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Mei/May 2017
Zoetis Animal
Health Pages
Introduction
W
e all love the arrival
of newborn lambs.
In the same breath,
few things are
more frustrating
and distressing than lambs dying for
no obvious reason. Lamb mortality
remains a huge economic concern
to both intensive and extensive
sheep farming systems, but some
consideration also needs to be given to
the welfare side of the issue, affecting
both the ewe and the lamb.
(1,2,3)
As
with most aspects of farming, there is
no ‘one recipe’ that works on each and
every farm, however, this article series
will aim to serve as a brief summary
and refresher which will touch on
some of the most important aspects
affecting lamb survival.
(1)
The management and farming
strategies that influence lamb survival
should start long before the birth of the
lambs.
(3)
The advantages of an increase
in the number of lambs born will be
outweighed by the disadvantages of
losing those lambs due to decreased
survival.
(1)
Most lamb losses occur during the
first week of the lamb’s life, with
nearly half of these deaths occurring
on the day of birth.
(1,2,3)
The afore-
mentioned highlights the importance
of the post-partum period to the lamb’s
survival.
(3)
The several causes and
aspects that can lead to neonatal
lamb mortality differ according to the
management system.
(1,2)
Extensive
sheep farming systems will more likely
lose lambs from dystocia, starvation
or exposure, whereas, the intensive
systems will be faced more with
threats of infectious diseases and
parasites.
(1,2,3)
Lamb birth weight, colostrum
intake and hypothermia
Lamb birth weight is a major risk
factor in lamb mortality.
(1,2)
An
intermediate birth weight within the
breed is optimal, with increased
mortalities seen at both high and low
birth weights.
(1,3)
Large
lambs might
be predisposed
to birthing
difficulties,
whereas small
lambs may be
more inclined
to die from
starvation and
exposure.
(3)
Lambs with low
birth weights
have a high
birth coat/birth
weight ratio or
in other words, a higher surface area to
volume ratio.
(3)
Heat loss is influenced
mainly by surface area whereas heat
production is more related to body
weight.
(3)
Due to their relative larger
surface area, smaller lambs will lose
more heat to the environment, placing
them at greater risk of developing
hypothermia than larger lambs.
(1,2,3)
At birth, the ewe’s protected uterine
environment is replaced with an
external environment full of challenges
which can include cold or wet weather
and, most likely, predators.(1) After
birth, the lamb’s core temperature
drops by approximately 1 to 2 °C
from the warm uterine environment
of 39 °C.
(3)
To counteract and
FOR ANIMALS. FOR HEALTH. FOR YOU.
Lamb mortalities (Part 1)
Dr. Chantelle Erwee, Zoetis South Africa (Pty) Ltd, Technical Manager: Ruminants
Regulars
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