Dynamic Dams for Lamb Production – How do SAMMs stack up?
Dr Neal Fogarty, NSW Department of Primary Industries, OrangeTake home messages
There was a range of up to $15 gross margin /DSE between ewe progeny performance among sires within breeds differences between sire progeny groups were considerably greater than differences between sire breeds with overlap among breeds lamb turn off rate was the major profit driver ewe progeny for the SAMM sire tested had 17% higher GM/DSE than the average of the 91 sires tested, with higher lambing rate contributing most to the advantage
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 are shown in Fig. 1. 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 (see Fig. 2).
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
Fig. 1. Range of low and high sires for annual $Gross Margin / DSE for 1stX ewes
Sire breeds (number of sires): BL=Border Leicester (18); EF=East Friesian (12); Fi=Finnsheep (12); Cp=Coopworth (9); WS=White Suffolk (7); Cr=Corriedale (6); Mer=Merino (2); SAMM (1),
Fig. 2. Deviation of crossbred progeny of SAMM sire compared to average of 91 sires of various breeds
$GM= annual $gross margin / dry sheep equivalent; 1stX ewe lambing rate: LW% = lambs weaned/ewe joined, LB% = lambs born/ewe joined, Twin% = lambs born/ewe lambing; 2ndX lambs: Wgt = postweaning weight, Fat = carcase GR, Mus = carcase eye muscle depth; 1stX ewe wool: Cfw = clean fleece weight, Fd = mean fibre diameter
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