Run sustainable, dual-purpose sheep

oelof Bezuidenhout reviews an on-farm trial in the southern Free State, showing that the Smithfield district best supports dual-purpose sheep, and that switching between breeds doesn’t guarantee long-term benefits.
Issue date 17 August 2007

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Farmers often chop and change breeds on a whim. Hearing wool growers brag about high prices tempts mutton farmers to switch to Merinos. When wool goes down, Merino men are attracted to the high lambing rates and easy-care attributes of mutton breeds. But changing or crossing breeds because of short-term price differences isn’t necessarily the best long-term strategy. Instead, farmers should use the genetic differences between individual animals within a breed, improving their existing flocks through selection. Breeding technology such as BLUP can help farmers identify good breeding material and buy in superior genes. A three-year trial T he advantages were confirmed in a three-year trial in the southern Free State district of Smithfield.

The study showed that, while differences between breed performance could be significant within a specific year, they were also inconsistent, and breeds that beat their competitors one year were beaten in turn the next. It’s therefore ill-advised to switch between breeds based on short-term performance. H owever, the study, which compared dual-purpose breeds with pure mutton breeds, found dual-purpose breeds tended to generate a higher average income. This proves it’s better to retain the wool component than to focus solely on mutton. fact remains that different breeds are developed for different regions and that significant genetic variations exist within a breed and between breeds. With this in mind, the on-farm test aimed to develop production and economic benchmarks for different sheep breeds for the region. The experiment was a joint venture between Smithfield Agriculture, Cape Mohair and Wool (represented by John Melville), Voermol Feeds (represented by Hendrik van Pletzen) and Virbac. It was carried out on Pieter Hanekom’s farm Skiethoek. Trial procedure For their project the researchers chose Merino, Dohne Afrino, SA Mutton Merino (SAMM) breeds, and a synthetic cross mutton breed referred to as X-mutton.

The project was conducted over a three-year period to ensure more reliable long-term results. Each farmer who took part initially contributed 10 weaned ewe lambs, which were thereafter managed as one flock. The different breeds were only separated during mating with rams of the same breed, then returned to the common flock. The project followed a health programme suggested by Virbac, and internal parasites were monitored through faecal samples. Records were kept of the number of ewes with the ram, the number of lambs born and the number of lambs weaned. Ewes and lambs were weighed at strategic times, such as at mating, lambing and weaning.

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The wool production of every ewe and lamb was recorded and mid-rib samples were taken during each shearing. Because sheep breeds differ in size, they aren’t comparable on a one-on-one basis. But, as mating mass is a good indication of ewe size, all production and income was standardised to a 50kg ewe. Lamb production per 50kg ewe was measured comprehensively over the entire trial period, taking into account lambing percentage, mothering ability, milk production, survival, weaning percentage and weaning weight. Clean wool production per 50kg ewe took into account the wool production of both the ewe and her offspring. Mutton income was calculated in the same way. Wool from each breed and each sheep in the trial was evaluated separately, and all the characteristics influencing wool price objectively measured. For the first two trial years, sheep were shorn every 10 months, and in the last year, at 12 months. Mutton and wool prices applicable at each specific time were taken into account. The outcome The results clearly showed production and income differ between breeds in a given year – but the differences aren’t consistent over all three years, and each breed had different success rates from year to year.

The average income for the different breeds per 50kg ewe over the three years was: Merino R418,83, Dohne R413,05, Afrino R383,15, SAMM R389,11 and X-Mutton breed R345,55. In all breeds, lamb production was lowest in the first trial year (2001/2002) because of lower milk production in young ewes. Lamb production in the dual-purpose breeds (Merino and Dohne) increased over the three-year period, while lamb production in SAMM and X-Mutton breeds was highest in the second year.

Ewe lambs born during the project were taken in as replacement ewes. At the end of the trial, the numbers were as follows: Merino 49, Dohne Merino 13, Afrino 27, SAMM 15 and X-mutton 24. Only one participant entered Dohne and SA Mutton Merinos, accounting for their lower numbers. Note that data on breeds with fewer representatives is less reliable than data on breeds with more. Over the three years, total income increased in all breeds due to increased production and improved product prices. The results of the study are summed up in Table 1. Source: Hendrik van Pletzen, John Melville and Pieter Hanekom in the SA Journal of Animal Science.