This article addresses 8 nutritional factors that affect poultry litter quality and how to overcome many litter-related production and welfare problems.
Various types of litter such as rice hulls, peanut hulls, sand, chopped straw, corn stover, etc. are often used as bedding materials in poultry houses. When improperly managed, these materials may cause production and welfare problems including mould growth, caking, breast blisters, foot pad dermatitis (FPD), and aspergillosis, all of which lead to serious economic losses. Attempts have been made to control such problems through management strategies. In this article, however, the focus is made on poultry nutrition as a key factor that maintains litter quality and hence alleviates many of the litter-related problems.
Certain batches of feed may include excess ingredients such as wheat bran, sesame cake, or corn grain, all of which are laxatives contributing to the production of wet or badly-smelling droppings. These ingredients should, therefore, be well balanced with others having costive nature to alleviate such physiological effects on poultry.
Diets containing drugs such as coccidiostats are associated with metabolic changes that also lead to wetter droppings. A change of feed ingredients will frequently overcome this problem. Such a dietary change should be made in a way that suits changes in the activities of microflora present in the bird’s intestine during medication.
Given in Table 1 are the results of a study on the effects of the physical form of the diet and feeding system on litter moisture and quality. Feeding birds with pellets resulted in higher moisture and poorer litter quality than fines or mash groups. Possibly, feed intake on pellets was higher, resulting in higher water intake. Feed restriction also resulted in higher moisture levels and poorer litter quality. It could be that water intake was stimulated in this case because birds felt unsatisfied during feed restriction.
It was found that the increase of 1 percentage point in protein level increases water consumption by 3% with a resulting increase in water excretion, which adversely affects litter quality. This is particularly true in the case where soybean meal is used as the main protein source in the diets, due to the presence of certain components that can be responsible for a higher water intake and excretion, such as fibre, fermentable sugars, and potassium.
Feeding reduced protein diets (e.g. -2%) helps reduce water intake and excretion and hence maintains litter quality. This can also reduce N excretion with up to 24% reduction in ammonia emission. Further decreases in protein levels of the diet will, however, require that all essential amino acids are included, preferably in a crystalline form, with a careful balance of the amino acids to be considered to avoid impairment of the chicken’s performance.
Poor quality fats in poultry diets which cannot be utilised and are fully excreted often lead to greasy litter. This litter may become rancid with time and hence contributes further to the bad smell in the house. Further, there is often an increase of excreta moisture and a negative impact on the water-binding capacity of the litter through considerable fat excretion. Wet litter surface and a higher prevalence of “hock burns” were also observed with dietary fat sources of low quality, i.e. more saturated and less unsaturated fatty acids with a high soap content (salts of fatty acids). The high soap contents may elevate excreta moisture due to an irritation of the gut mucosa and hence reduce water absorption. It may also impair the drying properties of the mixture of excreta and litter due to the formation of a layer covering the wet excreta and thus preventing evaporation.
Increasing dietary sodium levels can increase litter moisture content and impair litter quality. The effects of sodium on litter quality are, however, more pronounced during the winter than during the summer. Likewise, Increasing dietary potassium and magnesium levels result in increased water-to-feed ratio, impaired litter quality, and increased excreta and litter moisture (Table 2). For calcium and phosphorus, the effects on litter moisture and quality seem to vary with age, i.e. the effects are less pronounced in young birds than older birds.
In one study, it was shown that the enzyme complex of cellulase, xylanase galactosidase, amylase, and protease added to corn-soybean diets decreased the digesta viscosity and reduced severity of FPD in broilers at 57 days of age.
Other additives can also be added to the diet to trap ammonia and hence improve litter and air quality in the poultry house. Among these additives is zeolite, a type of mineral with a porous or lattice-like structure which, when included in the diet, binds ammonia in the faeces and prevents it from being emitted into the air. More recently, it was reported that silicon dioxide added to the diet tended to improve FPD scoring although it did not affect litter moisture.
Also, acidification of the diet may help alleviate the ammonia production problem. This can be achieved by adding calcium benzoate or by lowering the dietary electrolyte balance. The acidic diet will result in acidic manure, causing ammonia (NH3) to be converted to ammonium (NH4), which is more water-soluble and not readily emitted into the air.
Poultry will waste a significant amount of feed if feeders are overfilled, adjusted too low, or poorly designed. In this case, faecal N may increase by 1.5% for each 1% increase in feed waste. This will affect litter quality since the ammonia emission rate will subsequently be increased. Feeders should, therefore, be designed in such a way that it is difficult for the birds to push the feed out of the feeders. In this way, the feeder height should be adjusted so that the top of the feed pan is level with the bird’s neck, with the feed fill level to be adjusted to only 25% of the feeder pan.
Too much water in the house also results in excess ammonia emission and poor litter and air quality. To alleviate the problem, the nipple drinker system should be adopted for better control over water intake and wastage.
References are available from the author upon request.