The South African Meat Merino (SAMM) is a remarkable breed of sheep known for its dual-purpose capabilities, providing both high-quality meat and wool. This breed, originally known as the German Mutton Merino, has a rich history dating back to its introduction to South Africa from Germany in 1932. Over the decades, SAMM has undergone extensive breeding programs to enhance its adaptability, meat quality, and wool production. Today, SAMM is a vital breed in various countries, including Australia, where it continues to make significant contributions to the sheep farming industry.
Merino Sheep
North Caucasian meat and wool breed of sheep
Historical Development
Originally known as the German Mutton Merino, the first 10 ewes and one ram were imported to South Africa from Germany in 1932 for an Agricultural Department breeding program. The goal was to develop a breed that could thrive in the South African environment while producing both quality meat and wool. After decades of selective breeding aimed at improving wool quality and physical conformation, the breed was officially recognized as the South African Mutton Merino (SAMM) in 1971.
Dual-Purpose Focus
The SAMM was initially developed to be a dual-purpose sheep, excelling in both meat and wool production. Its adaptability to the South African environment was a key focus, allowing the breed to thrive under various climatic conditions.
Introduction to Australia
The SAMM breed was first introduced into Australia in 1996. Initially named the South African Meat Merino upon introduction, Australian breeders voted in 1999 to adopt the name Prime SAMM to distinguish it from other Merino breeds.
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Performance in Australia
Extensive trials and breeding programs were conducted to assess the performance of SAMM in Australian conditions. Commercial Merino ewes were randomly allocated to either SAMM rams or commercial Merino rams during the breeding seasons of 1996 and 1997. The results were significant: lambs sired by SAMM rams were, on average, heavier at birth and had better survival rates to weaning compared to purebred Merino lambs. SAMM-sired lambs also reached slaughter weight faster, showing higher proportions of ram lambs achieving target weights before the onset of the dry Mediterranean summer. Two-tooth ewes sired by SAMM rams were also heavier at maturity, though they produced slightly less wool compared to purebred Merinos. This balance between meat and wool production underscored the dual-purpose nature of SAMM and its adaptability to Australian farming conditions.
Genetic Attributes and Research
Recent studies have delved into the genetic basis of SAMM's prominent characteristics. Whole-genome sequences of SAMM were analyzed alongside those of Australian and Chinese Merinos to identify selection signatures associated with growth, carcass traits, and meat quality. A total of 313 genes in 277 regions were identified, with notable genes including GHR, LCORL, SMO, NCAPG, and DCC, which are involved in growth and carcass traits.
Schematic representation of the experimental design followed to create the six genotypes.
When judging SAMM sheep, it is important to consider the overall balance of traits. Emphasis should be placed on conformation (60%) and wool quality (40%). Judges should avoid focusing on a single trait and instead evaluate the sheep's comprehensive qualities, recognizing that an excellent sheep with a minor fault should not be immediately culled.
Pigment: Desirable light pink skin with light brown eyelids and light amber hooves.
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SAMM Sheep: Wool Production and Quality Traits
According to both the Department of Agriculture, Land Reform and Rural Development (DALRRD 2021) and SA Stud Book (2015), the majority of sheep breeds in South Africa are woolled breeds, most of these being Merino type breeds. Wool from these pure breeds are sought after as they generally have low fibre diameters (finer wool), meaning that it is easier to process into high value apparel textiles (Holman and Malau-Aduli 2012; Ferreira et al. 2021). Globally, South Africa is the second largest producer of Merino-type apparel wool and is responsible for 11% of world production (Ferreira et al. 2021).
White-wool producing breeds like the Dormer and Ile de France produce carpet wool, which is less sought after than Merino type wool due to its coarseness. A small portion of locally produced wool is also classified as coarse, coloured and Karakul wool (DALRRD 2021) and is generally not very desirable to buyers.
In general, South African wool is highly sought after as the South African wool industry is known for producing uniform, high quality wool clips (Ferreira et al. Current market demands are centred around fine wool, and the highest prices are paid for wool with a fibre diameter of 17 μm (CWSA 2020) with prices declining as fibre diameter increases. It is therefore to the benefit of producers to produce finer wool. These factors include not only fibre diameter but also staple strength, coefficient of variation, comfort factor, spinning fineness, clean fleece yield and fibre curvature, among others (Holman and Malau-Aduli 2012).
