A theoretical approach to improving interspecies welfare comparisons

The number of animals bred, raised, and slaughtered each year is on the rise, resulting in increasing impacts to welfare. Farmed animals are also becoming more diverse, ranging from pigs to bees. The diversity and number of species farmed invite questions about how best to allocate currently limited resources towards safeguarding and improving welfare. This is of the utmost concern to animal welfare funders and effective altruism advocates, who are responsible for targeting the areas most likely to cause harm. For example, is tail docking worse for pigs than beak trimming is for chickens in terms of their pain, suffering, and general experience? Or are the welfare impacts equal? Answering these questions requires making an interspecies welfare comparison; a judgment about how good or bad different species fare relative to one another. Here, we outline and discuss an empirical methodology that aims to improve our ability to make interspecies welfare comparisons by investigating welfare range, which refers to how good or bad animals can fare. Beginning with a theory of welfare, we operationalize that theory by identifying metrics that are defensible proxies for measuring welfare, including cognitive, affective, behavioral, and neuro-biological measures. Differential weights are assigned to those proxies that reflect their evidential value for the determinants of welfare, such as the Delphi structured deliberation method with a panel of experts. The evidence should then be reviewed and its quality scored to ascertain whether particular taxa may possess the proxies in question to construct a taxon-level welfare range profile. Finally, using a Monte Carlo simulation, an overall estimate of comparative welfare range relative to a hypothetical index species can be generated. Interspecies welfare comparisons will help facilitate empirically informed decision-making to streamline the allocation of resources and ultimately better prioritize and improve animal welfare.

Effects of beak trimming on the performance, beak length, behavior, and carcass traits of a local broiler breed reared in battery cages

This study investigated the effects of beak trimming on a local broiler breed. A total of 648 one-day-old birds were randomly allocated into three treatments: no trimming (NBT), infrared beak trimming (IRBT), and hot-blade beak trimming (HBBT). The performance, beak length, behavior, carcass traits, organ percentages, and meat quality were inspected. The body weight (BW) from 7 to 35 days in the IRBT group was significantly lower than that in the NBT group, and the BW from 7 to 49 days was lower than that in the HBBT group (p < .05). Compared with untrimmed birds, birds in the IRBT group had lower average daily feed intake (ADFI) from 15 to 21 days, and higher heart percentage and L* value in the breast muscle. The upper beak length at 28 and 49 days of age were longest in untrimmed birds, intermediate in birds in the HBBT group, and shortest in the IRBT groups (p <.05). No evidence was found that HBBT caused changes in performance, behavior, carcass traits, organ percentages, and meat quality except for lower change in spleen percentage. Taken together, IRBT had more influence at inhibiting early BW, ADFI, and upper beak length than HBBT in the local broiler breed.

Understanding How Infrared Beak Treatment Affects the Beak Tissue and the Healing Response of Brown and White Feathered Layer Pullets

Simple Summary

Beak treatment of commercial laying hens remains an important management practice as it is one of the most effective methods of controlling and preventing cannibalism. Infrared beak treatment is the most recent beak treatment method to be utilized and the available literature shows that it has less of a negative impact on birds compared to older methods of beak treatment. Although there is considerable research evaluating the impact of infrared beak treatment on the production and welfare of laying hens, it is still not fully understood how it affects the beak tissue during the first few days post treatment. This is important to understand as it can provide insight into whether or not treated birds are experiencing pain, which has consequences for both welfare and productivity. This study examined the effect of infrared beak treatment on the histology of the beak during early life (first 21 days). Epithelial regeneration started as soon as five days post treatment. There was no evidence that infrared beak treatment resulted in the formation of neuromas or any other indication of chronic pain.

Abstract

Infrared beak treatment has less of a negative impact on laying hen welfare compared to other methods of beak treatment; however, it is still not fully understood how infrared beak treatment affects the beak tissue during the first few days post treatment. The objective of this study was to examine the histology of infrared beak treated vs. untreated beaks of 2 strains of layer chicks during early life. One-hundred Lohmann Brown-Lite (LB) and 100 Lohmann LSL-Lite (LW) chicks were obtained; 50 chicks per strain were infrared beak treated post hatch (IR) with the remainder being sham untreated controls (C). Data collected included presence of beak sloughing, length, and histology. Histology slides were analyzed and scored on a scale of 0 to 4, with 0 indicating no lesions and 4 indicating severe inflammation. Sloughing of the treated beak tissue began at 10 days and was complete by 20 days. IR pullets had shorter beak lengths once sloughing was initiated and less overall beak growth. No differences in healing scores were found between treated LB and LW beaks; all treated LB beaks were healed by 21 days while some LW beaks still showed inflammation. Overall, infrared beak treatment was effective at reducing beak growth post treatment. Healing occurred post treatment in both strains as evident by complete regeneration of the epithelium and a reduction in inflammation.

Morphologically abnormal beaks observed in chickens that were beak-trimmed at young ages

A survey of beak morphological abnormalities was performed on 6,201 chickens (egg-laying hens and chickens for meat production belonging to 25 flocks) brought to a poultry processing plant. The observed abnormalities varied among flocks with occurrence rates ranging from 0.48 to 46.67%. The occurrence was high in flocks subjected to beak trimming and varied significantly according to chicken breed, with the highest rates of abnormalities in a certain chicken breed. The most widely observed abnormalities were: 1) uneven growth of the upper and lower mandibles, mostly with elongation of the lower mandible (accounting for 64.8% of all abnormalities); 2) misalignment of the upper and lower mandibles, causing lateral deviation or crossing (16.3%); 3) sharp or jagged deformities of the mandible tips (10.1%); 4) permanent open beak, a deformity in which the beak did not close completely even when closed (5.8%); and 5) formation of tubercular swellings at the tips of the upper or lower mandibles (3.1%). This is the first report on the occurrence of beak abnormalities in beak-trimmed poultry in Japan.

