Cereal straw is the most abundant of crop residues and is an important feed resource especially in tropical countries. The limitations to its use arise from its high cellulose and lignin and low nitrogen content. The objectives of this research were to investigate the use of urea for the treatment of wheat straw and incorporation of the forage into dairy cow diets.
In Experiment 1, 8 lactating Holstein Friesian cows were used in two 4 x 4 Latin Squares with three week periods. The treatments were; A - red clover silage (CS) ad libitum. B - 5kg DM/day CS + urea treated straw (TST) ad libitum. C - as for B but using untreated straw (UST), D - as for C but the straw was wetted at feeding to produce the same DM as TST (WST 600 g DM/kg). TST was treated with 5% urea (DM basis) and stored for 4-13 weeks. All cows were fed 6.4 kg DM/day of molassed sugarbeet pulp (MSBP) and o.6 kg DM/day of cottonseed meal (CSM).
In Experiment 2, 10 Holstein Friesian cows were used in an incomplete Latin Square design of four 3 week periods. The treatments were; E - CS, F - 25% UST + 75% CS, G - 50% UST + 50% CS, H - 25% TST + 75% CS, I - 50% TST + 50% CS. All forages were offered ad libitum, arid in F to I pairs of forages were mixed. The urea was applied to TST at a rate of 7.5% (DM basis). The concentrate was 4.7 kg DM/day of MSBP and 2.3 kg DM/day of soya meal.