Wet Manure/Litter in Poultry Houses: Approaches to Ameliorate the Issue

Introduction

With genetic improvement changes, today poultry species are more sensitive to nutritional and management changes which can easily induce osmoregulatory perturbation that can cause flushing (Many, 2023). A typical layer farm of 100,000 hens produces 1,500 to 2,000 tons of manure every year (Chai, 2012). And 1000 broilers chickens produce up to 1370 lbs of manure per in a growing cycle (Parker et al., 1959). Manure is acquired by the agricultural industry for land fertilization. Fresh manure contains about 75% moisture that must be reduced prior to storage and land application (Henuk and Dingle, 2003, van der Hoeven-Hangoor, 2013). However wet manure may be rejected because of high moisture which can lead to higher transport cost, faster reproduction of pathogens and flies and the generation of odors. Additionally, wet manure tends to lose a higher ratio of nitrogen (N) as moisture plays a key role in the generation and emission of ammonia (NH3) from chicken manure.

Consequences of wet manure in poultry,

If litter/manure is not kept at an acceptable moisture level, very high bacterial loads and unsanitary growing conditions may result in producing odors and ammonia, insect problems (particularly flies), soiled feathers, footpad lesions and breast bruises or blisters. When birds are raised in suboptimal conditions, carcass downgrading may occur at the processing facility. The levels of condemnation and downgrades are increased due to breast blisters, transport loss, and dirty eggs. Additionally, it has been found that when the litter is damp, or crusty, footpad dermatitis is increased, which can be confirmed histologically and by physical observation. In a wet litter or manure environment, there is a high ammonia content that causes respiratory disease, poor weight gains due to nutrient loss and poor feed conversion ratio (FCR). Wet litter-manure also increases mortality and morbidity, which increases the medication costs. Similarly, the incidence of parasites such as coccidia, and round worms not only reduce bird performance but also increase the anticoccidial and de-wormers costs. Specifically, in layers and breeders’ houses, the incidence of wet manure-litter has been reported to be high. There are many potential causes and approaches to address the issue. The approach depends on the type of issue which can be non-infectious such as improper nutrition and feeding, management, genetics, and environment or it can also be infectious by bacteria, viruses, protozoa, coccidia and mycotoxins.

NON-INFECTIOUS

Nutritional and feeding

There are many nutritional approaches and strategies that can be followed to address the wet manure and wet litter problems in poultry houses.

Excess of protein in diet: Urinary and fecal water elimination are major factors leading to the accumulation of moisture in poultry house litter. A solution to the problem of "wet litter-manure" would thus involve determination of those factors responsible for the elimination of excessive amounts of water via the renal and alimentary routes. One of these causal factors is diet. It has been reported that the amount of water consumed, as well as the amount of excreta voided by growing chickens varied almost directly with the protein level of the diet. A high dietary protein content (Collett, 2012) or insoluble fibers in the diet, which can have a high-water binding capacity in the GIT (van der Hoeven-

Hangoor et al., 2013, Chaplin, 2003), can increase the water content of droppings. Feeding to reduce protein content in the diet (~2%) helps to reduce the water intake and hence maintain manure quality (Wheeler and Edward, 1949). This is particularly true when soybean meals are used as the main protein source in diets due to the fermentable sugars, and high potassium which also stimulates water intake. High potassium can induce polydipsia, polyuria, and wet litter. It has been found that 1% increase in protein increases water intake by 3% with a resulting increase in water excretion which adversity affects litter and manure moisture content (REF). It has been reported that when birds were changed from a lower to a higher soybean meal level, both water intake and droppings weight increased. Interestingly, when the change is made to a diet of lower soybean meal content, these values decrease. The water intake and elimination are greatest when birds are fed diets with more than 34% soybean meal. In diets with the same percentage of protein from other protein sources (ex. fish meal and meat scrap), the effects of soybean meal are apparently greater than those of fish and meat protein. Both water intake and elimination increased as the animal protein in the diet was replaced by soybean meal, even though the total protein content of the diet did not vary. Excess undigested protein or poor-quality feed protein levels in the feed will increase the production of uric acid in the kidneys, leading to wet droppings. The use of enzyme protease has been shown to increase soybean meal digestibility, reduce its inclusion and wet manure incidence in poultry houses (personal observation).

High mineral content. Dietary mineral levels and ratios between minerals play an important role in excreta moisture content (Ziaei et al., 2008; Jankowski et al., 2011). For example, increasing dietary sodium levels, one of the minerals of the Dietary Electrolyte Balance (DEB) can increase litter and manure moisture content. The effect of sodium on litter and manure moisture content is more pronounced in winter season due to the inappropriate ventilation in poultry houses. Sodium is pivotal given the variations in sodium concentrations in feeding grains. Similar effects are observed with higher potassium and magnesium content of diets which may alter the water: feed ratio increasing the excreta moisture content. Magnesium for example, has been reported to cause a watery appearance of the feces (Stillmak and Sunde, 1971). Also, wet manure has been observed with the high intake of sulphate or Chloride. That is the reason why nutritionists should pay special attention to the high levels of sulfate and magnesium in the drinking water when formulating a feed ration. The DEB minerals, sodium, chloride and potassium also play a significant role in the wet manure incidence. Increasing the DEB above 250 mEq/kg significantly increases excreta moisture content.

Additionally, other macro minerals are also implied in the wet manure incidence, for example, calcium (Ca+), phosphorus (P-), and appropriate Ca:P ratio. It has been observed that hens fed diet deficient in calcium have wet droppings. Jensen (1977) observed that broilers fed diets containing 0.6% calcium had diarrhea and wet litter that disappeared within 3 days after increasing dietary calcium to 1%. In another study, it was found that the excreta of hens fed the 0.05% calcium diet became extremely watery compared to hens fed 3.0% Calcium. It has also been reported that water consumption may not increase in hens to feed the low calcium diets, but the water to feed ratio is higher, which causes the wet litter-manure problem.

