Senwes Scenario December 2018 / January 2019 | Page 24
AGRICULTURAL
21 | Nutrition and Immunity
of Feedlot Cattle
cy. An extreme immune response not only
wastes resources but may cause local cell
damage and depress productivity.
WHAT IS THE EFFECT OF
NUTRITIONAL STATUS ON
RESISTANCE TO INFECTION?
Good nutrition improves disease resis-
tance of stressed cattle, by helping to
counteract the suppression of the immune
system caused by stress hormones and
by providing nutrients essential for main-
taining and activating the immune system
as required.
Generally, nutrition has most impact on
health during the first month on feed and
particularly for highly-stressed or lighter
weight cattle. Many of the cattle entering
feedlots are marginally deficient in several
trace minerals, especially if they previous
ly grazed dormant native range or pas-
ture. Receiving rations should be ade-
quately supplemented with trace minerals,
vitamin A and vitamin E. Feeding higher
levels than normal of these nutrients in
the receiving period can compensate for
reduced intake and marginal deficiencies
on arrival.
After cattle have recovered from stress
induced immune suppression and are
adapted to the finishing diet, balancing
feedlot diets to meet requirements for
growth usually provides adequate nutrients
for immune function.
In order of priorities, providing a palat-
able diet on arrival and encouraging feed
and water consumption is most important.
There is little benefit from adding expen-
sive nutrients to an unpalatable diet.
Research has shown that it can take up to
a week or more for all calves in a pen to
consistently consume some feed within a
single day. Average intake is only 1.5% of
body weight in the first 2 weeks for light-
weight feeder calves. Anything that can
be done to enhance intake after arrival
reduces the length of time in which the
immune system is compromised by short-
term nutrient deficiencies.
WHAT IS OPTIMAL IMMUNITY?
The optimum immune response is the
one that is the shortest in duration and
the lowest in intensity while successfully
eliminating the pathogen. Reducing chal-
lenges to the immune system by providing
a clean environment and reducing stress
can improve growth rate, even in the
absence of disease.
In normal healthy cattle, there is a
trade-off between growth and immuni-
ty – both cannot be maximized at the
same time. This is not usually a practical
concern because the immune system
functions very well at nutrient levels ideal
for growth. Compared to the adapted
feedlot steer, the stressed feeder calf
is in a unique situation because of the
conflicting nutrient demands for immune
activation (vaccination and/or disease
exposure), responding to stress, recove
ring from short-term nutrient deficiencies,
and growth. This animal has potential to
respond to some key immune enhancing
nutrients with significantly increased gain
and improved immunity.
Om die produktiwiteit van produksiestelsels
vir beeste te verbeter.
Adviesdiens vir herkouervoeding
Voerprosessering, voedingsbestuur en formulering
van voere vir volhoubare produksieprestasie
Formuleer en verskaf konsentrate om formulasies te
komplimenteer
Dr. Kobus Swart 083 262 0946 • [email protected]
22
SENWES SCENARIO | TECHNOLOGY & INNOVATION 2018