Design, Construction and Performance Evaluation of Automatic Poultry Egg Incubator J.L. Taulo, D. Chimungu, Chimungu, and L. Mwakayoka Mwakayoka Malawi Industrial Research and Technology Development Centre P.O. Box 357, Blantyre
ABSTRACT Artif Artifici icial al incub incubati ation on is rapid rapidly ly becom becoming ing the predom predomin inant ant metho method d for incubatio incubation n of poultry poultry eggs worldwid worldwide. e. It is favoured in order order to increase increase the production of chicks and protein intake, particularly in the developing countries. Electrical incubators incubators are the best where the supply of electricity is readi readily ly avail availabl able e and cheap. cheap. In this this study, study, an autom automati atic c poultr poultry y egg incubator was designed, fabricated and tested to evaluate its performance. A total 3362 eggs [trial 1 (n = 683, BA1); trial 2 (n = 1404, HL2); trial 3 ([n=398, BA); and trial 4 (n=598, HL and n =279, HL)] were used for hatchability tests. The eggs were divided into two treatments: treatm treatment ent 1 (60% (60% RH; RH; temper temperatu ature re =3 =38°C 8°C;; n=1275 n=1275)) and treatm treatment ent 2 (65% RH; temperature = 39°C; n = 2087). Each treatment group of eggs was incubated in an individual incubator, according to its experimental temper tem peratu ature re and rel relati ative ve hum humidi idity ty dur durin ing g in incub cubati ation. on. The incubating cham chambe berr was was main mainta tain ined ed thro throug ugho hout ut the the incu incuba bati ting ng peri period od with within in a temperature range of 35°C to 38° C and relative humidity range of 48 % to 70%. The preliminar preliminary y results results of this ongoing ongoing study based on the four incubation trials showed that the percentage fertility and hatchability of eggs were 80% and 66%, respectively. Chicken Chicken eggs incubated at a lower temperature (38° (38°C) and lower humidity (60%) presented the highest level of hatchability (73%) compared to higher temperature (39° (39°C) and relative humid hum idity ity (65 (65%). %). The These se res result ults s sug sugges gestt tha thatt the loc locall allyy- ma manuf nufact acture ured d electr ele ctric ic egg inc incuba ubator tor may be us used ed for art artifi ificia ciall in incub cubati ation, on, aim aimed ed at enhancing production of day-old chickens.
INTRODUCTION A major major food security security challenge challenge in Malawi Malawi is meeting increased increased demand demand for chicks and protein intake from poultry products. While the production of chic chicke ken n prod produc ucts ts appe appear ars s to be on the the incr increa ease se,, it is curr curren entl tly y estimated that 55% of farming households keep chickens (MoAIFS, 2004). These These have have been been reare reared d for both both egg and meat meat produc productio tion. n. Estim Estimate ates s show that in 1998, the Malawi chicken population was at 10,365,700 with egg production of 28 million per month and 800, 000 chicks per month (DA DAHI HI,, 199 1999) 9).. Th Thes ese e ar are e no nott ad adeq equa uate te to sa sati tisf sfy y lo loca call de dema mand nd.. Th The e country had to import extra 900 tonnes of poultry meat and 28.6 million eggs to meet the 1997 demand. During the same year, Malawi imported
1 BA = Mikolongwe Black Austrolop 2 HL = Hy-line (broiler)
910,000-day-old broiler chicks and 80,000 day-old layer chicks to bridge the demand gap in broiler and layer industry, respectively. Finding ways to increase the production of chicks and protein intake would be a benefit not only to consumers but would also serve to stimulate greater productivity on the part of small-scale producers. This would include the development of small-scale hatcheries (incubators) to cater for small-scale backyard system in households, and help reduce the waiting period for commercial farmers for chicks from commercial hatcheries, which ranges from two to three weeks (Stewart, personal communication). Artificial incubators have been used since ancient times for hatching poultry eggs in many parts of the world. Aristotle writing in the year 400 BC told of Egyptians incubating eggs spontaneously in dung heaps. The Chinese developed artificial incubation as early as 246 BC. These early incubation methods were often practised on a large scale, a single location perhaps having capacity of 36,000 eggs. The application of incubation principles was a closely guarded secret, passed from one generation to the next. The proper temperature was judged by placing an incubating egg in one’s eye socket for accurate determination. Temperature changes were effected in the incubator by moving the eggs, by adding additional eggs to use the heat of embryological