New Zealand Journal of Agricultural Research abstracts
Genetics of susceptibility to facial eczema in Friesian and Jersey cattle
C. A. MORRIS1
L. J. BURTON2
N. R. TOWERS1
N. G. CULLEN1
J. M. RENDEL2
D. L. JOHNSON2
1AgResearch
Ruakura Agricultural Research Centre
Private Bag 3123
Hamilton, New Zealand
2Livestock Improvement Corporation
New Zealand Dairy Board
Private Bag 3016
Hamilton, New Zealand
Abstract A total of 528 calves from 3 calf crops, sired by 34
Friesian and 28 Jersey bulls, were challenged with sporidesmin, the toxin
causing facial eczema (FE), in order to determine the genetic variation in
susceptibility to FE. The challenge was either by grazing toxic pasture or by
oral dosing, and the response was monitored by blood sampling to measure the
elevations of serum gamma-glutamyltransferase (GGT), glutamate dehydrogenase
(GDH), and other possible indicators (enzymes or metabolites: bilirubin,
aspartate transaminase, ferroxidase, bile acids, and 5'nucleotidase). The last
calf crop was sired, in part, by bulls phenotypically selected from the second
calf crop using GGT records. Data were analysed using the repeated records
option of a restricted maximum likelihood programme. A sire model was used,
with sires and maternal grandsires included to determine pedigree. The
uni-variate heritability estimates for logeGGT were 0.29 +/- 0.15 in Friesians
and 0.77 +/- 0.13 in Jerseys, and for logeGDH they were 0.20 +/- 0.12 and 0.64
+/- 0.13, respectively. Corresponding repeatabilities were 0.86 +/- 0.01 and
0.84 +/- 0.02 for logeGGT, and 0.66 +/- 0.03 and 0.69 +/- 0.03 for logeGDH. The
genetic correlations between the two enzymes were 0.99 for Friesians and 0.95
for Jerseys. Genetic correlations between the five other enzymes or metabolites
and logeGGT were generally high (0.79 to 0.99), with the exception of
ferroxidase which was not correlated with logeGGT. The next best indicators of
FE susceptibility after GGT and GDH were aspartate transaminase and
5'nucleotidase, which were phenotypically correlated with GGT, were heritable
(in Jerseys) and repeatable, and showed elevation in response to challenge. The
"High" and "Low" GGT-selected sire groups in the last calf crop had
significantly different progeny mean GGT levels in both breeds. It was
concluded that selection against high GGT concentrations following FE challenge
should reduce the susceptibility to FE in subsequent generations.
Keywords facial eczema; cattle; heritability; susceptibility;
genetic correlation
New Zealand Journal of Agricultural Research, 1998, Vol. 41: 347-357
0028-8233/98/4103-0347 $7.00/0 (c) The Royal Society of New Zealand
1998
PDF file of entire paper: medium quality (607K); (scanned from paper original: notes about this process)
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