Hl. Muller et al., ENERGY-UTILIZATION OF FODDER BEETS IN LAC TATING DAIRY-COWS, Journal of animal physiology and animal nutrition, 71(4-5), 1994, pp. 234-246
A respiration experiment was conducted in 18 lactating diary cows to i
nvestigate the effect of adding 0, 22 and 44 kg fodder beets to a hay-
grass silage ration on energy, N balance and milk production parameter
s. Faeces and urine were analysed in a balance test using quantitative
collection technique, and energy retention and utilization measured b
y means of the CN and RQ method. In addition, effects on the milk-fat
pattern and several blood-plasma parameters were studied. The milk yie
ld fell by up to 21 % with rising intakes of fodder beets. However, th
e milk-fat content increased such that the daily milk-fat output was u
naffected by the beets. On the other hand, the lactose produced fell s
harply, and the excretion of milk protein also showed a downward trend
. The fat pattern shifted in favour of palmitic acid at the expense of
the C18 fatty acids (stearic, oleic and linoleic acid). The blood pla
sma values 2 hours after the beet feed showed a more marked decline of
glucose and higher levels of beta-hydroxybutyrate compared to the con
trol. The inclusion of beets increased the digestibility of DM and ene
rgy in the total ration, while the digestibility of crude fibre remain
ed unchanged. The metabolizability of energy was raised by up to 4 per
centage points. Energy retention, on the other hand, decreased markedl
y with beet feeding. Compared to the control cows, the efficiency of u
tilization of ME in the total ration for milk and energy deposition wa
s lower by 6.4 percentage points on 22 kg beets and by 8.4 percentage
points on 44 kg beets. The partial utilization of the beets, with refe
rence to their sugar content, was 13 percentage points lower than the
utilization of the remaining ME in the ration. However, no differences
were observed between the treatments with regard to the relative valu
es of N retention.