development of older eggs, and regulating the flow of fresh air through the hatching area. Humidity was evidently not a problem as primitive incubators were located on highly humid areas, and the heat source, often burning materials, furnished water around the eggs. Turning was done as often as five times in a 24-hour period after the fourth day of incubation. Studies have shown that poor incubation success results from timely combination of either high or low environmental temperature and inadequate relative humidity inside the hatchery or incubator (Decuypere and Michels, 1992), and when lack of ventilation affects oxygen renewal (Alda,2003). Embryonic mortality may result from fungi contamination during incubation, and hatchery houses are ideal environments for fungi development-high temperature; high relative humidity and high level of organic material. Successful incubation environment depends on maintaining favourable conditions for hatching fertile eggs. As is known, temperature, humidity, ventilation and turning frequency during the incubation period markedly affect the hatchability of fertile eggs and chick quality (Shafey et al, 2007). Temperature is a very important factor affecting embryo development (Romanoff, 1972), hatchability (Deeming and Ferguson,1991; Wilson, 1991), and post hatch performance (Lundy, 1969; Wilson, 1991). The temperature experienced by a developing embryo depends on three factors; incubator temperature, ability of heat to pass between the incubator and the embryo and metabolic heat production of the embryo itself (French, 1997). Overheating speeds up the rate of development,
causes abnormal embryos in the early hatches, and consequently lowers the percentage hatchability. Setting off optimum incubation temperatures leads to best hatchability (Swann and Brake, 1990; French, 1997) and chick quality (Decuypere &Michels, 1992; French, 1997). Optimum incubation temperature of most avian species is 37 °C to 38°C and minor deviations negatively affect incubator performance and embryo development (Wilson, 1991). Studies investigating the effects of incubation temperature on the hatchability of poultry species have been reviewed by Kosin (1964) ; Landauer (1967); Lundy(1969); and Meir & Ar (1990). Several broad conclusions were drawn in these reviews: 1) optimum continous incubation temperature for poultry is between 37°C to 38°C, although hatchability is possible between 35°C to 40.5 °C. Egg temperature varied greatly among the species in natural incubation (Kosin, 1964; Wilson et al., 1979). Landauer (1967) reported that the increase in temperature during incubation was very critical for embryos. Moreover, it was reported that growth was retarded or ceased and the incidence of poor second quality chicks increased as the temperature was raised (Wilson, 1991). Humidity is another parameter in reaching optimal hatchability and chick quality. Water accounts for 68.25% of total eggs mass before incubation (Martin and Arnold, 1991). The amount of moisture lost from the eggs during incubation can affect hatchability (Lundy, 1969) and chick weight (Burton and Tullet, 1985). The temperature can highly influence the relative humidity, and both contribute to water loss during incubation, this way temperature and humidity must be carefully monitored during incubation, because the embryo is not able to control the water loss of egg (Ar, 1991). For optimum hatchability during incubation, eggs need to lose 11-14% of their weight [in the form of water vapour](Banwell,2007). Scientific research and extensive field tests have demonstrated that the relative humidity of air in an incubator for the first 18 days should be approximately 60%, and during the last 3 days, it should be increased to about 70%. High moisture in the incubator prevents normal evaporation and results in low hatchability. Low moisture causes chicks to stick to the shell. Egg turning regulates accumulation of protein in amniotic fluid, affecting embryo growth, hatchability and consequently chick quality. Turning also influences thyroid hormone levels and corticosteroid production, affecting embryonic response to stress (Tona et al, 2005). It prevents the germ from migrating through the albumen and adhering to the shell. The importance of egg turning has been documented in several studies. Tona et al. (2003) indicated that turning in the first week of incubation enables proper formation of extra-embryonic membrane while in the last week avoids embryonic malpositioning. In a related study, Elibol and Brake (2004) confirmed that the absence of turning resulted in presentation of the head in the small end of the egg. Egg turning facilitated the transfer of york nutrients to the embryo via the sub-embryonic fluid (Deeming,
