Digestibility of raw soybeans in extruded diets for dogs determined by different methods

Figures & data

Table 1. Analysed DM content, chemical composition, and qualitative variables of raw soybeans.

Item	Raw soybeans
DM, g/kg	907.20
Analysed chemical composition^a (on as-fed basis)
CP, g/kg	361.30
CF, g/kg	63.20
Acid-hydrolysed fat, g/kg	188.00
Ash, g/kg	41.30
GE, MJ/kg	21.83
Qualitative variables^b (on as-fed basis)
Urease, ΔpH	1.86
Trypsin inhibitor, mg/g	15.91
Protein soluble in KOH, %	89.30

^a In duplicate.

^b In triplicate.

DM: dry matter; CP: crude protein; CF: crude fibre; GE: gross energy.

Table 2. Ingredients and analysed DM and chemical composition of the experimental diets.

Item	Diets, g raw soybean/kg
	0	60	120	180	240	300
Ingredients, %
Maize (yellow dent)	60.47	56.84	53.21	49.59	45.96	42.33
Raw soybean	0.00	6.00	12.00	18.00	24.00	30.00
Poultry by-product meal	28.16	26.47	24.78	23.09	21.40	19.71
Mineral-vitamin supplement^a	0.50	0.47	0.44	0.41	0.38	0.35
Sodium chloride	0.50	0.47	0.44	0.41	0.38	0.35
Ammonium propionate	0.24	0.23	0.21	0.20	0.18	0.17
Butyl-hydroxy-toluene	0.10	0.09	0.09	0.08	0.08	0.07
Poultry fat	7.03	6.61	6.19	5.76	5.34	4.92
Hydrolysed poultry liver	3.00	2.82	2.64	2.46	2.28	2.10
DM, %	91.84	91.96	92.61	92.81	91.36	92.68
Chemical composition (DM basis)
Ash, %	7.30	7.12	6.97	6.82	6.70	6.49
CP, %	21.59	22.12	23.76	23.92	24.41	25.01
Acid-hydrolysed fat, %	11.01	12.22	13.23	13.91	14.87	15.02
CF, %	2.40	2.60	2.83	2.91	2.96	3.13
ME^b, MJ/kg	15.53	15.78	15.98	16.14	16.35	16.38

^a Provided per kilogram of feed: vitamin A (retinol) = 20.000 IU; vitamin D3 = 2.000 IU; vitamin E (α-tocopherol) = 48 mg; vitamin K3 = 48 mg; vitamin B1 = 4 mg; vitamin B2 = 32 mg; pantothenic acid = 16 mg; niacin = 56 mg; choline = 800 mg; Zn as zinc oxide = 150 mg; Fe as ferrous sulphate = 100 mg; Cu as copper sulphate = 15 mg; I as potassium iodide = 1.50 mg; Mn as manganous oxide = 30 mg; Se as sodium selenite = 0.20 mg; antioxidant = 240 mg.

^b ME = 0.1465 × CP + 0.3558 × ether extract + 0.1465 × NFE.

DM: dry matter; CP: crude protein; GE: gross energy; ME: metabolisable energy.

Table 3. Linear (L) and quadratic (Q) effects of increasing raw soybean dietary inclusion levels on trypsin inhibitory (TI), urease activity, apparent total tract digestibility (CTTAD), ME, and faecal characteristics of dogs.

Item	Equation^a^,^b	R^2	Sx,y	p-value L	p-value Q
Mash diet
Urease, ΔpH	Y = 0.0001x²+0.0013x + 0.0118	0.9900	0.0060	<.0010	<.0010
TI, mg/g	Y = 0.0002x²+0.0016x + 0.1214	0.9800	0.0280	<.0010	<.0010
Extruded diet
Urease, ΔpH	Y = 0.0001x² − 3E-06x + 0.0039	0.7200	0.0070	<.0010	<.0010
TI, mg/g	Y = 0.0005x²+0.0004x + 0.0168	0.9800	0.0280	<.0010	<.0010
CTTAD
DM	Y = −0.0005x + 0.8229	0.9900	0.0050	<.0010	.9340
OM	Y = −0.0004x + 0.8585	0.8000	0.0070	.0160	.0640
CP	Y = −0.0008x + 0.8286	0.9300	0.0080	.0020	.2030
AHF	Y = 0.0005x + 0.8949	0.7900	0.0100	.0170	.4210
GE	Y = 0.0004x + 0.8601	0.9200	0.0050	.0030	.2710
ME, MJ/kg DM	Y = 0.1607x + 18.1802	0.8700	0.0320	.0070	.7920
Faeces
DM, %	Y = −0.0082x² +0.0761x + 36.3611	0.9900	3.6710	<.0010	.0020
Score^c	Y = −0.0009x² − 0.0089x + 4.1786	0.9400	0.0310	<.0010	.0330
pH	Y = −0.0002x²+0.0073x + 6.4043	0.5900	0.3980	<.0010	<.0010
Ammonia, g/kg	Y = −0.0017x²+0.0807x + 1.4211	0.9400	0.3090	<.0010	<.0010
Output^d	Y = 0.0045x + 0.4505	0.9200	0.0850	<.0010	.1920

