Proper litter management ranks close to air, water, feed and health care as essential elements in a profitable turkey enterprise. While the main concern of a good litter management program used to be centered on consideration of bird health, environmental concerns now dictate that the generation of dust and odour also be addressed. Thus, type of litter material and the addition of products intended to increase the value and environmental friendliness of the final product should be taken into account. The increased emphasis on organic and environmental friendly fertilizers places a different emphasis on the use and value of turkey litter. Thus any litter management program which reduces the amount of ammonia or dust is the avenue to pursue.

The summer months are usually relatively free from litter problems, however, with winter conditions and thus less air being moved through the house, ammonia fumes can be a problem. The question is often asked as to what is the proper litter moisture level to strive for? While optimum litter moisture level may vary with type of litter material used and season of the year, it is suggested that a level of around 30% moisture should be ideal. Such a moisture level is too dry for fly production and too moist for dust. Litter with a moisture level of 40%, or greater, is at the point where a fly problem could result, depending on pen temperature. Also at this level of moisture pen odours can start to be encountered. Litter below 20% moisture, while not conductive to fly or odour production, is right for dust production and thus the danger of Aspergillus problems occurring.

It is difficult to maintain a uniform litter moisture level in a pen as wet spots can occur near waterers and dry conditions in areas with less bird traffic. However, litter management practices should ensure that such conditions are addressed at times of the year when they are most likely to occur as litter condition can have a significant effect on pen environment and thus the health and well-being of the birds as well as the attendants.

There are products available that are reported to reduce pen moisture levels. An example of such a product is the antibiotic virginiamycin. In a test report (Turkey World, Dec. 1992) wood shavings, which usually contain between 20 to 24% moisture, were analyzed for moisture every two weeks until the birds were 16 weeks of age. By two weeks of age litter moisture had dropped to around 9%, due to initial normal drying. As the birds grew, litter moisture levels increased more rapidly for the controls than those birds fed virginiamycin. At 16 weeks litter moisture for the control birds was 53% versus 42% for those fed the antibiotic.

Wet litter conditions lead to increased ammonia levels in a pen which in turn can have a negative effect on performance. There are products available that have been reported to reduce gut ammonia levels and thus have a favourable effect on bird health. Such products, referred to as urease inhibitors, contain extracts from the Yucca plant and they are reported to inhibit the production of ammonia by bacteria in the intestinal tract.

In a recent report (Anthony et al 1994) some interesting litter conditions were reported with chicken broilers reared to 6 weeks of age. Rice hulls were used as litter and had an initial moisture content of 6% and a pH value of close to 7 (neutral). By 4 weeks of age litter moisture had plateaued at 35%. Litter pH had also increased and plateaued close to pH 9 at a similar age. Pen CO₂ and O₂ levels remained relatively constant over the 6 week test period while NH₃ levels, which were almost non detectable to two weeks of age, rose very quickly to levels in excess of 100ppm by 4 weeks of age. Supplementing the diet with a urease inhibitor significantly increased pen ammonia levels while at the same time reducing cumulative mortality due to ascites by almost 50%. Gut ammonia levels were found to be lower for those birds fed the urease inhibitor, thus indicating that a greater percentage of NH3 may be excreted rather than being retained in the gut.

Several recent reports from Japan (Karasawa et al 1994 a, b) have reported that penicillin will reduce anaerobic bacterial counts in the caeca and thus almost completely inhibit ammonia production from urea. Other reports indicate that alum (aluminum sulphate) added to poultry litter, markedly reduce the release of ammonia and tied up phosphorus, so that a significant reduction was noted in water run off from fields fertilized with treated litter.

The above reports are interesting in that they provide evidence which suggests that a significant portion of excreted nitrogen may be able to be converted to more stable end products as compared to ammonia. While several commercial products have been referred to above, they were only mentioned as examples, as there are other products reported to have similar effects on ammonia and nitrogen excretion.

Excessively wet droppings are a concern to many turkey producers, especially during the colder winter months of the year. Pathogens, excess dietary salt or protein, as well as toxins have all been implemented as causative factors. There seems to be no common or accepted causative agent. The problem is usually seen starting around 9 to 10 and continues to around 15 to 16 weeks of age. Part and probably a significant portion of the problem could be the result of birds, especially heavy toms, finding their environment too warm.

