Manure

Coprophagy, or feeding on manure, is not new in animal nutrition. For example, livestock feeding on a farm has frequently involved a system of beef cattle followed by hogs and subsequently chickens. Under such a programme the nutrition of the hogs and chickens is based on manure. The current interest in manure as a feedstuff is mostly due to the problem of waste disposal from intensive livestock and poultry operations. Apart from this problem it has been recognized that large amounts of nutrients are wasted. The re-use of manure is one way of creating edible protein from waste material which is often disposed of uneconomically and also creates a nuisance. The amount of excreta produced is considerable: a 2-kg hen produces 0.8 kg a week, a 650-kg cow 150 kg, an 80 kg pig 40 kg and a 45 kg pig 22 kg. 

Manure has served as a substrate for both yeast and algae used as feedstuffs, and it has been tried as a substrate for maggots used as a poultry feed; however, the simplest way to use it is as a direct feed. 
TOXICITY. Fresh manure seems to contain no toxic products unless it is allowed to putrefy. Some parasites and diseases can be disseminated in manure; there is less risk if the manure is made into a silage. Manure containing nematode eggs was completely free of them four weeks after ensiling. Heating and cooking have the same effect. The transmission of diseases from poultry to cattle via manure is unlikely. Similarly, there appears to be no serious problem with drug residues in poultry manure, except for copper- and arsenic-containing drugs. As cattle and especially sheep are sensitive to copper, manure from animals receiving high levels of copper in their diets should be fed with care. 

PIG MANURE

Pig manure is important in the pig-vegetable-fish-duck chain that is common in Southeast Asia. The integrated system has long profitably used by Chinese farmers (ref. 306). 

Swine manure contains over 20% crude protein. Because of this high content of crude protein, dried fresh swine manure has been used in experimental work as poultry feed with no adverse effects on either meat or eggs. The same product has been used to advantage in pig finishing rations at the 15% level. It has also been included in sheep rations at the level of 40% (in pellets) with good results. 

CATTLE MANURE

A low digestible energy content and a relatively low crude protein content are the two primary deficiencies which limit the usefulness of ruminant excreta as a supplementary ingredient in feed. The dehydration of cattle excreta for use as an ingredient in cattle feed is clearly uneconomical. 

Steer manure has been fed to finishing beef cattle either mixed fresh with other feeds or as wastelage. When fed fresh, the manure is collected daily from the pen and blended with the ration in the ratio of 2:3. The mixture is kept in a closed container overnight and fed the following day. When fed as wastelage, fresh manure is mixed with ground grass hay in the ratio or 57:43 and stored in a silo, where it ferments and acquires a silage odour. Wastelage from Coastal Bermuda hay averages 13% crude protein and 60% digestible nutrients. The product has been combined with concentrates for feeding to finishing cattle and has also been used as the sole feed for ewes and beef cows. A complete ration recommended for feedlot cattle consists of 40% fresh cow manure mixed with 42% cracked maize and 18% maize silage. The mixture is ensiled for ten days before feeding. When wastelage is fed alone for a long period, it may be necessary to add vitamin A and phosphorus or feeds rich in these growth factors. Feeding manure to dairy cows produces no effect on lactation or milk taste. Dried fresh manure smells like a mixed feed. The dryness of dehydrated manure seems to lessen palatability, but manure fermented as silage is well accepted. Once cattle become accustomed to this feed there is no effect on consumption. Wastelage should not be stored in a rusty structure. 

Manure from finishing cattle has been fed to pigs to utilize the undigested grain it contains. Besides, manure is a fermented product and contains growth factors, especially the B-complex vitamins and some essential amino acids. Dried fresh cow manure included in rations for growing birds (but not for layers) has produced much faster growth in some cases, possibly because of hormone activity in the manure. 

POULTRY MANURE

With the intensification of poultry keeping, not every poultry farm has enough land on which to spread manure. The results of many experiments indicate that dried poultry manure can be successfully included in the feeds of both ruminants and nonruminants. 

Fresh poultry manure is about 30% crude protein on a dry basis, about half of which derives from uric acid. For ruminants the digestibility of the crude protein is close to 80% and that of the organic matter about 65%. Poultry manure is also rich in minerals, which makes further mineral supplementation of rations containing dried poultry manure unnecessary. 

As fresh poultry manure ferments very quickly, it must be dried without delay if it is to be used for feeding. The drying temperature should be no higher than 90 C so as not to damage the protein in the manure and no lower than 70 C so as to sterilize the manure. It should then be ground to facilitate the removal of feathers. 

Uric acid can be utilized by rumen microbes for protein production (see NONPROTEIN NITROGEN). As uric acid is not easily dissolved in the rumen fluid and the ammonia is only slowly released, it is therefore more efficiently utilized than other nonprotein nitrogen (NPN) sources. The rumen flora seems to take about three weeks to adapt before it can fully utilize uric acid. For ruminants dried poultry manure can be used like any other protein concentrate. When dried poultry manure ration is maintained at a normal energy level, the weight gains or milk production are satisfactory. Its low energy value (about the same as hay) may cause low palatability when it is fed at high levels, but various steps can be taken to improve palatability, such as the addition of molasses or fat. The feeding of dried poultry manure does not affect the flavour of meat or milk. 

The feeding of dried poultry manure to pigs has been less successful. Levels of 5-10% do not usually affect the growth rate, but the feed conversion ratio becomes poorer with further additions to the ration. At higher levels, growth rates are depressed as well, probably because dried poultry manure is low in the essential amino acids needed by pigs and because of the excessive amount of calcium. In poultry diets it has been found that dried poultry manure can be included up to 5% for broilers, up to 20% for Leghorns and up to 40% for layers without adversely affecting production; however, feed efficiency was inversely proportional to the amount included in the diet. 