Next to fibre diameter, staple or tensile strength is considered the most important factor in determining wool quality and therefore price, as it affects the processing quality of wool (Holman and Malau-Aduli 2012; Ferreira et al. 2021). It is measured in Newtons per kilotex (N/ktex) and is defined as the maximum force needed to break a staple (Holman and Malau-Aduli 2012).
Wool-producing enterprises usually make use of pure breeds with crossbreeding considered to be detrimental to the objectives of wool farmers and being met with scepticism by the wool industry. Owing to the ratio between wool and meat prices as well as improvements in reproduction rate, the bulk of farm income is generated from slaughter lambs.
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As a result, some wool producers have turned to crossbreeding with terminal sires to improve farm income and buffer their income stream against fluctuations of the wool market (Cloete et al. 2004; Van der Merwe et al. 2020). Even in enterprises where the main focus is lamb production, rather than wool, crossbreeding can improve production output markedly (Carneiro et al. 2007; de Sousa et al. 2019). Crossbreeding is therefore a popular practice globally.
In South Africa, most crossbred progeny destined for slaughter will be finished off in feedlots or similar intensive finishing systems where profit margins are generally small.
While crossbreeding undeniably offers significant benefits to slaughter lamb producers (Sidwell and Miller 1962; Scales et al. 2000; Malhado et al. 2009), the effect of crossbreeding on wool production is less well documented. Therefore, this study aimed to quantify the wool production and quality traits of four crossbred lines relative to purebred Merino (a specialist wool producing breed) and Dohne Merino (a dual-purpose breed) lines as a supplement to the growth modelling of said lines (Theron et al.
Experimental Design and Results
The lambs used in this trial were born on Langgewens Research Farm in the Swartland region of the Western Cape, South Africa, during late autumn and early winter. The lambs were weaned at approximately 100 days of age and four rams and four ewes of each genotype transported to Elsenburg Research Farm, where they were placed in individual pens (1.5 × 2 m) and reared until one year of age and data collected for a growth modelling exercise that has been published elsewhere (Theron et al. 2023). The lambs were adapted to a commercial feedlot diet (Table 1) over a seven-day period using a step-up program and were allowed ad libitum access to this feed for the rest of the trial period. They also had unrestricted access to potable water for the entire period.
At the end of the growth period, all animals were shorn by a commercial shearing team and the fleeces collected and weighed. Mid-rib samples were taken from each fleece and sent to the South African Wool Testing Bureau (WTBSA) for analysis and testing. Traits analysed were clean yield, fibre diameter, standard deviation of fibre diameter, coefficient of variation of fibre diameter, comfort factor (the percentage of fibres below 30 μm), staple length and staple strength.
The results received from the WTBSA as well as clean fleece weight were subjected to a 2 (sex) × 6 (genotypes as described above) factorial design analysis of variance (ANOVA) using Statistica 14 (Tibco Statistica 2020). Sex and genotype were set as main effects for the analyses, and the possible interactions between these main effects were also considered. Each of the 12 possible treatment combinations was represented by 4 replications. The results for the main effects of sex and genotype from the ANOVA are given in Table 2 as least squares means.
Neither clean fleece weight nor the percentage clean yield differed significantly between sexes or genotypes, from which it can be inferred that wool production would be similar regardless of sex or genotype for this experimental outlay.
The mean fibre diameter (MFD) differed among genotypes (P < 0.001) but not between sexes (P = 0.142). Merinos, as expected, had the lowest MFD of 18.26 μm, significantly lower than Dohne Merinos (20.66 μm). In turn, Dohne Merinos had significantly finer wool than Dohne x Ile de France (24.49 μm) which did not differ significantly from the Dohne x Dormer (24.53 μm) and Merino x Ile de France (25.13 μm) groups.
The coefficient of variation of fibre diameter and standard deviation of fibre diameter differed significantly between sexes and genotypes. Ewes had a smaller coefficient of variation (17.02%) and standard deviation of fibre diameter (3.92 μm) than rams, indicating a more uniform clip. Dohne Merinos had the lowest coefficient of variation of fibre diameter (16.3%), while purebred Merinos and Dohne Merinos had the lowest standard deviation of fibre diameter of respectively 3.24 μm and 3.38 μm. Thus, purebred Dohne Merinos produced the most uniform clip with regard to fibre diameter.
Comfort factor, which relates to the degree of possible irritation wearing of a wool garment, can have upon the skin, differed between sexes (P = 0.030) and genotypes (P = 0.018). Wool from ewes (93.82%) had a higher comfort factor than that from rams (85.61%), while purebred Merinos (99.44%) and Dohne Merinos (98.85%) were the genotypes with the highest comfort factor.
