The Metabolizable Energy Values and Digestibilities of Menhaden Fish Meal, Fish Solubles, and Fish Oils

Three energy balance experiments, using three-week-old male White Rock broilers, were conducted to determine the metabolizable energy (M.E.) content and the digestibility of the protein and the fat of ten menhaden fish meals, ten menhaden fish solubles and six menhaden fish oils. Results of Experiment 1 showed that the fish meal tested at three different levels of dietary inclusion had an average protein digestibility of 58.4% and a fat digestibility of 93.1% with no significant difference due to the levels of fish meal in the diet. The average M.E. value of the fish meals was 3.37 kcal./g. on a dry-matter basis, with a low coefficient of variation (5.6%), and 69.1% was metabolized. In Experiment 2 condensed fish solubles were determined to have protein and fat digestibilities of 57.1 and 88.7%, respectively. On the average, 70.4% of the energy in fish solubles was metabolized, and the M.E. content was 2.03 kcal./g., on an “as is” basis. The M.E. value had a coefficient of variation of 10.8%. This relatively high variation is probably due to the low levels of solubles incorporated in the test diets. The six oils tested had a fat digestibility of 90.6% and a M.E. value, on an “as is” basis, of 8.45 kcal./g. which was 89.9% of the gross energy.