DM: dry matter; OM: organic matter; CP: crude protein; AHF: acid hydrolysed fat; GE: gross energy; ME: metabolisable energy; R²: linear (for linear equation) or quadratic (for quadratic equation) coefficient of determination.

^a y = estimated.

^b x = dietary raw soybean content (g/kg).

^c Faecal score = 1 (watery stools) to 5 (dry stools).

^d Faecal output = g wet faecal output/g DM intake.

Table 4. Urease and trypsin inhibitor activity in mash and extruded diets containing increasing raw soya bean levels (n = 3).

Item	Diets, g raw soybean/kg						SEM
	0	60	120	180	240	300
Mash diet
Urease, ΔpH	0.000	0.160	0.210	0.520	0.710	1.020	0.110
TI, mg/g	0.000	0.490	0.750	1.220	1.810	3.090	0.085
Extruded diet
Urease, ΔpH	0.000	0.010	0.010	0.010	0.010	0.030	0.001
TI, mg/g	0.000	0.130	0.290	0.790	0.990	1.820	0.047

TI: trypsin inhibitory.

Table 5. Dry mater intake, apparent total tract digestibility (CTTAD) of nutrients and energy, ME, and faecal characteristics of dogs fed diets containing increasing raw soybean levels (n = 6).

Item	Diets, g raw soybean/kg						SEM
	0	60	120	180	240	300
DMI, g/d	209	208	208	210	209	208	1.800
CTTAD
DM	0.823	0.819	0.817	0.814	0.811	0.808	0.005
OM	0.856	0.856	0.855	0.852	0.850	0.841	0.005
CP	0.832	0.821	0.818	0.813	0.808	0.806	0.006
AHF	0.891	0.902	0.903	0.903	0.905	0.910	0.007
GE	0.858	0.864	0.866	0.867	0.870	0.871	0.005
ME, MJ/kg DM	18.410	18.420	18.500	18.930	19.110	19.090	0.032
Faeces
DM, %	36.410	36.320	36.530	34.810	33.560	31.340	0.573
Score^a	4.200	4.000	4.100	3.600	3.500	3.100	0.012
pH	6.430	6.380	6.540	6.520	6.570	6.600	0.064
Ammonia, g/kg	1.340	2.010	2.090	2.280	2.330	2.330	0.063
Output^b	0.470	0.470	0.480	0.530	0.570	0.590	0.018

DM: dry matter; OM: organic matter; CP: crude protein; AHF: acid hydrolysed fat; GE: gross energy; ME: metabolisable energy; SEM: standard error of the mean.

^a Faecal score = 1 (watery stools) to 5 (dry stools).

^b Faecal output = g wet faecal output/g DM intake.

Table 6. Average and variances (between parentheses) of the apparent total tract digestibility (CTTAD) of nutrients and energy and ME (MJ/kg) of raw soybean (RSB) estimated by the substitution and difference methods in dogs (n = 6)^a.

