Urea-Treated Wheat Straw in Diets of Butana Milking Cows

Abstract

A feeding trial was conducted at Atbara Livestock Research Station to determine, for a complete lactation period, the performance of Butana cows when fed a ration that wheat straw exclusively comprised its roughage portion. Wheat straw was either fed untreated (control) or after being ensiled for 4 weeks with 4% urea at 30% humidity. Both types of straw were mixed at the time of feeding with 25% molasses on dry matter basis. Each type of straw was fed to one of two comparable groups of six, individually penned, lactating Butana cows. Each cow was daily supplemented with 3.0 kg of a concentrate mixture. Green berseem (Medicago sativa) at the level of 7.0 kg per cow was offered only once per week. The parameters considered were dry matter feed intake, milk production, milk composition and live weight changes. A digestibility trial, using male sheep was carried out at the Small Ruminants Research Unit (Kuku) to determine the effect of urea treatment on the nutritive value of wheat straw. No significant differences were found in all parameters considered in the feeding trial. However, the treatment group of cows was superior, and scored 13.8, 21 and 35% increments of straw dry matter intake, fat corrected milk and body weight gains, respectively, over the control group. The average milk production per lactation reported for selected, optimally fed Butana cows at Atbara Station of 1807 kg in 283 days. or 6.3 kg day was surpassed by the treatment group (1962 kg 292 days, or 6.7 kg I day), while that of the control group (1674 kg in 292 days, or 5.7 kg/day) surpasses a somewhat less level reported for Butana cows at the same station (1390 kg I 253 days. or 5.4 kg/day). The crude protein content, following urea treatment of wheat straw was significantly improved to 11.3% compared with 4.2% for untreated wheat straw. Treating wheat straw with urea significantly raised its organic matter digestibility and metabolic energy by 28 and 29%, respectively, over the untreated straw. It was concluded that properly supplemented wheat straw can successfully be included as the sole source of roughage in rations for Sudanese dairy cattle and that further improvement in performance can be achieved through urea treatment of the straw.