Submitted on: 31 October 1999.
Revised on: 29 November 1999.
Accepted on: 27 December 1999.
SOUTH AFRICAN JOURNAL OF ANIMAL SCIENCE
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Submitted on: 16 May 2001.
Revised on: 13 June 2001.
Accepted on: 03 July 2001.
SOUTH AFRICAN JOURNAL OF ANIMAL SCIENCE