NUTRITIVE VALUE, TANNIN BIO ASSAY AND PROCESSING EFFECTS OF ACACIA PODS AS SUPPLEMENTS TO GOATS IN MOGOTIO SUB-COUNTY, KENYA

Abstract

Tannins are anti-nutritional factors in forages. This research was conducted in Emining ward, Baringo County- Kenya. The objective was to evaluate nutritive value, tannin bioassay and processing effects of mature green pods of Acacia species as supplements to goats and characterize rumen cellulolytic bacteria. A total of 20 bucks aged 4-5 months were randomly sourced from Radat market, sprayed against ectoparasites and dewormed against endoparasites. Each buck was housed individually in a goat pen raised 1 m high with slatted floor measuring 1.5 by 1.5m. All the bucks were fed on a basal diet of Rhodes grass hay (Chloris gayana) mixed with wheat bran at 3:1 ratio. They were divided into five treatments groups of four each and allocated to five treatments. T1- (control-untreated) pods of identified mature Acacia brevispica, A. mellifera and A. tortilis, (T2-shade –dried pods for 48hours, T3-(sun dried pods for 48 hours, and T4- pods soaked in wood ash-alkali solution (10-12 Ph.) mixed at 200g ash per/liter of water for 48 hours respectively while T5 was basal diet only. Nutrient composition was determined by proximate analysis and Van-Soest laboratory procedures (AOAC-1995) and tannin bioassay by Cio- calteu/makkar procedures (2005). Organic matter digestibility was assessed by invitro gas production technique and food conversion efficiency determined as a percentage of the total weight gain by the total feed taken. At end of 3-months, 3 bucks were randomly selected from each treatment group and killed humanely. Hot, cold carcass and organ weights were recorded and the effects of tannins on gut rumen cellulolytic bacteria were isolated, quantified using serial dilution, enumeration of colony forming units and characterized morphologically by Gram staining. Analysis of variance in Stratigraphic Centurion XII was used to test for significant difference between dependent variables. Mean differences were separated using Least Significant Difference. Acacia mellifera (9.03±0.57) had the highest percentage (p=0.0011) of moisture and crude protein. A. tortilis (4.73±0.77) and A. brevispica (4.13±0.14) had the lowest percentage of ash (p<0.05) from that of A. brevispica (0.0244). In all Acacia species, methane gas produced increased per day with more produced in alkali treated pods (p<0.05). Among the Acacia species, all supplements processed in alkali were ingested in large amounts (p<0.05) with A. tortilis pods taken in large amounts (416.50±6.50) compared with the others (p=0.0012). For control treatment 1, more of A. tortilis supplement was consumed in as compared with the others (p=0.0011). Initial weight of the Small East African Goat (SEAG) did not differ prior to feeding with supplements (p>0.05). Feeding with A. tortilis resulted to the highest final weight (14.20±0.36g). Bucks fed on Acacia tortilis- alkali-treated-pods resulted in best average daily gain of 15.03±2.01g followed by A. brevispica (14.13±1.94g) with a significant difference (p<0.05) with that of A. mellifera. Low food conversion ratio was recorded in Acacia tortilis treated in alkali as compared to other treatments. Pre- and post- slaughter weights as and kill out percentage did not differ among and within treatment. In conclusion, A. tortilis pods showed high nutritional components, alkali processing resulting in highest tannin reduction and highest rumen bacterial counts. Organ weights differed among and within treatments with the largest liver weight recorded in goats fed with Acacia. brevispica and A. mellifera pods. Alkali treated A. tortilis pods resulted in significantly high rumen cellulolytic bacteria. Alkali processing is recommended for tannin reduction and A. tortilis met most of the nutritional requirements and was recommended as goat supplement.