P.H. Robinson
Atlantic Ruminant Research Group
Agriculture and Agri-Food Canada
Fredericton, N.B.

Materials and Methods

Primiparous dairy cows in early lactation were utilized to evaluate the palatability, nutritive value, and impact on milk quality of a seal meal. Compositional and in situ analysis of various seal meal samples completed prior to initiation of the study suggested that seal meal contained approximately 15% fat, 7% calcium, 4% phosphorous and 60-65% crude protein of which approximately 60-65% was undegraded in the rumen (UIP). Based upon these preliminary analysis, diets were designed which progressively replaced a combination of corn gluten meal, blood meal and canola meal with seal meal at a level equal to approximately 1.9, 3.8 and 5.7% of dry matter intake.

Results and Discussion

Even at the highest level of inclusion of seal meal, a level higher than would be expected to be used in practice, incidences of refusals of the concentrates containing seal meal were limited to three cows in the 72 hours immediately after introduction of seal meal. Milk quality as assessed by milk flavour, milk fatty acid profile for healthfulness to humans and fat:protein ratio for processing characteristics were little influenced by seal meal inclusion levels, although oxidized milk flavour declined and the proportion of desirable unsaturated and hypocholestremic fatty acids increased as the inclusion level of seal meal increased. Intake of dry matter and its components, as well as production of milk and its components, decreased, or tended to decrease, as the seal meal substitution level increased. However, total animal energy output was the same for all seal meal substitution levels. This masked a shift in energy output from milk to body weight gain, which appears to have been the result of a progressively greater deficiency of UIP as the seal meal substitution level increased, which in turn was primarily due to an underestimation of the UIP level of the seal meal utilized in this study.

Conclusions

The seal meal utilized in the study appeared palatable to dairy cows, under the conditions of the study, and improved milk quality. The decrease in animal performance, which occurred as the seal meal substitution level increased, appears to have been due to a specific nutrient deficiency in the diet rather than the seal meal per se. Pending confirmation of this hypothesis, it would appear that a net energy of lactation value of 1.75 Mcal/kg and a UIP value of approximately 35% would be desirable in this regard.

For further information contact the Alternative Feeds Coordinator at the Pynn’s Brook office or the Corner Brook/Headquarter’s Office.