Earthworms as alternative protein ingredient in poultry feed.
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In poultry feed accounts for 70% of the total cost of production hence there is a need to have a high-quality and yet low cost feed. The protein sources used in poultry feeds (Rastrineobola argentea & soy beans) are also human food thus creating competition between poultry and humans who are faced with a challenge of Protein Energy Malnutrition (PEM). Objectives set to address this included; establishment of optimal breeding conditions for two earthworms species, determining their nutrient composition plus formulation of poultry feed based on earthworms as protein ingredient and comparing it with existing poultry feed by carrying out performance tests using broiler chicken. Experimental conditions studied for optimal breeding included pH (6, 7 & 8), moisture (60%, 80%) and temperature (Indoor and outdoor). For nutrient composition analysis moisture was determined using the open air oven at 105oC (AOAC 950.46), crude protein Kjeldah method (AOAC 920.53), ash content using the muffle furnace at 550o C for 6 hours (AOAC 923.03), fat content using the soxlet method (AOAC 920.39) and mineral content using the Atomic Absorption Spectrophotometer (AAS). To develop an earthworm based feed the weight of R. argentea (mukene) in the existing poultry feed was replaced at varying levels of 75%, 100% and 125% w/w earthworm powder. To evaluate feed performance four sets of broiler chicken each containing twelve birds were fed on mukene based feed as reference, 75% w/w, 100% w/w and 125% w/w earthworm powder respectively. Weight gain and Protein Efficiency Ratio (PER) of the broiler chicken were used to evaluate feed performance. The study established optimal conditions for the breeding of two earthworm species; Eudrilus eugeniae and Lumbricus rubellus (pH 7, indoor temperature and 60 to 80% moisture). E. eugeniae species which had the highest population growth rate was selected for up-scaling to a larger size farm employing the pit method. Proximate analysis on composition of the dried whole earthworm material showed that E. eugeniae has higher fat, magnesium and potassium content than L. rubellus. Comparison between earthworm based feed with R. argentea (mukene) based feed using Protein Efficiency Ratio (PER) of broiler chicken revealed a PER of 4.1 ± 1.83 (p = 0.17) implying that earthworms can be used as protein substitute for R. argentea. The study found no significant difference in weight gain of chicken fed on R. argentea based feed compared to those fed on 100% (w/w) earthworm protein (p = 0.17) and 125% (w/w) earthworm protein (p = 0.11). However, earthworm based feed formulation containing lower earthworm protein (75%) had a significantly lower PER of 3.78 ± 1.18 (p = 0.04) than that of R. argentea based feed 4.65 ± 1.1. The study has shown that earthworm species E. eugeniae can be used as alternative protein source in poultry feed without much effect on broiler performance. However, because of the large quantity of dry worm materials required in large scale feed formulation at commercial level, the study recommends poultry farmers to establish small scale rearing beds to routinely supplement poultry feeds with live earthworms to improve poultry performance.