Marking more from Merinos
Beth Paganoni, Department of Agriculture and Food, Western Australia (DAFWA)
Andrew Thompson, Murdoch University
Claire Macleay, Department of Agriculture and Food, Western Australia
Steve Wainwright, University of Western Australia
Marking more from Merinos requires the marriage of astute management and carefully selected genetic direction. Our Maternal Efficiency Flock (MEF) is a research flock that has attempted to achieve both, in order to demonstrate the reproductive potential and economic viability of the Merino as a dual purpose, high-performing ewe. The MEF was established in 2009 when 300 cull ewes were purchased by the Department of Agriculture and Food, Western Australia (DAFWA) from two ram breeders in Western Australia. The flock was moved from a commercial property near Katanning to the University of Western Australia’s (UWA’s) Ridgefield Future Farm in January 2010. Each year the ewes have been mostly single-sire mated to industry sires and sires from within the MEF specifically selected for carcass traits (high post-weaning weight, eye muscle and fat depth) and ‘easy-care’ traits such a low wrinkle and high resistance to flystrike. The flock has never been mulesed.
All the progeny generated by these ewes and subsequent generations have been measured for feed efficiency and methane production at post-weaning age, and fat, muscle, liveweight, wool traits and reproduction across multiple ages. To our knowledge, the MEF is the only self-replacing sheep flock in the world with such comprehensive measurements of feed efficiency and methane. All the progeny are fully pedigreed and have Australian Sheep Breeding Values registered with Sheep Genetics Australia.
|Ewe year of birth||Ewes joined (n)||Ewe live weight at joining (kg)|| |
Lambs born to ewes joined (%)
Lambs marked to ewes joined (%)
Birth weight singles (kg)
Birth weight multiples (kg)
Growth rate to marking singles (g/h/d)
Growth rate to marking multiples (g/h/d)
|Birth type||Lambs born (n)||Lambs marked to lambs born (%)||Birth weight (kg)||Marking weight (kg)||Growth rate to marking (g/h/d)|
Recent lamb marking results from the MEF show not only the high-performing potential of the Merino ewe, but also some of the variation in genetic potential of Merinos that we have measured for reproduction.
The research flock is maintained under commercial grazing conditions, all ewes are weighed monthly and scanned for litter size, and all lambs born are identified to dam, weighed and tagged at birth. Despite current recommendations for maximum reproduction, to meet ethical requirements ewes are joined in full wool and shorn during early pregnancy. The average age of adult ewes is three years. A unique management characteristic of the flock is that most of the adult ewes were joined as ewe lambs at seven to eight months of age.
In 2015, adult ewes were joined on 22 January and rams removed on 23 February. Weather conditions during lambing this year were above average, but feed on offer (FOO) was low, with <1000kg dry matter/hectare of FOO across all lambing paddocks. Adult ewes were 62kg and condition score 3.1 at joining, 65kg and condition score 3.5 in mid pregnancy, 67kg and condition score 2.9 at day pre-lambing.
In spite of tight feed conditions, ewes performed well with four year-old ewes marking 144% and three year-old ewes marking 121% lambs to ewes joined (Table 2). Two year-old ewes marked 90% lambs to ewes joined. This was their second joining experience as they were all joined as ewe lambs in 2014. In 2014 our ewe lambs marked 42% lambs to ewes joined, which also represents our typical marking response for ewe lambs in the project. Lamb growth rates to marking appeared to be higher for singles than multiples, but similar for lambs born to two, three or four-year old ewes (Table 2).
The survival and birth weights of single-born lambs were higher than multiple born lambs (Table 2). Only 12 ewes were recorded as having triplet lambs, and while their birth weights were lower than twin-born lambs, their marking weights were similar, indicating that only the heavier born triplet lambs survived to marking.
The majority of the adult ewes are joined to single-sires (approximately 50-60 ewes/sire), for the ease of recording sire pedigrees for lambs. As a result, we can look at the direct paternal genetics of the lambs born, and also the reproductive performance of ewes (dams) from different sires (grandsires of the lambs).
|Sire of lambs||Singles born (n)||Multiples born (n)||Lambs marked to lambs born singles (%)|| |
Lambs marked to lambs born multiples (%)
|Birth weight singles (kg)||Birth weight multiples (kg)||Growth rate to marking singles (g/h/d)||Growth rate to marking multiples (g/h/d)|
|Sire of ewes||Ewes joined (n)||Ewes weight at joining (kg)||Lambs marked to ewes joined (%)||Birth weight of singles (kg)||Birth weight of multiples (kg)||Growth rate to marking singles (g/h/d)||Growth rate to marking multiples (g/h/d)|
Table 3 shows the marking rates of lambs born to different sires which varied from 85-100% for singles and from 79-100% for multiples. The high survival of multiple born lambs is likely to be a result of birth weights in the optimum range for maximum survival (four to six kg; Table 3). Birth weight will be determined in part by genetics and in part by nutrition of the ewes and their consequent liveweight and condition scores at joining, mid and late pregnancy.
Table 4 shows the reproductive performance of ewes (daughters) from different sires. Only sires with 15 or more daughters joined are shown. Marking percentage from sire groups ranged from 18-173%, although the latter high marking rate of 173% was from a low number of daughter ewes joined (n=15). Nonetheless, some sire groups with 30-60 daughter ewes were achieving in excess of 125% (Table 4).
The variation in reproductive responses in our sires specifically selected for ‘easy-care’ and carcase traits showed that there is a large variation in the reproductive performance available for selection. Irrespective of whether the enterprise favours wool or meat, reproduction is a key profit driver for both enterprises and should be considered as a primary inclusion to breeding objectives.
It is prime lamb marking time across the state now. Do your own sums and see where your flock sits. Are you achieving satisfactory reproduction? Will you be joining us at the 100%+ club this year? What would you like to be achieving and how are you going to get there? Consideration of breeding values for direct reproductive traits such as number of lambs weaned (NLW) will assist, as will selecting for indirect traits that are correlated with high reproduction such as weight, muscle and fat. Effective selection and astute management can improve income from meat and wool, and increase disease resistance – all leading to increased profitability.
For more information about the MEF, or if you are interested in benchmarking your own flock performance to marking, contact Beth Paganoni, DAFWA, South Perth, +61 (0)8 9368 3662.