Cognition and behavior in sheep repetitively inoculated with aluminum adjuvant-containing vaccines or aluminum adjuvant only.

Sheep health management strategies often include the use of aluminum (Al)-containing vaccines. These products were associated with the appearance of the ovine autoimmune/inflammatory syndrome induced by adjuvants (ASIA syndrome), which included an array of ethological changes in the affected animals. The aim of this pilot study was to investigate cognitive and behavioral changes in sheep subjected to a protocol of repetitive inoculation with Al-containing products. Twenty-one lambs were assigned to three groups (n = 7 each): Control, Adjuvant-only, and Vaccine. Vaccine group was inoculated with commercial Al- hydroxide containing vaccines; Adjuvant-only group received the equivalent dose of Al only (Alhydrogel®), and Control group received Phosphate-buffered saline. Sixteen inoculations were administered within a 349-day period. Ethological changes were studied in late summer (7 inoculations) and mid-winter (16 inoculations). Animals in Vaccine and Adjuvant-only groups exhibited individual and social behavioral changes. Affiliative interactions were significantly reduced, and aggressive interactions and stereotypies increased significantly. They also exhibited a significant increase in excitatory behavior and compulsive eating. There were increased levels of stress biomarkers in these two groups. In general, changes were more pronounced in the Vaccine group than they were in the Adjuvant-only group. Some changes were already significant in summer, after seven inoculations only. This study is the first to describe behavioral changes in sheep after having received repetitive injections of Al-containing products, and may explain some of the clinical signs observed in ovine ASIA syndrome.

Behaviour and welfare of fattening lambs supplemented with varying sizes and types of straw.

The aim was to evaluate the effect of size (long or chopped wheat straw), type (barley or wheat) and presence/absence (1 week) of straw supplementation on behaviour and welfare of fattening lambs. Sixteen lambs (65 days) were individually housed to be used in two simultaneous experiments (8 lambs each) for 5 weeks of fattening. After a habituation period, they were offered straw that differed either in size (Experiment 1) or type (Experiment 2), which was followed by a week without straw and then reallocation of straw. Maintenance behaviours, play and stereotypies were analysed using video recording. Physiological stress responses were measured using blood samples taken at the end of the week without straw and after the reallocation of the straw. A preference test was performed during the last week. Concentrate and roughage consumption, average daily gain and conversion index were estimated. Lambs provided with long straw spent more time eating forage, playing and performed fewer stereotypies (Experiment 1). Lambs given wheat straw increased their play behaviour compared with those given barley straw, without affecting stereotypies (Experiment 2). When the straw was removed, lambs performed more behaviours associated with stress; however, this was not reflected in blood stress indicators. Lambs clearly preferred long straw over chopped straw, but no clear preference was observed between wheat and barley straw. The amount of forage intake was consistent with the time spent eating forage, but the amount of concentrate intake did not vary with eating concentrate behaviour, since the amount of concentrate intake was higher when the straw was removed, especially in Experiment 2. Our results show that size more than type of straw supplement impact the behaviour of lambs. Long straw reduces the stereotypies and increases play. This may improve the welfare and performance of fattening lambs, adding ethical value to a highly appreciated product.

Effect of postweaning handling strategies on welfare and productive traits in lambs.

Postweaning management strategies that include an element of social enrichment may reduce weaning stress and improve welfare and productive performance. We analyzed the effect of postweaning handling strategies on welfare and production traits in lambs. After weaning, 36 lambs were assigned to 3 experimental groups with 12 lambs each (control [C], fattening with gentle human female contact [H], and fattening with 2 adult ewes [E]). The average daily gain (ADG) was estimated. Blood samples were taken, and infrared thermography was used to estimate stress variables. There were significant differences among treatments (in favor of alternative strategies) regarding production and stress variables (cortisol, glucose, and creatine kinase). The results suggest that the lambs handled gently during the fattening were less reactive and better able to modulate their physiological stress. The E group adapted better to acute stress than the C group but was less efficient in modulating chronic stress. Both treatments showed higher slaughter live weights and better ADGs compared with the control. The use of social enrichment at weaning, especially to establish a positive human-nonhuman animal bond, alleviates lamb weaning stress and improves welfare and performance.