1989a). With modern incubators, automatic turning devices allow the eggs to be turned on hourly basis. However, for table-top incubators, manual turning of eggs is very crucial to the developing embryos. Different types of poultry egg incubators have been recommended for small-scale operations. Irtwange (2003) designed and constructed a passive solar powered poultry eggs incubator to provide free energy from the sun. Because of the high cost of electricity tariff coupled with epileptic power supply particularly in some developing countries, fabricated tabletype paraffin incubators will be acceptable for small-scale hatchery operations. The operation of such incubator for hatching eggs of domestic fowls, turkeys, ducks, quails, etc will greatly expand and enrich the poultry industry. Artificial incubation is favoured in order to increase the production of chicks and protein intake, particularly in the developing countries. Electrical incubators are the best where the supply of electricity is readily available and cheap. In Malawi, various designs of small-scale electrical egg incubators have been developed and some designs are presently manufactured commercially. Malawi Industrial Research and Technology Development Centre has designed and tested three different models of the technology: for small scale (up to 150 chicks), medium-scale (between 150 and 500 chicks) and large-scale (up to 2160 chicks) production. The original design contained no moving parts other than induced draught fans and manually operated swivel trays. The main supply of energy is electricity through use of incandescent lamps to convert light into thermal energy. Field tests proved successful as the unit attained hatchability above 70%. A serious limitation of such design was that it requires a person to monitor the environment inside an incubator to ensure that the eggs receive the correct heat, air and moisture to hatch successfully. However, to better-fit technology to the needs of small-scale day-old chick producers, a need has been identified to re-engineer the unit, to allow simple but automatic monitoring of the environmental conditions. The present work on development of locally made small-scale, automatic poultry egg incubator has been going on for several years. This project was initiated as an answer to the long delays experienced by farmers in Malawi in acquiring a consignment of day-old chicks and the forbidding cost of imported incubators. By establishing local capacity to manufacture efficient and affordable incubators, access to this product would be improved and eventually lead to a sustainable production of eggs and broilers to ensure food self-sufficiency. Therefore, this paper presents the report of the design and construction of an automatic poultry egg incubator using materials that are readily available in the local market with the aim to increase the rate of chicks’ production among small-scale farmers in Malawi. The performance of the incubator was also evaluated.
MATERIALS AND METHODS Automatic Electrical Egg incubator The incubator used in this study (Figure 1) was designed in the Department of Technical Services, Malawi Industrial Research and Technology Development Centre. The incubating cabinet has two compartments. Compartment one (top-most) which houses the induced fans and heating element; and compartment two (bottom) which serves as the setter and hatcher contains egg trays and plastic basin which works as a humidifier. The incubator measures 1.22 m (front wall) by, 1.56 m (lateral wall) by 1.78 m (height) and had 4 trays holding 360 eggs each. The structure is made of angle irons and covered with chipboards. The structure houses egg tray holders and its turning mechanisms. The frame is made of 30x30x3 mm angle irons enclosing 16mm chipboards.The egg tray turning mechanism is made of 25x25x3 mm angle irons and 25x3mm flat bars. Induced draught fans that are centrally position along the width circulate the air; a heating element is positioned in the front of the fans. The frame has side top holes that allow fresh air to enter the incubator and release exhaust air at the side bottom holes. The drive mechanism was designed to turn trays at 450C; the sizing of the drive was based on forces created while turning the full load trays. The calculations were based on the assumed egg weight of 60 g. A timer, limit switches and contactors are used to control the turning intervals as shown in the electrical wiring diagrams. One direction drive motor is used where the angular movement is translated into longitudinal movement. The temperature in electronically controlled through a temperature controller, the heat is supplied through 1kw heating element. The heat is circulated through the incubator by blowing fans that are positioned behind the heating element.
