Coconut and to a lesser extent krabok oil, depress rumen protozoa in beef cows

Abstract

Krabok and coconut oil were assessed for their ability to affect rumen protozoa via a 3×3 Latin square design experiment with three rumen cannulated beef cows. The diets consisted of a concentrate supplemented with either 25.5 g/kg of tallow (control) or the same quantity of coconut oil or krabok oil. The animals were fed at 1.5% of their body weight per d for 28 d per period. The samples of rumen fluid were collected on day 23 and 27 of each period, 3, 6, 9 and 12h after morning feeding. Rumen protozoa numbers, as well as amylolytic, cellulolytic and proteolytic bacteria were counted microscopically. Fragments of the 18S rRNA gene were amplified in a nested PCR using general eukaryotic and ciliate protozoa-specific primers (Euk1a and 539r followed by 316f- Euk516r-GC). Diversity of the ciliate community was analyzed by Denaturing Gradient Gel Electrophoresis (DGGE) (7% acrylamide, 35-50% gradient; 38 V for 16h at 60 ºC) and gels were processed with BioNumeric software. Protozoa numbers decreased by 0.33 log units in the coconut (P<0.05) and 0.21 log units in the krabok oil diet (P<0.05) compared with the control diet. The ciliate value was not significantly different between treatment but were strongly (R2=0.88) linearly associated with protozoa counts. The concentration of total VFA was not affected (P=0.804) by the diet. Except propionic acid which showed a trend (P=0.056), the proportions of the remaining VFA were not significantly (P>0.10) different between treatments. The propionate proportion was only reduced by supplementation of coconut oil to the TMR. Neither oils affected amylolytic, cellulolytic or proteolytic bacteria counts. Cluster analysis of the DGGE profile showed two clusters of ciliate communities, one including all the T diet-fed animals. All except one DGGE profile of a cow fed the KO diet group into the second cluster. Coconut oil, and to a lesser extent krabok oil, has a marked effect on the numbers of rumen protozoa.