Dinh Van, T.

Klieve, A. V.

McLennan, S. R.

Ouwerkerk, D.

Poppi, D. P.

Tolosa, M. X.

University of Queensland eSpace

S14 Session I: Taxonomic and functional diversity of gut microbes
content prepared from a high WSC perennial
ryegrass (cv. Ba11353; HSGS) in a two period
changeover experimental design. Liquid phase
rumen samples were collected 2 h after feeding.
Total and cellulolytic bacteria were estimated
using a most-probable-numbers method and
protozoa by direct counting. Bacterial and pro-
tozoal diversity in the samples was estimated by
PCR-DGGE using, respectively, 16S and 18S
ribosomal DNA specific primers. Cellulolytic
bacteria numbers were lower (7.42 vs. 35.7 ×
107·mL–1 respectively, P = 0.004) and total pro-
tozoa higher (13.2 vs. 8.12 × 105·mL–1, P = 0.025)
in the rumen fluid of animals fed the HSGS diet,
however total bacteria were not significantly
affected by the offered diet (3.71 vs. 2.41 ×
109·mL–1). As expected the bacterial commu-
nity displayed more diversity than the protozoal
community as indicated by DGGE. Cluster anal-
ysis of DGGE band polymorphism showed that
the experimental period explained most of the
similarity in both bacteria and protozoa. How-
ever, within experimental periods, samples of
amplified bacterial rDNA taken from animals
fed the same diet shared the highest level of sim-
ilarity, while no clear pattern was observed for
rumen protozoa. Our results suggested that dif-
ferences in silage WSC content can cause sig-
nificant shifts in microbial community structure.
Effect of molasses diets on population profiles
of rumen bacteria. M.X. Tolosaa,b, T. Dinh
Vana, A.V. Klieveb, D. Ouwerkerkb, D.P. Poppia,
S.R. McLennanb (a Schools of Animal Studies
and Veterinary Science, University of Queens-
land, St Lucia QLD 4072, Australia; b Depart-
ment of Primary Industries, Animal Research
Institute, Yeerongpilly QLD 4105, Australia).
The objectives of this study were to obtain pro-
files of the predominant rumen bacterial species
of beef cattle fed diets containing varying pro-
portions of low-quality Pangola grass-hay and
molasses. Four rumen-cannulated Brahman-
cross steers were fed molasses as 0, 25, 50 and
75% of the diet once daily. Urea comprised 3%
of the molasses. Steers were allocated to one of
four diets in a 4 × 4 Latin square design with peri-
ods of 28 days. Following a 3-week adaptation
period, rumen fluid samples were taken imme-
diately prior to feeding and 8 h after feeding over
two consecutive days. Total genomic DNA was
extracted from the rumen fluid samples by bead
beating. Subsequently, 16S rDNA was ampli-
fied by polymerase chain reaction with primers
specific for the fragment between variable
regions 2 and 3 (V2-V3) of the gene. The ampli-
fied V2-V3 products were analysed using DGGE.
A comparison of two sets of four DNA samples,
each set representing the two extreme dietary
conditions (diets containing 0 and 75% molas-
ses) belonging to two different animals, revealed
the presence of dominant species in the rumen
samples from the steer fed the highest molasses
treatment that were not present in the samples
obtained from the control steer. Furthermore,
there were no differences in this steer between
the DGGE banding pattern derived from the
morning and afternoon, and between two con-
secutive days. Therefore, it can be concluded
that predominant species of the rumen bacterial
community appear to be particularly stable
throughout the day and over at least a two-day
period in animals fed a given diet. Further stud-
ies are being undertaken to identify those pre-
dominant species. A longer-term objective of
this research is to investigate linkages between
diet, rumen microbial populations and the effi-
ciency of microbial protein production.
Differences in rumen microbial population
induced by the quality of dietary forage. M.
Fondevilaa, G. Muñoza, G. de la Fuentea, M.
Pérez-Quintanab, J. Balcellsa (a Departamento
de Producción Animal y Ciencia de los Alimentos,
Universidad de Zaragoza, Miguel Servet 177,
50013 Zaragoza, Spain; b Departamento de
Química y Biología, Universidad de Matanzas,
Matanzas, Cuba).
Previous studies showed that the lower the qual-
ity of dietary forage, the higher the degradation
of poor quality roughages. Therefore, rumen
bacterial and protozoal populations of sheep
given alfalfa hay (AH), untreated (US) or ammo-
nia-treated (TS) straw were studied. Four rumen
cannulated sheep were adapted to diets for
14 days in three consecutive periods. Samples
for bacterial and protozoal counts were taken
just before the morning feed. In addition, pH and
volatile fatty acid concentration (VFA) were
determined 0, 4 and 8 h after feeding. Average
pH ranked US > TS > AH (6.87; 6.60 and 6.33;
P < 0.05). The proportion of acetate was lower


Effect of molasses diets on population profiles of rumen bacteria

http://espace.library.uq.edu.au/view/UQ:187387/UQ187387_OA.pdf

Effect of molasses diets on population profiles of rumen bacteria

Abstract

Similar works

Full text

Available Versions

University of Queensland eSpace