Evaluation of a seal by-product meal as a feedstuff for dairy cows

Seal by-product meal (SBPM) is produced from seal carcasses collected during the Newfoundland seal harvest. It typically contains 60% crude protein (CP) on a dry matter (DM) basis, 15% fat (DM), 19% ash (DM) and 5% moisture. Eleven early lactation primiparous Holstein dairy cows were offered a mixed ration of 59.5% (DM) timothy grass silage and 40.5% (DM) whole crop barley silage. Two grain based concentrates were formulated to contain either 11.5% SBPM or a combination of corn gluten meal, blood meal and canola meal. Concentrates were isonitrogenous, had similar proportions of ruminally degraded and undegraded CP, and were fed in combinations to provide 0%, 33%, 67% or 100% of the concentrate containing SBPM to provide a 50:50 ratio of forage to concentrate in the total DM offered. The highest level of inclusion of SBPM was higher than that which might be expected in practice in order to define polynomial responses to its inclusion. Even at the highest level of inclusion of SBPM, incidences of refusals of the concentrate containing SBPM were limited to three cows in the 72 h immediately after introduction of SBPM. Milk quality as assessed by milk flavour and milk fatty acid profile for healthfulness to humans, as well as fat:protein ratio for processing characteristics, were little influenced by increasing SBPM inclusion although oxidized milk flavour declined and the proportion of desirable unsaturated and hypocholestremic fatty acids increased. Intake of DM and its components, as well as production of milk and its components, decreased or tended to decrease as SBPM substitution increased. Total animal energy output was the same for all SBPM substitution levels, although energy output tended to shift from milk to body weight gain as the inclusion level of SBPM increased. This appears to have been the result of a progressively greater deficiency of ruminally undegraded intake CP as the SBPM substitution level increased, which in turn was probably due to an underestimation of the undegraded CP level of the SBPM utilized in this study.