15 / 20
AUTUMN 2016 ISSUE
LIVESTOCK MATTERS
14
HERD HEALTH
James explains: ‘It takes around one hour to
make an evaluation of a bull’s breeding
soundness, depending on its temperament
and the handling facilities! But once the vet
has set up the tools required, like the
microscope with heated stage for evaluation
of sperm motility, then any further bulls can
be tested in around 20 minutes.
‘Good handling facilities and a crush which
gives the ability to examine the underside of
the bull, help speed the procedure.‘
The BBSE covers the full range of parameters
that impact on fertility and fitness.
It includes assessments of libido, body
condition score (optimum range is 3.0-3.5
in a working bull) and checking for lameness.
‘This is a common issue: bulls are heavy,
especially the Continental beef breeds, and their
feet are under a lot of pressure,‘ says James.
Young bulls can also be prone to ‘ascending
infections’ from riding other animals: bacterial
infection spreads up the reproductive tract
and into, for example, the testes, where it
can lead to pus or blood in the vas deferens
which kills the sperm. Similarly, the accessory
glands (which provide fluids that make up the
ejaculate) can become infected.
‘Size does matter! A scrotal circumference of
34cm is the minimum standard. But young
bulls can sometimes not have the size to
produce high quality sperm,‘ explains James.
Sperm is assessed for percentage of live versus
dead sperm, motility and any morphological
abnormalities. James explains: ‘Any infections
or diseases that increase temperature are
detrimental to sperm quality. It can take a
month for normal spermatogenesis to resume.
Also, stress increases levels of cortisol in the
blood and this has the same effect.
‘Some bulls suffer erectile dysfunction, and
spiral deviation is another physical feature
which prevents sperm from being deposited
in the right place.
‘Physical injury to a bull’s penis is also
always a possibility.‘ And that was the case
with one of Sam Barker’s Longhorn bulls…..
Keep your eye on the bull!
Sam Barker and his wife Claire, and parents
Steve and Julie, run a 110-cow herd of
Longhorn cattle on an organic all-grass system
with no bought-in feeds. Boxed beef and
pies are sold via the farm shop, farmer
markets, and the internet.
Sam explains: ‘When we switched from
organic dairying to beef production in 2004,
our aim was to produce quality meat rather
than looking for quantity. So we selected
the Longhorn breed, and continued on our
organic system.
‘When we first started, we needed to finish
animals all year round. So we ran the bull
with the cows for a 6-month period, and
had a very extended spring calving block.‘
But following advice from his vet James
Marsden, Sam accepted that he could have
a short calving block and then alter the
forage ration to adjust subsequent growth
rates to get a spread of finishing times. Once
cattle reach 24 months of age, they are
allowed to finish ‘at their own pace’, and are
slaughtered around the 28-30 month mark.
By 2008, Sam had converted the herd into
a single short block of spring calving.
But then in summer 2012, one of Sam’s bulls
damaged its penis partway (3 weeks) into
the breeding period. This was only discovered
when James visited to PD the cows. It took
several weeks to find a replacement bull,
and ultimately led to a 2-month gap with no
calvings the following spring.
From this situation, a small autumn calving
herd was created, and the herd was run with
two calving blocks.
However, Sam has discovered there are
benefits in autumn calving. ‘The farm is
capable of producing good quality forage,
and the sandy soil means minimal damage
to the pasture over the winter. I’m weaning
the autumn-born calves at 10 months instead
of seven, to stop their dams getting too fat.
The calves are outwintered with their mothers,
thereby avoiding pneumonia risk and the
extra work of being housed. I’m not seeing
any growth check at weaning, and they
grow faster overall,‘ says Sam.
‘By comparison, the spring-born calves are
weaned late November. This stresses them
and additionally there is the stress of being
housed. So there’s a greater risk of
pneumonia.
‘So this year, I shall sell or slaughter the
heifers from the spring calving group. And
instead, I’ll only rear replacements from the
autumn calvers. The aim is to calve these
down at 2 years of age, and gradually
transition to a single calving block – in the
autumn.‘
James adds: ‘This year, we PD-ed the spring-
calving group 70 days after the bull had
gone in and found that 75% were over 30
days in-calf. So we're on track to achieve a
compact calving block.
‘We are also aiming to be weaning a calf
from at least 95% of heifers and cows, and
finishing them at 26-30 months of age.‘
James explains: ‘So as well as giving all
bulls a pre-breeding examination, it’s also
important to keep an eye on them throughout
the breeding period, and watch that they
remain physically fit and active.
‘Sam was lucky. Having an unfit bull turned
into a ‘happy accident’ as he discovered that
calving in autumn is the best option for his
herd.‘
Longhorns, despite their long horns, are a very placid breed
Pregnancy diagnosis of the spring calvers shows the
herd is on-track to calve down in a compact block
Lameness is a common problem, particularly in
continental breeds