Effects of nest boxes in natural mating colony cages on fear, stress, and feather damage for layer breeders1,2,3

The impact of providing hiding spaces to farmed animals: A scoping review

Many wild animals perform hiding behaviours for a variety of reasons, such as evading predators or other conspecifics. Unlike their wild counterparts, farmed animals often live in relatively barren environments without the opportunity to hide. Researchers have begun to study the impact of access to hiding spaces ("hides") in farmed animals, including possible effects on animal welfare. The aims of this scoping review were to: 1) identify the farmed species that have been most used in research investigating the provision of hides, 2) describe the context in which hides have been provided to farmed animals, and 3) describe the impact (positive, negative or neutral/inconclusive) that hides have on animals, including indicators of animal welfare. Three online databases (CAB Abstracts, Web of Science, and PubMed) were used to search for a target population of farmed animals with access to hiding spaces. From this search, 4,631 citations were screened and 151 were included in the review. Fourteen animal types were represented, most commonly chickens (48% of papers), cattle (9%), foxes (8%), and fish (7%). Relatively few papers were found on other species including deer, quail, ducks, lobsters, turkeys, and goats. Hides were used in four contexts: at parturition or oviposition (56%), for general enrichment (43%), for neonatal animals (4%), or for sick or injured animals (1%). A total of 218 outcomes relevant to our objectives were found including 7 categories: hide use, motivation, and/or preference (47% of outcomes), behavioural indicators of affective state (17%), health, injuries, and/or production (16%), agonistic behaviour (8%), abnormal repetitive behaviours (6%), physiological indicators of stress (5%), and affiliative behaviours (1%). Hiding places resulted in 162 positive (74%), 14 negative (6%), and 42 neutral/inconclusive (19%) outcomes. Hides had a generally positive impact on the animals included in this review; more research is encouraged for under-represented species.

Effects of Housing System on Anxiety, Chronic Stress, Fear, and Immune Function in Bovan Brown Laying Hens

The scientific community needs objective measures to appropriately assess animal welfare. The study objective was to assess the impact of housing system on novel physiological and behavioral measurements of animal welfare for laying hens, including secretory and plasma Immunoglobulin (IgA; immune function), feather corticosterone (chronic stress), and attention bias testing (ABT; anxiety), in addition to the well-validated tonic immobility test (TI; fearfulness). To test this, 184 Bovan brown hens were housed in 28 conventional cages (3 birds/cage) and 4 enriched pens (25 birds/pen). Feces, blood, and feathers were collected 4 times between week 22 and 43 to quantify secretory and plasma IgA and feather corticosterone concentrations. TI tests and ABT were performed once. Hens that were from cages tended to show longer TI, had increased feather corticosterone, and decreased secretory IgA at 22 weeks of age. The caged hens fed quicker, and more hens fed during the ABT compared to the penned hens. Hens that were in conventional cages showed somewhat poorer welfare outcomes than the hens in enriched pens, as indicated by increased chronic stress, decreased immune function at 22 weeks of age but no other ages, somewhat increased fear, but reduced anxiety. Overall, these novel markers show some appropriate contrast between housing treatments and may be useful in an animal welfare assessment context for laying hens. More research is needed to confirm these findings.

Effect of a Synbiotic Supplement on Fear Response and Memory Assessment of Broiler Chickens Subjected to Heat Stress

The aim of this study was to evaluate the effect of a synbiotic containing a probiotic (Enterococcus faecium, Pediococcus acidilactici, Bifidobacterium animalis, and Lactobacillus reuteri) and a prebiotic (fructooligosaccharides) on fear response, memory assessment, and selected stress indicators in broilers subjected to heat stress. A total of 360 1-day-old Ross 708 chicks were evenly divided among three treatments: a basal diet mixed with a synbiotic at 0 (G-C), 0.5 (G-0.5X), and 1.0 (G-1.0X) g/kg. After 15 d, the broilers were exposed to 32 °C for 9 h daily until 42 d. The object memory test was conducted at 15 day; touch, novel object, and isolation tests were conducted at 35 day; tonic immobility (TI) took place at 41 day. At 42 day, plasma corticosterone and tryptophan concentrations and heterophile/lymphocyte (H/L) ratios were measured. Compared to controls, synbiotic-fed broilers, regardless of concentration, had a shorter latency to make the first vocalization, with higher vocalization rates during the isolation test (p = 0.001). the G-1.0 group had the lowest H/L ratio (p = 0.001), but higher plasma tryptophan concentrations and a greater number of birds could reach the observer during the touch test (p = 0.001 and 0.043, respectively). The current results indicate that the synbiotic can be used as a growth promoter to reduce the fear response and stress state of heat-stressed broilers.