2007; Guevara et al. 2008; Barry et al. 2009; Dobenecker et al. 2010; Brambillasca et al. 2010; Hendriks et al. 2013; Menniti et al. 2014) while the solid line indicates results obtained with the technique proposed by Vervaeke et al. (1989) with no addition of gastric lipase and emulsifiers. BS: Bile salts (cholic acid-deoxycholic acid sodium salt mixture); Tw20: Polysorbate 20 (polyoxyethylene sorbitan monolaurate; Tween 20, Sigma Aldrich); L: Gastric lipase.

Table 4. In vitro digestibility (mean values ± SD) of a wet canned food for adult dogs as determined using different concentrations of pancreatin (g/L of phosphate buffer) and bile salts (g/L of total volume of digestive solutions) and literature data.

			Digestibility, %
Bile salts, g/L	Pancreatin, g/L	N	DM	CP	EE
20	10	3	84.8 ± 0.28	85.2 ± 0.28	86.0 ± 0.26
20	12.5	3	84.8 ± 0.40	89.3 ± 0.28	85.2 ± 0.39
25	10	3	85.3 ± 0.07	87.1 ± 0.06	90.9 ± 0.05
25	12.5	3	84.8 ± 0.20	86.7 ± 0.17	89.4 ± 0.14
Literature^a		10	82.2 ± 4.91	84.6 ± 3.19	94.3 ± 3.36

DM: dry matter; CP: crude protein; EE: ether extract.

^a Means obtained from: Dust et al. 2005; Yamka et al. 2006; Vhile et al. 2007; Kempe and Saastamoinen, 2007; Guevara et al. 2008; Barry et al. 2009; Dobenecker et al. 2010; Brambillasca et al. 2010; Hendriks et al. 2013; Menniti et al. 2014.

Table 5. In vitro digestibility (mean values ± SD) of a dry extruded food for adult dogs as determined using different durations of the gastric digestive phase and literature data.

		Digestibility, %
Duration, h	N	DM	CP	EE
2	3	86.4 ± 1.46	91.5 ± 1.10	94.9 ± 3.69
4	3	84.2 ± 2.20	91.1 ± 0.92	94.5 ± 4.26
Literature^a	10	82.2 ± 4.91	84.6 ± 3.19	94.3 ± 3.36

Within a column, different letters indicate a significant difference (p < 0.05).

^a Means obtained from: Dust et al. 2005; Yamka et al. 2006; Vhile et al. 2007; Kempe and Saastamoinen, 2007; Guevara et al., 2008; Barry et al. 2009; Dobenecker et al. 2010; Brambillasca et al. 2010; Hendriks et al. 2013; Menniti et al. 2014.

Figure 2. Relationship between digestibility of dry matter (DM), crude protein (CP), ether extract (EE) and starch of 16 dry extruded pet food samples determined in vivo (n = 5) and in vitro (n = 3). In vivo DM digestibility (%) = −1.15 + 1.00 ± 0.13 in vitro DM digestibility (%); r² = .810; p < .001. In vivo CP digestibility (%) = 18.7 + 0.71 ± 0.19 in vitro CP digestibility (%); r² = .510; p < .01. In vivo EE digestibility (%) = 37.8 + 0.60 ± 0.20 in vitro EE digestibility (%); r² = .383; p < .05 In vivo starch digestibility (%) = 48.2 + 0.52 ± 0.31 in vitro starch digestibility (%); r² = .161; p > .05.

Vervaeke IJ, Dierick NA, Demeyer DL, Decuypere JA. 1989. Approach to the energetic importance of fibre digestion in pigs. II. An experimental approach to hindgut digestion. Anim Feed Sci Tech. 23:169–194.

 Web of Science ®Google Scholar

Dust JM, Grieshop CM, Parsons CM, Karr-Lilienthal LK, Schasteen CS, Quigley JD, Merchen NR, Fahey GC. 2005. Chemical composition, protein quality, palatability, and digestibility of alternative protein sources for dogs. J Anim Sci. 83:2414–2422.

 PubMed Web of Science ®Google Scholar

Yamka RM, Harmon DL, Schoenherr WD, Khoo C, Gross KL, Davidson SJ, Joshi DK. 2006. In vivo measurement of flatulence and nutrient digestibility in dogs fed poultry by-product meal, conventional soybean meal, and low-oligosaccharide low-phytate soybean meal. Am J Vet Res. 67:88–94.

 PubMed Web of Science ®Google Scholar

Vhile SG, Skrede A, Ahlstrøm Ø, Hove K. 2007. Yttrium oxide (Y2O3) as an inert marker in digestibility studies with dogs, blue foxes and mink fed diets containing different protein sources. J Anim Physiol Anim Nutr. 91:381–389.

 PubMed Web of Science ®Google Scholar

Kempe R, Saastamoinen M. 2007. Effect of linseed cake supplementation on digestibility and faecal and haematological parameters in dogs. J Anim Physiol Anim Nutr (Berl). 91:319–325.

 PubMed Web of Science ®Google Scholar

Guevara MA, Bauer LL, Abbas CA, Beery KE, Holzgraefe DP, Cecava MJ, Fahey JGC. 2008. Chemical composition, in vitro fermentation characteristics, and in vivo digestibility responses by dogs to select corn fibres. J Agr Food Chem. 56:1619–1626.

 PubMed Web of Science ®Google Scholar

Barry KA, Hernot DC, Middelbos IS, Francis C, Dunsford B, Swanson KS, Fahey GC Jr. 2009. Low-level fructan supplementation of dogs enhances nutrient digestion and modifies stool metabolite concentrations, but does not alter faecal microbiota populations. J Anim Sci. 87:3244–3252.

 PubMed Web of Science ®Google Scholar

Dobenecker B, Frank V, Kienzle E. 2010. High calcium intake differentially inhibits nutrient and energy digestibility in two different breeds of growing dogs. J Anim Physiol Anim Nutr. 94:109–114.

 Web of Science ®Google Scholar

Brambillasca S, Purtscher F, Britos A, Repetto JL, Cajarville C. 2010. Digestibility, fecal characteristics, and plasma glucose and urea in dogs fed a commercial dog food once or three times daily. Canadian Vet J. 51:190.

 PubMed Web of Science ®Google Scholar

Hendriks WH, Thomas DG, Bosch G, Fahey Jr GC. 2013. Comparison of ileal and total tract nutrient digestibility of dry dog foods. J Anim Sci. 91:3807–3814.

 PubMed Web of Science ®Google Scholar

Menniti MF, Davenport GM, Shoveller AK, Cant JP, Osborne VR. 2014. Effect of graded inclusion of dietary soybean meal on nutrient digestibility, health, and metabolic indices of adult dogs. J Anim Sci. 92:2094–2104.

 PubMed Web of Science ®Google Scholar