New Zealand Journal of Agricultural Research abstracts
Effects of time of calving on the productivity of pasture-based dairy systems:
A review
S. C. GARCIA*+
C. W. HOLMES*
*Institute of Veterinary, Animal and Biomedical
Sciences
+Agricultural Services
Massey University
Private Bag 11222
Palmerston North, New Zealand
email: s.c.garcia@massey.ac.nz
Abstract Effects of season of calving, date of calving within
season, and pattern of calving on different components of pasture-based systems
of dairying and on the system as a whole are reviewed. Season and pattern of
calving can influence the shape of the lactation curve (by influencing the
level of yield at peak of lactation, the rate of decline after the peak, or the
total days in milk), the annual milk yield and milk composition, the herd's
reproductive performance, and animal health. For systems in which the cows
calve in spring, an earlier study reported small advantages from later calving,
whereas more recent studies have shown advantages from earlier calving. These
latter advantages resulted from extra days in milk, provided that sufficient
feed was available for the herd in early lactation. A combination of early
calving and extra feed in early lactation may achieve the benefits and avoid
the disadvantages of early calving. Comparisons between autumn and spring
calving systems showed that autumn-calved cows require more supplements during
early lactation (winter) and usually have lower daily milk yields at peak
lactation than spring-calved cows. However, autumn-calved cows can have higher
annual yields of milk and milksolids than spring-calved cows, mainly as a
consequence of both longer lactations and higher daily milk yields during late
lactation. Time of calving is a key element in construction of the farming
system, which can be integrated with stocking rate, pasture supply, and
availability of supplementary feed.
Keywords calving season; pastoral; dairy systems; feeding
management
New Zealand Journal of Agricultural Research, 1999, Vol. 42: 347-362
0028-8233/99/4203-0347 $7.00/0 (c) The Royal Society of New Zealand
1999
PDF file of entire paper: medium quality (1398K); (scanned from paper original: notes about this process)
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