Item	Diets, g raw soybean/kg					p-value	Qc^b
	60	120	180	240	300
Substitution method
CTTAD
DM	0.7590 (0.0029)	0.7710 (0.0023)	0.7640 (0.0017)	0.7650 (0.0002)	0.7670 (0.0001)	.9890	0.4000
OM	0.8530 (0.0177)	0.8440 (0.0017)	0.8290 (0.0014)	0.8290 (0.0004)	0.8000 (0.0002)	.3970	0.8230
CP	0.6340^d (0.0407)	0.7020^c (0.0020)	0.7160^c (0.0018)	0.7250^c (0.0005)	0.7580^c (0.0002)	.0350	0.9020
AHF	1.0990^c (0.0166)	1.0040^d (0.0145)	0.9660^d (0.0069)	0.9570^d (0.0021)	0.9600^d (0.0021)	.0110	0.6170
GE	0.9700^c (0.0035)	0.9290^d (0.0018)	0.9130^d (0.0003)	0.9130^d (0.0002)	0.9040^d (0.0001)	.0210	0.6180
ME	18.7000^e (1.7281)	19.5000^d,e (0.9835)	21.6000^c (0.0972)	21.6000^c (0.0971)	20.7000^c,d (0.0842)	<.0010	0.6170
Difference method
CTTAD
DM	0.7590 (0.0018)	0.7710 (0.0023)	0.7640 (0.0032)	0.7650 (0.0002)	0.7670 (0.0001)	.9890	0.4160
OM	0.8530 (0.0164)	0.8450 (0.0016)	0.8300 (0.0014)	0.8300 (0.0004)	0.8030 (0.0002)	.7040	0.8180
CP	0.7120^c (0.0124)	0.7540^d (0.0019)	0.7620^d (0.0007)	0.7670^d (0.0006)	0.7730^d (0.0001)	.0410	0.7890
AHF	1.0430^c (0.0091)	0.9760^c,d (0.0045)	0.9510^c,d (0.0018)	0.9460^d (0.0014)	0.9500^c,d (0.0002)	.0310	0.5780
GE	1.0420^c (0.0092)	0.9700^c,d (0.0049)	0.9440^d (0.0005)	0.9420^d (0.0004)	0.9260^d (0.0001)	.0110	0.6140

DM: dry matter; OM: organic matter; CP: crude protein; AHF: acid hydrolysed fat; GE: gross energy; ME: metabolisable energy.

^a It was not possible to estimate the ME of RSB by the difference method.

^b Qc = A calculated Q value greater than the observed value in the table (0.506) indicates difference between the highest variance and the total sum of the other variances by the Q-Cochran test at 5% significance level.

^c,d,e Means followed by different letters are different by the Kruskal–Wallis test (p < .05).

Table 7. Average and variances (between parentheses) of the apparent total tract digestibility (CTTAD) of nutrients and energy and ME (MJ/kg) of raw soybean (RSB) estimated by the substitution, regression, and difference methods in dogs (n = 6)^a.

Item	Substitution	Difference	Regression^b	p-value	Qc^c
CTTAD
DM	0.76700 (0.00012)	0.76700 (0.00014)	0.76700 (0.00003)	.98800	0.45600
OM	0.80000 (0.00023)	0.80300 (0.00022)	0.81000 (0.00008)	.45800	0.44700
CP	0.75800 (0.00023)	0.77300 (0.00013)	0.77300 (0.00003)	.09200	0.57000
AHF	0.96000 (0.00210)	0.95000 (0.00021)	0.94200 (0.00008)	.07900	0.41700
GE	0.90400 (0.00014)	0.92600 (0.00012)	0.92300 (0.00001)	.06300	0.51200
ME	20.7000 (0.08421)	–	21.10000 (0.01134)	.29300	0.42500

DM: dry matter; OM: organic matter; CP: crude protein; AHF: acid hydrolysed fat; GE: gross energy; ME: metabolisable energy.

^a The CTTAD and ME values estimated by the substitution and difference methods were based on the diet containing 300 g RSB/kg, except for the difference method, that could not estimate the ME of RSB.

^b Regression equations of the following CTTAD: DM = 0.7667 + 0.0565x (R² = 0.74); OM = 0.8100 + 0.0048x (R² = 0.67); CP = 0.7728 + 0.006x (R² = 0.73); AHF = 0.9420 – 0.0047x (R² = 0.57); GE = 0.9231 – 0.0062x (R² = 0.62); ME (MJ/kg) = 21.1329 – 2.9958x (R² = 0.90), with p < .05 for linear effect.

^c Qc = A calculated Q value greater than the observed value in the table (0.707) indicates difference between the highest variance and the total sum of the other variances by the Q-Cochran test at 5% significance level.