Feeding ensiled poultry excreta to ruminant animals in Syria
M Hadjipanayiotou*, L Verhaeghe**, L M Labban, A Shurbaji, Abd El-Rahman Kronfoleh, M Al-Wadi, M Amin, T Naigm, H El-Said and Abdul Kader Al-Haress
Animal Production Research Division, Deir
Ministry of Agricultural and Agrarian Reform, Damascus, Syria
(Present address: *Agricultural Research Institute, Nicosia, Cyprus;
**FAO, Animal Production and Health Division,
Via delle Terme di Caracalla, 00100 Rome, Italy).
Silages made of poultry litter (40% of total DM) with forage maize (56% of total DM), molasses (2%) and whey (2%), and/or poultry litter with sugar-beet pulp (1/4-5 parts) or grape marc (1/2.5 parts), were made. Silages had pH value below 5 and a pleasing aroma and colour. Silages were fed as partial replacement for conventional feedstuffs to lactating Shami cows, Awassi ewes, growing heifers, fattening bull calves, young Awassi ramlambs and Syrian Mountain kids. Animals on silages performed better than, or at least equally well as, those on the control diet. No disease problems were encountered from including poultry excreta silage in the diets. The energy value of poultry litter-forage maize silage based on animal performance data was estimated at 2.28 (bull- fattening study) and 1.97 (Shami growing heifers study) Mcal ME/kg DM. The corresponding ME value of sugar-beet pulp-poultry litter silage was 2.18 Mcal ME/kg DM. The nutritive value (per Syrian Pound spent) of the silages was significantly greater than that of barley when the prevailing prices of barley are taken into consideration. This higher value certainly covers the additional expenses associated with ensiling and improves the economics of the Syrian farmers using these silages.
KEY WORDS: Poultry litter, ensiling, ruminants, growth, milk production
Poultry excreta can be a valuable feed for ruminants (Fontenot et al 1971). The chemical composition of poultry excreta, especially the high nitrogen content, suggests that feeding it to ruminants would be an excellent way to convert nutrients in the waste into animal products for human consumption. The feeding of poultry excreta to ruminants has been widely practised and studied. Noland et al (1955), cited in Roothaert and Matthewman (1992), were some of the first authors to describe the use of poultry litter as a source of nitrogen for ruminants. A major obstacle in giving poultry excreta to ruminants is the danger of pathogenic organisms.
Research work (Jakhmola et al 1988) has shown that poultry waste can be rendered free of pathogens by autoclaving, fumigation and dry heat alone or in combination with formaldehyde. However, dry litter has a lower nitrogen content and higher costs (Roothaert and Matthewman 1992). Other methods of processing such as ensiling (Hadjipanayiotou 1982; Daniels et al 1983) and deep stacking (Strickler 1977) have also been proposed.
The ensiling process, a natural biological method of processing is characterized by the production of heat and organic acids, followed by quiescence at which time the pH of the fermented mass becomes stable at about 4 (Barnett 1954). Ensiling with or without additional water (to bring the moisture content of the mixture to an optimum level), forage, grain or other agricultural residues may offer other advantages such as enhancing the nutritive value of conventional or nonconventional feedstuffs, reducing effluent losses, dustiness and improving palatability (Islam and Hossain 1990).
The present paper reports on silages made of poultry excreta with various agricultural by-products and data from demonstration trials using animals fed on such silages.
Materials and methods
Silages composed of poultry excreta with agricultural residues and/or green forage maize were made at three governmental stations (Deir el-Hajjar, Hama and Sweida) situated in different parts of the Syrian Arab Republic (SAR).
