New Zealand Dairy Statistics 2010-11 - LIC

C. Calving
i) Planned start of calving and median calving dates
The trend in calving dates within and between regions is best shown by the “planned start of calving” date. The planned start of calving date
is 282 days from the date that mating is started in the herd. The farmer has control over, and the ability to change, the start of mating.
Mating and calving information is recorded on the LIC Database for approximately 85% of all herds.
Calving spread can be controlled to some degree by farm management (for example, cow condition score at calving, level of nutrition in the
four to six weeks prior to mating, and the use of CIDR devices and other reproductive technology). The actual start of calving can be
meaningless, since the fi rst calving in a herd can be premature, occurring well before the rest of the herd calves. Hence the median calving
date (the date that occupies the middle position after the dates are arranged in ascending order) is used as an indicator of actual calving
spread.
The forecast planned start of calving and actual median calving dates for cows (excluding fi rst calvers) for the 2010/11 season are shown in
Graph 5.4.
Graph 5.4: Planned start of calving and median calving dates for cows (excluding fi rst calvers) by LIC region
44
Date
30 Aug
20 Aug
10 Aug
31 Jul
21 Jul
11 Jul
1 Jul
New Zealand Dairy Statistics 2010-11
Northland Waikato Bay of Plenty/ Taranaki Manawatu/ South Island
East Coast
Wairarapa
Region
Planned start of calving 2011/12 Median calving 2010/11
The planned start of calving for fi ve-yearly intervals since 1996/97 is shown in Graph 5.5. The trend for four of the six regions (Waikato
(formerly Auckland), Bay of Plenty/East Coast, Taranaki, and South Island) is for a similar or an earlier planned start of calving. Planned start of
calving in Northland is now the 15 July, 6 days later than in 1996/97. Manawatu/Wairarapa (formerly Wellington/Hawkes Bay) seems steady on
or about the 28 July.