Last update: November 22, 2010 12:07:11 PM E-mail Print

 

Average production of five Merino lines over three lambing opportunities

in a terminal crossbreeding system with Dormer and Suffolk sires

 

S. W. P. Cloete 1,2#, J. J. E. Cloete 1,3, M. J. Herselman 4 & L. C. Hoffman 1

 

  1Department of Animal Sciences, University of Stellenbosch, Private Bag X1. Matieland 7602, South Africa

2Elsenburg Agricultural Centre, Private Bag X1, Elsenburg 7607, South Africa

3Elsenburg College of Agriculture, Private Bag X1 Elsenburg 7607, South Africa`

4Grootfontein Agricultural Development Institute, Private Bag X529,  Middelburg 5900, South Africa

#E-mail: Schalk Cloete

 


The production performance of ewes was assessed in a terminal  crossbreeding experiment involving five Merino dam lines and two terminal crossbreeding sire lines. Ewe lines were SA Mutton Merino (SAMM), SAMM rams crossed to Merino ewes (SAMM cross), Dohne Merino, as well as specialist Merino lines selected for clean fleece weight (FW+) and for an increased reproduction (Rep+).   Dormer and Suffolk rams were used as sires. Ewe survival was independent of dam line (Chi2 = 3.39; P > 0.20). Dual-purpose ewes were heavier than Merinos on average and ultimately at 3.5 years (P < 0.01; Table 1).

 

Considerable variation was found between ewe lines for reproduction parameters, but few significant differences were found. Total weight of Iamb slaughtered per joining averaged 32.9 kg for FW+ Merino ewes compared to ≥ 42.0 kg for SAMM, SAMM cross and Rep+ Merino ewes, but these differences were only significant at the 7% level (Table I). Expressed as percentage of average ewe live weight, means ranged from approximately 60% in FW+ Merino ewes to above 80% for Rep+ Merino ewes (P < 0.05). Average clean fleece weight for SAMM ewes were approximately half that of Merino ewes. The Dohne Merino and SAMM cross lines yielded intermediate averaged clean fleece weights (P < 0.0 t). Wool production of SAMM ewes amounted to approximately 3% of ultimate live weight, compared to above 8%

in the two Merino lines(P < 0.01). The outcome from an economic simulation suggested gross returns per small stock unit (SSU)of R285 for SAMM ewes, R306 for SAMM cross ewes, R322 for Dohne Merino ewes, R354 for FW+ Merino ewes and R365 for Rep+ Merino ewes, when current product prices were used. The simulated income derived from the the highest yielding Rep+ line was R80 per SSU higher than that obtained from the lowest yielding SAMM line. The marked differences In gross income between ewe lines warrants further research on the efficiency of terminal dam lines. Sire line did not affect ewe performance markedly, and the choice of sire line could be based on other considerations.