Monitoring onset of puberty in three genetic strains of
Holstein-Friesian dairy cattle
L.R. McNAUGHTON, S.R. MORGAN, P. GORE, G.A. VERKERK, C.W. HOLMES
AND T.J. PARKINSON
Dexcel Ltd, Private Bag 3221, Hamilton, New Zealand
E-Mail:
NZSAP 2002 Abstract No. 9
Proceedings of the New Zealand Society of Animal Production 62:
30-33
Live weight and age at puberty were determined in three strains
of Holstein-Friesian dairy cattle in each of two consecutive years. The
strains were overseas-origin high-breeding-worth genetics (OS), New
Zealand-origin high-breeding- worth genetics (NZH), and New
Zealand-origin low-breeding-worth genetics (NZL), similar to the New
Zealand dairy cow of the 1970s. Onset of puberty was monitored by weekly
measurement of progesterone in a total of 271 heifers. Animals were
considered to have attained puberty when plasma progesterone
concentrations were greater than 2ng/ml in two out of three consecutive
samples. Live weight at puberty differed between the strains (OS >
NZH > NZL; P<0.05) but not between years. Age at puberty was
affected by strain in Year 1 (OS > NZH > NZL; P<0.01), but not
in Year 2. The greater live weight required to attain puberty in OS
genotype animals must be recognized in target live weights for rearing
of heifers.
Keywords: NZSAPAB;
puberty; Holstein-Friesian; age; live weight; nutrition;
genotype
Last Updated 30/07/2002
