ISSN:
1365-2494
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
In 1988 and 1989, swards of grass (G0), while clover (C0) and grass/white clover (GC0) receiving no N fertilizer, and a grass sward supplied with 420 kg N ha−1 (G420), were grazed by non-lactating sheep to maintain a sward surface height of 6 cm. Herbage organic matter (OM) intakes averaged between 1200 and 1700 g OM ewe−1 d−1. For treatments G0, C0, GC0 and G420 respectively, the ewes' live weight gain was 102, 112, 100 and 110 g d−1 and changes in body condition scores were +0·28, +0·52, +0·36 and +0·44 units season−1. However, the effect of treatment was not significant for either variable. There were similar levels of output of faecal N ewe−1 but significantly more urinary N ewe−1 was excreted on treatments C0 and G420, where the concentrations of N in herbage laminae were also higher. For example, in 1989, total daily N excreted was 39·7, 64·4, 44·0 and 63·3 g N ewe−1 for G0, C0, GC0 and G420 respectively. Taking into account the mean daily stocking rates, which were 19·4, 26·6, 27·2 and 36·5 ewe ha−1, the total faeces and urine returns over the season were 161, 358, 249 and 484 kg N ha−1 for each treatment respectively. The herbage OM intakes ewes−1 d−1 measured in September and October were similar for C0 and G420, and so the intake of herbage OM ha−1 d−1 was related to stocking rate, i. e. the estimated herbage intake ha−1 over the growing season for the white clover monoculture was 73% of that for N-fertilized grass. Excretal nitrogen returns to the pasture from grazed mono-cultures of clover were high, and similar to those from a grass sward receiving 420 kg fertilizer N ha−1. Consequently potential losses of N to the environment are high under these management systems.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1365-2494.1995.tb02291.x
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