New Zealand Journal of Agricultural Research abstracts
Lifetime survival of Jersey-sired cows following natural challenge with
facial eczema during first lactation
C. A. Morris
S. M. Hickey
G. Denicolo
AgResearch
Ruakura Research Centre
Private Bag 3123
Hamilton, New Zealand
H. J. Tempero
Livestock Improvement Corporation Ltd
Private Bag 3016
Hamilton, New Zealand
Abstract During a serious natural outbreak of facial
eczema (FE) in March-May 1989 in the Northland, Auckland, and Taranaki regions
of New Zealand, over 1500 Jersey-sired 1st-lactation heifers in 60 spring-calving
herds were blood sampled between 24 April and the end of May. The objective
was to monitor their response to the FE challenge, as measured by serum activity
of the enzyme gamma-glutamyltransferase (GGT); 43 (72%) of the herds contained
heifers that had been exposed. In these herds, compared with the remaining
(“non-exposed”) herds, the cumulative percentages of heifers (still present
for the blood sample) which were culled or had died were not significantly
affected by type of herd. In the exposed herds only, the difference in loge
GGT between cows culled or dead by the end of the 1st lactation and those
that survived was 0.52 ± 0.23 loge i.u. litre-1 (P < 0.05). The
survival of animals to the end of the 2nd lactation in exposed herds was
5.9% lower in heifers with serum GGT > 100 i.u. litre-1 than in those
with lower GGT levels (P = 0.05); the survival difference in heifers with
serum GGT above or below a threshold of 200 i.u. litre-1 was 9.1% (P <
0.01). From all animals blood sampled in the exposed herds (daughters from
65 sire groups), the heritabilities of survival past the end of the 1st,
2nd, 3rd, and 6th lactations following the FE field challenge were 0.01 ±
0.03, 0.02 ± 0.05, 0.02 ± 0.05, and 0.00 ± 0.05, respectively.
The heritability estimate for loge GGT in the FE challenge season was 0.32
± 0.10. This study has shown significant negative associations between
the GGT level after an FE challenge and cow survival.
Keywords facial eczema; dairy cows; liver enzyme;
survival; heritability; GGT
A01024 Received 16 August 2001; accepted 24 June 2002; published 30 September
2002
New Zealand Journal of Agricultural Research, 2002, Vol. 45: 165-170
0028-8233/02/4503-0165 $7.00/0 © The Royal Society of New Zealand
2002
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