Session one of the Tullamore Farm virtual series took place on Tuesday night and focused on an overview of the sheep system, including recent performance and lambing progress. Several topics discussed on the night attracted close attention from viewers with some generating follow-on questions. A flavour of these discussions is detailed below.
Since the first Mule sheep arrived on the farm in 2017, those visiting the farm or following performance have raised the same question – why opt for the Mule ewe and how is the breed performing? When this year’s crop of lambs is sold, we will have four years’ data and be in a position to make more concrete assertions on their performance.
There are a few things that are already fairly apparent, however. Leaving aside the fertility issues of the 2020-21 season – which will be discussed later – the Mule ewe has achieved its target of delivering high levels of output with mature ewes scanning from 2.13 to 2.26 lambs per ewe joined in recent years.
Maternal instincts are excellent and farm manager Shaun Diver is quick to praise the lambing ability and maternal instinct.
One area on which the jury remains out is ewe longevity. Shaun says he has kept ewes to six or seven years of age while building numbers and that the mouth of these has been relatively good while, in contrast, he has ewes with a broken mouth or lost teeth after four years. This is something we are hoping to hone in on further in performance recording.
Shaun has been keen to select a range of ewe types from sharp-headed ewes with a black speckle to whiter-faced and brown-headed ewes to satisfy another question we are frequently asked – is there any significant difference in performance between these breed types?
The most obvious difference among mature ewes is in the size and mature weight.
Ewes have been weighed pre-joining rams for the last two seasons as part of the link-up with Sheep Ireland to record performance.
Ewes weighed anywhere from 65kg to in excess of 100kg and it will be interesting to evaluate if there is any correlation between ewe liveweight and output/lamb performance once this year’s crop of lambs has been reared. The variation in ewe liveweight is also having a significant influence on the cull ewe value and replacement cost.
It is also pretty clear at this stage that the slaughter performance of progeny will typically be an R grading lamb with recent year’s data averaging around 80% to 85% R grades and the remainder U grades.
Lamb performance on the recently reseeded swards has been relatively good but we have not been able to get an accurate gauge of its true potential in recent years due to successive drought periods limiting grass growth and leading to early weaning.
The average lamb drafting weight has been in the region of 45kg with a 45% kill-out typical. This ranges from drafting lambs at 40kg to 43kg early in the season, while as the season progresses ram lambs have been drafted at higher liveweights of 48kg to 50kg to hit the desired fat score and optimise carcase weight limits.
A small level of concentrates has been required to finish ram lambs and Shaun is planning to feed a small level early rather than having a high percentage of lambs remaining on the farm late into the year and requiring a high meal input to finish satisfactorily.
The infertility issues resulting in 17 out of 165, or 10.8% of mature ewes put to the ram ending up empty were well documented in recent months.
There was no apparent ram fertility issues identified with the raddling pattern of ewes normal and not pointing to higher repeat rates.
Kidney and liver samples were collected from the cull ewes to see if there were any issues in mineral levels that could be contributing to the higher barren rate, while the farm’s vet Donal Lynch has carried out blood sampling through the flock. This has yielded no abnormal results and it is looking increasingly likely that the issues had to be linked to ram performance or an issue post-breeding leading to early embryo loss.
As well as a higher barren rate, there is a higher percentage of single litters. While the in-lamb rate is still respectable at 1.99 lambs, it is still below recent years levels. Early indications from about 4o ewes lambed to date show that the mature ewes are giving birth to single lambs with a higher birth weight than ideally desired.
Shaun says that a high percentage of these lambs have been in excess of 7kg, which is leading to some ewes requiring assistance. One upshot of this so far has been that it has presented an opportunity, which has not been present in recent years, to cross-foster triplet-born lambs to ewes carrying one lamb. This should hopefully reduce the number of lambs that need to be reared artificially in 2021.
Yearlings versus hoggets
The farm has switched to bringing in replacements entirely as yearling hoggets for 2020-21.
The breeding season was just over three weeks, which in hindsight was probably too short for the lighter Mule ewe lambs, in particular with 12 out of the 40 put forward for breeding not going in lamb.
Shaun experimented with lambing yearling hoggets, along with two-year-old hoggets in spring 2020, and says he had fewer issues with the yearlings. It is hard to base any analysis on one year’s experience so there will be a strong focus to assess if yearlings repeat this positive performance in 2021. It will be interesting at this stage to compare output levels and replacement costs of the two replacement options, along with now adding to the mix how this compares to retaining homebred replacements.
Mules versus Texels
A familiar request at the open day held in 2019 was a request among farmers to retain progeny of the Mule ewes and put them to the test. This is expected to deliver lambs with a higher grade but the expected consequence of this is the litter size is likely to reduce by 0.1 to 0.15 lambs per ewe joined. Farmers are also interested to see if this cross has any effect on increasing ewe longevity.