Because wet droppings occur within 3 days after receiving a calcium deficient diet, these findings might be helpful in identifying causes of thin-shell egg problems produced by accidental short-term interruption of calcium intake. However, other studies observed the opposite when reducing calcium which showed to be beneficial on litter quality; this is especially true when using phytase. Therefore, it is recommended to review and apply appropriate matrix values for calcium, phosphorous and sodium in the formulation of the phytase.

Phytase sodium matrix: it has been observed that phytase increased excreta moisture. Exogenous phytase significantly increases sodium digestibility in the proximal jejunum, and ileum (Debicki-Garnier and Hruby (2003). The dietary sodium of phytase should be adjusted via appropriate matrix values. In some phytase products in the market, the sodium contribution may be up to 0.02% (12.5% of a formulated sodium of 0.16%). Excessive, and unidentified sodium levels could contribute to wet litter-manure as it increases water intake and disrupts the electrolyte balance. Exogenous phytases have been associated with wet litter-manure at the academic and commercial experience.

Soluble fiber: High fiber levels from alternate raw materials may also impact wet manure incidence. Coarser grain particle size tended to improve wet litter incidence. A factor that may increase wet manure is the feed restriction as it has been demonstrated that birds that are placed on a restricted feeding program consume much more water than usual. However, water soluble non-starch polysaccharides (NSP) adversely affect digestibility by stimulating mucous production and increasing intestinal viscosity, resulting in wet litter-manure. The inclusion of NSP enzymes in poultry diets to counter elevate digesta viscosities caused by soluble Non starch polysaccharides (NSP) may prevent wet manure. Exogenous β-glucanases in poultry diets maintain good litter quality despite the presence of soluble arabinoxylans.

Genetic selection and feed structure:modern breeding and selection procedures for high appetite and feed intake may increase the feed passage rate. This reduces the enzyme – nutrient contact, leading to reduced protein digestibility and reduced feed efficiency.

Poor quality of dietary fat or rancid fat: Rancid fats can compromise digestibility and can cause gastrointestinal disturbance and wet manure/litter

Management:

There are programs to manage the wet manure issue in poultry farms: 1. the use of exhaust fans, manure drying tunnels or shed, air duct heating and in-house composting (high-rise layer houses) (Koenig et al., 2005). Available feed and water space, distribution of feeders, drinkers, air quality, ventilation, litter, temperature, and density. Any change in temperature and humidity that lowers the pressure of the systems and large particle sizes can cause wet litter if poultry house humidity is high. Wet litter problems occur quite easily in overcrowded houses. It is important that adequate food and water space be provided in hot climates and additional drinkers be used during the very hot periods of the year. Leaking watering systems, when not maintained in good working order, can also cause wet litter problems.

Environmental:

Both heating and ventilation systems must be continually monitored to ensure that the moisture content of the litter is controlled and the litter remains friable. The sealed litter is often referred to as being “caked.” A severe litter moisture problem can result, if large areas of the house floor surface are caked. It is more common, however, to find localized areas of caking near leaky watering cups, nipples, troughs or roofs. The litter in these housing locations must be continually stirred or replaced to prevent the problem from becoming worse. caked litter must be removed between flocks and replaced with new litter.

INFECTIOUS

Wet litter is commonly used to describe nonspecific diseases of gastrointestinal and urinary tract. With disease onset, performance problems like increased feed conversion ratio, poor body weight gain, increase in marketing age, predisposition to other secondary bacterial infections and condemnation losses – start precipitating one after other.

Bacterial infections caused by E. coli, Salmonella, Clostridium, Campylobacter and Spirochaetes result in wet litter. Dysbacteriosis may also be induced due to several other factors which upset the usual microbial balance in the intestine.

Viruses associated with malabsorption of nutrients have an adverse effect on the consistency of the bird's droppings. Viruses such as reovirus, infectious bronchitis and infectious bursal disease, Newcastle Disease Virus, Adenovirus, Rotavirus, and Astrovirus cause diarrhea. Rotavirus infections cause diarrhea which is the main clinical sign. This is followed by litter eating and inflamed vents. Reovirus infections cause mucoid diarrhea with pasty vents. In nephron pathogenic form of Infectious bronchitis viral infections, the water intake will be high and result in diarrhea and wet litter.

The protozoan parasites causing coccidiosis due to Eimeria species, often cause dysentery and frequent wet litter. Heavy loads of internal parasites such as roundworm and tape worm infestation cause diarrhea.

Coccidia infections result in direct damage to the mucosal lining of the gut and will result in wet droppings

Mycotoxins are known to irritate the digestive tract and to cause marked pathological changes in the kidneys; this is especially true with Ochratoxin, Oosporin and Citrinin. Consumption of mycotoxins may cause the droppings to be excessively wet. Nephrotoxins such as Ochratoxin and Citrinin can compromise renal function causing polyuria and polydipsia.

Conclusion

When dealing with wet manure issues, nutritionists and field technicians should review many factors including those more nutritional related such as the levels of protein, especially the proportion coming from soybean meals, the electrolyte balance (Na+ K-Cl), and macro-minerals. Other highly variable nutritional ingredients such as meat and bone meals, bakery meals and dried distillers with soluble grain (DDGS) should also be ruled out. Other management and pathological diseases should also be reviewed including mycotoxins and coccidiosis.