Stress related physiological changes in cattle brought for slaughter
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Date
2002
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Department of Physiology, College of Veterinary and Animal Sciences, Mannuthy
Abstract
The study was conducted in adult female cattle with an average body
weight of about 250 kg which were transported for slaughter to Meat
Technology Unit (MTU), College of Veterinary and Animal Sciences,
Mannuthy, to evaluate the effect of transport stress on certain physiological
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parameters. Group I animals comprised of 12 numbers, of which six animals
each were transported from Livestock Research Station (LRS),
Thiruvazhamkunnu and Cattle Breeding Farm (CBF), Thumburmuzhi and they
were designated as the low density stocking group (LDS) given a floor space
allowance of 1.88 m2/animal. Eight adult female cattle brought for slaughter by
trucking at Corporation slaughter house, Thrissur which were given with a floor
space allowance of 0.95 m2/animal formed the Group Il or high density
stocking group (HDS) and eight adult female cattle brought for slaughter from
University Livestock Farm, Mannuthy by walk formed the Group III category .
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Body weight was recorded in LDS group cattle (group I) before and
after the journey and it was observed that the percentage reduction in live
weight was 2.18 per cent which was not that much appreciable due to the ideal
transporting conditions provided for them. Blood samples were collected with
and without anticoagulant (1) before transport, (2) immediately after the
journey (zero hour post-transport) and (3) after a resting period of 18 h from
LDS cattle. From HDS group, (2) immediately after the
journey (zero hour post-transport) and (3) after a resting period of 18 h from
LDS cattle. From HDS group, immediately after unloading (zero hour post-
transport) and after 18 h of rest blood collections were done. Blood samples,
were analysed for various haematological parameters as well as for mitogen
induced Iymphocyte culture studies. The serum samples were also used for
estimation of biochemical parameters as blood glucose level (BGL),
concentration of cortisol, total serum protein, blood urea nitrogen (BUN) and
activities of enzymes viz., creatine kinase (CK) and lactate dehydrogenase
(LDH). Comparison of the data collected at three intervals viz., before
transport, zero hour and 18 h post-transport was done within the LDS group,
whereas, the comparison within HDS group was done at zero and 18 h
post-transport. Comparison of the effect of transport at zero hour and a
post-transport resting period of 18 h was also done between LDS and HDS
groups.
It was observed that LDS group of cattle had a significant increase in
volume of packed red blood cells (VPRC), haemoglobin (Hb) concentration and
total leucocyte (WBC) count at zero hour. It was observed that most of the
values returned to the pre-transport level after 18 h of rest. There was
significant increase in biochemical parameters, like blood glucose level (BGL),
concentration of cortisol, blood urea nitrogen (BUN) and creatine kinase (CK)
activity immediately after transport and many of them returned to pre-transport
level after 18 h post-transport suggesting that 18 h of resting period was
sufficient before slaughter.
In HDS cattle higher values were recorded for the haematological traits
VIZ. VPRC, Hb concentration and total WBC count and for biochemical
parameters like BGL, concentration of cortisol, BUN and CK activity when
compared to LDS group. Most of the values did not decline to restore much,
even after giving 18 h of rest indicating that these animals experienced severe
stress during the journey.
In the present study it was also found that the cortisol concentration
influenced Iymphoblastogenic response to mitogen which was poor in the
presence of autologus serum containing more than SO ng/rnl cortisol
concentration as observed in both LDS (131.2 ±.18.33 ng/ml) and HDS (160.88
I
± 21.87 ng/ml) groups immediately after transport which indicated the immuno
suppressive property of cortisol.
Meat samples were collected from all the groups of cattle within an hour
of slaughter and used for determination of pH and glycogen content at one hour
and six hours post-slaughter. It was observed that meat samples of LDS and
non-transported cattle showed a comparatively lower pH after six hours of
slaughter which was inversely related to their glycogen content. It was also
found that the meat samples of HDS cattle did not attain a significantly lower
pH even at the end Of six hours post-slaughter owing to the reduced glycogen
content when compared to LDS and non-transported groups of cattle which
could result in dark cutting condition.
It can be concluded that gentle handling, optimum transportation
conditions and proper rest before slaughter in good lairage environment are
required to minimize the stress in cattle brought for slaughter and to ensure
production of good quality meat.
Description
PG
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Citation
172041