Effects of ruminal administration of soy sauce oil on functional fatty acids in the rumen, blood and milk of dairy cows.

OBJECTIVE: Soy sauce oil, a byproduct of whole soybean processing by the soy sauce industry, was evaluated as a source of linoleic acid for dairy cows for the purpose of manipulating the composition of milk. METHODS: Eight dairy Holstein cows fitted with rumen cannulas were used for ruminal administration of soy sauce oil for a 28-day period using a 4×4 Latin square study design with 4 doses (0, 200, 400, and 600 g soy sauce oil/d). RESULTS: Although dry matter intake and milk yield were not affected by soy sauce oil administration, ruminal concentrations of total volatile fatty acids and acetate were decreased, specifically at 600 g/d administration. While milk fat percentage was decreased with administration of soy sauce oil, proportions of linoleic, vaccenic and conjugated linoleic acids in the rumen, blood and milk were increased with increasing soy sauce oil dose. CONCLUSION: These results suggest that soy sauce oil feeding could be useful for improving milk functionality without adverse effects on animal production performance when fed at less than 400 g/d.

Effect of ruminal administration of soy sauce oil on rumen fermentation, milk production and blood parameters in dairy cows.

OBJECTIVE: To evaluate soy sauce oil (a by-product of making whole soybean soy sauce) as a new dietary lipid source, a large amount of soy sauce oil was administered into the rumen of dairy cows. METHODS: Four Holstein dairy cows fitted with rumen cannulae were used in a 56-day experiment. Ruminal administration of soy sauce oil (1 kg/d) was carried out for 42 days from day 8 to day 49 to monitor nutritional, physiological and production responses. RESULTS: Dry matter intake and milk yield were not affected by soy sauce oil administration, whereas 4% fat-corrected milk yield and the percentage of milk fat decreased. Although ruminal concentration of total volatile fatty acids (VFA) and the proportion of individual VFA were partially affected by administration of soy sauce oil, values were within normal ranges, showing no apparent inhibition in rumen fermentation. Administration of soy sauce oil decreased the proportions of milk fatty acids with a carbon chain length of less than 18, and increased the proportions of stearic, oleic, vaccenic and conjugated linoleic acids. Conjugated linoleic acid content in milk became 5.9 to 8.8 times higher with soy sauce oil administration. Blood serum concentrations of non-esterified fatty acid, 3-hydroxybutyric acid, total cholesterol, free cholesterol, esterified cholesterol, triglyceride and phospholipid increased with administration of soy sauce oil, suggesting a higher energy status of the experimental cows. CONCLUSION: The results suggest that soy sauce oil could be a useful supplement to potentially improve milk functionality without adverse effects on ruminal fermentation and animal health. More detailed analysis is necessary to optimize the supplementation level of this new lipid source in feeding trials.