An assessment of the uses of cacros (opunliaficus-indica) in the semiarid areas of Wukro Wereda, northern Ethiopia

Abstract

The study was conducted in Wukro Wereda eastern zone of Tigray to identify and record the Opuntia varieties found in the area, to retrieve and document indigenous technical knowledge on management and uses of Opuntia varieties and to evaluate the feed value of Opuntias to livestock. The methods employed were interviews using a semi-structured questionnaire, field survey of Opuntias and evaluation of chemical composition and feeding trials using sheep. The survey results indicated the existence of two varieties of Opuntia in the area, namely spineless and a spiny cactus. The spineless variety is the dominant one. Forty percent of the farmers in the area have cactus land ranging from 0.01 to 0.039 ha, 27% of the farmers possess cactus land ranging from 0.04 to 0.1 ha and 30% own cactus land ranging from 0.11 to 0.5 ha with an average land q/'0.11 ha. Cactus is important economically and ecologically in six main wqys namely; source of human food, livestockfodder, hedge, bee forage, soil erosion control and source cash. All farmers (100%) feed cactus mainly for cattle; while 63% feed it for sheep. Ninety six percent of the farmers feed cactus to their animals daily during the dry season while the rest (4%) feed cactus to their animals every other day or every! three days. Burning and scraping are the two common processing methods used to remove the spines before feeding. In spite of the extra work and fuel involved in feeding a spiny cactus to livestock, this is becoming normal practice in a dry season. The survey result also revealed that bloat and diarrhoea are the main problems associated with feeding of a cactus to livestock and the reasons for the problems include an excess intake of cactus and feeding it alone. Samples takenfrom plants grown in natural conditions were analysedfor DM, CP, ash, CF, EE. NFE., NDF, ADF, ADL and mineral concentrations (P, Ca, Mg, Na and K). Moisture concentration was extremely high (92.5%), while CF, EE, P and Na concentrations were low; 12.26, 3.23, 0.28 and 0.14%, respectively. There was a significant (P<O.05) difference in P, Ca, Mg, K, ash and EE concentrations between the two varieties. Compared with ruminant nutrient requirements, Opuntias were high in ash, APE, Ca and K, moderate in CP and Mg and low in EE, CF, P and Na contents. The statistical analysis of the data showed no significant (P>O.05) difference between the two Opuntia varieties in terms of voluntary feed intake and n~ Digestibility. Cactus was a palatable, sheep-preferred cactus to tef straw. The total daily DM intake of sheep fed on a burned spiny cactus averaged 2.2% of their live body weight and 2.5% of their live body weight for those fed on a spineless cactus. Cactus varieties were also highly digestible (69%). Hence, it is concluded that Opuntias can serve as a link between crop residues, forages such as legumes and NPN sources by supplying readily digestible organic matter. However, for a normal diet intended to cover both maintenance and production requirements, the ration must be balanced with supplementary protein and phosphorous.