Page 86 - British Blue 2025 Yearbook

RECIPIENT MANAGEMENT
'How recipient management is key to the success of
advanced breeding, whilst increasing productivity and
sustainability'
Emma Stuart BVM&S MRCVS, Paragon Vet Group, Newbiggin, Penrith
Genetics have a key role to play in improving the long-
term performance of livestock herds but genetic progress
from the maternal side can be slow as females typically
only produce one calf per year. In contrast, a single bull of
high genetic merit can produce thousands of offspring
through artificial insemination. Given the equally
important role of both males and females in enhancing
herd genetics, adopting technologies that maximise
offspring numbers from superior dams - such as
conventional embryo flushing (MOET) and in vitro
production (IVP) - will help accelerate herd genetic
progress. Increasing the long-term productivity,
sustainability and profitability of herds can be more readily
achieved by selecting for characteristics such as enhanced
feed efficiency, fertility, longevity and disease resistance,
which can be facilitated by genomic testing.
Once embryos have been produced, the success of any
embryo transfer (ET) programme relies heavily on good
stockmanship and management of the recipients. As a
general rule, maiden heifers are preferred as they average
a 5-10% better pregnancy rate compared to cows. Maiden
heifers should be at least 15 months old, cycling regularly
and weigh a minimum of 350kg before ET. However, when
transferring embryos from larger beef breeds or embryos
sired by a bull with a poor calving ease index, cows may
be preferable, making sure to select those with no history
of reproductive or health problems. Cows should have
passed peak yield before being synchronised for ET as the
stress of lactation will reduce pregnancy rates it is also
preferable to use younger animals - 4th calvers or less.
Purchased recipients should have at least a six week
settling period as they will often have an unknown
nutritional and reproductive history. Allowing time for
isolation, testing and vaccination programmes which
should be discussed with your vet. Diseases such as IBR,
BVD, Leptospirosis or deficiencies of copper and selenium
could have a devastating effect on an ET programme.
Routine husbandry treatments such as vaccinations,
worming, fly repellent, etc. should all be completed prior
to the commencement of an ET programme reducing any
stress factors. Recipient animals should be in good health
and a condition score of ~2.5/5 at transfer, as pregnancies
are lower when recipients are either too fat or too thin.
Ideally, recipients should be segregated and managed as
a separate group. Avoid major changes in diet or routine
six weeks both pre and post-transfer. The aim of the diet
is to achieve a moderate rising plane of nutrition. A long
fibre-based diet such as hay, big bale silage or straw is best,
whilst lush, wet grass should be avoided. A low-protein
coarse mix as a concentrate supplement can be fed, while
sugarbeet pulp can be useful if more energy or fibre is
needed. In our experience, recipients managed indoors
have 5-10% better pregnancy rates than those managed
at grass.
Several trace elements have a major role in reproduction
including copper, selenium, manganese, phosphorus and
zinc - some form of supplementation is likely to be of
benefit in all ET programs which should be discussed with
your vet. Recipients should be fed 100g per day of a good
quality powdered mineral for at least 6 weeks before the
planned transfer date. Boluses can also be used and
supplemented with free access mineral buckets.
Finally, to maximise the success of any synchronisation
programme and increase pregnancy rates, good heat
detection is vital. This can be done by recording the time
of onset of standing heat for each recipient and
communicating this to the technician.
The guidelines above outline key components for
maximising pregnancy rates - the ultimate goal of any
embryo transfer programme. If donor cows and semen of
high genetic merit have been selected, the resulting calves
should have improved characteristics, which will further
enhance the productivity and sustainability of the national
herd. As an added bonus, these animals should, in turn,
be more profitable!
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