Managing Turkeys for Optimum Health and Performance04 June 2014
As pressure increases to reduce further antibiotic use in animal production, we need to come up with smarter ways to prevent and control diseases. Editor, Jackie Linden, reports on some of the work to come up with effective alternative solutions from a recent turkey conference.
Aims of the 8th Turkey Science and Production Conference, which took place near the UK city of Chester earlier this year, were for delegates to meet each other, do business and learn to compete with the other meat industries, according to organiser, Dr James Bentley.
Several of the papers presented at the Conference offered an overview of some of the more innovative means of improving the health and productivity of commercial turkeys by examining more closely various aspects of management and feeding with the view to disease prevention without resorting to antibiotics unnecessarily.
Turkey Management Requires Attention to Detail
Every time we observe a turkey flock – even one that appears healthy – we must consider the possibility that subclinical disease may be present. That was the main message from Helen Wojcinski of Hybrid Turkeys in her presentation aptly entitled ‘Management and multiple disease challenges: When worlds collide’.
She stressed the need to look carefully for clinical signs or actively measure bodyweights, flock uniformity, feed and water consumption as well as air and water quality. If not, mortality may occur or flock performance will drop below standard and when that happens, it is already too late.
Subclinical disease or underlying environmental challenges will allow disease agents to become additive and the consequences on performance and mortality to become magnified, said Dr Wojcinski.
The presence of multiple pathogens can be particularly challenging to the health of the birds. Citing research work from Virginia Tech University in the US, she showed that infections with E. coli alone caused just four per cent mortality and pericarditis in growing turkeys but this increased significantly if the birds had been previously exposed to Newcastle disease virus, Bordetella avium and/or haemorrhagic enteritis virus,
Consideration of these dynamics must be taken into consideration in the management of our turkey flocks, Dr Wojcinski added, especially when we introduce stressful events into a flock such as vaccine administration or flock movement.
Roslin Research Increases Understanding about Foot Pad Dermatitis
Reviewing the research on foot pad dermatitis (FPD) in turkeys, Dr Paul Hocking of the Roslin Institute and Royal (Dick) School of Veterinary Studies at the University of Edinburgh confirmed that FPD is mainly a consequence of wet litter, whatever its cause. Experiments indicate that the moisture content of the litter should be below 30 per cent. Excessive drinking behaviour, high dietary potassium and gut infections can all result in wet litter.
When the litter is very wet – up to 70 per cent moisture – all breeds and types of turkey become affected by FPD but there is considerable individual variation in the incidence of the condition, he found.
Dr Hocking added that the evidence points to FPD lesions being painful to the birds – and therefore a welfare issue – as well as reducing performance.
These two factors offer are a strong argument for identifying and investing in methods to reduce the prevalence of FPD in commercial turkey flocks, he concluded.
Turkey Foot Pad Health – Management via the Gut
Managing a healthy and balanced microflora in the intestinal tract is a pre-requisite for optimal health and performance of all poultry, said Dr Sven Keller, and supplementing their diets can be a useful strategy.
Dr Keller, Technical Service Manager with Novus Deutschland, stressed that the site in the gastrointestinal tract where these antibacterial feed additives become active is crucially important to their efficacy.
Manufacturing technology can ensure that the active substances are released gradually, down to the lower gut, he said, and he showed the results from trials in which the addition of 500g per tonne of a blend of aromatic compounds including benzoic acid (Avimatrix, Novus) modified the gut microflora and improved final weight, feed efficiency and foot pad health.
Dietary Electrolytes Impact Turkey Health and Performance
Dr Sally Noll outlined her work at the University of Minnesota on the effects of alternative feed ingredients on dietary electrolyte balance (DEB) in market turkeys.
Research in the 1970s and 1980s brought awareness of the importance of DEB in poultry in terms of the birds’ health and performance but since that time, feed formulations have changed to include distillers dried grains (DDGS) and canola meal and feed enzymes such as phytase are routinely used nowadays.
From her work, Dr Noll concludes that electrolytes and DEB continue to affect bird performance and litter conditions; chloride levels above 0.3 per cent increased litter moisture and bodyweights were adversely affected in older turkeys Canola meal and DDGS both increased the overall chloride level in the feed.
