Digestibility studies in sheep fed sorghum, sesbania and various grasses grown on medium saline lands

Abstract

Low animal productivity due to malnutrition is common in developing countries. Saline lands could be exploited for various salt tolerant forages without interfering human food production. This study aimed to evaluate the fodder potential of three hybrid forage Sorghum species viz. Sorghum bicolor (Hunnigreen), Sorghum sudanese (Jumbo), Brown midrib forage sorghum (Revolution-BMR); two annual grasses viz. Guinea grass and Ruzi grass and one legume, Sesbania aculeata under field conditions. These forage species were sown with same agronomic factors in the soil having ECe 2.8 ± 0.3 and pH 8.0 ± 0.2. At 50 and 80 days after sowing (DAS) the cultivars were harvested and their DM yield, nutrient contents and digestibility were determined. Eighteen 7-month-old ewes weighing 25 ± 3.2 kg were placed in metabolic pens and received the above forage species ad libitum. Nutrient digestibility was determined by total collection method. The dry matter yield was highest ( P < 0.05) in Hunnigreen at 50 or 80 days of sowing (6.4 and 13.2 t/ha). An increase in DM yield (104.8, 115.4, 72.7, 74.3, 84.7 or 127.2%) at late cutting stage of 80 DAS was noted in Hunnigreen, BMR, Jumbo, Guinea grass, Ruzi grass and Sesbania, respectively, compared with those at early stage (50 DAS). However, a decrease of 3.7, 16.1, 18.1, 36.1, 11.1 or 11.7% was noted in crude protein concentration in Hunnigreen, BMR, Jumbo, Guinea grass, Ruzi grass and Sesbania, respectively, compared with those at early stage. On the basis of equivalence economic benefit comparing with wheat straw, the cultivars followed an order of Hunnigreen > Jumbo > Revolution > Sesbania > Ruzi and Guinea grass and maximum benefit of US$ 392.4/ha was noted for Hunnigreen at late harvesting stage. The results indicated that brown midrib forage sorghum (Revolution-BMR) appeared to be highly nutritious feed and could be successfully planted alone or as mix crop with Sesbania aculeata while Hunnigreen ( Sorghum bicolor) showed a tremendous potential for medium saline lands.