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Effects of sunflower seed supplementation and different dietary protein concentrations on the ciliate protozoa population dynamics in the rumen of sheep

Ivan, M., Entz, T., Mir, P.S., Mir, Z., McAllister, T.A.
Canadian journal of animal science 2003 v.83 no.4 pp. 809-817
Helianthus annuus, Protozoa, ammonium nitrogen, corn silage, crude protein, dietary protein, fatty acid composition, high protein diet, linoleic acid, population dynamics, rumen, sheep, soybean meal, sunflower seed, volatile fatty acids
The effects of feeding a linoleic acid-rich sunflower seed supplement and different levels of dietary protein on protozoal numbers and fermentation parameters in rumen fluid were determined in an 84-d experiment with rumen-cannulated sheep. The experiment comprised four treatments, two with low crude protein diets [12% of dietary dry matter (DM)] and two with high protein diets (16% of DM). On both low and high protein diets, one treatment was without (Control) and one with the sunflower seed (high linoleic acid variety 6150) supplement (14% of dietary DM). The four diets used were based on corn silage and corn grain, and soybean meal was used to achieve the desired concentration of dietary protein. The sheep were fully fed each morning and rumen fluid samples were taken 2 h later on various days of the experiment (daily during the first 14 d for enumeration of protozoa). In addition, rumen fluid was sampled at different hours after feeding on day 43 of the experiment. Results showed a protozoa-decreasing effect (P < 0.001) of sunflower seeds causing a decline in protozoa numbers after 2 d of supplementation. The effect of protein on protozoa numbers was dependent on the presence of sunflower seed supplement. Measurements on day 43 showed increased protozoa numbers (P < 0.05) and ammonia nitrogen concentrations (P < 0.001) due to higher dietary protein, and decreased protozoal numbers (P < 0.05) and ammonia nitrogen (P < 0.001) due to the sunflower seed supplement, without significant effects (P > 0.05) on volatile fatty acid concentrations. The linoleic acid-rich sunflower seed supplement was highly effective in reducing both protozoa numbers and ammonia nitrogen concentrations in rumen fluid.