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Extensification of grassland use in the Welsh uplands: sheep performance in years 1–6
Author(s) -
Fothergill M.,
Davies D. A.,
Morgan C. T.
Publication year - 2001
Publication title -
grass and forage science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.716
H-Index - 56
eISSN - 1365-2494
pISSN - 0142-5242
DOI - 10.1046/j.1365-2494.2001.00254.x
Subject(s) - grazing , pasture , stocking , stocking rate , agronomy , lolium perenne , biology , perennial plant , zoology , nutrient , weaning , randomized block design , ecology
An experiment was established in 1991 on a 25‐year‐old perennial ryegrass/bent ( Lolium perenne L. /Agrostis capillaris L.)‐dominated pasture in Wales to study the effects of reducing nutrient inputs to previously fertilized upland pasture. The effects of the removal of applications of (1) N (denoted by CaPK) (2) N, P and K (Ca) and (3) N, P, K, and Ca (Nil) were compared with a treatment which received applications of all four nutrients (CaPKN) over a 6‐year period (1991–96) in a randomized block design replicated three times. The experiment was managed under a continuous variable stocking regime (ewes and lambs until weaning and ewes thereafter) maintaining a sward surface height of 4·0 cm throughout the grazing season. Although individual liveweight gain of the lambs was unaffected by the treatments, there was a significant reduction ( P < 0·05) in total lamb liveweight gain, ewe stocking rate and length of grazing season as a result of the withdrawal of nutrients. Over the 6 years total lamb liveweight gain was reduced by 17%, 32% and 45% and ewe stocking rate by 21%, 36% and 49% on treatments CaPK, Ca and Nil, respectively, compared with treatment CaPKN. The effect of withdrawing nutrient inputs on ewe stocking rate was progressive and by 1996 the Nil input treatment displayed a 63% reduction compared with the CaPKN treatment and this was also coupled with a 21‐day reduction in length of the grazing season. During the post‐weaning period, ewes from the Nil input treatment recorded a liveweight loss in 1995 and only a modest liveweight gain in 1996. This coupled with significantly lower body condition scores ( P < 0·01) of these ewes in the autumn indicated that the Nil input treatment could lead to reductions in reproductive performance.