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Animal welfare is a crucial factor for every poultry producing company.
Namely, retailers, consumers, animal protection organizations and government officials in numerous countries are increasingly focusing their attention on broiler welfare.
Those times when we were just concerned with the provision of food, water and basic care for our animals, as the main components of animal welfare are long gone…
Today, the worldwide debate about broiler chicken welfare also includes an analysis of mortality and culling rates – Can this involve second grades or confiscation to euthanize?-, stocking density in the shed, lighting, footpad dermatitis (contact dermatitis) and feather condition, air quality, litter quality, level of lameness, lesion prevalence, and behavior.
The OIE – World Organization for Animal Health -, even has a chapter named “Animal welfare and broiler chicken production system, which includes the aforementioned topics as a global reference standard for the welfare of broiler chickens.
While all these groups – companies, retailers, animal protectionists and governments – are engaged in improving the outcome of broiler chicken welfare, their views often differ as to the manner in which such animal welfare results should be assessed and measured.
There is one aspect, however, on which all these groups agree, and it involves the importance of the assessment and prevention of footpad dermatitis -pododermatitis- in broiler chickens. This inflammatory process not only translates into an animal welfare issue, but also leads to financial consequences at the farm, since it raises the mortality rate and the feed conversion ratio, and it also lowers the quality of the final product, which generates a consequent concern in the slaughterhouse, because it is impossible to sell chicken paws having serious lesions.
matitis, and in principle, pododermatitis in broiler chickens is a consequence of a long-term contact of the footpad skin with a soaked or wet litter (poor conditions). Initially, black scabs, inflammation of the footpad surface and fingers are seen, potentially progressing to hyperkeratosis – a thickening of the plantar surface and to the development of plantar ulcerous lesions.
What is pododermatitis?
It is a contact dermatitis, and in principle, pododermatitis in broiler chickens is a consequence of a long-term contact of the footpad skin with a soaked or wet litter (poor conditions). Initially, black scabs, inflammation of the footpad surface and fingers are seen, potentially progressing to hyperkeratosis – a thickening of the plantar surface and to the development of plantar ulcerous lesions.
Ultimately, unless it is controlled, grave pododermatitis can result indiscomfort, lameness, reduction of the feed conversion ratio, and increase of secondary bacterial infections in chickens.
The occurrence of pododermatitis in chickens has caused many animal welfare audits of broilers to include an assessment of paws in slaughterhouses as a tool to measure the animal welfare in the flock from day one until slaughtering age.
There are differences when assessing and measuring animal welfare results, but not every group agrees on how to prevent footpad dermatitis
Both university research studies and global reports on broiler chicken husbandry agree on the multifactorial origin of footpad dermatitis or pododermatitis.
Many of such multifactorial causes are related to the presence of wet litter. For poultry farmers and veterinarian doctors working in broiler chicken farms, the challenge is to determine the cause in an attempt to improve wet litter situations and avoid future recurrences.
There is no doubt that wet litter control is easier in dryer climates and during periods when ventilation is greater inside the stocking sheds, due to high outdoor temperatures.
In addition, in the development of footpad dermatitis, there is a set of factors which interact to generate wet litters, such as::
However, apart from genetics, regions or chicken farm management, various factors can be involved as possible causes. Chicken farmers and vets can find a variation in the incidence and severity of pododermatitis within one chicken shed and in one broiler chicken farm.
The various causes for wet litter in broiler chickens must be evaluated by investigating either a farm where wet litters are found or a flock showing a pododermatitis issue.
From the day they arrive at the shed until the day they are caught to be slaughtered, most broilers spend their life on foot or sitting on the litter material. Therefore, the litter must be comfortable and it must also absorb the moisture in the environment (chicken manure, drinking water…).
Several research studies have shown that straw is not a good litter material due to its low absorption rate.
Whenever possible, poultry farmers consider wood shavings to be an ideal litter material, due to its greater moisture absorption, and because it is easy to disaggregate (either by using tools or by the birds’ scratching).
