Comparing the in vivo dry matter digestibility of perennial ryegrass in sheep and dairy cows

Bijeenkomst: EGF2015
Auteur: Garry B., Kennedy E., Baumont R., Boland T.M., Wright M.M., O’Donovan M. and Lewis E.
ISBN: 978-9090-289-61-8
Jaar van uitgifte: 2015
Producttype: Paper
Pre-grazing herbage mass (PGHM) affects grass quality and intake. Higher PGHM swards usually have lower dry matter intake (DMI) and in vitro dry matter digestibility (DMD) than lower PGHM swards, leading to reduced performance in lactating dairy cows. In vivo digestibility experiments involving cows are often laborious and expensive and, as a result, sheep are often used instead. The objective of this experiment was to compare the in vivo DMD of perennial ryegrass (Lolium perenne L.) at high and low PGHM in lactating dairy cows and wether sheep. A Latin-square design experiment was repeated twice (TS1 (April-May) and TS2 ( July-August)) using eight wether sheep and eight spring-calving lactating dairy cows to determine the in vivo DMD of two different PGHM swards (1,700 kg dry matter (DM) ha‑1 (low mass; LM) and 4,000 kg DM ha‑1 (high mass; HM)). There were no interactions between PGHM, animal species and TS. The in vivo DMD of perennial ryegrass reduced from LM to HM and from TS1 to TS2. There was a tendency for cows to have lower in vivo DMD of perennial ryegrass than sheep. The greater in vivo DMD of LM compared to HM may be due to the greater proportion of leaf and lower true stem proportion in LM. As there were no interaction effects on in vivo DMD, sheep DMD and cow DMD are similar to each other across all PGHM and all seasons.