Dynamic Dams for Lamb Production – How do SAMMs stack up?

The Maternal sire Central Progeny Test (MCPT) progeny tested 91 sires entered by breeders from many maternal breeds. Those breeds with the most sires tested were the Border Leicester (18), East Friesian (12), Finnsheep (12), Coopworth (9), White Suffolk (7) and Corriedale (6), with 2 Merino and one SAMM sire also tested. The MCPT was run over 8 years at 4 sites (Cowra, NSW, Hamilton and Rutherglen Vic and Struan, SA) and common link sires allowed comparison of sires across years and sites. The major focus was on evaluation of their 1stX ewe progeny (out of the same Merino base ewes at each site) which were grown out and mated for 3 lambings and the growth and carcase merit of their 2ndX lambs.
While there were some significant differences between the maternal sire breeds in performance of their progeny, the variation among individual sires within the breeds was far greater for most production traits. The range among the 18 Border Leicester sires tested was over $40 gross margin (GM)/ ewe / year in the profitability of their 1stX daughters. Variation in lambing rate of the 1stX ewes was the major profit driver with differences of up to 45% for lamb weaning rate between 1stX ewe progeny groups of sires within a breed. In addition there were significant differences in 2ndX lamb growth (up to 3.6 kg for post weaning weight) and carcase fat (2.2 mm GR or almost half a fat score). These differences contributed to the gross margin through the total weight of carcase turned off and varying proportions of the carcases meeting market specifications. There were also large differences between breeds and sires within breeds for early age of puberty, milk production and weight and fibre diameter of wool from the 1stX ewes. Most breeds had at least some sires that had high performing 1stX daughters.
We also took account of differences in feed requirements which may affect stocking rate. Bigger ewes eat more and feed requirements vary for the ewe and her lambs during lactation and subsequent growth of lambs to slaughter. Total feed requirements for individual ewes and their lambs were estimated from their performance. The gross margins (GM) for the ewe progeny of the sires were then compared on an annual dry sheep equivalent (DSE) basis (although this assumes that feed quality and costs are the same for requirements in all seasons, which is not the real farm situation).

The annual $GM/DSE over 3 years for the ewe progeny of the one SAMM sire entered in the test was $41.23. This was made up of returns from the number of 2ndX lambs slaughtered, their carcase weight (with price determined by matching a weight and fat grid specification plus skin value) and the wool produced (weight and price based on micron). The gross margin took account of management and marketing costs for the ewes and lambs. The ranges in annual $GM/DSE among the sire progeny groups of the other sires tested within the various breeds, including the 2 Merino and one SAMM sire. There was a wide range of $8 to $15 GM/DSE between the sire groups within the various breeds that had several sires tested and there was considerable overlap between the breeds.

The ewe progeny of the SAMM sire had a 16% higher $GM/DSE than the average of ewe progeny all the sires. This advantage came mainly from a higher lambing rate, especially for lambs weaned/ewe joined. The 2ndX lambs also grew a little faster and the ewes had finer micron wool. There was no difference from the average for ewe wool weight or 2ndX carcase merit .

The MCPT results clearly show that the differences between the breeds were generally small compared to the differences between the individual sires tested. Lamb producers need to ensure that their ewe flocks comprise superior maternal genetics. This means breeding or purchasing crossbred ewes that are by rams with high LAMBPLAN EBVs for the traits that match the lamb enterprise and ensuring that they are bred from high performing base ewe flocks.

The MCPT project was supported by Meat & Livestock Australia, The Australian Sheep Industry CRC and was run by NSW Department of Primary Industries, Department of Primary Industries, Vic and SARDI.

Detailed results from MCPT are available at:
http://www.agric.nsw.gov.au/reader/sheep-meat/dynamic-dams.html

WILLIAMS EWE PRODUCTIVITY TRIAL

Agriculture WA Narrogin

The ability of SAMM sheep to produce more lambs and more meat has earned them the number one ranking in the Williams ewe productivity trial in WA.

The trial started in 2000 when seven groups of about 50 lambs were delivered to the trial farm. They were given an even-up shearing and run together to minimise pre-trial environmental effects. They were mated as hoggets to the same group of terminal sires and their progeny and their own performance were compared.

The group of SAMM cross ewes from Kojonup were the only SAMM infused sheep in an otherwise Merino ewe trial and provided an insight to the strengths of the breed. The trial was linked with a previous ewe trial held at Katanning which compared five different Merino lines.

The teams were shorn three times during the trial period and although the SAMM cross ewes received some of the lowest prices for wool their total income from wool over the three year period was only $13.99/head less than the poorest returning Merino line.

The ewes were joined to terminal sires the first year and to performance bred Merinos for the next two years and the SAMM cross ewes stood out for their lamb production. Data from wool production was analysed using wether trial software and uses a five-year average to calculate wool price to eliminate the possible spikes and troughs that could occur if using an on-the-day value. Trial coordinator Ken Hart from Agriculture WA Narrogin office said the lamb information was not so straightforward, as there was no tool to facilitate the calculations.

He said the wool from the lambs was valued using the average team value for their mothers’ wool and applying a formula. “This way we were able, to some extent, allow for differences in the quality of the lambs’ wool. The comparative value of the wool produced by the SAMM cross lambs was not because of the quality, but rather that there was so much more of it because of the number of lambs,” Ken said.

Because researchers were interested in genetic merit they did not calculate costs. “Having more lambs would increase the cost of shearing, etc., so the net value may actually be less than lambs with better quality wool but this has not been considered.”

The sale value of the lambs was calculated using their live weaning weight and applying a value of $2/kg. He said this was probably far from ideal, but there was not a tool that could calculate an average price over time. “Basically as lambs become more valuable the teams that perform better at lambing will improve relative to other teams.”

The final year of data is yet to be finalised and the full results will be presented during the 2004 Agribusiness Sheep Updates in Perth in late July.

In the direct comparison the SAMM cross ewes had a weaning percentage of 91.5 (or 43 lambs) in 2001 and 117pc (55 lambs) in 2002 compared with the next best team that had and 57.8pc in 2001 and 80pc in 2002.

Average SAMM weights at weaning were 25.5 kilograms for lambs born in both years compared with the next best group at 23.6kg for 2001-drop lambs and 23.9kg for 2002-drop lambs.

The poorest performing team weaned 23.3pc lambs as maidens and 50pc as second lambers with lambs weaning weights as low as 20.4kg from maidens.

T