Determination of nutritive value of Acacia Tortilis and its effect on body weight gain of Goats

Abstract

The study was conducted in the south western low lands of Eritrea at Shambuko Agricultural Research Station in Gash Setit Province, 260 Km West of the capital, Asmara, at an altitude of 1000 m. A total of fifteen Barka yearling male goats, the most common breed of goats in this ecological zone were fed separately in individual pens with diets consisting of 100% grass hay based diet as a control or treatment I, grass hay combined wi th different proportions of Acacia t o r t i Ii s pods at 25%, 50% and 75%, hereby refered to as treatment II, III and IV, respectively. However, treatment V as an upper control diet was constituted of 100% A. tortilis pods based diet. On the basis of crude protein (CP) content alone, the grass hay used in this study can be rated as low quality, even though some of the species happened to contain above 7% crude protein content. Th eg r ass hay was a 1soh i g h inn e u t r a 1 detergent fiber (NDF) and acid detergent lignin (ADL), and relatively low in P, Mg and Na. The supplementary diet used in this study reported here had CP level above the critical minimum for small ruminants and low levels of lignin and NbF. Body weight gain was significantly affected by the supplements (P<0.05). However, treatments II and III; and IV and V gave about the same live weight gains despite their distinct difference in ration composition. Diet I with 100% grass hay, gave significantly (P<0.05) lower OM digestibility than all the other diets. Voluntary DM intake of the goats was found to be significantly (P<0.05) different. While animals on diet V (100% pod) were found to consume at the same rate as the control diet (100% grass hay). The study indicated that there was no significant linear relationship (P>0.05) between the tree canopy cover and pod production (R2=0.153), neither was there a significant relationship between pod production and the circumference of the trunk (P>0.05, R-2_0.033 ) . Based on the results from these studies it was recommended that A. tortilis pods could be used as the main sources of protein for improved animal production in the semi-arid areas of the world, although further studies on the optimum levels of Acacia pods in the ration for maintenance, growth and production are suggested