Research Digest: November 2008

Welfare aspects of beak trimming layers evaluated

Beak trimming of layer chickens has been used to reduce or inhibit undesirable behaviors in birds such as pecking, aggression, and cannibalism. This practice has been under scrutiny because of the implications of these methods on animal welfare. Some believe that the pain experienced by birds during being trimming is outweighed by the benefits associated with reduced aggression, feather pecking, and cannibalism. There are specific methods for evaluating whether or not birds experience pain such as lethargy, guarding behaviors, reduced feed intake, and development of neuromas. These researchers examined the effects of trimming beaks using an infrared beak trimmer on layer chicks. Seventy-two layer chicks were separated into three different groups including:

1. hot-blade trimming (HB),
2. infrared treatment (IR),
3. control treatment.

Day-old chicks were pair-housed by treatment. Photographs of the beaks, behavior of the birds, and production indices were collected and evaluated at various intervals for a 9 week period after treatment. All beaks were normally shaped prior to the study, and no perceptible treatment-related differences in shape occurred over time. After treatment, the HB birds had shorter beaks relative to the other 2 groups. Control and infrared treated beaks remained comparable in length until the beak tissue eroded in IR beaks after the treatment. After the two-week period, beak length increased in all treatments over time. Two weeks after the treatments, as expected, the control birds had the longest beaks. The HB birds had intermediate length beaks and birds that were treated with the infrared had the shortest beaks. Birds treated with the hot blade showed abnormal deviations from a normal upper-to-lower mandible length ratio than the IR or control birds. Production parameters were significantly affected for beak trimmed birds and became observable after 2 days and persisted for 5 weeks. Growth and feed intake were significantly lower in birds that were beak trimmed with a hot blade or infrared, when compared with control birds. The infrared birds performed the worst of the groups until the fourth week of the study.

After 4 weeks, the infrared birds performed similarly to the hot blade trimmed group. Feed waste (spillage of feed as birds ate from the feeders) was lowest in the infrared trimmed group and was generally greatest in the control group. Eating and drinking behaviors were significantly affected by beak trimming with both methods. When birds were beak trimmed using infrared, they were less active and spent less time eating and drinking than control birds. Pain associated behavior in hot blade trimmed birds often ranked intermediate in duration and incidence, but was not significantly different compared with behavior measured in the control and infrared treated birds. However, after 1 week, the effects of the beak trimming treatment on behaviors were not present. The authors concluded that their results indicate that acute pain occurred when birds were exposed to both trimming methods and although the negative impact of trimming appeared to be greatest in the infrared treated birds initially, these effects disappeared relatively quickly and subsequent performance was similar in both trimmed groups. This study is important in that it assists the poultry industry by providing them scientifically based information concerning ways to improve the welfare of chickens.

Marchant-Forde, R. M., A. G. Fahey, and H. W. Cheng, 2008. Comparative effects of infrared and one-third hot-blade trimming on beak topography, behavior, and growth. Poultry Science 87:1474-1483.

Capturing fat from poultry waste streams

Because of the rising cost of feed ingredients and fuel, the poultry industry is continuously looking for ways to meet their needs in a more economical way. One method that is gaining interest is recovery of nutrients, in particular, fat from poultry wastewater streams. An experiment was conducted to compare the proximate composition of particulate matter recovered from poultry processing wastewater (PPW) generated by broiler slaughter plants. Poultry processing wastewater is the cumulative wastewater stream generated during the processing of poultry following primary and secondary physical screening (typically to 500 µm) that removes gross offal.

Composite samples of PPW from three broiler slaughter plants (southeast United States) were collected over eight consecutive weeks. All three broiler slaughter plants examined in this study process young chickens with an average live weight of 4.4 pounds. At each plant, a single composite sample was collected using an automatic sampler programmed to collect around 1 quart of wastewater every 20 min for 24 hours during one normal processing day each week. Each composite sample was thoroughly mixed, and was passed through a series of sieves (2.0 mm, 1.0 mm, 500 µm, and 53 µm). The amount of particulate solids collected on the 2.0 mm, 1.0 mm, and 500 µm sieves was insignificant. The solids recovered from the 53-µm sieve were subjected to proximate analysis to determine percent moisture, fat, protein, ash, and fiber. The average percentages of fat, protein, ash, and fiber for all samples on a dry-weight basis were 55.3, 27.1, 6.1, and 4.1, respectively. Fat made up over half of the dry-weight matter recovered, representing poultry processing wastewater particulate matter between 500 and 53 µm. Despite the variation in number of birds processed daily, further processing operations, and number and type of wastewater screens utilized, there were no significance differences in percentage of fat and fiber between the slaughter plants.

If fat can be recovered using a physical method that does not involve heating, such as a screen, then it can be used as a high-quality feed ingredient or converted to biodiesel. This study showed that there is a tremendous potential for extracting fat and thus, feed ingredients and fuel from the back end of poultry plants. If this can be done in cost effective manner, then this could become a significant revenue stream.

Kiepper, B. H., W. C. Merka, and D. L. Fletcher, 2008. Proximate composition of poultry processing wastewater particulate matter from broiler slaughter plants. Poultry Science 87:1633-1636.

Stressing birds may enhance salmonella colonization

In modern poultry production systems, environmental stressors such as high temperature, noise, or disease may influence bird performance and susceptibility to colonization by pathogens such as Salmonella enteritidis (SE). Researchers conducted experiments to determine the influence of exposing groups of birds to feed withdrawal for 24 hours and exposing groups of birds to high temperature (86 F) for 24 hours on intestinal characteristics of broilers.

Attachment of SE to ileal tissue was determined using an in vitro ileal loop assay. Changes in commensal intestinal microbial populations were determined using denaturing gradient gel electrophoresis, and changes in the morphology of the ileum were determined by histological examination. Ex vivo attachment of SE to ileal tissues increased by 1.5 logs in broilers when they were held off of feed for 24 hours. Similarly, ileal tissues from birds subjected to 86 F for 24 hours had increased ex vivo attachment of SE compared with birds held at 73.4 F. Exposure to 86 F for 24 hours also altered the microbial community in the ileum and cecum of the birds. Subjecting birds to 86 F for 24 hours reduced crypt depth in intestines, but had no effect on villus height or villus to crypt ratio.

The authors concluded that this research shows that acute stressors in poultry production systems can cause changes in the normal intestinal microbiota and epithelial structure, which may lead to increased attachment of SE. Prior research has shown a significant linkage between air sacculitis and other diseases and salmonella. This research helps to explain the physiological reason why this occurs.

Burkholder, K. M., K. L. Thompson, M. E. Einstein, T. J. Applegate, and J. A. Patterson, 2008. Influence of stressors on normal intestinal microbiota, intestinal morphology, and susceptibility to Salmonella enteritidis colonization in broilers. Poultry Science 87:1734-1741.