Amino acid analysis and biological evaluation of detoxified <em>Thevetia</em> seed meal

Abstract

Thevetia peruviana seed meal was detoxified using two methods – acid hydrolysis followed by ethanolic extraction of the released aglycones and direct ethanolic extraction of the cardiac glycosides. Acid detoxification followed by alcoholic extraction of the aglycones gave a meal with 95% reduction in the glycoside content (from 42.7 to 2.15 g kg^-1), while direct alcohol detoxification led to a 98% reduction in the glycoside content of the seed meal (from 42.7 to 0.83 g kg^-1). The two treated Thevetia seed meals (TSM) were used to formulate poultry diets by introducing 0, 5, 10 and 15% of treated TSM into the feed composition which is equivalent to 0, 16.7, 33.3 and 50% replacement of soybean meal. The results showed that up to 15 % inclusion of alcohol detoxified TSM (≈ 50% replacement of soybean meal) produced no mortality and gave satisfactory growth performance of the cockerels used for the experiment. The performance of birds on alcohol detoxified diets was comparable with that of birds on the control diet. However, diets formulated with acid detoxified TSM gave fairly satisfactory performance only with 5% inclusion of the detoxified meal in the diet (i.e., 16.7 % replacement of soybean in the meal). Higher inclusion levels (5 and 10% inclusions) resulted in reduced feed intake and retention, reduced activity and high mortality (25 – 33% mortality). The birds were uncoordinated, walked limply and generally exhibited poor growth performance. Amino acid analysis of the detoxified TSM also showed that the alcohol-detoxified meal had a better amino acid profile and higher essential amino acid contents than either the raw meal or the acid-detoxified meal. The acid-detoxified meal had the lowest content of all amino acids analyzed except the acid amino acids which were increased. Generally, alcohol detoxification appeared to be the best and most effective of the two detoxification methods examined.