Egg Incubation Fertile eggs of two layer breeds, Black Austrolops and Hy-line were obtained from Mikolongwe Veterinary and Charles Stewart Hatcheries, respectively. The eggs were selected by size and origin, identified and arranged onto the empty trays. The incubator was also fumigated and test run for twenty four hours before egg setting. Eggs were placed in an incubator, provided with an automatic turning facility, at a set temperature of 37.5°C and 60% relative humidity. A plastic basin with water was placed under the egg tray as humidifier. This relative humidity of 60% was provided for these eggs in the incubator for 18 days and it was increased to 70% until hatching. Eggs were turned at an angle of 45° every hour. Fertility was determined via candling on the seventh day of incubation. The eggs were candled on the eighteenth day again, and those exhibiting embryonic mortality were determined and removed from the machine. The incubation period was determined and the hatched chicks were checked for deformities while the un-hatched eggs were opened up to determine the type and cause of mortality. The effect of temperature on the hatchability of fertile eggs and the incidence of embryonic mortality and deformed chicks were determined. The eggs staged as infertile were the ones with true infertility or pre-incubation mortality. They were also staged as early dead embryos or intermediate dead embryos according to embryo mortality stage. Unhatched eggs classified as late dead were the ones with final stage mortality or piped eggs with dead embryos. The fertility and hatchability percentages equations (1) and (2) [Okonkwo, 2002].
were
determined
using
% Fertility=Number of fertile eggsNumber of eggs loaded(set) x 100 % (1)
% Hatchability=Number of eggs hatchedNumber of fertile eggs set x 100 % (2)
A total 3362 eggs (trial 1 [n = 683, BA]; trial 2[n = 1404, HL]; trial 3 [n=398, BA]; and trial 4[n=598, HL and n =279, HL) were used for hatchability tests. The eggs were divided into two treatments: treatment 1 (60% RH; temperature =38°C; n=1275) and treatment 2 (65% RH; temperature = 39°C; n = 2087). Each treatment group of eggs was incubated in an individual incubator, according to its experimental temperature and relative humidity during incubation. The incubator was split into two areas (left and right) and thermometers and hygrometers placed in the geometric center to register temperature and relative humidity. Statistical Analysis All experimental designs were completely randomised, with four treatments and 8 replicates per treatment. The data was analysed using general linear models procedure of SAS for analysis of variance, Comparisons between treatments were made using least-square –means test, and differences were considered significant at P<0.05, when not otherwise indicated. RESULTS AND DISCUSSIONS Hatchability Table 1 shows the calculated hatchability tests parameters for the electricity- powered automatic poultry egg incubator. There were significant differences on percentage hatchability, fertility, and mortality. The results obtained during the first trials show that out of 683 eggs set in the incubator, 283 eggs were infertile. The percentage fertility of egg was 58.6%. Also out of 400 fertilised eggs, 224 eggs were hatched (Table.), which resulted in a percentage hatchability of 66.87%. The second hatchability trial produced the lowest results. Out of 1404 eggs set in the incubator, 764 eggs were infertile. The percentage fertility of eggs was 45.58%. Also out of 640 fertilised eggs, 337 eggs were hatched, which resulted in a percentage hatchability of 57.22%. Parameter
Trial 1
2
3
4*
4**
Number of eggs set
683
1404
398
598
279
Number of eggs hatched
224
337
225
498
29
Number of eggs, did not hatch
95
247
70
100
253
58.6
45.58
86.2
90.7
69.3
66.87
57.22
73.1
83.7
10.4
Fertility (%) Hatchability (%) Mortality:
Dead in Germ
26
38
35
28
240
(%)
3.8
2.7
8.8
4.7
86
Dead in Shell
16
5
13
72
46.2
(%)
8
0.8
4.2
12.0
89.6 Hatchability results are shown in Table 1 above. Treatments 3 and 4 had hatchability 7-15% higher than treatment 1 and 2. The study found that out of 398 eggs set in the incubator, 49 eggs were infertile. The percentage fertility of egg was 86.2%. Also out of 343 fertilised eggs, 225 eggs were hatched (Table.), which resulted in a percentage hatchability of 73.1%. The ..treatment group resulted in 3 to 10% lower hatchability rate the .. and ,, groups. Out of 626 broiler eggs set in the incubator, 61 eggs were infertile. The percentage fertility of eggs was 90.7%. Also out of 598 fertilised eggs, 498 eggs were hatched, which resulted in a (broiler) percentage hatchability of 83.28%. Out of 519 eggs (black austrolop) set in the incubator, 104 eggs were infertile. The percentage fertility of eggs was 69.2%. Also out of 279 fertilised eggs, 29 eggs were hatched, which resulted in a (broiler) percentage hatchability of 10.4%. embryo mortality and those piping reduced the hatchability of the ,,group by..