ISSN:
1365-2494
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Bite depth was measured in four experiments in which grazing cows were offered, individually, patches of perennial ryegrass swards, typically 0·9 m × 0·9 m, of contrasting structural composition within linear sequences of eighteen to twenty-seven patches. Bite depths were analysed in relation to the independent effects of pseudo-stem height, re-growth depth, stubble height and sward height. In vegetative swards comprising predominantly leaf, with re-growth and stubble strata of vegetative origin, bite depth was strongly related to sward height. However, when the leaf–stem contrast between strata increased, bite depth was strongly correlated with the depth of re-growth. Cows were observed to penetrate into a mature stubble stratum with increasing sward height, indicating that stubble height is only a partial regulator of bite depth. In an experiment designed to investigate the independent effects of pseudo-stem and sward height, pseudo-stem was only a partial regulator of bite depth. Evidence to support the concept that bite depth is a fixed proportion of sward height across swards of different structure was inconsistent, but there was evidence of a maximum bite depth of 0·70 of sward height. There were also indications that bite depth was conditioned by the number of bites removed. This suggested that cows initially took a cautious approach to grazing, building up bite depth with feedback over the first 20–30 bites in a new patch. Behaviour at the current patch was not affected by the characteristics of the preceding or succeeding patch in sequence.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1046/j.1365-2494.2003.00361.x
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