Fræðaþing landbúnaðarins - 04.02.2005, Blaðsíða 102

Table 5. The effects of parity and treatment on hepatocyte fat infiltration score and concentration of NEFA,
glucose and BHB in blood.
Parameter Effect Est. Lcast Sq. Means P value
Hepatocyte fat score - Prepartum Parity 1 0,1400 0,7106
2 0,3517
>3 0,7513
Hepatocyte fat score - Postpartum Parity 1 0,1995 0,0003
2 1,8932
>3 1,6374
Hepatocyte fat score - Postpartum Treatment HH 1,2586 0,2955
HL 1,1329
LH 1,0445
LL 1,5375
Discussion
The avoidance of excessive body reserve mobilisation is of paramount importance as far
as prevention of production diseases is concemed. In the current study the LH feeding
regime shows the most favourable metabolic conditions. This is contrary to a number of
reports which show the beneficial effect of generous prepartum grain feeding on the
NEFA levels in plasma (Kunz and Blum, 1985; Ingvartsen et al., 1995; Minor et al.,
1998; Holcomb et al., 2001). Others, however, show no effect (Dann et al., 1999;
Vandehaar et al., 1999). Holtenius et al. (2003) recently reported that cows fed a higher
energy level during the dry period had a greater degree of insulin resistance before and
afiter calving, which induced higher plasma NEFA concentrations compared to those in
cows fed below requirements. This might explain the different results in studies
examining the effect of dry cow feeding. The dip in dry matter intake in periparturient
cows has been found to be negatively correlated with plasma NEFA (Ingvartsen et al.,
1995) and consequently much interest has been directed towards avoiding low dry matter
intake.
It is well known that a low energy diet in the dry period can cause a degeneration of the
ramen epithelium and thereby a reduced volatile fatty acid (VFA) absorption capacity
(Liebich et al., 1982; Mayer et al., 1986). Hence the theory of exposing the ramen to a
acid load in order to stimulate the development of the ramenal papillae. Work
investigating this have however failed in substantiating this theory (Ingvartsen et al.,
2001) and found no effects of the VFA-load treatment on postpartum feed intake and
performance.
Furthermore in the same study Ingvartsen et al., (2001) compared three feeding strategies in
early lactation: separate feeding of silage ad libitum and restricted feeding of concentrate
with a daily increase in allowance of 0.3 kg (C-0.3) or 0.5 kg (C-0.5) up to a total of 10.2
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