The aim of the experiment was to compare the welfare and weight gains of artificially reared lambs when gradually separated from their mothers or separated from them early and immediately or gradually moved from maternal to reconstituted milk. Forty Comisana lambs were assigned to a control dam-suckled (DS) group and three test groups of 10 each. The lambs in the GRAD group were gradually separated from their dams reducing the time spent with the mothers by degrees over 10 days, while the lambs in the substitute (SUB) and EM groups were abruptly removed from their dams 24-30 h postpartum. After separation, the lambs in the SUB group were provided with a milk substitute, while the lambs in the EM group were subjected to a gradual transition from ewe milk to the milk substitute over 10 days. At 12 and 32 days of age all the lambs underwent open-field tests, during which their behavioural responses to isolation and to an inanimate stimulus - a hobby horse - were measured. In addition, blood samples were collected immediately before the isolation test, and then 10 and 60 min after to evaluate cortisol concentrations. Cell-mediated immune responses in vivo to phytohaemagglutinin (PHA) injection were evaluated at 7, 21 and 35 days of age, while antibody titres against chicken egg albumin (OVA) were determined at 2, 10, 20, 30 and 42 days of age. The weight gains of the lambs were also recorded weekly. When isolated in a novel environment, the GRAD lambs performed less frequent climbing attempts (P<0.05) than did the DS lambs. After the introduction of a hobby horse, the GRAD lambs displayed a longer latency time to move than did the DS, SUB (P<0.01) and EM lambs (P<0.05), and a shorter duration of movement than the DS lambs (P<0.05). The lambs in the GRAD group showed a higher cortisol release and a lower cell-mediated immune response than the three other groups; their antibody titres were also lower than those of the EM and SUB lambs. The GRAD lambs exhibited a lower growth rate than the animals in the DS (P<0.01), EM (P<0.05) and SUB groups (P<0.001). Our results suggest that a gradual separation from the mothers adversely affects behavioural, immune and endocrine responses of artificially reared lambs.
|Publication Title||Applied Animal Behaviour Science|
|Author Address||Facolta di Agraria di Foggia, Istituto di Produzioni e Preparazioni Alimentari, via Napoli 25, 71100 Foggia, Italy. firstname.lastname@example.org|
|Cite this work||
Researchers should cite this work as follows: