In Situ Nitrogen and Dry Matter Disappearance of Soybean Meal, Mexican Anchovy, Maine Herring, and Menhaden Fish Meals

Two ruminally cannulated Holstein steers were used to determine the in situ nitrogen (N) and dry matter (OM) disappearance of soybean meal, Mexican anchovy fish meal, Maine herring fish meal, and Menhaden fish meals from seven processing plants. Protein sources were placed in the rumen of each steer on two occasions 1 week apart for 1, 2, 4, 8, 16, and 24 h in a randomized block design. Nitrogen disappearance of soybean meal was 95% at 24 h, while that of Menhaden fish meals was between 29.4 and 41.1 %. The percent N disappearance of the Menhaden fish meals was higher (P<.05) than either the Maine herring or the Mexican anchovy fish meal (22.7 and 23.4%, respectively). Dry matter disappearance of soybean meal was nearly complete (92%) at 24 h. Menhaden fish meal OM disappearance ranged from 38.8 to 46.3% at 24 h, which was higher (P<.05) than the Maine herring (28.7%) or the Mexican anchovy (36.9%) fish meal. Results indicate that protein escape of Menhaden fish meal may vary among processing plants, but will usually range between 60 and 70%. Also, species of fish processed may affect protein escape.