The effect of secondary compounds of birdsfoot trefoil and red clover on
dairy cow grazing preferences
C.H.E.C. Poli, J. Hodgson, G. C. Arnold and G.P. Cosgrove
College of Sciences, Massey University, Palmerston North, New Zealand
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Proceedings of the New Zealand Society of Animal Production. 1998,
58: 110-112
The responses of grazing animals to specific plant secondary compounds
were examined in trials in which dairy cows grazed spaced plants of
either birdsfoot trefoil (Lotus corniculatus L.) with high and low
concentration of extractable condensed tannins (2.54 and 0.62 % in the
DM respectively for high and low tannin genotypes), or red clover
(Trifolium pratense L.) with high and low formononetin concentration
(0.68 and 0.29 % in the DM respectively for high and low formononetin
genotypes). Plants were established in 4 linear sequences of 26, each
providing three blocks (replicates) of balanced sets of 2 plant species,
2 concentrations of test components, and plants either not trimmed or
trimmed to minimise physical differences between genotypes within
species. The sequences were grazed by four trained cows and selective
behaviour was determined by the number of grazing bites per plant.
Observations were repeated in March (P1) and April (P2). On average,
animals grazed more on non-trimmed than on trimmed plants (7.6 vs 3.1 ±
0.711 bites/plant in P1, P=0.0001; and 8.4 vs 3.6 ± 0.858 bites/plant in
P2, P=0.0002), but did not show clear discrimination between red clover
and lotus (6.3 vs 4.4 ± 0.711 bites/plant in P1, P=0.053; and 6.3 vs 5.7
± 0.858 bites/plant in P2, P=0.620). However, though the distribution of
bites between red clover plants with high and low formononetin was
similar (7.2 vs 5.5 ± 0.76 bites/plant in P1, P= 0.130; and 7.3 vs 5.3 ±
1.08 bites/plant in P2, P= 0.191), they showed strong preference for low
condensed tannin concentration in lotus ( 2.1 vs 6.6 ± 1.11 bites/plant
in P1, P= 0.0068; and 3.9 vs 11.1 ± 1.35 bites/plant in P2, P= 0.069).
Keywords: NZSAPAB;
selective grazing; red clover (Trifolium pratense); birdsfoot
trefoil (Lotus corniculatus); extractable condensed tannin;
formononetin.
Last Updated 12-09-1998
