Time course of changes in antioxidant activity of milk from dairy cows fed a trehalose-supplemented diet.

This study was to investigate the time course of changes to the antioxidant activity of milk from cows fed a trehalose-supplemented diet, and to determine possible underlying mechanisms for observed changes. Six Holstein cows were used, and subjected to two experimental feeding periods consisting of a 1% trehalose-supplemented diet for 10 days, followed by a basal diet only (no trehalose) for 10 days. 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities in milk were gradually increased during the trehalose supplementation period and were highest at the end of the second period. However, trehalose was not detected in the milk and plasma of dairy cows fed a diet supplemented with trehalose for 10 days, indicating that the increased antioxidant activity in the milk of trehalose-fed cows is not due to the direct transfer of trehalose to the milk. Plasma DPPH activities exhibited a similar time course to that seen for milk. Relative superoxide dismutase (SOD) activities in the rumen were higher 3 days after the end of trehalose supplementation than at any other time during the experimental periods. These results suggested that the improved antioxidant activity in milk and plasma of cows fed a trehalose-supplemented diet was due to improved ruminal relative SOD activity.

Effect of supplementation of soy sauce oil and Ca salts of fatty acids on rumen fermentation, milk production and conjugated linoleic acid in milk of dairy cows.

Eight cows were used to evaluate the effects of supplementation of soy sauce oil (SO) or Ca salts of fatty acids (FA) on rumen fermentation and milk production. The control diet (CO) consisted mainly of hay, corn silage and a concentrate. In the experimental diets, 400 g/day per cow of SO or FA (soybean oil and rapeseed oil) was supplemented to the CO diet. Experimental period for the three treatments was 14 days, and milk samples were taken during the last 2 days and rumen sample was taken on the last day. Dry matter intake was not affected by the treatments. The number of rumen protozoa at 0 h increased by SO and FA diets. Total volatile fatty acids at 2 h after feeding of SO diet was decreased compared to CO. The milk composition yield did not differ among treatments, although the percentages of fat and protein were decreased by SO and FA diets. The proportions of C8-C16 fatty acids in milk fat decreased, and those of C18 increased by SO and FA diets. The proportion of cis-9, trans-11 conjugated linoleic acid in milk fat by SO and FA diets increased by 120% and 135%, respectively. In spite of the slight suppression of rumen fermentation by SO diet, negative effects on feed intake and milk production were not detected.