Effect of Rare Earth Elements on Feed Digestibility, Rumen Fermentation, and Purine Derivatives in Sheep

Figures & data

Table 1. The ingredients and chemical composition of the basal diet.

	Values
Ingredients, g/kg DM
Alfalfa hay, ground	400
Corn stalk, ground	300
Cracked corn	182
Wheat bran	23
Sunflower meal	30
Soybean meal	55
Salt	5
Calcium phosphate	3
Minerals and vitamin premix^°	2
Chemical composition^#
DM, g/kg	853±8
CP, g/kg DM	123±5
ADF, g/kg DM	283±4
aNDF, g/kg DM	435±7
Calcium, g/kg DM	6.3±0.05
Phosphorus, g/kg DM	2.5±0.03
ME, MJ/kg^§	9.88

DM, dry matter; CP, crude protein; ADF, acid detergent fibre; aNDF, neutral detergent fibre; ME, metabolisable energy.

°Contained: Se, 0.04 ppm; Zn, 45 ppm; Mn, 40 ppm; I, 1.0 ppm; Co, 1.0 ppm; Fe, 45 ppm; Cu, 20 ppm; vitamin A, 2500 U/kg; vitamin D, 400 U/kg; vitamin E, 200 U/kg.

^#Included analysed values except metabolisable energy.

^§ME (Mcal/kg)=digestible energy (DE)×0.82; DE was calculated estimated by the equation: DE(Mcal/kg)=total digestion nutrient (TDN)×4409 kcal; TDN was calculated on the basis of analysed nutrient composition of diets.

Table 2. Effects of rare earth elements supplementation on ruminal pH and fermentation in sheep.

Item	Treatments^°				SE	Contrast
	Control	REE-low	REE-med	REE-high		Linear	Quadratic
pH	6.72	6.62	6.53	6.58	0.020	0.01	0.01
Ammonia N, mg/100 mL	11.83	11.30	9.73	11.55	0.326	0.32	0.05
A, mol/100 mol	64.34	65.38	65.80	64.17	0.580	0.99	0.21
P, mol/100 mol	19.75	21.93	23.43	22.29	0.500	0.02	0.04
Butyrate, mol/100 mol	6.45	6.33	6.29	6.21	0.041	0.06	0.91
A:P	3.32	2.90	2.72	2.92	0.073	0.01	0.01
Total VFA, mM	87.55	91.48	93.79	91.21	0.847	0.04	0.07

REE, rare earth elements; A, acetate; P, propionate; VFA, volatile fatty acids.

°Control (without REE); REE-low, REE-med and REE-high with 100, 200 and 300 mg/kg dry matter REE, respectively.

Table 3. Effects of rare earth elements supplementation on nutrient digestibility in the total tract of sheep.

Item	Treatments^°				SE	Contrast
	Control	REE-low	REE-med	REE-high		Linear	Quadratic
DM	0.617	0.636	0.657	0.632	0.005	0.01	0.01
OM	0.610	0.630	0.654	0.629	0.004	0.01	0.01
CP	0.615	0.641	0.678	0.645	0.008	0.01	0.01
aNDF	0.491	0.539	0.583	0.529	0.010	0.01	0.01
ADF	0.461	0.510	0.565	0.470	0.012	0.01	0.01

REE, rare earth elements; DM, dry matter; OM, organic matter; CP, crude protein; aNDF, neutral detergent fibre; ADF, acid detergent fibre.

°Control (without REE); REE-low, REE-med and REE-high with 100, 200 and 300 mg/kg dry matter REE, respectively.

Table 4. In situ ruminal digestion kinetics and effective degradability of Leymus chinensis and soybean meal.

Item	Treatments^°				SE	Contrast
	Control	REE-low	REE-med	REE-high		Linear	Quadratic
Leymus chinensis
DM
a^#	0.118	0.167	0.275	0.150	0.018	0.01	0.01
b	0.587	0.650	0.724	0.637	0.021	0.01	0.01
c, /h	0.013	0.011	0.008	0.011	0.005	0.01	0.01
ED	0.351	0.394	0.504	0.380	0.018	0.01	0.01
aNDF
a^#	0.029	0.036	0.058	0.032	0.003	0.01	0.01
b	0.694	0.845	0.940	0.773	0.032	0.01	0.01
c, /h	0.011	0.010	0.010	0.011	0.001	0.02	0.01
ED	0.279	0.329	0.375	0.306	0.012	0.01	0.01
Soybean meal
DM
a^#	0.397	0.386	0.352	0.330	0.004	0.01	0.02
b	0.600	0.611	0.645	0.632	0.012	0.01	0.01
c, /h	0.022	0.021	0.019	0.020	0.003	0.01	0.01
ED	0.570	0.558	0.519	0.507	0.013	0.01	0.74
CP
a^#	0.363	0.378	0.416	0.345	0.005	0.03	0.01
b	0.635	0.597	0.509	0.616	0.020	0.01	0.01
c, /h	0.029	0.027	0.021	0.018	0.001	0.01	0.38
ED	0.600	0.585	0.560	0.501	0.014	0.01	0.01

REE, rare earth elements; DM, dry matter; ED, effective degradability; aNDF, neutral detergent fibre; CP, crude protein.

°Control (without REE), REE-low, REE-med and REE-high with 100, 200 and 300 mg/kg dry matter REE, respectively.

^#Parameters were calculated from the fitted equation y=a+b(1–e ^-c(t-L)) for t>L, where y=percentage of DM disappearance from the nylon bag at time t, a=soluble fraction, b=slowly degradable fraction, c=fraction rate constant at which b is degraded, L=lag time (h), and t=time of incubation (h). Effective degradability (ED) was calculated using equation a+bc/(c+k), where k=0.02/h for Leymus chinensis and 0.052/h for soybean meal, respectively.

Table 5. Effects of rare earth elements supplementation on urinary purine derivatives in sheep.

Item	Treatments^°				SE	Contrast
	Control	REE-low	REE-med	REE-high		Linear	Quadratic
Urinary excretion, mmol/day Allantoin
Allantoin	11.99	14.21	16.39	13.63	0.50	0.01	0.01
Uric acid	2.72	2.94	3.15	2.91	0.06	0.78	0.03
Xanthine and hypoxanthine	0.31	0.33	0.33	0.32	0.01	0.56	0.12
Total PD	15.03	17.48	19.87	16.85	0.54	0.01	0.01

REE, rare earth elements; PD, purine derivatives.

°Control (without REE), REE-low, REE-med and REE-high with 100, 200 and 300 mg/kg dry matter REE, respectively.