Phytase modified the response in feed conversion, she found in her research.
Canola meal and DDGS also contain more sulphur than other feed ingredients and including this nutrient in the DEB calculation better predicted the correlation with performance.
Feed additives such as phytase need to be considered for their effects on DEB as mineral relationships are better understood, Dr Noll concluded.
Further Benefits of Phytase Explored
Rob ten Doeschate of AB Vista presented research results that suggest the destruction of phytate by dosing high levels of an appropriate phytase in turkey feeds may offer some additional benefits beyond the already well-established impacts on phosphorus availability.
There are few published studies on the effects of phytase at higher-than-normal levels of inclusion on turkeys. However, he described three studies that show at least numerical improvements in feed conversion efficiency and/or weight gain of growing turkeys fed these so-called “superdosing” levels of phytase, two of them using Quantum Blue (AB Vista).
While further trial work is needed to confirm these results in the field, Dr ten Doeschate concluded that the evidence is growing for the non-phosphoric benefits of superdosing phytase and that the mechanisms for these effects are becoming ever clearer.
Tackling Pathogens With Fewer Antibiotics
Antibiotics are still regularly used in the early rearing stages for turkeys, according to Biomin’s Poultry Technical Manager, Andrew Roberton, to protect the birds against both respiratory and gastrointestinal diseases.
He explained that acids can reduce antibiotic use for digestive problems by maintaining a healthier gut and reducing diarrhoea. Particularly interesting is the possibility of preventing the translocation of bacteria from the intestine to other organs.
Organic acids are already quite widely used, he added, but the newer enhanced acids can have positive effects on the battle against pathogens in the early stages of turkey production. The inclusion of permeabilising substances to these acid products allows a reduction in the inclusion rate of the organic acids, freeing up space in the diet, which is already very concentrated.
Blackhead Control Remains a Challenge
The factors that make blackhead (histomonosis) such a challenge to control in turkey flocks were explained by Dr Jeroen De Gussem of Poulvac in Belgium. Without control, morbidity and mortality can be up to 100 per cent.
In earlier times, effective treatments were available and widely used to control the disease and its cause, the protozoon, Histomonas meleagridis. However, the products that were effective for both prevention and treatment have been withdrawn from use in Europe and other regions due to human health risks.
As Dr De Gussem explained, the search for alternatives has been fraught with difficulties. Strict biosecurity at the farm can help keep the pathogen out of the turkey house but once there, it spreads rapidly between the birds on the workers, rodents and insects and as the result of cloacal drinking. The protozoan forms a cyst during adverse conditions that can survive for long periods.
Opportunities for histomonosis control exist in the form of physical barriers, drugs and vaccines, he continued, but each has its limitations.
A promising strategy is to get the turkey to produce antibodies to the pathogen in advance of infection and Dr Hess in Austria has shown the concept can work in vitro using an attenuated strain.
Dr De Gussem developed this work, successfully achieving 100 per cent protection in turkeys but the vaccine had to be inoculated intracloacally and there is always the risk of attenuated forms reverting to pathogenicity.
More recently, Dr Hess has has further success using the cysts to induce protection in a similar way to coccidiosis vaccines in chickens.
Hepatic Lipidosis in Turkeys and Its Control
First described in turkeys in 1994, hepatic lipidosis (HL) has been affecting turkey breeders since the mid-80s, according to Cuddy Farms’ Dr Peter Gazdzinski. It has been reported in meat-type hens and toms but most affected are turkey breeder hens between 12 and 25 week of age and it can affect all breeds.
Mortality usually appears suddenly and may reach between one and 15 per cent over a 10-day period, after which no further signs may be seen and egg production is normal.
Dr Gazdzinski reported that the incidence of HL increased suddenly in 2008 and 2009. No virus could be isolated from affected birds.
However, serological tests showed antibodies to avian encephalomyelitis (AE) virus already in turkeys as young as five weeks of age. The farms brought forward their usual AE vaccination programme in the drinking water from 22 or 23 weeks to 11 weeks, with a second vaccination at 24 weeks in combination with fowl pox by wing web.
Not a single case of HL has been observed in the flocks since.
Dr Gazdzinski suggested that HL in turkeys may have a complex aetiology in turkeys, involving both viral and metabolic causes.