Zulkifli Idrus on Poultry Welfare

Conversations with Clive: #5
October 25, 2023

Zulkifli Idrus is Professor and Former Director of Institute of Tropical Agriculture and Food Security at Universiti Putra Malaysia.

In August 2023, Prof. Zulkifli Idrus talked to Clive Phillips for the Conversation with Clive series. In this series, leading farm animal welfare scientists and academic experts share with Clive Phillips their thoughts and experience of farm animal welfare issues, including those related to intensive animal farming systems.

Timing of key topics discussed in the 40 minute conversation:

  • 00:50 Clive introduces Zulkifli Idrus
  • 03:50 The wild Red Junglefowl. [Note: They are the antecedents of all modern domestic chicken breeds, initially domesticated around 8000 years ago. This long period of domestication and artificial selection has lead to substantial changes in the physiology and behavior of modern domestic breeds. Comparative research by Zulkifli’s group has determined that Red Junglefowl are considerably different to that of their modern commercial chicken counterparts, including exhibiting a greater degree of fearfulness, as determined by a "tonic immobility" test.]
  • 05:30 Biggest welfare problems for the modern meat (broiler) chicken.
  • 05:55 Rapid growth rates have negative effects on developing skeletons, including leg injuries.
  • 06:25 Cardiovascular problems and susceptibility to sudden-death syndrome related to heart failure.
  • 06:55 Skin problems (contact dermatitis) from inactive birds resulting in Breast blisters, foot-pad dermatitis, hock burn from prolonged contact with wet, soiled litter.
  • 07:20 Feed restriction - methods used to reduce chicken’s access to weight-promoting feed stock.
  • 07:50 Potential for leg and wing injuries during harvesting (collecting the birds for transport to slaughter).
  • 08:25 Industry staff have to be aware that these birds are prone to bone fractures and joint dislocations.
  • 08:45 Physical catching and transportation of meat chickens is a major welfare consideration.
  • 09:25 Biggest welfare challenge in Malaysia and tropical countries is heat stress, particularly during transport.
  • 09:50 Nutrition has a big impact on the ability of meat chickens to tolerate high temperature.
  • 10:00 Showering crated chickens with water just prior transportation (using a misting system) is found to reduce the physiological stress response caused by transportation.
  • 10:30 Supplements such as probiotics and prebiotics can be very beneficial in reducing stress of transportation.
  • 11:00 Gut-brain axis - gut microbiota changes due to environmental stressors can negatively impact the physiological systems (i.e., health) of the bird. Protecting the gut microbiota (otherwise known as the "gut microbiome") has protective effects for chicken’s tolerance to stressful events.
  • 11:45 Supplements such as probiotics and prebiotics have been found to positively influence the general behavior of meat chickens.
  • 12:00 Probiotics have also been found to be beneficial for ducks subjected to crating stress (being contained in boxes for transportation).
  • 12:15 Use of antibiotics in domestic poultry may adversely affect the gut microbiome, in addition to untoward effects in increasing antibiotic resistance in human disease conditions.
  • 12:35 Future challenges with climate change and increasing temperatures.
  • 12:55 Recent "hot spell" of several months has significantly impacted Malaysian commercial poultry farming due to heat.
  • 13:10 Many Malaysian farmers still raising birds in naturally-ventilated housing systems [rely in ambient breezes from the environment to cool the birds] rather than modern, mechanically-ventilated systems [using fans and insulation to prevent birds overheating], and thus heat stress is still a major problem nationally.
  • 13:25 Malaysian poultry are transported only at late evening to reduce effects of heat stress in birds.
  • 13:40 Heat stress is also considered in transporting live poultry for long durations, such as internationally (to neighboring Singapore).
  • 14:05 Ambient heat is different in different zones within the truck transporting live poultry. Birds further away from loading doors are more likely to suffer from heat stress.
  • 14:40 No current regulations on live poultry transport in hotter times of the year. Reliance on industry standards and self-regulation to ensure minimal bird deaths during transport, in Malaysia.
  • 15:05 Lairage occurs for 1-2 hours before slaughter in Malaysia, and relies on good environmental conditions (ventilation, sprinkler system) to reduce heat stress and the incidence of death in the bird.
  • 15:30 From the grow-out farms, Malaysian poultry generally are transported, sorted and processed at a plant within 4-5 hours.
  • 16:00 Early research work conducted in familiarizing birds with catching, handling and crating early in life did not find this significantly reduced stress effects with later crating and transportation at market age, compared to birds without the early crating experience. Duration of transportation appears to be the main stressor effect overall, associated with rising corticosterone and incidence of fear responses.
  • 17:00 Stocking density in meat chickens is not regulated in Malaysia due to wide-ranging climatic and housing conditions as well as breed differences. However, less than 30kg/m2 is recommended in modern, mechanically-ventilated housing systems.
  • 18:15 High stocking density directly affects the chickens’ litter quality - and more contact dermatitis problems (skin lesions caused by sustained contact with an irritant). In the hot, humid conditions of Malaysia, meat chickens (broilers) at higher stocking densities have been found to have better welfare outcomes when raised in cages compared to floor-pens with a litter substrate. This is due to the prevalence of foot-pad contact dermatitis in the latter group. These observations contrast with studies conducted in non-tropical, temperate environments, where caged chickens have poorer welfare outcomes. Heat-stressed chickens tend to drink more than non-stressed birds, and this leads to more moisture in faeces and poorer litter conditions leading directly to higher incidence and severity of contact dermatitis.
