The recent 8th International Conference on Poultry Welfare provided an overview of research on management and housing of poultry flocks. The conclusions of researchers should be carefully monitored since these have an inordinate influence on legislation and regulations. The caveat relating to many of the studies is that they are conducted on a small scale and findings may not necessarily reflect the realities of commercial production.
Much of the research is directed at alternatives to confined systems since conventional cages will be banned in the EU from 2012 onwards and there is considerable question as to the benefits and the disadvantages of barn and range systems. Much of the research conducted in the EU has attempted to define the performance and welfare characteristics of communal cages. This approach to confined housing has emerged as a system regarded as intermediate between conventional cages and non-confined housing.
A cage is a cage
Unfortunately the results of the studies initiated in 2007 are now moot since there is considerable doubt as to the acceptability of this system in terms of both EU legislation and consumer perception. As far as the acceptability of confined housing in the U.S. is concerned the HSUS regards “a cage is a cage is a cage.”
It is striking that virtually all of the studies end with the conclusion that “further research is necessary” suggesting that science is presently unable to provide explicit guidance on the adoption and design of either caged or non-confined systems.
The second significant concern with current welfare research is a complete lack of consideration of the economics of production. Perhaps university and institutional-based scientists, secure in their incomes, are oblivious to the realities of profitability and return on investment, which are in the long run determinants of commercial acceptability and the availability of eggs at prices consumers can afford.
Review of eight abstracts
Abstracts with specific relevance to the U.S. egg industry were selected for review:
1. Laying Hen Production Systems: Welfare and Social Sustainability
This contribution from Dr. Joy Mench of the University of California, Davis and colleagues at Michigan State University, considered an overview of directions in flock welfare primarily driven by EU legislation and the result of the November 2008 California Proposition.
The presentation was predicated on a speculative presumption that the trend against cage housing would extend to other states. This has not been evident and in fact there has been minimal conversion from conventional cage systems in the U.S. The American Egg Board has funded a project to address problems of sustainability and welfare, both “hot button” concerns. It is intended to develop white papers on values and public acceptability, economic issues, flock welfare, food safety and environmental sustainability. The proposed multi-disciplinary approach involving ethicists, social scientists and presumably poultry scientists will prepare reviews which will be subjected to subsequent evaluation. Basically the approach may generate recommendations for direct application to production.
This cynical observer considers that the exercise will be prolonged, will support an inordinate number of university personnel in diverse areas of the sciences and humanities, and ultimately will be of minimal benefit to the industry and consumers.
2. The Welfare of Laying Hens in Four Different Housing Systems in the UK
The reviews conducted by the University of Bristol Group, which has a long history of concern for scientific aspects of welfare, contrasted conventional cages, furnished cages, barns and free range systems. The project involved visits to farms, questionnaires, post mortem examination and observation of hen behavior. It appears that the least skin damage and keel protrusion were associated with conventional cages with free-range producing the most lesions. Barns and enriched cages were intermediate.
Vent peck was least obvious in enriched cages followed by conventional cages. Both barn and free range systems showed a higher prevalence of this undesirable behavior. In contrast conventional cages were associated with the highest percentage of keel fractures at depopulation but this may have been inherent to the methods of handling and removal from cages superimposed on skeletal integrity.
The conclusion that enriched cages contributed to the welfare benefits is subject to interpretation, especially as cost benefit was not considered.
3. Effect of Housing Systems on Innate Immunity
Scientists in Italy contrasted physiological parameters in brown-feathered flocks housed in either conventional multi-tier cages, barns with and without external access, and fed either conventional or organic diets. Organic diets were associated with low alpha-tocopherol plasma levels, lower heterophil to lymphocyte ratios and lower levels of immune response as measured by the hemolytic complement assay, lysozyme and aptoglobin values.
As with many studies conducted by scientists evaluating housing, welfare and nutrition there was no data on production efficiency notwithstanding the small size of the comparison groups, comprising 250 hens. Accordingly it is not possible to correlate physiological findings with production efficiency and hence economic benefits.
4. Effect of Hot Blade and Infrared Beak Trimming on Beak Condition, Production and Mortality of Laying Hens
Dr. P.C Glatz of the Pig and Poultry Institute in South Australia has emerged as a world expert on beak treatment. Currently infrared (IR) treatment at the hatchery is becoming an accepted practice and is used as the only modification through the rearing period. In many cases producers re-trim beaks during the rearing period since re-growth following day-old treatment may be inadequate.
