Effect of prolonged high-concentrate feeding on ruminal protozoa concentrations
1996
Franzolin, R. | Dehority, B.A.
Five ruminally cannulated steers, with ad libitum access to feed, were gradually adapted from an all-forage diet to a 75% concentrate diet over a 6-wk period. Three animals were then randomly assigned to an all-concentrate diet (87% whole corn) and the other two were fed a 90% concentrate plus 10% forage diet. These diets were fed for 17 wk and then reversed between groups for 11 additional weeks. Over the last 22 wk, addition of 10% forage to the all-concentrate diet had no effect on the concentration of total protozoa; however, Isotricha and Epidinium percentages increased (P < .05). Although concentrations varied markedly, protozoa persisted throughout the entire period of high-concentrate feeding (both diets) in three of the animals. In contrast, the other two animals were defaunated most of the time, except for the sporadic appearance of Entodinium species for 1- or 2-wk intervals. Average pH in these latter two animals was lower (P < .05) during the entire 28-wk high-concentrate feeding period. Because these two animals had a lower ruminal pH than the other three, even when fed all forage, it seems that the ruminal environment varies between individual animals. Thus, the maintenance of a protozoal population in animals fed high-concentrate diets may be related to physiological conditions such as rate and extent of salivary production, rate of fluid and particulate matter passage within each animal, and so on.
Show more [+] Less [-]AGROVOC Keywords
Bibliographic information
This bibliographic record has been provided by National Agricultural Library