It has been shown that the depth of the litter can be related to the incidence and severity of footpad dermatitis in broiler chickens.
Some poultry farmers start their flocks on deep litters (> 10 cm deep) to guarantee a Good isolating barrier between chicks and the ground, and in order to provide a thicker layer of absorption material as the flock grows.
Other poultry farmers may start with less litter material and then add some more to wet spots, as the flock grows.
Both methods can work if managed correctly.
Keeping the upper layer as dry as possible is the most important factor for the prevention of pododermatitis
Both drinker systems and water quality in the farm can have a direct impact on litter moisture.
Water spillage or waste can result in a probable onset of pododermatitis in the flock or lot of broiler chickens. Therefore, we must control those specifics in order to avoid paw issues.
Fresh, good quality water is important for chicken welfare. Flushing and maintenance of water lines are essential to avoid the formation of a biolayer (biofilm) and the buildup of materials that can be harmful to the drinker, and thus result in water leaks.
Companies should carry out drinker line maintenance and cleaning procedures between flocks or lots in order to avoid wet litter in a proactive manner
Various studies performed by several universities have shown that the type of drinker used for broilers can affect the waste and spillage of water, and thus the level of moisture in the litter material.
The height and flow rate of the drinker are key factors for animal welfare in every flock or lot of broiler chickens.
The height of the drinker must increase as birds grow. If drinkers are too low, the birds Will probably waste water when drinking and that will result in a wet litter close to the drinker line. On the other hand, if drinkers are too high, it will be difficult for the birds to get enough water.
If the pressure in the drinker is too high, this will also result in an increase of water spillage and thus, in wet litter.
If the pressure in the drinker is too low, the birds will not be able to drink enough water and this will result in both welfare and economic issues for that lot or flock.
Drinker maintenance is one of the most critical elements for the prevention and management of wet litter. During the daily inspections of the flock, the farm staff should assess drinkers in order to verify the presence of leaks, and in case they are found, repair them as necessary to avoid potentially deleterious water leaks.
Both the height and water pressure of the drinkers must be appropriate to the age of the chickens to avoid water spillage
Genetic companies recommend certain specific nutritional standards for more profitable broiler diets, and they also contemplate nutritional needs of the chicken as it grows and develops. However, the quality of the ingredients, the formulation being used and the actual feeding schedule will influence the development of wet litter conditions, which is an undesirable outcome, when the feed helps create excessive moisture in the manure produced by the animals.
The quality of the ingredients being used is not only important for growth, development and health of broiler chickens, but it also affects water consumption and the hardness of manure.
All vegetarian diets and diets containing anticoccidial products can result in moist droppings.
On the other hand, a frequent change of the ingredients being used in broiler chicken feed can influence bacterial populations within the intestinal tract, thus having an adverse effect on fecal consistency.
Formulation mistakes which bring about a high salt (sodium or potassium) content can result in an increase of water consumption, and therefore an increase of the wet litter condition.
Similarly, high density and high raw protein content feed above recommended levels for the age or lineage of the broilers can result in wet bed issues.
This is due to an increase of uric acid excretion, an increase of water consumption and a high level or ammonia in the environment.
All of these circumstances for a long or significant period of time can promote the onset of footpad dermatitis issues in broiler chickens.
A frequent change of ingredients can influence bacterial populations in the intestinal tract.
The ventilation system is vital for broiler chicken welfare. The purpose of ventilation is controlling the temperature for an optimum comfort of the fowls, letting fresh air in and exhausting gases (ammonia, carbon dioxide, and so no), and removing moisture and dust from the broiler chicken shed.
Ventilation is important 24 hours a day, 7 days a week.
An automatic control ventilation system is recommended, because it can be adjusted in a fast and efficient manner, based on temperature and humidity sensors.