  • 19:40 Counts of pathogenic bacteria in the gastrointestinal systems of chickens are also found to be lower in caged birds, compared with chickens raised in floor-pens with a litter substrate. However, counts of the pathogenic species of bacteria Salmonella - is found to be comparatively lower in floor-penned chickens. This is thought due to the ingestion of wood shavings in the litter that contain substances such as tannins that have a protective role against Salmonella overpopulation in the gut.
  • 21:00 Welfare of layer chickens. Cages, barns, aviaries free-range - what gives the best welfare outcomes, including the reduced reliance on nest-building materials?
  • 22:10 Are nests necessary for modern specialist egg-laying breeds of chickens? [Note: According to Hemsworth paper (animal welfare group at the University of Melbourne) of caged laying hens with and without nesting material did not have significant differences in corticosterone, a hormone produced in response to stress.]
  • 22:55 Different breeds (e.g., all-purpose, meat and egg-laying village fowl and modern egg-laying chickens) are likely to have different behavioral requirements, although the unavailability of nesting material does not appear to significantly affect the modern egg-laying chicken’s physiology or stress levels, though more research is needed.
  • 24:30 Corticosterone measurements taken from eggs have questionable validity for indicating the stress experienced by the hen. [Note: Caulfield, M.P.; Padula, "M.P. HPLC MS-MS Analysis Shows Measurement of Corticosterone in Egg Albumen Is Not a Valid Indicator of Chicken Welfare." Animals 2020, 10, 821.]
  • 25:25 Free-range systems for commercial egg-laying breeds are not found to be suitable in hot and humid conditions such as that found in Malaysia, with birds found to do best in closed and controlled housing systems.
  • 26:00 Exposure to parasites in free-range system presents a risk to welfare.
  • 26:25 Feather-pecking and cannibalism occur generally more frequently in free-range hens, however there appears to be wider variation in quality of welfare in free-range systems overall, compared with caged, mechanically-ventilated production systems.
  • 27:00 Strengths and weaknesses to consider when contrasting free-range and fully-caged systems for egg-laying chickens. While free-range systems permit bird’s expression of a natural behavioral repertoire, caged systems provided better welfare outcomes in terms of hygiene and health (e.g., slower parasite burden risk, better infection control, minimal predation opportunities of behavior).
  • 28:10 Cost-benefit analysis considerations are central considerations. These include the costs of rearing chickens at locations presenting challenging climatic conditions, and consumer awareness and willingness to pay for premium product affording better welfare outcomes.
  • 28:50 "Designer eggs" [high Omega-3, lower cholesterol content] sell well in Malaysia, however consumer choices based on welfare qualities posed by the different rearing systems is still not as important a consideration, as there is comparatively little awareness of this issue in that market.
  • 30:00 Important role still required by welfare researchers and the relevant agencies to keep consumers informed about animal welfare considerations with their purchases.
  • 30:15 Future possibilities to reduce animal welfare costs, such as potential presented by synthetic egg products produced without animal protein - "vegan eggs" - still not valued by Malaysian consumers.
  • 31:05 The killing of surplus male chicks in the egg-laying production systems is an important ethical consideration in Europe and other nations, but not as important in Malaysia at this current time. However, early sexing methods such as non-invasive CRISPR analysis show promise for identifying the sex of early-stage embryos, that may then assist with the selection of eggs to be developed into viable female chicks.
  • 32:30 Alternative housing systems - barn and aviary systems - are not currently used in Malaysia.
  • 33:05 Coccidiosis and lighting are problematic in free-range layer chicken systems designed to maximize opportunity to engage in natural behavioral repertoire.
  • 33:15 Low lighting intensities may predispose chickens to injuries as they may misjudge attempts to reach elevated perches.
  • 33:55 Blue and Green lighting have been found to calm chickens, whereas red lighting has been found to be linked with increased cannibalism and feather-pecking behavior, although it can reduce lameness by increasing activity.
  • 35:35 Beak-trimming methods to control social aggression (feather-pecking and cannibalism) have moved from traditional mechanical "hot blade" to a highly focused beam of infra-red lighting to remove the sensitive tip of the beak, with less pain to the chick.
  • 36:10 Other poultry - duck welfare requirements and water use in semi-intensive systems for layer ducks, where ducks have regular access to water for swimming. Meat (broiler) ducks are raised for 42-49 days in intensive systems without access to water for swimming. Integration of ducks in paddy fields is not practiced in Malaysia any more although it is common practice in other countries such as Bangladesh and Madagascar. Turkeys require artificial insemination as selective breeding for size precludes natural mating, and are not commonly bred in tropical region.
  • 39:10 Closing remarks on the importance of using local data to focus appropriate strategies to improve welfare quality in poultry.
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