Preparation of fresh forages for incubation and prediction of
nutritive value
L.G. Barrell, J.L. Burke, G.T. Attwood, G.C. Waghorn and I.M.
Brookes
AgResearch, Grasslands Research Centre, Private Bag 11008,
Palmerston North, New Zealand
Proceedings of the New Zealand Society of Animal Production.
2000, 60: 5-8
In vitro and in sacco digestion offers a rapid and inexpensive
method for evaluating nutritive value of ruminant feedstuffs. This study
compared the conventional freeze dried and ground (FD) preparation with
chopping to 6-mm lengths (C) and mincing (M) to represent chewed forage.
In sacco and in vitro comparisons were made with perennial ryegrass
(RG), white clover (WC) and Lotus corniculatus (LC). The mean
proportions of large (>1.0mm) and soluble dry matter (DM) for the three
forages were: M, 0.38 and 0.44; C, 0.76 and 0.21; FD, 0.35 and 0.34
respectively. Disappearance of DM and crude protein (CP) during the
first 12 hours of rumen incubation was substantially lower for chopped
forages. Minimal lag times before the onset of protein degradation were
observed following mincing. Yields of ammonia from proteolysis in in
vitro incubations were lowest for C and usually highest for M
preparations. Preparation also affected yield but not proportions of
VFA. These data show that ranking of forages for digestibility is
affected by preparation and mincing appears to be a more suitable
preparation for assays than chopping and freeze drying and grinding.
Keywords: NZSAPAB;
forage preparation; particle size; in sacco; in vitro.
Last Updated 12-07-2000