% below,, indicating distress embryos. This reduction in hatchability was attributed to increased rate of live pips. Temperature distribution This research aimed at evaluating environmental conditions inside the incubator. The incubator was split into two areas (left and right) and thermometers and hygrometers placed in the geometric center to register temperature and relative humidity. Table shows production data after hatching. Differences in temperature and relative humidity distribution on left and right, (as well bottom trays ), and also a tendency of lower temperature in these areas were detected; temperature and relative humidity was not distributed homogenously (p<0.05). Available hatchery technology should provide good incubation conditions. However, hatchery equipment and machines frequently do not perform as expected given that temperature adjustments in the setter are not accurate enough to elicit uniform temperature distribution inside the equipment, leading to poor hatchability (Bramwell, 2002). This information was herein confirmed. Temperature values lower than those recommended by literature (37 to 38C) were actually recorded at the lower trays of the incubator, and considered critical points for temperature setting.
Relative humidity Figure shows a typical day diurnal variation of relative humidity of the incubating chamber. A relative humidity range of % to % was maintained in the incubating chamber throughout the incubating period. The temperature and relative humidity obtained in the incubator were within the limit of recommended environmental conditions for incubation[10,16]. The results obtained during the test show that out of 700 eggs set in the incubator, 15 eggs were infertile(Table.). The percentage fertility of egg was 67%. Also out of 78 fertilised eggs, 62 eggs were hatched (Table.), which resulted in a percentage hatchability of 30%.
All sampled areas presented lower relative humidity (RH) values than recommended in literature (Robertson, 1961; Lundy, 1969), ranging from 48% to 65% (Fig 2). These lay below threshold for maximum hatchability (Wilson, 1991; French, 1997). Values of RH were not also homogenously distributed in the incubator (p<0.05). Certain areas had comparatively lower RH values (). Usually RH can vary more than temperature without depressing hatchability. Values of RH lower than 50-60% may induce evaporative cooling and consequent ambient temperature, which may lead to embryo dehydration, increased incubation time and consequent hatching depression or delay (Decuypere et al., 2003). The effects of different temperatures on hatchability characteristics are shown in Table.. Data obtained by the research indicated that the temperature applied during the growth period in artificial incubation of chicken eggs significantly affected the hatchability of fertile eggs and embryo mortality. Hatchability of fertile eggs declined with temperature, for maximum hatchability a lower temperature lower than 37.2 C is desirable in the incubation period. Embryonic mortality tended to increase at 37.2C. Percentages of late dead and fertile hatchability were highest for the 60% and 65% treatment, respectively. These data demonstrated that.. RH appears to have a detrimental effect on embryonic development, as evidenced by the increased percentage of late dead. CONCLUSIONS Simple and relatively cheap artificial incubators that are produced locally are favoured for the increase in production of chicks and protein intake in Malawi. Therefore, in this study, an automatic poultry egg incubator was designed and fabricated using locally sourced materials to make it relatively affordable to the average poor farmer dwelling in a rural area. The incubator consisting of of .. 1440 capacity was tested in Blantyre, to evaluate its performance. The results obtained showed high thermal performance of the system. The incubating chamber was maintained with a dry bulb temperature range of 36 to 38.5, and the chamber was also
maintained within a relative humidity range 58 to 61 % throughout the incubating period. The percentage of fertility of egg and percentage hatchability were found to be .., respectively.
ACKNOWLEDGE MENTS This study was undertaken collaboratively with Mikolongwe Veterinary Station with support of the Malawi Industrial Research and Technology Development Centre on Agricultural Machinery Design Programme. The authors express their gratitude to the staff of Technology Production Unit (TPU) for their careful handling of the egg incubator unit. We also thank R.W. Mkandawire, C.S. Chigwe and K.N. Kalonda for their critical review of this manuscript and their valuable suggestions.
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