DVM, Staff Veterinarian, University of Pennsylvania School of Veterinary Medicine, New Bolton Center Poultry, Laboratory, PA, U.S.A
The term "disease" according to the online Merriam-Webster Dictionary means “a condition of the living animal or plant body or of one of its parts that impairs normal functioning and is typically manifested by distinguishing signs and symptoms”. Egg production veterinarians are called on to diagnose “disease” problems of all sorts; high mortality, low egg production, poor body weight gains, excessive egg shell breakage, lame birds, etc. Most of us think of only infectious agents as causing diseases. The reality is that a majority of disease problems are caused by mis-management. In this presentation, management-related diseases seen in pullet and layer flocks will be reported that egg producers need to be aware of and avoid.
Management is defined by Merriam-Webster as “the act or art of managing: the conducting or supervising of something (as a business)”. In the case of pullets and layers, it means the application of feeding, lighting, watering, ventilating, beak trimming, vaccinating, medicating, monitoring, catching, moving, etc.
There are several management factors that enter into the problem of cannibalism (vent trauma and peckouts). Beak trimming is likely the most important factor involved. Poor beak trimming, leaving longer than normal beaks, give the birds a tool to use to show aggression against their penmates. Layers of certain strains or pullets to be placed into high light intensity situations need a more severe beak trim than pullets placed into light-controlled facilities.
This is a real challenge with the requirements for beak trimming no later than 10 days. To achieve a beak that is between 4 and 6 mm from the nostril to the end of the beak as a mature layer, the beak needs to be trimmed 1 mm (1 dime’s width) from then nostril and cauterized 2 to 2.5 seconds with a relatively cool (dark cherry red, approximately 600 – 650C), sharp blade. In some cases, 10 day beak trimming has resulted in over 2 % mortality per week in brown-egg, organic layer flocks housed in curtain-sided houses. As this is not satisfactory, the grower may opt to beak trim at 7 to 8 weeks of age but will lose audit points or fail to satisfy organic standards for beak trimming after 10 days.
The use of higher light intensity lights than necessary has lead to increased cannibalism, feather pulling, and nervous behaviour (hysteria). The high light intensity allows flockmates to visualize the everted oviduct during oviposition and pecking occurs. Also, allowing outside light to flood the houses unimpeded through windows or curtains has lead to peckout mortality. In cage-free housing, a change in nest usage and increased competition for nest space can occur due to birds avoiding highly lit nests. Using the appropriate wattage light and spacing aids greatly in reducing cannibalism. The use of light screens over curtain or window openings will greatly help in those type houses.
Space allotments can play a role in the incidence and severity of cannibalism. Not giving enough floor, nest, water, or feeder space has been found to lead to nervous flocks and flockmates that are aggressive. Recent investigations of peckouts in cage-free flocks placed in former broiler breeder houses showed that the nest space given was too little for egg-type birds and peckout mortality became a problem.
A past case of coccidiosis in 17-day-old pullets brings to light the importance of maintaining normal humidity and ventilation during growing to minimize the relative number of sporulated oocysts. A Cocci-Vac vaccinated flock of caged pullets was poorly ventilated during a recent winter growout allowing the cage papers, which were left in the cages longer than usual to 14 days of age to allow better cycling of the vaccinal organisms, to become wetter than normal. This allowed an increase in the normal number of sporulated oocysts and 5 % of the chicks were lost to cecal coccidiosis. Proper ventilation resulting in humidity levels of 40 to 60 % should be maintained. Removing cage papers at the normal 10 days and adding paper or plastic plates in flocks that have been vaccinated with coccidial vaccine will reduce this sort of problem.
The mis-management of chain feeding systems in cage houses has led to past problems with calcium depletion and soft bones of layers especially on the return-side of the system. Not running the feeder long enough to fully make a cycle around the tier has been one problem. A second problem is using a slow speed chain feeder allowing the feed-side birds a chance to pick out and eat the large particle calcium as the feeder runs shorting the return-side birds this important ingredient. Lowered egg production due to lower body weights of the return-side birds has also been an issue.
The management of age when pullets are moved to the layer house can affect the incidence and severity of E. coli related problems. The later pullets are moved to the layer house, especially a multi-age complex, the greater the problem related to the amount of time the birds have to mount an immune response to the disease agents present on the layer farm before the birds begin placing all their energy into egg production. The ideal is to move pullets at least 1 week prior to first eggs to allow them to become immune to the resident flora while not in production.
Some producers backfill older layers into flocks just prior to molt to fill cages left less than full due to mortality during the first cycle. This management practice leads to increased E. coli problems due to stress of introducing a new member to the cage and introduces a different viral and bacteria flora. In addition, these older birds immune systems are not as capable of resisting bacterial disease thus increasing the exposure of the other cage-mates.
Lack of good water quality management has led to very severe losses due to Colibacillosis. Using known contaminated water sources leads to more E. coli infections. A producer with contaminated wells prevented problems by adding iodine disinfectant to the water. When a worker filled an empty iodine disinfectant barrel with water and this barrel was used as if it was fully potent disinfectant, a loss of 6 % of the young layer flock ensued in two weeks.
A case of hysteric pullets that led to gangrenous dermatitis due to Staphylococcus spp. and Clostridia spp. bacteria infections of the scratch wounds was caused by manure scrapers under the cages that were running too fast. These fast-moving scrapers would excite the birds every time they ran. A different gear was used to slow the scrapers and the problem ceased to occur.
Ammonia induced corneal ulcers
Numerous cases of ammonia induced corneal ulcers have occurred due to mis-management of the ventilation system in winter resulting in high humidity levels, increased manure or litter moisture, and increased ammonia emission.
One particular case occurred not due to lack of fan running time but due to not monitoring conditions in the house. The ammonia and humidity could not be removed by the ventilation system due to poorly constructed fan housing of the fans in the front third of a pullet house. The housing allowed air to enter around the perimeter of the housing thus bypassing the normal air inlets and not ventilate the house properly.
Low egg production
Poor peaks in egg production are a common complaint investigated by the veterinarian. The major problem found involved is poor quality pullets. A recent investigation of low egg production was made where a flock only peaked at 78 % and was 3 weeks late in coming into production. The owner sent the breeder representative and several other veterinarians to find what sort of disease agent was affecting the flock. When the producer was asked about the history of pullet growing, no records of body weights or vaccinations were forwarded indicating there was likely no monitoring done. These birds were found to be 0.3 lbs. lower than target at housing. No infectious disease agent problems here!
Surprisingly, this is not an uncommon finding even in today’s egg industry. This verification step is all-important to know if the nutrition and management program is yielding the results expected. Finding low body weight pullets at 18 weeks of age is not the time to start fixing the problem.
Interventions available to the grower when pullets are found to be underweight are as follows:
1) adding probiotics, botanicals, antibiotics, or extra fat every other week to the feed,
2) making adjustments in house temperatures, feeding times, light intensity,
3) adding extra vitamins to the water, or
4) feeding a higher nutrient dense feed.
Paying attention to basic details of management will help avoid many disease related problems. Keep FLAWS (Feed-Lights-Air-Water-Space) and other management related practices in mind when servicing and trouble-shooting flocks. Use monitoring programs for egg production, egg weights, body weights, feed consumption, etc. to act accordingly and use the tools available to improve results.
From Proceedings of the “Midwest Poultry Federation Convention”, St. Paul, Minnesota, U.S.A.