Measurement of fecal glucocorticoid metabolites and evaluation of udder
characteristics to estimate stress after sudden dry-off in dairy cows with
different milk yields
Sudden dry-off is an established management practice in the dairy industry.
But milk yield has been increasing continuously during the last decades. There
is no information whether the dry-off procedure, which often results in
swollen and firm udders, causes stress, particularly in high-producing dairy
cows. Therefore, we evaluated the effect of a sudden dry-off on extramammary
udder pressure and the concentration of fecal glucocorticoid metabolites
(i.e., 11,17-dioxoandrostane, 11,17-DOA) as an indirect stress parameter.
Measurements were carried out within the last week before dry-off and until 9d
after dry-off considering 3 groups of milk yield (i.e., low: <15 kg/d, medium:
15-20 kg/d, and high: >20 kg/d). Udder pressure increased in all yield groups
after dry-off, peaked at d 2 after dry-off and decreased afterwards. Pressures
were highest in high-yielding cows and lowest in low-yielding cows. But only
in high-yielding cows was udder pressure after dry-off higher than before dry-
off. Baseline 11,17-DOA concentrations depended on milk yield. They were
highest in low-yielding (121.7 ± 33.3 ng/g) and lowest in high-yielding cows
(71.1 ± 30.0 ng/g). After dry-off, 11,17-DOA increased in all yield groups and
peaked at d 3. Whereas in medium- and high-yielding cows 11,17-DOA levels
differed significantly from their respective baseline during the whole 9-d
measuring period, low-yielding cows showed elevated 11,17-DOA levels only on d
3 after dry-off. However, especially the increase in 11,17-DOA after dry-off
between the 3 yield groups was considerably different. Mean 11,17-DOA increase
from baseline to d 3 was highest in high-yielding cows (129.1%) and
considerably lower in low-yielding cows (40.1%). The highest fecal 11,17-DOA
concentrations were measured on d 3 after dry-off, indicating that the stress
was most intense on d 2, which is due to an 18-h time lag; at about the same
time, udder pressure peaked. Our results showed a negligible effect of a
sudden dry-off on low-yielding cows. High-yielding cows, however, faced high
extramammary pressures and increased glucocorticoid production. Considering
animal welfare aspects, a review of the current dry-off strategies might be
warranted