Effect of γ-aminobutyric acid on growth performance and immune function in chicks under beak trimming stress

This experiment was undertaken to examine the effect of beak trimming stress on the growth performance and immune system, and to consider possible roles of γ-aminobutyric acid (GABA) in this stress response. Results showed that body weight, feed intake and relative spleen weight were significantly increased by GABA at 80 mg/kg (P < 0.05) under beak trimming stress, whereas the relative organ weights of the bursa of fabricius and thymus were not significantly affected (P > 0.05). Adrenocorticotropic hormone concentration in serum was highest for chicks fed the GABA-deficient water and was significantly decreased by the supplement of GABA at days 1, 3 and 5 after beak trimming (P < 0.05). The supplement of GABA significantly increased the proportions of CD4(+) and CD8(+) lymphocytes, especially at the dose of 60 mg/kg (P < 0.05). The levels of interleukin (IL)-1β, lipopolysaccharide-induced tumor necrosis factor-α and IL-6 in serum were significantly decreased by GABA at 80 mg/kg (P < 0.05). All the three cytokines expressed in the spleen were significantly decreased by GABA at 80 mg/kg when birds were under beak trimming stress (P < 0.05). It is concluded that beak trimming suppressed the immune response of chicks, whereas the immune response of chicks could be improved by GABA supplementation.

Beak condition and cage density determine abundance and spatial distribution of northern fowl mites, Ornithonyssus sylviarum, and chicken body lice, Menacanthus stramineus, on caged laying hens

Adult White Leghorn hens (Hy-Line strain W-36) were inoculated with either northern fowl mites or chicken body lice, and the ectoparasite populations were monitored over periods of 9 to 16 wk. Two beak conditions (beak trimmed or beak intact) and 2 housing densities (1 or 2 hens per 25 × 31 cm suspended wire cage) were tested. Populations of both ectoparasites were at least 10 times lower on beak-intact hens compared with populations on beak-trimmed hens. Cage density did not influence mite numbers, but higher numbers of lice (2 to 3 times) developed on hens held at the higher cage density. Louse distribution on the body and louse population age structure were also influenced by host beak condition. Beak-intact hens had a higher proportion of lice under the wings, whereas beak-trimmed hens had the majority of lice on the lower abdomen. Louse populations on beak-trimmed hens also comprised relatively more immature stages than populations found on beak-intact hens. The effects are likely related to decreased grooming efficiency by beak-trimmed hens and, in the case of lice, the higher host density. The high mite and louse populations on most commercial caged laying hens are probably a direct result of beak trimming. However, selection of more docile breeds that can be held without trimming may allow the hens themselves to reduce ectoparasites below economically damaging levels. This could benefit producers, animal welfare advocates, and human health by reducing 1) costs of beak trimming, 2) pesticide treatment costs (including human and bird chemical exposure concerns), and 3) objections to beak trimming from the animal welfare community.

Different effects of infrared and one-half hot blade beak trimming on beak topography and growth

This study examined the effects of infrared beak treatment (IR-BT) and hot blade beak trimming (HB-BT) on beak length and production in laying hen pullets. Seventy-two 1-d-old birds were randomly assigned to the HB-BT, IR-BT, or control group. Birds were pair housed by treatment, and beak images and production indices were obtained posttreatment at fixed intervals for 10 wk. Immediately after treatment, HB-BT beaks were shorter than control or IR-BT beaks (P < 0.01), whereas control and IR-BT beaks remained comparable in length until the onset of tissue degeneration and erosion of the IR-BT beaks at 1 to 2 wk posttreatment. At wk 2 posttreatment, beaks were longest in control birds, intermediate in IR-BT birds, and shortest in HB-BT birds (P < 0.01). Thereafter, an increase in beak length in all treatments was observed over time (P < 0.01), but HB-BT beaks had the greatest regrowth. The beak length of birds in the HB-BT group was similar to that of birds in the IR-BT group from wk 3 to 8, and then grew longer at wk 9 and 10 posttreatment (P < 0.01). The effects of treatments on BW emerged at d 5 posttreatment. The BW of birds in the HB-BT group was suppressed up to and including wk 9 posttreatment compared with that of control birds (P < 0.05) and was significantly lower than that of birds in the IR-BT group between 2 and 4 wk posttreatment (P < 0.05). Birds in the IR-BT group did not differ from control birds after wk 3 posttreatment (P < 0.05). By the final week of the study, differences in BW across treatments were no longer apparent (P > 0.05). For the most part, feed intake was higher in control birds, intermediate in birds in the IR-BT group, and lowest in birds in the HB-BT group until wk 9 posttreatment (P < 0.05). Similarly, feed waste was generally higher in control birds and least in birds in the HB-BT group (P < 0.05). The IR-BT treatment appeared to be more effective at inhibiting beak regrowth, with a less pronounced effect on feed intake than the HB-BT treatment in laying hen pullets.