1. Mean ± SE p value
Digestibility (D value) 0.31 ± 0.01 ***
Microbial crude protein (mg/mL) 0.43 ± 0.06 ***
Propionate:acetate ratio 0.32 ± 0.01 ***
Total volatile fatty acids (mM) 52.47 ± 1.60 **
Ammonia-nitrogen (mg/mL) 1.04 ± 0.01 ***
Figure 1: Fermentation parameters for 10 Holstein-Friesian steers from the same farm. Animals are ranked for fibre digestion efficiency from best
(left) to worst (right) with overall score and carcass classification (EUROP) in parenthesis. The legend shows mean values to which the x-axis is set
for each parameter and the overall effect of animal (** p < 0.01, *** p < 0.001). Error bars = SE (n = 3).
Within cattle herd variation in in vitro rumen
fibre digestibility
K McDermottab, HMR Greatheada
a School of Biology, University of Leeds, LS2 9JT UK b bs10k4m@leeds.ac.uk
1. Message
The large within herd variation in
rumen DM digestibility (up to 62%)
measured using the in vitro model of
rumen fermentation implies the
source of this variation was
exclusively microbial in origin.
4. Results
5. Conclusion
Large within herd variations in rumen DM digestibility and associated fermentation parameters were shown using an in vitro
rumen model enabling a ranking of animals for fibre digestion efficiency.
6. Future Work
− Sequence bacterial 16s rRNA from the most and least efficient ranked animals
− Inoculate least efficient fluid with most efficient and observe effect on DM digestibility
− Repeat with animals of known performance history and compare with their performance in vitro.
References: 1Aikman, P.C. et al; J Dairy Sci, 2008, 91: 1103-14, 2Guan, L.L. et al; FEMS Microbiol Lett, 2008, 288: 85-91
(15, -O 4L) (19, -O 3) (23, -O 3) (24, -O 4L) (29, O+ 4L) (30, O+ 4L) (31, O+ 4H) (33, O+ 4L) (35, -O 4L) (36, -O 4L)
2. Introduction
Ruminants have an important role to play in sustainable food
production systems due to their ability to convert fibrous feedstuff,
unsuitable for human consumption, into high protein food. Some
animals are much better than others at digesting fibre and variation
exists between different breeds1 as well as between individuals of the
same breed from the same herd2.
Objective: To determine within herd variations in rumen DM digestibility
and associated fermentation parameters using an in vitro rumen model
3. Methods
− Rumen fluid was collected from 10 Holstein-Friesian steers from the same farm at time of slaughter and was used to
inoculate in vitro batch culture fermentation bottle (6 bottles per animal)
− Fermentations were run for 24 hours with 0.5 g of dried grass as a substrate (Northern Crop Driers Ltd, UK)
− Dry matter (DM) digestibility, total gas pressure, pH, and concentrations of volatile fatty acids (VFA), ammonia-nitrogen
(NH3-N) and microbial crude protein (MCP) were measured
− Results were expressed per gram of dry matter added and analysed in IBM SPSS Statistics 21 using a one-way ANOVA
or Kruskall-Wallis test (MCP)
− Results for DM digestibility, MCP, propionate:acetate ratio, total VFA and NH3-N concentration were used to rank each
animal for fibre digestion efficiency by scoring animals from best (1) to worst (10) for each parameter (Figure 1); the best
performing animal had the lowest overall score.