The effect of milk source on body weight and immune status of lambs

• Milk source may affect the final lamb performance.
• These factors had a negative impact on the animal welfare.
• Artificial reared weaned lambs were heavier than the natural reared ones.
• Lambs from both rearing systems had a similar immune status.
• Whole powdered cow milk is a good and cheaper option for lambs feeding.

Milk source is one of the several factors that can affect lamb body weight (BW) and immune status before weaning. The aim of this experiment was to evaluate the effect of milk source (natural rearing method, named NR group, vs. artificial rearing method using a commercial milk replacer, named MR group vs. artificial rearing method using whole powdered cow milk, named CM group) on the BW and immune status of lambs during the milk feeding and weaning period. In this study, 60 lambs were equally divided according to sex and then randomly divided in three groups (NR, MR and CM). Blood plasma was collected to measure the immunoglobulin concentration (IgG and IgM), the chitotriosidase activity and complement system activity, total complement activity (TCA) and alternative complement activity (ACA). Results showed that lambs reared with NR presented, in general, higher BW, IgG, IgM, TCA and ACA than animals reared with MR or CM at 3 and 5 days after birth (P<0.05). These differences, however, disappeared during weaning. At the end of weaning, animals from MR and CM groups showed higher BW than NR lambs (15.28, 16.89 and 17.66 kg in NR, MR and CM groups, respectively, P<0.05). In addition, MR and CM groups showed higher IgM concentrations than the NR group (1.05, 1.90 and 1.60 mg/mL in NR, MR and CM, respectively, P<0.05). Present findings may improve the management in sheep farms, reducing the expenses of the artificial rearing systems if the described alternative milk feeding source (whole powdered cow milk for human consumption) is selected for feeding lambs reared under an artificial rearing system. Accordingly, these results can be used for increasing the economic benefits of the sheep producers.