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Posted by: Patrick Haccou | on juli 29, 2008
Suffolk trials show easier care potential
The work has also demonstrated that breeders do not need to turn to New Zealand to get hold of the genetics they need.
Three groups of lambs sired by New Zealand-bred tups imported as embryos, high index rams and traditional tups selected on eye were bred at Morfa Mawr, Ceredigion, out of 506 mixed-aged Mule ewes.
Technical help was provided by the breeding company Innovis to collect semen to artificially inseminate the ewes, which were heat-synchronised. The aim was to ensure all the different types of Mules in the flock were matched to the different sire groups.
Seventy-five per cent conceived and the ewes scanned at 1.93 lambs/ewe. In early February, 99% of 702 lambs were born alive.
Janet Roden, who supervised the work, told breeders who attended a flock inspection on the trial farm, owned by the Institute of Biological, Environmental and Rural Sciences, Aberystwyth, that ewes received identical post-insemination treatment.
Blind performance monitoring
In fact, eartag records were locked away so there was “truly blind” performance monitoring. Even she did not know which lambs had been sired by the different tups until shortly before the inspection was staged.
When the Abersystwyth University research associate presented lambing and pre-weaning results, she said the greatest variation was found within populations of lambs born to the different types of sire rather than between populations.
Only 2.3% of lambs were lost within the first 48 hours after parturition, with no differences in survival rate between lambs sired by the different sire groups.
The average birth weights were 6.1kg for singles and 5kg for twins. Lambs sired by the four New Zealand rams were marginally lighter at birth and presented fewer lambing problems.
Monitors recorded the level of help ewes needed, on a scale ranging from none to “call the vet”. Overall, only 6% of lambs required assistance to start suckling and most of these were triplets.
Individual and groups of sires
Lamb vigour was assessed and it was found that variation – judged by the ability to stand up and suckle – was greater between individual sires than between groups of sires.
At eight weeks, the heaviest lamb weighed 34kg, singles averaged 26kg and twins 21kg. Those out of UK high-index rams averaged 21.6kg, those sired by traditional Suffolks 20.7kg, while New Zealand-sired lambs averaged 20.0kg.
All the progeny were also assessed for dagginess on a scale of 1 to 4. While 15% of the New Zealand-sired lambs were dirtier than Dr Roden would like, they were slightly less daggy than the 25% in the two other sire groups, though one traditional tup was ranked second overall for cleanliness.
An attempt will be made, using faecal egg counting, to assess the link between dirtiness and variation in worm resistance between the 10 sires.
A full breakdown of variations in lambing ease, early vigour and weight gains will be published when Dr Roden has details of time to slaughter, carcass weights and lamb grades. The aim is to get lambs that classify 3L without using any creep feed.
“The initial results have revealed considerable variation in the easy care attributes of lambs sired by different rams that breeders can exploit,” said Dr Roden.
Immediate labour and cost reduction
Robyn Hulme, Suffolk Society commercial director, agreed and claimed commercial producers could gain immediate labour and cost reduction advantages by sourcing rams recorded for easy-care traits.
“An increasing number of Suffolk breeders are now concentrating on selection policies emphasising minimum labour input. Over 250 members are recording lambing ease and lamb vigour.”
The trial proved beyond doubt the importance and advantages of recording, which had been society policy for a number of years.
Prys Morgan, industry development manager at Hybu Cig Cymru, which sponsored the trial, claimed the results showed how breeders could use performance recorded stock to meet their individual farm requirements.
The final report, including detailed costings, would appear on the HCC website later in the year.
CAP: Lambs by high index UK Suffolk tups had the highest eight week weights, while those by New Zealand bred sires were less daggy, said Janet Roden.
by Robert Davies (About this Author)