Title

Concentrate levels and Saccharomyces cerevisiae affect rumen fluid-associated bacteria numbers in dairy heifers

Author Info

G. J. Lascano, Pennsylvania State University - University ParkFollow
G. I. Zanton, Pennsylvania State University - University Park
A. J. Heinrichs, Pennsylvania State University - University Park

Publication Date

12-2009

Recommended Citation

Postprint version. Published in Livestock Science, Volume 126, Issue 1-3, December 1, 2009, pages 189-194.

NOTE: At the time of publication, the author G.J. Lascano was not yet affiliated with Cal Poly.

The definitive version is available at https://doi.org/10.1016/j.livsci.2009.06.019.

Abstract

Total viable rumenbacteria counts through the use of colony-unit forming assays lack accuracy because they only include culturable bacteria capable of initiating cell division. Thus, bacterial counts can be underestimated. The use of fluorescent characteristics of cell membranes allows flow cytometry to enumerate and distinguish dead from live bacteria cells. The objective of this experiment was to investigate the viable and total ruminal bacteria counts when 3 levels of forage:concentrate in diets were fed at restricted levels with the addition of Saccharomycescerevisiae (YC). Three cannulated post-pubertal Holstein heifers (age 18 ± 1.0 months) were fed corn silage (CS)-based diets in a 3-period (35 d) Latin square design. Heifers were fed the diets for 21 d with no yeast addition, followed by 14 d where yeast culture (YC) was added (1 g/kg as-fed basis); (Yea-Sacc¹⁰²⁶, Alltech, Inc., Nicholasville, KY). A low concentrate (LC) TMR (80% CS, 20% concentrate; 12.4% CP, 35% NDF), a medium concentrate (MC) TMR (60% CS, 40% concentrate; 12.3% CP. 28% NDF), and a high concentrate (HC) TMR (40% CS, 60% concentrate; 12.6% CP, 25% NDF), were fed once per day. Rumenfluid was sampled − 2, 0, 2, 4, 6, 8, 10, 12 h after feeding. Samples were immediately stained with fluorescent dyes using the BacLight kit (Molecular Probes Inc., Eugene, OR) and analyzed with a Coulter XL-MCL single laser flow cytometer. Mean rumen viable bacteria counts linearly increased among treatments (4.96, 4.78, 6.73 × 10¹¹ ± 0.53 × 10¹¹ cells/ml; P = 0.02) for LC, MC and HC respectively, and YC addition increased number of viable bacteria cells (P < 0.01). Total and viable bacteria counts decreased for the first 2 h after feeding then increased 4 h post-feeding. Dietary concentratelevel and YC can alter rumenbacteria counts as measured by this method.

Disciplines

Dairy Science

Copyright

2009 Elsevier