Assessment of molasses-urea blocks for goat and sheep production in the Sultanate of Oman: intake and growth studies

The goal of this study was to develop a molasses-urea block (MUB) for purposes of supplementing trace minerals to domestic ruminant livestock in Oman. To accomplish this, the utility of molasses and date syrup as fermentable energy sources, of straw, date flakes and wheat bran as fibre sources, and of cement and lime as binders were evaluated. The proportion of cement needed for adequate hardening of the block was also studied. Molasses- and date syrup-based blocks hardened equally well. However, the higher cost of date syrup precluded its use. Wheat straw yielded a low-density block that hardened slowly. Date fibre retained moisture and hardened extremely slowly. Wheat bran-based blocks hardened quickly and yielded dense blocks. Hence, wheat bran was judged to be the superior source of fibre. Lime did not effectively bind the blocks. A cement content of 15% allowed hardening of the blocks within 2-3 weeks. A level of 10% cement in the block reduced the hardening rate by about 50%. Sheep and goats consumed both the straw- and wheat bran-based blocks but at different rates. Consumption of the straw-based block by sheep ranged from 50 to 179 g/head per day, whereas the denser wheat bran-based block was consumed at a rate of 8-20 g/head per day. Consumption of the straw-based block by goats was low (8 g/head per day) compared to that of wheat bran-based blocks (16-24 g/head per day). On the basis of the intake of the bran-based block by sheep, a block was designed that would provide approximately 50% of an animal's trace mineral requirements per day. This block consisted of 45% molasses, 10% urea, 5% trace minerals, 2.5% NaCl, 22.5% wheat bran and 15% cement. Sheep consuming this block gained more weight than sheep fed a conventional mineral block or sheep receiving no mineral supplementation. MUBs are inexpensive (9.5 US cents/kg). We conclude that MUBs have utility for providing trace elements in ruminant diets.