DEIR EL-HAJJAR: The silage was prepared in an underground concrete silo pit (41.2 x 5.0 x 2.4 m). It was composed (DM basis) of 40% poultry litter, 56% green forage maize, 2% molasses and 2% whey. Approximately 500 kg of poultry litter (86% DM) were used per full trailer (2,500 kg chopped forage, 39.3% DM) of green forage maize. Poultry litter was a mixture of excreta, wasted feed, beddings and feathers. It was screened (20 mm screen) to remove any wood, some feathers and composted material. The chemical composition of the silage is in Table 1. About 30% of screened poultry litter was spread on the floor of the empty trailer, another 30% was spread on top of the trailer full with forage, and the rest was spread on the material while being unloaded in the pit. Molasses was dissolved in whey and spread on the material while being emptied in the pit. The mixture was pressed using a tractor passing over the mixed material. The pressed material was covered using black polythene sheet. A thin layer of soil and used tyres was placed over the plastic. The soil and tyres were placed first at the back of the pit to expel the air. Preparation of the silage was completed in two days and the silo was opened after a fermentation period of 8 weeks.
HAMA: Silage composed of 13,000 kg sugar-beet pulp (16.67% DM) and 3,250 kg poultry litter (89.9% DM) was made in an earthen pit silo (8.0 x 2.6 x 1.1 m); the ground floor of the pit was covered with a layer of long wheat straw. The two sides of the pit were covered with polythene sheet. Screened litter was placed above the straw and then in alternating layers 800-840 kg sugar-beet pulp and 200- 210 kg of litter per layer. On top of every two layers of pulp/litter, the material was pressed by a tractor passing over it.
The last layer was pulp; the silage was made in one day and was opened after 60 days. Covering of the silage was done as in Deir El-Hajjar.
At the same silo pit, silage composed of 8,200 kg sugar-beet pulp (17% DM) and 620 kg chopped straw was made in August 1991. Urea fertilizer at the rate of 1% DM basis was spread while making the silage. Preparation of the silage was as above.
SWAIDA: The silage was prepared in an above-ground silo pit (8.0 x 2.6 x 2.5 m) made of concrete blocks. It was composed of 7.75 tonnes grape marc (53.5 % DM) and 3 tonnes of cage layer excreta (43.1% DM). The two ingredients were placed in alternate layers and the material was pressed by people walking on it. The last layer was grape marc. The silage was prepared in one day and was opened after 70 days. Covering of the silage was as in Deir El- Hajjar.
Twenty two growing Shami bull calves and 28 growing Shami heifers were divided into two groups based on their liveweight and age. The two groups were randomly allocated to the control or the silage group. In the silage group, poultry litter-forage maize silage replaced part of the conventional feedstuffs (Table 2). Actual quantities of the individual feedstuffs consumed are in Table 2. Within trials, animals on the two treatment diets were housed in two adjacent pens; they had free access to water and they were weighed at the beginning and at the end of the 43-day trial. In the same station (Deir El-Hajjar), Shami dairy cows were also used to study the effect of feeding poultry litter-forage maize silage on milk yield. Thirty two cows were divided into two groups based on their milk yield and randomly allocated to the control or the silage group. Another eight cows were also randomly allocated to the two groups (treatment diets) at calving. The animals were allowed to adjust gradually to the experimental diets. Individual milk yield was recorded once a week. Due to technical difficulties final weight was not recorded for all animals. In the analysis of body weight data, therefore, only the animals with both records are included (Table 3). The animals were offered concentrates at the milking parlour twice daily and roughages in their group pen. The two groups were housed in adjacent pens and had free access to water. Individual milk yields were recorded once weekly.
One hundred and four growing female kids of the Syrian Black Mountain goats were divided into two groups based on their liveweight and age. The two groups were randomly allocated either to the control or the grape marc-cage layer excreta silage. The animals were weighed at the beginning and at the end of the 40-day trial. The two groups were housed in two adjacent pens and they had free access to water. The feeds were offered in approximately two equal portions daily.
One hundred and thirty eight Awassi rams, and forty six Awassi lactating ewes at the declining stage of lactation, were used to study the effect of replacement of conventional feedstuffs (Tables 5 and 6) with sugar-beet pulp-poultry litter silage. The rams were divided into groups based on their weight and age and the ewes according to their weight and milk yield. Within trials, animals from the two groups were housed and fed in two adjacent pens. Rams and ewes were individually weighed at the beginning and at the end of the 60 and 49-day trials, respectively. Group milk yield was recorded daily and individually once a week.
