Artificial weaning in sheep: stress response and animal welfare. Review

The establishment of ewe-lamb bond occurs at lambing, and is modified along the lactation period until natural weaning. Artificial weaning is a management commonly used in sheep productive systems commonly performed before natural weaning. Artificial weaning provokes strong behavioral and physiological responses indicative of stress, and is considered as one of the most stressful situations in the life of the animal. Those responses negatively affect animal health and welfare, and the productive results. Therefore, it is important to elucidate which factors affect those responses, and to develop strategies to decreases the negative response. This review summarizes the available information on the establishment of ewe-lamb bonding, and how this bond evolves during the lactation period until natural weaning. Moreover, it describes the behavioral and physiological stress responses to artificial weaning, and the main factors that affect those responses at physiological, behavioral and productive levels. Finally, it presents information on some strategies available to decrease the negative effects of artificial weaning. Includes original information on the influence of quantitative and qualitative changes of pasture allowance in extensive sheep production systems and the stress responses of lambs to weaning; and handlings that potentially may be applied to decrease the stress response to artificial weaning. It suggests whether is room to study and to develop practical alternatives to modulate the stress response to weaning.