Much of the interest in the feeding of poultry manure has been centred on deep litter, which is a mixture of a suitable litter material and poultry droppings developed over a period of six months or more and maintained in a dry, friable condition. The litter is placed in a layer between 3 cm and 25 cm thick on the floor of the poultry house, mainly to absorb the moisture from poultry excreta, which is about 80% water when voided. This moisture is subsequently disposed of by evaporation and is also used in decomposition. Microorganisms thrive on the manure in the litter and break it down. This microflora produces growth factors, notably vitamin B12, and antibiotic substances which help control the level of pathogenic bacteria. Consequently, the growth rate and health are often superior in poultry raised on deep litter. Various types of litter materials are used, such as sawdust, wood shavings, groundnut hulls and bagasse. The litter material must be sufficiently water-absorbent, reasonably coarse so that packing does not occur, and capable of decomposition. The addition of lime helps keep the litter dry, and the addition of superphosphate reduces the escape of ammonia from the litter, thus maintaining the nitrogen content at a higher level. 

When used as feed, the litter should be dried immediately after removal from the poultry house and preferably milled and run over a magnet to remove stray metal scraps. Dried litter can be stored for a long time. Poultry litter has also been ensiled to prevent deterioration. For feeding it should be mixed with energy- rich feedstuffs. The following formula has been recommended: litter 65%, citrus meal 25%, molasses 9% and minerals and vitamins 1%. When mixed in the feed, poultry litter does not keep and must be used quickly. The depth of the litter, as well as the material, affects the nutritive value. Poultry litter is a low-cost material which has given good results in both dairy cows and beef cattle. 

Citrus meal is a good litter producer. The subsequent chicken litter is a very good energy-rich feed. It should be noted, however, that citrus seeds must not be included in citrus meal used for litter as they may cause poultry mortalities. 

Litter silage has been produced by packing broiler litter into an upright airtight silo, adding water until the total moisture content was 35-38% and leaving the silo sealed and undisturbed for six weeks. This has proved to be an excellent ingredient for cattle feed, and the process partially destroys harmful microorganisms. 

SEWAGE

Activated sewage sludge is made by a fermentation process, in which the organic matter in sewage is metabolized by a variety of microorganisms under heavy aeration. This process is most common in modern sewage treatment plants for the production of large amounts of activated sludge. This end product is a gelatinous mass of microorganisms, rich in nitrogen and vitamin B12. It can be used as a source of vitamin B12 in animal nutrition, for which the inclusion of 2% in rations will in most cases satisfy the requirement. The inclusion of a higher percentage of activated sludge as a source of nitrogen has been less successful, because high levels decrease intake and cause diarrhoea. The maximum amount for pigs is about 5% and for poultry and ruminants 8%. The crude protein digestibility for ruminants is about 55%. 

GUANO

Droppings from birds or bats contain up to 10% nitrogen and are rich in phosphorus (up to 5% for fish-eating birds). For ruminants it can be used as a nonprotein nitrogen source. It should be used in the same way as urea and usually gives the same response. 

					As % of dry matter
				DM	CP	CF	Ash	EE	NFE	Ca	P	Ref
Manure from steer
on a hay ration,
fresh				17.9	8.4	22.5	18.8	3.1	47.2			186
Manure from steer
eating silage plus
concentrate, fresh				17.4	11.4	22.2	12.0	2.4	52.0			"
Layer manure, dried				92.3	28.3	12.0	16.5	1.8	41.4	5.10	1.60	23
Wood-shaving broi-
ler litter, dried				88.9	30.6	14.6	19.0	2.8	33.0	2.48	2.26	57
Groundnut-hull
broiler litter,
dried				89.1	32.0	15.1	17.9	2.8	32.2	2.77	2.86	"
Bagasse chicken
litter, dried				92.3	2.8	44.9	2.2	0.8	49.3			264
Citrus meal broi-
ler litter					26.5	11.8	9.5	3.0	49.2			201
Wheat bran broiler
litter					27.2	17.1	19.9	1.7	34.1			351
Maize-cob broiler
litter					26.5	16.7	13.9	4.3	38.6			"
Sugar-beet pulp
broiler litter					31.6	14.1	17.7	1.9	34.7			"
Rabbit manure					20.0	28.5	14.5	1.2	38.5			516
Bat guano, Trinidad				91.9	22.9	41.6	11.2	2.4	21.9			117
							Digestibility (%)
					Animal		CP	CF	EE	NFE	ME	Ref
Wood-shaving litter					Sheep		70.4	66.1	62.7	68.6	2.23	57
Groundnut-hull litter					Sheep		73.0	66.8	56.3	69.7	2.31	"
Citrus meal litter					Sheep		82.0	72.8	85.6	81.6	2.90	201
		Amino acid composition as % of crude protein
Manure from cattle fed on maize silage											Ref	24
Arg	Cys	Gly	His	Ils	Leu	Lys	Met	Phe	Thr	Try	Tyr	Val
2.0	0.8	3.6	1.5	2.9	2.6	4.3	1.0	tr	3.9	-	tr	3.4
Groundnut-hull broiler litter											Ref	57
Arg	Cys	Gly	His	Ils	Leu	Lys	Met	Phe	Thr	Try	Tyr	Val
1.6	4.1	8.1	7.8	2.0	3.2	1.9	0.4	1.7	1.8	-	1.3	2.5

References

23, 24, 25, 57, 117, 184, 186, 201, 264, 351, 516