Behavioral pattern in Texel x Corriedale terminal crossbreeding: Maternal behavior score at birth, lambs’ feeding behaviors, and behavioral responses of lambs to abrupt weaning

Lambs are more stressed at early weaning when housed with their twin

The objective of this study was to compare the behavioural and immunological responses of twin lambs housed together with their siblings or not after weaning. The study was performed with seven multiparous Milchschaf ewes and their twin lambs (n = 14), which were weaned abruptly at 63 days of age and assigned to two experimental groups: (1) lambs that were housed together with their sibling after weaning (group GT, n = 6) and (2) lambs that were separated from their siblings and remained with other lambs from the same flock (group GS, n = 8). Before and after weaning, the distance between twins, the number of times in which the sibling was the closest lamb, the lambs' behaviours, and the average daily gain were recorded. The lambs' immune response was assessed with the phytohemagglutinin skin test after weaning. The closest lamb before weaning was the sibling in all cases (P < 0.0001 for all). The frequency in which GT lambs were observed closest from its twin increased on the day of weaning (P = 0.002). During the day of weaning, GT lambs vocalised and paced more than GS lambs (P = 0.001 and P = 0.01, respectively). Twenty-four h after the phytohemagglutinin injection, the skinfold thickness was greater in GS than GT lambs (P = 0.03). In conclusion, twin lambs housed together with their siblings were more stressed at weaning, displaying more intensive behavioural changes and a poorer immunological status than twin lambs housed separated from their siblings.

What Do We Know and Need to Know About Weaning in Sheep? An Overview of Weaning Practises, Stress and Welfare

Artificial weaning is the separation of the mother and her lamb, involving the forced ending of suckling and milk supply by the ewes to their lambs. Artificial weaning time varies depending on the purpose of each sheep farm and the characteristics of the lambs, including age and weight of the lambs, and their ability to eat solid food. Artificial weaning is performed from 24 h postpartum until around the age of natural weaning (up to 12 mo of age). Artificial weaning results in the breaking of the ewe-lamb bond, the end of suckling and the complete replacement of milk by solid food, frequently added to changes in both the physical and social environment. It triggers behavioural, physiological and immunological changes that generate negative consequences on the health of both ewes and lambs, as well as on the growth of the lambs, rising animal welfare concerns. As artificial weaning is considered one of the most stressful situations in the life of farm mammals, it is important to consider the factors involved in those responses to develop adequate strategies and improve sheep welfare at weaning. The most frequently used method is the abrupt separation of the ewes and their lambs. However, the adaptation of the animals after weaning can be improved by alternative weaning methods (e.g., progressive, two-steps weaning and mixed regimes), hormonal treatments (e.g., administration of progesterone), and pre- and postweaning management (e.g., the use of creeping feeding, and the presence of conspecifics or humans after weaning). This review presents and summarises information on the stress response and animal welfare issues at artificial weaning in sheep and some management practises that can be used to reduce these problems. The major points included are the ewe-lamb bond at birth and during the lactation period; the stress response at weaning; the factors involved in the stress response at weaning; the different types and weaning methods and their repercussions on animal welfare; and some strategies that can be used to improve sheep welfare at weaning. Lastly, we propose directions for research needed to develop practical alternatives to minimise sheep's stress response at weaning.

Behavioral and physiological responses to early weaning in ewes and their single or twin lambs

As during the early postpartum, ewes and their twin lambs have a weaker bond than ewes that rear single lambs; it might be expected that early artificial weaning would trigger less intense behavioral and physiological responses in mothers and their twin lambs than in mothers and their single lambs. The aim of this study was to compare the behavioral and physiological responses of ewes and their twin or single lambs to early weaning. The study was performed with 19 Saint Croix ewes: 10 bearing single lambs and nine bearing twins (data from only one sibling from each pair of twins was collected). Lambs were weaned at 43 days old. Body weight, stress-related behaviors, and blood protein concentrations were recorded in ewes and lambs before and after weaning. Single lambs were heavier and paced more frequently during the day of weaning than twin lambs (10.6 ± 0.4 vs 8.9 ± 0.4 kg; P = 0.007 and 4.1 ± 0.4 vs 1.5 ± 0.4%; P = 0.0003, respectively). In addition, ewes rearing single lambs paced and vocalized more than twin lambs' mothers the day of weaning (pacing, 42.4 ± 1.1 vs 20.0 ± 1.2%; P < 0.0001; vocalizations, 43.1 ± 2.6 vs 21.3 ± 2.7%; P < 0.0001). Litter size affected only ewes' albumin concentration, without other effects in protein concentrations in ewes or lambs. In conclusion, early weaning triggered stronger behavioral responses in mothers and their single lamb than in mothers and their twin lambs.