The growth rate of turkey has increased markedly during the past decade. As body weight increases so also does metabolic heat production. Metabolic heat production is very important to an animal in a cool environment, as it is utilized to maintain normal body temperature without the expenditure of energy to keep warm (eg. the burning of body fat stores, or the altering of blood flow and the shifting of metabolism to maintain deep body temperature when faced with a cool environment). However, excess metabolic heat is a problem for an animal in a warm environment as it must take corrective measures to get rid of this heat. It can pant, increase peripheral blood flow, etc. in order to dissipate excess heat, functions which all require energy which is then not being used for growth. Or the bird can increase its water consumption as cool water is an excellent heat sink and by passing more water through its body, the bird cools down. However, at the same time it excretes more water.

While the above may sound reasonable one might ask why the wet litter problem is not seen with chicken broilers, since, as reported by Summers (Tech-Info #4) the broiler is growing faster than the turkey to around 5 to 6 weeks of age. While this may be true, the broiler at this age is relatively small as compared to a 9 to 10 week old tom turkey. The smaller the animal the greater the surface area, in relation to body heat production, and thus the easier it is for the animal to get rid of excess body heat (eg. the often used comparison in a physiology class of the humming bird versus the elephant).

Potential daily gain of a turkey reaches a plateau around 12 to 13 weeks of age and then decreases. Thus, metabolic heat production follows a similar pattern. Ferket (1994), using a thermodynamic mathematical model, produced a curve depicting the estimated comfortable environmental temperature for a turkey as a function of age, considering metabolic heat production, (Fig. 1). At 12 weeks of age, when the turkey is growing at its’ maximum genetic potential, it is most comfortable at a temperature of around 50° F.

Many growers keep their pen temperatures in the 60 to 65° F range during the 9 to 16 week period. Hence, the birds may be consuming excess water in order to try and counter excess metabolic heat production at this time. Growers are reluctant to reduce pen temperatures below 60 to 65° F as they argue that feed consumption will increase. This would be true, only if the bird needs the additional feed energy to keep warm. There will be no increase in feed intake by reducing pen temperature, providing the temperature is not reduced below the bird’s thermal neutral range.

Beyond 13 weeks of age, metabolic heat production will be reduced as weight gain slows down. Hence, the birds will be comfortable at a higher environmental temperature. Usually beyond 12 weeks of age dietary protein, as well as calcium levels are reduced. Excess of these nutrients are known to increase water consumption. This, along with a change in metabolic heat production, may account for the change in litter moisture levels usually noted during the last stage of the turkey growth cycle.

The whole area of feeding heavy turkeys is one that should be given serious consideration, not only with a view to reducing feed costs per unit gain and/or per kg of edible protein produced, but also to investigate the possible effect of diet composition on litter quality and hence health of the flock as well as potential litter value.

The recent article of Summers, (Tech-Info #4) addresses the question of feeding heavy turkeys. As the article points out, the turkey unlike the chicken broiler, will, for the most part of its life, be partitioning a greater proportion of the nutrients it consumes into meeting body maintenance requirements as compared to growth. Hence, perhaps some significant changes in diet composition of turkey grower and finisher diets should be considered as it has been well established that the nutrient requirements for maintenance differ markedly from those required for growth.

References

Anthony N.B. J.M. Baloq, F.B. Staudinger, C.W. Hall, R.D. Walker and W.E Huff 1994. Effect of a urease inhibitor and ceiling fans on ascites in broilers: 1. Environmental variability and incidence of ascites. Poultry Sci. 73: 801-809.

Ferket P.R. 1994. Flushing may be related to growth rate in turkeys. Turkey World , April- May, pp 10.

Karasawa, Y., T. Ono and K. Koh 1994. Relationship of decreased caecal urease activity by dietary penicillin to nitrogen utilization in chickens fed a low protein diet plus urea. British Poultry Sci. 35: 91-96.

Karasawa, Y., T. Ono and K. Koh 1994. Inhibitory effect of penicillin on caecal urease activity in chickens fed on a low protein diet plus urea. British Poultry Sci. 35: 157-160.

Summers, J.D. Heavy turkeys – are they being properly fed? Tech-Info #4. Poultry Industry Centre – Arkell.

Turkey World; Feeding Virginiamycin reduces litter moisture: December 1992, pp18.