The maternal-offspring relationship in tailed and docked ewes and their lambs

Maternal behavior in the hours after lambing is critical for establishing
the lamb–dam bond. In rodents, early-life pain alters maternal behavior,
but it is unclear whether routine painful procedures like tail docking
have similar long-term effects in sheep. We tested whether neonatal tail
docking in female lambs altered (1) their maternal behavior and their
offspring’s behavior after lambing and (2) behavioral and physiological
stress responses to separation. Polypay ewe lambs were tail docked using
the rubber ring method between 24 to 36 hours of age (n=11) or left
undocked (n=10). At approximately 13 months of age, they gave birth to
singleton (n=6) or twin (n=15) litters. Between 30 to 60 minutes after the
last lamb’s birth, the ewe and her lamb(s) were moved to an individual
maternity pen, where behaviors were video recorded for 2 hours. Between 6
to 12 hours after lambing, the lambs were separated from their dam for 15
minutes, with video recordings taken from 15 minutes before separation
until 15 minutes after reunion. Eye temperatures of ewes and lambs were
assessed using infrared thermography immediately before and after
separation as indicators of physiological stress. For all video
recordings, we analyzed the duration the ewe spent eating, pacing, lying,
and grooming her lamb(s), as well as the duration the lambs spent wagging
their tail, nursing, and lying. Transitions from lying to standing were
also recorded for ewes and lambs in the 2-hour postnatal period. All
models included the dam’s tail docking status as a fixed effect with
litter size (singleton vs twin) as a factor covariate; separation models
also included observation period (before, during, and after separation).
We found no significant effect of the dam’s tail docking status on
maternal and offspring behavior following lambing or on their responses to
separation. However, lambs of undocked ewes tended to spend more time
lying in the postnatal period compared to lambs of docked ewes. Behavioral
changes during and after separation – including increased pacing and
reduced eating in ewes during separation, and increased grooming and
nursing following reunion – suggest that separation was stressful,
regardless of the ewe’s tail docking status. No differences were observed
in eye temperatures before and after separation. Overall, we did not find
evidence to suggest that neonatal tail docking impairs the ewe’s ability
to bond with or care for her lambs later in life.