Original
Article About Dexters
"The Founder Effect: Origins,
Characteristics and Future of the New Zealand Dexter Herd - Part Two"
by Tony
Cutten and Alex Meades
Meadowpark Herd
The Meadowpark herd of Alex and Anne Meades, near Whangarei in the Northland
Province of the North Island, was until recently a family run dairy herd. As
well as natural mating and AI insemination breeding, Meadowpark has been
active in in vitro fertilization and embryo transfer breeding.
Meadowpark has produced 23 first generation registered bulls carrying the
Meadowpark name. These bulls have produced a further 17 second generation
bulls. Meadowpark genes are thus influential and have a wide distribution
throughout New Zealand over the history of the NZ herd since its origins in
the late 1970s.
New Zealand Dexter Farms
The average NZ Dexter farm is a small holding of around 10 acres (4
hectares), with many much smaller than this, and a minority of full
commercial farms of hundreds or thousands of hectares in size. A typical
herd may contain five or six cows and a similar number of young
stock. Perhaps 30-40% will have a herd bull. Most other Dexter herds will
use AI semen held by agencies such the Livestock Improvement Corporation (LIC)
or Ambreed Ltd. The vast majority of small Dexter herds in NZ would fall
into this category.
A Large NZ Dexter Herd
Glenaan is an extensive high-country grazing property of 4,000 hectares (3,000 grazeable), situated in the Rakaia
River valley of the South Island's
Southern Alps. Hamish Ensor's family grazes 4,000 Merino sheep, 300 Angus
and a herd of 52 Dexter cattle in tussock grassland up to 1,500 metres
(4,500 ft). Glenaan can be under snow for up to four weeks annually. This
necessitates hay/silage supplement feeding out to young stock. Older stock
are not fed supplement. Hamish is impressed with the foraging ability of the
Dexters under snow conditions.
Angus/Shorthorn based cows, and later 65 pure Angus cows, made up the
founding stock. Some 115 grade and purebred cows have been bred using six
bulls in the breeding program. The Dexters are run as a separate herd for
breeding purposes. Culling due to physical faults or colour faults of
approximately 7-10% of grade heifers and cows has been pursued. As a bigger Dexter
herd, Glenaan Dexters have influenced and will continue to influence
particularly South Island herds: two purebred (PB) bulls and 56 Grade 1
(first cross or G1) heifers have been
dispersed with 20 in-calf Grade 2 (second cross or G2) heifers to be sold in February 2003.
A NZ Dexter Dairy Herd
Ruahine Dexters (Jeff and Annie Stephenson) is a lower North Island Jersey-based
dairy herd at Dannevirke in the Manawatu. The farm is 200 acres (80 hectares)
and 210 cows are milked. The Stephenson's have been breeding Dexters for nearly 20 years
and were founding members of the NZ Chapter of the Australasian Dexter
Association. Hay or dairy supplement is fed out in winter/spring.
Thirty-four heifers and cows - 2 PB, 10 G3, 6 G2, and 16 G1 - have been
registered in over 15 years of Dexter
breeding.
Milking records from 2 test milkings of 12 Dexter cows, including 2 PB
(purebred) cows were made in the spring flush of October 2001 and in
mid-summer dry conditions in February 2002 - see Figure One below.
Figure One: Milking Test (mean of two tests) for Ruahine Dexter Herd
(Click on diagram below for larger version)
Seasonal
Results
Spring Flush 29 Oct 2001
Mean yield per cow (n=12)
= 11.41 litres (Range 4.9 - 17.3)
Summer Dry 12 Feb 2002
Mean yield per cow (n=12)
= 7.13 litres (Range 3.1 - 13.5)
Figure Two:
Milk Production by Age of Cow - Milking Test (by Age)
Notes: Numbers of cows in each age group are too small for statistical
significance. Age 3 years (n=3), age 11 years (n=2), all other age groups
refer to a single cow. First lactations are lower volume. Peak volumes are usually in 4-6
year olds.
(Click on diagram below for larger version)
On to Part 3
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