Effects of a slow-release coated urea product on growth performance and ruminal fermentation in beef steers

Figures & data

Table 1 Ingredients and chemical composition of diets.

	Control	Coated urea
Ingredients, % DM basis
Sorghum, grain ground	56.0	56.0
Steam-rolled corn	10.0	14.3
Oat straw	15.6	15.6
Molasses cane, liquid	10.1	10.1
Soybean meal, 44% CP, solvent extract	5.5
Mineral premix^*	2.2	2.3
Urea 281% CP	0.6	0.6
Coated urea^° 274% CP	1.1
Chemical composition, % DM basis
Ash	10.6	10.2
Neutral detergent fibre	25.6	24.1
Acid detergent fibre	10.3	10.0
Net energy for gain, Mcal/d	8.7	8.9
Crude protein	12.4	12.9
A, %CP	40.3	62.0
B1, %CP	26.6	15.5
B2, %CP	13.7	7.8
B3, %CP	10.5	4.7
C, %CP	8.9	10.0

* Ca, 1300 g; P, 400 g; Mn, 40 g; Fe 20 g; Mg, 2000 ppm; Zn, 3000 ppm; Cu, 2000 ppm; I, 500 ppm; Co, 100 ppm; Se, 100 ppm; Vit. A, 3,000,000 U; Vit. E, 5000 U; Monensin, 25,000 ppm.

° Optigen 1200 (Alltech Inc., Nicholasville, KY, USA).

Table 2 Overall body and carcass weight, total gain, intake, and carcass dressing of beef Cattle fed diets with soybean meal or coated urea.

	Control	Coated urea	SEM
Initial body weight, kg	328	330	27.6
Final body weight, kg	484	481	39.5
Total gain, kg	156	151	26.3
Daily dry matter intake^*, kg	13.4	12.9	0.78
Average daily gain^*, kg	1.9	1.8	0.15
Feed conversion^*, kg	7.0	7.1	0.98
Hot carcass weight, kg	299	295	25.4
Dressing carcass, %	61.8	61.3	3.04

* Time, P<0.05; time × treatment, P>0.05.

Table 3 Ruminal disappearance of DM and NDF of diets with soybean meal or coated Urea.

	Control	Coated urea	SEM
Dry matter, %
Soluble fraction, a	29.6	31.7	3.54
Potentially disappearance fraction, b	53.1^a	49.1^b	5.41
Total disappearance, a+b	84.8^a	78.7^b	6.12
Disappearance rate, k, /h	4.4	4.9	0.52
Neutral detergent fibre, %
Potentially disappearance fraction, b	65.9^a	62.1^b	5.62
Disappearance rate, k, /h	1.9	1.6	0.28

a,b means bearing different superscripts in a row differ significantly (P<0.05).

Table 4 Overall ruminal pH, lactate and volatile fatty acids (VFA), of steers fed diets with Soybean meal or coated urea.

	Control	Coated urea	SEM
PH^*	5.6	5.5	0.14
Lactic acid, mmol/L^*	2.4	2.5	0.32
Total volatile fatty acids, mmol/L^°	97.6	94.8	7.97
Acetate, mol/100 mol^°	52.0	52.3	1.55
Propionate, mol/100 mol^°	34.9	35.2	2.04
Butyrate, mol/100 mol^°	13.0	12.5	1.33
Acetate:propionate ratio^°	1.5	1.5	0.14

* Time, P<0.05.

° Time × treatment, P>0.05.

Figure 1 Overall ruminal ammonia N concentrations of steers fed diets with coated urea or soybean meal (Time= P<0.001; treatment = P<0.001).