Heifer calving age has long been regarded as a key measure of herd management policy and efficiency. It encompasses the crucial, but largely unproductive, rearing period of the animal. Nutrition and growth during this period are key to the heifer’s future earning capability.
The subject was the focus of a number of well publicised studies during the mid 1980’s and interest continued into the 90’s (references 1, 2, and 3).
This study aims to collate that picture with more recent experience and so reveal the longer term trends in UK heifer rearing policies and performance.
Three distinct 3-year periods were studied in order to compare and contrast results over time:
[A] Heifers calving during calendar years 1986 to 1988.
[B] Heifers calving during calendar years 1996 to 1998.
[C] Heifers calving during calendar years 2006 to 2008.
Calving data from each 3-year period were aggregated in order to assure results were representative of the period, and not unduly influenced by any possible climatic or other factors unique to any single year. The results presented here show the findings for Holstein heifers in each period.
1 - Heifer Calving Age in the 1980s
2 - Milk Yields versus Calving Age 1986-1998
3 - Heifer Calving Age in the 1990s
4 - Present Day Yields and Age patterns
5 - From 1986 to Today
(1) Poole A.H. 1989. National Milk Records Census 1988. MMB Farm Management Services study No. 5
(2) ADC / NMR 1998. Dairy Statistics from Milk Recording and Genetic Evaluations. Joint ADC/NMR Publication.
(3) Holstein Friesian Society. 1996. Average Age at Calving for Heifers 1994-1996.