Lambs prevented from suckling their mothers display behavioural, immune and endocrine disturbances

The aim of the experiment was to assess the effects of either maternal deprivation or prevented suckling on lambs. Thirty Comisana lambs were assigned to a control dam-suckled group (DS) and two test groups of 10 each. Test lambs were maintained with their mothers 24 to 30 h after parturition and subsequently offered ewe milk from buckets: EM lambs were separated from their mothers, while EM+D animals were reared with their dams but suckling was denied by covering ewe udders with juta bags. Behavioral, immune and cortisol responses of lambs were assessed throughout the experiment. EM+D lambs spent less time ( P < .001) on investigative behavior compared to the two other groups. When isolated in a novel environment, EM+D lambs exhibited a shorter duration of movement ( P < .01) and a longer latency time compared to DS and EM lambs ( P < .001 and P < .05, respectively) as well as a higher number of bleats ( P < .01) than EM lambs. EM+D lambs also displayed higher ( P < .001) plasma cortisol levels than the other two groups when isolated at 4 days of age. When subjected to discrimination tests, EM+D lambs spent less time near their companions ( P < .01) than EM lambs and took a longer time to reach their pen mates ( P < .01) than DS and EM lambs. EM+D lambs displayed reduced growth ( P < .001) compared to DS animals during the 0–7 and 8– 14-day periods. We conclude that frustration arising from maternal feeding deprivation results in altered endocrine and behavioral responses and reduced growth suggesting emotional disturbances of lambs.