Fræðaþing landbúnaðarins - 04.02.2005, Side 96

Fræðaþing landbúnaðarins 2005
Energy metabolism in the periparturient dairy cow
Grétar Hrafn Harðarson1 and Klaus Lonne Ingvartsen2
1 Agricultural University of lceland, 2 Danish Institute of Agricultural Science
Introduction
Production diseases i.e. diseases associated with improper nutrition or management are
common and very costly in Iceland. The diseases listed in this include: the fat liver
syndrome, ketosis, laminitis, mastitis, milk fever, retained placenta, metritis and
infertility. The diseases occur mainly around calving. They are all interrelated and form
the so-called periparturient disease complex.
The production year of cow can be split up into three phases according to metabolic state
of the animal (Holtenius 1994). Two to three weeks before calving a phase of catabolism
starts where emphasis is put on the preparation for parturition and the initiation of
lactation. This phase will last 8-12 weeks into the lactation depending on the feeding and
management strategies and the genetic potential of the animal. A period of equilibrium
follows the phase of catabolism where the partition of nutrients neither favours lactation
nor increased weight gain. The last period of the production year is a phase of anabolism
where the emphasis is put on increased weight gain as a long-term preparation for the
next lactation.
Table 1. A list of some important biological processes or metabolic changes associated with transition to
lactation in ruminants.
Process or metabolism Response Tissue involved
Fat metabolism de novo fat synthesis 41 absorption of fatty acids 4» esterifícation of fatty acids >t> lipolysis Adipose tissue
f use of lipid as energy Other body tissues
Glucose metaboiism f size of the liver f blood flow t rate of gluconeogenesis Liver
4* use of glucose as energy Other body tissues
Protein metabolism I1 protein synthesis f proteolysis Muscular tissue
^ protein synthesis Other body tissues
Feed intakc t feed intake Central nervous system
Digestion t hypertrophy of the digestive tract t absorption rate and capacity t metabolic activity Digestive tract
The phase of catabolism is the only period causing strain on the cow. In this period for
example the energy requirements increase by more than 300% in high yielding cows.
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