In the study conducted in Australia on 50 chicks, it was concluded that “beak condition” was significantly better for chicks treated by IR, compared to ten-day treatment involving removal of half of maxillary and 1/3 of mandibular beak, using a hot-blade machine. By mid-lay, there was no difference between the treatments with respect to appearance of the beak although the mandibular beak was consistently longer in birds subjected to day-old IR treatment.
Microscopic examination of beak tissue showed that neuromas occurred in mature birds subjected to either IR or hot blade trimming. It was concluded that additional research is required to establish the operating parameters to ensure uniform beak treatment using IR technology. This conclusion is supported by field experience in the U.S. It is noted that Dr. Glatz has compiled a manual “Beak Trimming Handbook for Egg Producers” funded by the Australian Poultry Cooperative Research Center. The objective of the handbook which incorporates training and codes of practice is to establish standards for trimming and welfare.
5. Welfare and Acute Phase Proteins in Laying Hens
Establishing a correlation between the physiological parameters in housing systems may be helpful in understanding the response of hens to their environment. In a detailed study conducted in Italy, serum alpha-1-acid glycoprotein [AGP] and albumin were measured as these parameters are apparently correlated with response to stress.
These acute phase proteins were measured at 15 days, 2 months and 4 months after housing. Significant differences were noted among the systems used to house subject hens. At the initial period hens in both conventional cages and enriched cages showed high values for AGP compared to free-range hens. These values declined however over the two subsequent sampling intervals indicating resolution of the initial stress response attributed to competition among cage-mates.
In contrast, hens housed on free-range showed a progressively increasing level of AGP consistent with prolonged stress presumably related to their environment. These findings are consistent with the fact that feather and vent peck in caged-housed pullets occurs soon after placement but that small groups of up to six hens develop a peck order which reduces competition and aggression.
The high rate of lay at peak production and subsequent persistence in well-managed flocks provided with adequate nutrition and protected against infection tends to negate the influence of stress associated with confined housing.
It is noted that most research on physiological response to housing is conducted on strains which have been bred for production in cages for over thirty generations.
6. Effect of Specific Noise in Laying Hens
Studies conducted in Spain demonstrated the deleterious effect of subjecting laying hens to sound levels exceeding 90dB for five hours during the daylight period compared to a standard environment with sound measured at 65dB. The experiment was conducted for an eight week period from 28 weeks of age onwards.
Fluctuating asymmetry comprising measurement of bi-lateral anatomical structures (wing, leg and wattle) showed differences between the groups with a greater degree of asymmetry in hens subjected to high dB values simulating truck, train and aircraft noise.
7. Effects of Human-Animal Contact with Layer Pullets Un-fearfulness
Docility in a flock is generally associated with frequent interaction with caretakers passing through houses during the rearing period. This aspect was studied at Wageningen, the Netherlands as a component of their Welfare Quality Project.
Treatments were applied over a five day period from 10 days of age onwards and then at 16 weeks of age. Floor-housed pullets were exposed to a caretaker walking through the house without talking, walking slowly while talking or walking slowly with intervals of squatting and broadcasting feed to pullets. Fear tests were performed at 20 and 40 weeks of age. The trial was compromised by intrusion of workers during construction in some rearing flocks.
No differences were noted in either body weight although there was a minor influence on uniformity. There was no difference in performance during the laying period. The researchers questioned whether human contact of greater duration would be beneficial. Field experience in the U.S. has shown that placid laying flocks result from a program of “socialization” by exposing young flocks to human contact during rearing.
8. Technical Results from Aviary Systems
Aviary Systems were evaluated by the Wageningen Group in a structured retrospective study involving five different flocks. Mortality ranged from 3% to 31% with higher levels attributed to cannibalism. Flock production ranged from 70% to 85% and there were large differences in the prevalence of floor eggs.
The conclusion from this study is that there are considerable inherent differences in performance from aviaries. Based on experience in the U.S., factors which influence livability and production include the similarity in design and lay-out of rearing and laying units, configuration of feeding and perching installations in aviaries , nutrition, stocking density, ventilation, lighting system and management including confinement of flocks to modules in the critical two week period following transfer.
Evaluate all results
The results presented by a diverse group of scientists and allied researchers must be carefully evaluated. It is imprudent to base legislation and regulation on laboratory-scale trials or experiments with narrow objectives. All trials and studies should take into account commercial realities with production parameters incorporated into the evaluation of housing systems and practices.