Feed parameters, milk production and key blood
metabolites during metabolic challenges
Although cows were accustomed to a cubicle housing system,
no effects on behavior, such as excessive vocalization
or restlessness, were detected due to tying of animals.
During both FRs DMI, energy intake and energy balance
were reduced as described in Sigl et al., [18]. Milk yield declined
during restricted feeding in early lactation by 4.6 kg
(P < 0.01), whereas ECM did not differ during both FRs.
Milk protein and milk fat were not influenced by FRs.
Serum glucose levels dropped during FR in early lactation
below 3.0 mmol/L, but increased during subsequent ad
libitum feeding (P < 0.001; Fig. 1). Blood NEFA values
were not affected by both FRs. From d 26 to 29 pp,
concentrations of BHBA increased to values of 2.65 ±
0.16 mmol/L (P < 0.001). Thereafter, BHBA levels decreased
in all cows, but did not reach initial values (P <
0.01). During FR in mid-lactation, no increases in blood
serum NEFA and BHBA levels were measured.