Implications. The implications of dystocia
on other diseases, herd exit, reproductive
performance, and milk yield are summarized.
Several detrimental consequences of dystocia in
primiparous dairy cows include increased risk
of retained placenta (2.5 to 4x), metritis (3x),
herd exit because of death or culling (3x), and
increased intervals from calving to first service
compared to normal cows without dystocia
(29, 72). Multiparous cows having dystocia also
had increased risk for metritis (3.5 to 4.9x ) and
herd exit (3.7x) but no predisposing effect on
retained placenta or days to first service (16,
29). However, in another study (72), cows of
all parities have increased risk for milk fever
and retained placenta, as a result of increasing
calving difficulty. Cows with dystocia also have
increased risk (6x) for reproductive tract
infections (diagnosed within 3 wk postpartum)
and cystic ovaries (2.9×) (17).
Reproductive performance is compromised
in cows with dystocia as increased number of
services and prolonged intervals to first service
and conception are recorded (72). Most studies
show little evidence for reduced milk yield
in cows with dystocia (21). However, those
studies have utilized entire lactation yields
(305-d mature equivalent) in the analyses. One
study (72) reported a decrease in 30-d, but not
in 90-d or 305-d yields of cows with dystocia,
and cows with surgical delivery associated with
stillbirth at parturition had a 5 to 9% decrease
in 305-d milk yield