EFFECTS OF SUGAR-BEET PULP ON RUMINAL AND LACTATION PERFORMANCES OF COWS HAVING DIFFERENT RUMEN FERMENTATION PATTERNS

This study was conducted to compare the rumen properties and lactation performance of two groups of eight Holstein cows having either a low (LA) or high (HA) ruminal acetate/propionate ratio when fed a control diet containing high concentrate, and then to compare the effect of feeding a sugar-beet pulp diet between the two groups. After feeding on the control diet, ruminal pH decreased more and total volatile fatty acid (VFA) concentration increased more in the LA group than in the HA group. However, intakes of fiber and starch, and buffering capacity from pH 7.0 to 6.0 in the rumen, did not differ between the groups. Rumen protozoa were fewer in the LA group, and Epidinium spp. was observed even in some LA cows having very small numbers of ciliates, while Ophryoscolex spp. was only seen in HA cows and always accompanied by Polyplastron multivesiculatum. Milk fat content in LA cows was very low (2.11%), and the concentration of all fatty acids from C4 to C18 was lower in the milk of LA cows than in that of HA cows. When sugar-beet pulp replaced part of the concentrate of the control diet, no effect was seen on the ruminal and lactation performances of the HA group, whereas the ruminal properties and milk fat content of the LA group became similar to those of the HA group. These results suggest that individual performances should be taken into account when the effects of a feed on dairy cows are studied. © 1990.