Chemical composition of feeds
The chemical composition of the silages is in Table 1. The silages had very good aroma and colour. The pH values and fatty acid content were within acceptable levels. No chemical analyses or pH measurements were made on the sugar-beet pulp-cereal straw-urea silage; the latter however, had a very good aroma and colour and was eagerly consumed by the Awassi sheep.
|Table 1. Chemical composition (%DM basis) of silages|
|Maize||Poultry litter and Sugar-beet||Grape marc|
Shami calves in the silage group performed at least equally well as those on the control (Table 2). Although in both trials animals from the silage group gained slightly more weight than those from the control, differences were not statistically significant.
|Table 2. Performance of male and female Shami calves given maize- poultry litter silage (Sil) or a control diet (Ctl)|
|N1 of animals||14||14||-||11||11||-|
|Initial age (days)||347||353||23||379||387||31|
|Daily gain (g)||278||316||38||698||890||111|
|Feed intake (kg/day)|
(a),(b) Forty-two and 43 days on test, respectively
It must be underlined however, that four young bull calves (less than 200 kg body weight) from the silage group were not doing well (control 866 vs silage 494 ?93 g weight gain/day). On the contrary, the older bull calves in the silage group gained significantly more weight than those on the control diet (control 601 vs silage 1116 ?128 g weight gain/h/day). Replacement rate of silage to conventional feedstuffs (DM basis) was 0.97 and 1.49 for the heifers and bull calves, respectively.
|Table 3. Replacement of conventional feedstuffs by poultry litter forage maize silage in the diets of dairy Shami cows(a)|
|Milk yield (kg/day)||5.36 (17)(b)||7.06 (20)||2.98|
|Initial weight (kg)||423 (8)||442 (11)||73.1|
|Final weight (kg)||400 (8)||415 (11)||69.3|
|Weight loss (g/day)||511 (8)||589 (11)||322|
|Feed intake (kg/day)|
(a)45 days on test (b)Values in parentheses are number of animals
The cows in the silage group tended (P=0.09) to produce more milk than those in the control group. There were no significant differences between the two groups for daily body weight loss (Table 3).
There were no significant differences in the initial, final or daily body weight gain of Mountain kids on the two treatments (Table 4).
|Table 4. Performance of growing female Mountain kids (n=52/treatment) on grape marc-cage layer excreta silage (a)|
|Daily gain (g)||66||86||11.2|
|Feed intake (g/d)|
(a) 40 days on test
Sugar-beet pulp-poultry litter silage replaced 51 and 35 percent of concentrate and straw, respectively without any adverse effect on body weight changes of Awassi rams (Table 5). The replacement rate of silage to conventional feedstuffs was 0.89 (DMB). Four rams in the silage group developed blindness which was cured after vitamin A injection.
|Table 5: Replacement of conventional feedstuffs with poultry litter-sugar-beet pulp silage in the diets of Awassi rams (a)|
|N1 of animals||67||66||-|
|Daily gain (g/day)||114||103||110|
|Feed intake (g/day)|
(a) 60 days on test
Replacement of 22, 15 and 15 percent of the concentrate, lentils and leguminous straw with silage did not affect significantly milk yield and live weight changes of Awassi ewes (Table 6).
|Table 6: Replacement of conventional feedstuffs with poultry litter-sugar-beet pulp silage in the diets of dairy ewes (n=23/treatment (a)|
|Dail gain (g/day)||88||80||1.56|
|Milk yield (g/day)||551||583||55.5|
|Feed intake (g/day)|
(a) 49 days on test
A pleasing aroma, indicative of an adequate fermentation, was noticed in all silages. No mould growth was observed in the silage containing sugarbeet pulp whereas very low levels of mould were detected in some of the silage containing forage maize. The difference between the two silages was probably due, not to the poultry litter, but to the fact that sugar-beet pulp is an ideal material for obtaining satisfactory compaction and therefore an anaerobic pattern of fermentation. To our knowledge, no other workers have ensiled sugar-beet pulp with poultry litter, but a pleasing aroma and good colour was obtained by other researchers when poultry litter was ensiled with forage maize (Harmon et al 1975), citrus pulp or weeds (Hadjipanayiotou 1982). In the grape marc-cage layer excreta silage mould developed at the sides of the silo pit, possibly due to penetration of air through the blocks and the low moisture and low fermentable carbohydrate content of the ingredients.