Even during cold periods or in winter, ventilation must strike a balance between the maintenance of an ambient temperature in the farm and the removal of ammonia and moisture, since any disturbance in the levels of such elements can cause an onset of pododermatitis.
During such periods, minimum ventilation systems are important to strike such balance between welfare and temperature control, and for the prevention of pododermatitis.
The size and type of fan must conform to the air inlets and the size of the shed.
As mentioned above, minimum ventilation and tunnel ventilation systems should be interconnected for an efficacious control of ventilation at all times.
Modern sheds also have ceiling fans. Such fans are very useful to mix the warm air with naturally builds up on the ceiling with the colder air inside the shed, and therefore they are very effective to help keep the litter dry and thus to save energy.
The temperature inside a broiler chicken shed can come from the fowls themselves, from solar radiation or from supplementary heaters.
As broiler chickens grow, they generate a higher level of metabolic heat.
Ventilation is necessary to assure that heat derived from the chickens, combined with the ambient heat within the house or shed is not excessive.
In order to achieve an ideal performance and welfare, broiler chickens must stay within their thermally neutral area or comfort zone at all times.
Moisture in broiler chicken sheds can come from
Normal relative humidity levels within the shed must range from 50% to 70%, but they must be determined based on the temperature.
While farm hands frequently measure air humidity, it is essential for the prevention and control of pododermatitis or footpad dermatitis that they also measure litter moisture.
Most production guidelines recommend a litter moisture of < 30 %.
Litter moisture can be easily assessed by picking a handful of it and squeezing it you’re your hands. Upon opening the hand, if the litter material falls freely it probably means that its moisture is lower than 30%. However, if it remains caked, that indicates that the level of moisture in the litter is too high.
Avian diseases which case gastrointestinal, liver or kidney disorders will bring about changes in the fecal consistency of the broilers.
The most frequent diseases that need to be controlled by veterinarians considering wet litter challenges are: coccidiosis, infectious bronchitis (nephropathogenic strains), malabsorption or dysbacteriosis and colibacillosis syndrome.
The distribution of light inside the shed, as well as on the lot or flock must be uniform to avoid pododermatitis
From the time chicks arrive at the shed until slaughtering age, specific lighting schedules are used to promote the chickens’ activity and growth.
In order to equate growth rates to fowl behavior, genetic selection companies recommend having darkness periods, such that chickens have time to rest. These darkness periods have a duration of at least 4 hours per day and they can be provided either in one time block or in shorter blocks along the day.
Research studies have shown that intermittent lighting programs are beneficial to reduce pododermatitis, due to a greater activity of the fowls.
In addition to the lighting Schedule, it is essential to have a proper distribution of the light to promote an even distribution of the flock inside the shed.
When the light is unevenly distributed within the shed, there may be areas of correspondingly wetter litter due to a greater concentration of the birds in certain areas.
This is particularly difficult to control in broiler sheds using curtains for ventilation or illuminated by the natural light through windows, since the increase of sunlight intensity can promote a migration of the fowls and an irregular distribution of the flock.
In some countries, stocking density is regulated by governments or by industry standards. Most broiler producing companies have instituted guidelines for the establishment of stocking density of broilers in sheds.
This stocking density within the sheds can be expressed as kilograms per square meter and it is based on the expected weight of broiler chickens at the slaughtering age.
In addition to a low stocking density, the distribution of feeders and drinker systems along the shed can be deemed as an essential measure for the prevention of pododermatitis.
If the stocking density of broilers is too high in the shed, or if the stocking density is high around the feeder or drinker lines, this will cause a greater pressure on the ventilation system capacity to remove moisture.
If we do not keep all these factors in mind regarding the distribution of feeder and drinker equipment and the stocking density in the shed, the litter can become wet, thus increasing the risk of a pododermatitis onset.
Pododermatitis is a highly important aspect in the world production of broiler chickens. However, if we pay particular attention to the aforementioned factors, it is to be expected that we may prevent it and control it in future broiler chicken flocks.
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