Staple length was unaffected by sex (P = 0.897) and genotype (P = 0.639), whereas staple strength was independent of sex (P = 0.942), but not genotype (P = 0.038). The staple strength of Dohne Merinos (29.38 N/ktex), Merinos (27.63 N/ktex) and Dohne x Ile de France (26.63 N/ktex) did not differ, but exceeded that of the Merino x Dormer cross (19.88 N/ktex; P < 0.05).
The National Wool Growers’ Association (NWGA) is the body in South Africa that is responsible for setting wool quality standards and controlling industry practices to meet international market criteria. As producers are paid for the quantity of wool produced, fleece weight is important.
The average fibre diameter of 18.26 μm is less than other observations reported in literature with Cloete et al. (2001) (21.9 μm), Cloete et al. (2003) (22.8-23.3 μm) and Cloete and Cloete (2015) (21.6 μm) all observing greater fibre diameters for Merinos. However, both the environmental conditions and the ages of the animals varied between the studies, possibly explaining the difference in the results. In the study of Van der Merwe et al. (2020) where animals were reared in an environment similar to this trial, an average fibre diameter of 19.6 μm was found for Merinos, and Snyman et al. (1998) reported values from 19.8 to 23 μm over three different flocks.
The average fibre diameter of 20.66 μm found for Dohne Merino in this study compares well to the value of 20.90 μm of Cloete and Cloete (2015), the 21.80 μm of Cloete et al. (2001) and the 21.00 μm of Van der Merwe et al. (2020) while also being close to the 19.36 μm of Van Wyk et al. (2008) on yearling sheep.
Matching these results to NWGA standards show that Merino wool would be classified as superfine, while Dohne Merino wool could be regarded as medium-fine. All the crossbred genotypes had fibre diameters in excess of 24 μm and would therefore be classified as overstrong and subsequently have a lower market value. Purebred Dormer and Ile de France breed averages in South Africa have been reported as 27 and 23-27 μm respectively by Snyman (2014a, 2014b). Other reported fibre diameters for yearling Dormers are 31.3 μm (Van der Merwe et al. 2020) and 28.8 μm (Muller et al. 2020). The crosses therefore show improved wool quality when compared to the sire breeds.
Although the crossbred groups did not differ significantly from one another, absolute values favoured the two Dohne cross groups even though purebred Merinos had significantly finer wool than purebred Dohne Merinos. This result was unexpected and could possibly be related to sampling, given the relatively small number of animals (n = 8) representing each genotype.
The increased fibre diameter in crossbred animals was expected, as both white-woolled terminal sire breeds are known to produce coarse wool. In the absence of purebred Dormer and Ile de France progeny, it was impossible to determine heterosis.
The standard deviation of mean fibre diameter observed for each group in the trial, although differing significantly between both sexes and genotypes, still fell within the guidelines set by the NWGA for each micron class. Thus, all the fleeces displayed satisfactory uniformity according to the standard deviation of mean fibre diameter.
The next important factor determining the suitability of wool for different applications is the comfort factor. This trait is related to wearing ease, as wool fibres with a diameter of less than 30 μm are deflected upon contact with the skin and therefore do not cause irritation when worn next to the skin. This makes such wool more suitable for apparel applications (Holman and Malau-Aduli 2012).
Both purebred lines exhibited comfort factors in excess of 95%, which is regarded as a threshold for wool worn next to the skin. Similar values were obtained by Van der Merwe et al. (2020). The wool of these traditional wool breeds (Merino and Dohne) would thus be suitable for processing into knitwear or underwear based on its fineness and wearing ease (NWGA 2002).
The Merino x Dormer and Dohne x Ile de France crosses displayed lower (P < 0.05) comfort factor values.
Staple length did not differ between the various groups, and all lengths exceeded 90 mm, therefore being classed as AA according to NWGA classification standards (NWGA 2002). The staple lengths of the purebreds were higher than those reported by Cloete and Cloete 2015.
| Trait | Merino | Dohne Merino | Dohne x Dormer | Dohne x Ile de France | Merino x Dormer | Merino x Ile de France |
|---|---|---|---|---|---|---|
| Mean Fibre Diameter (μm) | 18.26 | 20.66 | 24.53 | 24.49 | 26.01 | 25.13 |
| Comfort Factor (%) | 99.44 | 98.85 | N/A | N/A | N/A | N/A |
| Staple Strength (N/ktex) | 27.63 | 29.38 | N/A | 26.63 | 19.88 | N/A |
Table with Wool Quality Traits of SAMM