McCaskey and Anthony (1975, cited by Roothaert et al 1992) indicated that ensiled materials should reach a pH of less than 5 in order to destroy Salmonella and other pathogens. In the present studies, pH values lower than 5 were attained in all silages.
In line with previous studies (Fontenot 1981; Hadjipanayiotou 1984) there were no indications of harmful effects on humans consuming meat, milk or milk products from animals fed ensiled poultry litter. In addition, no disease problems were encountered from including poultry excreta silage in rations of growing cattle, sheep and kids and/or lactating cows and ewes.
Four rams in the silage group showed blindness which was cured after vitamin A injection. Animals from both groups were previously on the same feeding regime composed of a concentrate mixture (without any vitamins added) plus cereal straws. It is more likely that the poultry litter-sugar-beet pulp silage through its ethanol content enhanced depletion of the limited liver stores of retinol and the animals showed symptoms of vitamin A deficiency; similar findings have been cited by ARC (1980) in ruminant animals fed maize silage.
Sugar-beet pulp is normally dried in rotary dehydrators, in the sun and/or fed fresh. The first method is costly and even under optimal conditions, 43 litres of fossil fuel are required (Walid Dalati personal communication) to dry one tonne of fresh sugar-beet pulp (16-17 % DM); drying in the sun results in a considerable loss of soluble materials and in mould growth. On the other hand, due to the seasonality of the product only relatively small proportions of the annual production can be used fresh, and this only on large scale farms where transport and feeding management facilitate daily use of measurable quantities (ie: truck or tractor loads).
The ensiling technique might be a good alternative. Additional expenses, however, are associated with this process. Eighty four man/hours and 28 tractor/hours (2 tractors with their drivers, 14 hours each) were required in one of our large scale demonstrations for the preparation of 300 tonnes of silage composed of 240 tonnes sugar-beet pulp and 60 tonnes of poultry litter. Other expenses included polyethelene sheet (67 kg) for covering the silage and labour for screening the litter.
The energy value of poultry litter-forage maize silage based on animal performance data was estimated at 2.28 and 1.97 Mcal ME/kg DM when fed to Shami bull calves and growing heifers, respectively.
Similarly, the ME value of sugar-beet pulp-poultry litter silage fed to Awassi rams was estimated at 2.18 Mcal ME /kg DM. The current prices (ex factory/poultry house) for fresh sugar-beet pulp and poultry litter in the Syrian Arab Republic are (Syrian pounds [SP]/tonne) 600-650 and 260-470, respectively.
The economic value (per SP spent) of the nutrients in the silages was significantly greater than that of barley when the prevailing prices of barley were taken into consideration (6 to 9 SP/kg during the last three years). This higher value certainly covers the additional expenses associated with ensiling and improves the economics of the Syrian farmers using these silages.
It is concluded that the ensiling process tested in the present studies resulted in a feed safe for ruminant animals and that up to 50% replacement of conventional feedstuffs with such silages is possible. Blending litter with seasonal agro-industrial by- products gives better quality silages, enriched in nitrogen and macro/micro minerals, and reduces silage losses as effluent, which is very polluting (Barreveld 1989).
The authors are grateful to the staff of the FAO and UNDP offices in Damascus, R Sansoucy (Senior Officer, Feed Resources), S Badawi (Chief AGON, FAO, Rome) and K Qamar (CPO-AGON) for continuous support and encouragement and to his Excellency the Minister of Agriculture and Agrarian Reform, Mr M Gabbash, for making available all necessary facilities for the implementation of this work. This work was carried out in conjunction with the Animal Feeding Project "Greater and Improved Use of Agricultural Residues", a joint undertaking between the Government of Syria, the UNDP and FAO.
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(Received 20 April 1993)