Urea treatment as a means of preserving/processing moist wheat for intensively finished cattle

M. Lewis 1, B.G. Lowman 1 and M. Ford 2

1 Animal Biology Division, SAC, Bush Estate, Penicuik, Midlothian EH26 0PH, UK

2 Hydro Nutrition Ltd, York Road, Elvington, York YO4 5AR, UK

Introduction Wheat requires processing for feeding to cattle otherwise large amount remain undigested. Processing methods can be mechanical or chemical (sodium hydroxide or aqueous ammonia) but these require specialized equipment and/or the use of contractors. The objective of this trial was to evaluate moist wheat fed whole, but treated with urea at harvest as a means of generating ammonia in situ, in diets for intensively finished cattle

Materials and methods Eighty tonnes of wheat (variety Riband) was harvested on 21-22 August 1997 at a dry matter (DM) of 750 g/kg and treated immediately with 53 l/tonne of a urea solution (430 g urea/litre) to supply 30 g urea/kg wheat DM. Treatment was achieved by applying the urea to the wheat as it was augered into the storage silo, which was then sealed with polythene. The treated wheat, fed whole, was offered ad libitum to three pens of eight spring-born

Limousin X weaned suckled steers either unsupplemented (U)
or supplemented with soyabean meal (S)
or molasses (M) at 60 and 50 g DM/kg wheat DM respectively.
A fourth group was offered a standard ‘barley beef’ diet(C) composed of barley and rapeseed meal.

All groups received straw to appetite and appropriate mineral and vitamin supplementation. The cattle were weighed fortnightly and intakes measured on a group basis throughout the trial. The cattle were slaughtered on a commercial basis by subjective assessment to attain an MLC carcass fat class of 4L.

Results. The composition of the diets are given in Table 1 and cattle performance, intakes and feed costs in Table 2. The low residual urea content of the treated wheat (Table 1) indicated that 0.94 of the urea applied had been hydrolysed to ammonia. The wheat remained stable without deterioration throughout the 180 day feeding out period.

 

Table 1. Composition of the diets

U

S

M

C

Dry matter g/kg 693 701 690 870
CP g/kg DM 194 214 189 174
Urea g/kg DM 1.7 - - -
NDF g/kg DM 152 160 150 195
Starch g/kg DM 596 570 574 405
ME MJ/kg DM 13.6 13.5 13.4 12.9

Table 2. Cattle performance, intakes and feed costs

U

S

M

C

sed

Initial weight kg 317 313 320 317 37.4
Final weight kg 495 531 509 523 26
Days to slaughter 175 172 164 160 24.6
Liveweight gain kg/d 1.02 b 1.26 a 1.14 ab 1.29 a 0.11
Dry matter intake kg/d 6.65 7.29 7.32 7.48
Feed: gain 6.53 5.77 6.42 5.8
Feed costs p/kg LWG 67 63 69 69

Daily gain for the C and S groups (Table 2) were similar and significantly higher than for U, but this latter group contained one poorly performing animal. Performance of the C and S groups compared favourably with that of the top third of MLC Beef Plan survey results for cereal fed suckled steers (LWG - 1.25 kg/d). Undigested whole-wheat grains were evident in faeces from all wheat fed cattle but this appeared not to affect feed: gain to any great extent. Supplementation of U with a small amount of soya bean meal resulted in a large and financially worthwhile response in performance.

 

Conclusion Urea treatment of moist wheat at harvest is a cheap and simple system, which preserves the grain and increases its crude protein content. Treated wheat can be fed whole ad libitum without further processing to intensively finished cattle and, when supplemented with soya bean meal, gives a performance similar to that given by traditional intensive beef diets.

 

Acknowledgement Hydro Nutrition Ltd funded this work.