Relative performance and efficiency of five Merino and Merino-type dam lines in a terminal crossbreeding system with Dormer or Suffolk sires

Abstract

The production performance of ewes was assessed in a terminal crossbreeding experiment involving five Merino and Merino-type dam lines and two terminal crossbreeding sire breeds. Dam 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. Dual-purpose ewes were heavier than Merinos on average and at the ultimate joining at 3.5 years. Average clean fleece weight for SAMM ewes was approximately half that of Merino ewes while clean fleece weights for Dohne and SAMM cross ewes were intermediate. Differences between progeny in slaughter age, marketing weight, dressing percentage and carcass weight could largely be attributed to the comparison of purebred Merino lines with dual-purpose lines. The slaughter age of lambs from the two Merino lines was between 14 and 21% higher than that of the dualpurpose lines. Lambs from purebred SA Mutton Merino (SAMM) dams also outperformed lambs from SAMM cross ewes for slaughter age, slaughter weight and carcass weight. Considerable variation was found between dam lines for reproduction parameters, but few significant differences were found. Lamb output, defined as total weight of lamb slaughtered per joining, averaged 42.7 kg for SAMM ewes, 44.2 kg for SAMM cross ewes, 39.3 kg for Dohne ewes, 32.9 kg for FW+ Merino ewes and 42.0 kg for Rep+ Merino ewes, but differences between lines only tended to be significant. Sire breed did not affect lamb performance or ewe productivity markedly. An economic simulation indicated large differences in gross income per small stock unit between dam lines, warranting further research on the efficiency of terminal Merino-type dam lines. ________________________________________________________________________________________________

Returns on investment in sheep and goat breeding in South Africa

“…Two hardy composite dam lines of small size were evaluated relative to Dorper ewes as dams in a terminal crossbreeding situation (Schoeman et al, 1995). Further crossbreeding studies involving Merino and Merinotype dam lines were conducted at the Langgewens experimental farm in the Swartland (Cloete and Durand, 2000;Cloete et al, 2004a). The improvement of carcass characteristics by the terminal crossing of Dorper ewes with sires from specialist sire breed types was investigated at the Nortier experimental farm on the Western Seaboard (Cloete et al, 2007a).…”

Including genomic information in the genetic evaluation of production and reproduction traits in South African Merino sheep

“…The general history of the flocks are outlined by Schoeman et al (2010) with some updates presented by Nel, Gurman, et al (2022). The flocks are known as the Elsenburg Merino selection experiment (Cloete et al, 2004(Cloete et al, , 2009Nel, 2022); the Grootfontein Merino stud (Olivier et al, 1995;Snyman et al, 1998); the Cradock fine wool Merino stud (Olivier, 2014;Schoeman et al, 2010); the Tygerhoek fine wool experimental flock (Cloete et al, 2013) and the Langgewens resource population (Cloete & Cloete, 2015). The level of linkage across resource flocks is variable.…”

Genetic Traits of Relevance to Sustainability of Smallholder Sheep Farming Systems in South Africa

“…Sheep breeds selected for this production system are important, as breeds are required that have high reproduction performance and fast growth rate. Exotic breeds such as the Merino type breeds (Merino, Dohne Merino, South African Mutton Merino and Merino Landsheep) are commonly used in these systems due to their high prolificacy [1,44]. High stocking rates are maintained to achieve high production levels and have resulted in overgrazing of land thus resulting in a decrease of plant and animal biodiversity [45].…”

“…Examples of this being achieved include composites such as the Meatmaster and Van Rooy, which were derived from crosses between indigenous breeds such as the Damara/Ronderib Afrikaner and exotic breeds such as the Ile de France, Dorper, and SA Mutton Merino [38,83]. A terminal crossbreeding system can be an option, where all the F1 offspring are sold as slaughter lamb [44]. The benefits of an terminal crossbreeding is the effects of F1 hybrid vigor and complementarity, which can lead to an immediate improvement in the desired growth and reproduction traits [84].…”