Incubating capacity of broody hens and chick performance in Bangladesh

I M Azharul, H Ranvig* and M A R Howlider**

Department of Livestock Services, MOFL, Bangladesh and Network for Smallholder Poultry Development , KVL, Denmark; (Postal address:689/A Khilgaon, Shipaibag, Dhaka 1219, Bangladesh)
azharul72@yahoo.com
^*Department of Animal Science and Animal Health, The Royal veterinary and Agricultural University(KVL), Büllowsvej 17, 1870 Fredericksburg C., Denmark.
Han.Ranvig@ihh.kvl.dk
^**Department of Poultry Science, Bangladesh Agricultural University, Mymensingh, Bangladesh.
marhowlider@yahoo.co.uk

Abstract

A study was conducted to determine the optimum number of eggs to be incubated under a broody hen of given size and to compare hatchability of eggs and performance of chicks when different numbers of eggs were set under hens of different sizes. Two classes of broody hens, weighing 800-950 g (WC 1) and 950-1100 g (WC 2), were used to incubate 8, 11, 14 and 17 eggs under the traditional method in rural conditions of Bangladesh. Hatching eggs, from parents (Rhode Island Red ♂ × Fayoumi♀), average of 41.3 ± 2.77 (SD) g and with a shape index of 66%, were set under the hens.

No differences were found in hatchability rate (%) of fertile eggs among the different egg numbers and between the hen weight classes. Number of eggs had no effect on survivability of chicks, but hens of WC 1 had higher chick survivability (95.4%) compared to WC 2 (87.4%). Broody hens had a 40% reduced feed intake (wheat grain) and body weight loss of 12% during the incubation period.  Weight gain of chicks during last 4 weeks and 8 weeks of rearing (fed on a commercial diet) .were highest in case of 8 eggs (404 g), lowest with 17 eggs (329 g) and medium with 11 or 14 eggs (370 and 361 g respectively) of incubation. Feed efficiency was the same for all birds; it was high during the brooding period. During 8 weeks of rearing total feed consumption was reduced with the increased number of chicks. 

The current study demonstrates conclusively that the statement 'The smaller the broody hens the lower the incubating capacity' may not be true. Indigenous broody hens have the capacity of incubating (87.2% hatchability on fertile eggs) up to 17 eggs weighing an average of 41g. Small broody hens could protect the chicks better from predators, thereby increased chick survivability up to 95.4% compared to big hens (87.4%). However, the incubation of 14 eggs by broody hens will be more profitable to farmers of Bangladesh.

Key Words: Broody hens, eggs, hatchability, incubation, survivability of chicks

Introduction

In Bangladesh, traditionally indigenous hens are used both for egg production and subsequent hatching of eggs. Although broodiness is a hindrance for good egg production (Pampin and Ruiz 1998), the broody hen is doing a great job to hatch the chicks at very low costs. The broody hen is appropriate for the households as a hen can incubate two or three clutches of eggs in a year. The broody hen is also the best trainee for their offspring in showing them how to look for feeds and to tackle adverse situations i.e. finding protection from predators. In most cases people probably put more eggs than the hens are able to hatch. A significant number of eggs have probably been lost in the country by this way. The matter is important, as egg production from indigenous chicken is only 35 to 45 eggs per year (Bulbul et al 1983). Khan (1983) found that the indigenous fowl lays 50-80 eggs per year on average. So we should not allow any leakage to spoil a lot of eggs, which may subsequently reduce the total number of chickens. By optimizing the hatching capacity, the chicken population as well as number of healthy chickens could be increased markedly. The indigenous hens have small body size of around 1,140 g (Huque 1993). The size of hens and number of eggs set under each hen might influence the hatchability of eggs and the subsequent successful rearing of chicks (Haque et al 1991). An investigation was therefore designed to observe the effects of placing different numbers of eggs under hens of a given size to optimize the number of eggs to set for getting the maximum number of chicks and their performance in the early life of rearing period under rural conditions of Bangladesh.

Materials and methods

The experiment was carried out at Taragonj Upazilla, 40 km north of Rangpur District, Bangladesh. It was performed under the activities of Participatory Livestock Development Project (PLDP). A survey was first conducted to investigate the availability of a sufficient number of broody hens as well as the interest of the farmers.

Broody hens

Broody hens were chosen from two villages primarily by asking the farmers and later they were set on dummy eggs. The hens showing nesting behavior for 3 to 4 days were selected for the experiment. Using the dummy eggs is also a good way to synchronize and settle down all the hens to sit at a fixed time. At the beginning, 16 broody hens were selected, and two weeks later another 16 hens were found in the same way. Care was taken that the hens were in good health and had all their normal feathers. Broody hens were categorized into two classes:  weighing 800-950 g as WC1 and 950-1100 g as WC2. The age of the broody hens ranged from 1 to 4.5 years, assumed by the farmers. The hens were set in the afternoon (3-6 pm) with the original hatching eggs replaced by dummy eggs. The hens were usually allowed to come off their eggs at least once every day and to stay as they wanted usually 5 - 30 minutes. The sitting birds were provided with clean water twice daily in a plastic drinker, adequate amounts of whole grains (wheat) in a plastic feeder placed about 3 ft from her nest. Every day grain was supplied was weighed, and residuals were also weighed to determine the feed consumption of the birds.

Control of ectoparasites

To free the birds from the lice, the hens were thoroughly dusted 4 days prior to setting the hens, with Neguvon (0.3%) mixed with ash i.e. 3 g Neguvon powder was mixed with 1 kg of ash. If  lice appeared on a chicken during incubation, liquid Ivomec was also used by applying 2 drops on the neck of the hen. A local traditional method (rural people usually burn the hatching nest and all its materials immediately after incubation) was applied to free the hens from the ecto-parasites sulsuli(Dermanyssus gallinae) if they appeared on the broody hen and her newly born offspring. Sinduri (F. trombiculidae) is another kind of ecto-parasite. It is of a red color and generally lives in a cluster, mainly thoracic region of chickens of any age. A mixture of malathion (0.4%) was sprayed manually on Sinduri-affected places of birds (Permin and Hansen 1998).

Hatching eggs

The average size of the eggs  used for incubation was 41.3±2.77 g, of 5 days of age and shape index 66% with clean, good, strong shell texture, collected from parents Rhode Island Red (RIR) × Fayoumi (Fy). The offspring of those parents is locally called Sonali. Shape index (%) was calculated as the ratio of width and length of the egg multiplied by 100. The standard shape index is 73-80% (Kosenko et al 1985)

After collection from the Government poultry farm, eggs were carried about 2 km by rickshaw, carefully kept in plastic cages and placed with the smaller end down in a well-ventilated room for 4 days. On the 5th day, the selected eggs were carried to the research area about 40 km by bus and rickshaw and then kept for 2 to 3 hours before they were set under the hens.

The nest

A bamboo basket with the size of base 25 cm, height 18 cm, width up 40 cm (PLDP model) was filled to a half portion with ashes. Over the ashes, fine soft straws were placed and later pressed down to make a hollow for placing the eggs. The hen was then gently seated on the eggs and left undisturbed in a quiet corner usually under the bed (Banergee 1992).

Candling the eggs

To examine the infertile eggs and dead embryos in the shell (embryonic mortality), eggs were candled on the 7^th and 14^th day of incubation with a Candler box made of wood and torch light, making the house dark by closing the door and other openings. Infertile and other eggs with dead embryos were removed on the 14th day.

Brooding and rearing of chicks

Chicks were brooded and reared by the same hen that incubated them. They were confined in a day shelter, locally called Polo (base 70 cm, height 45 cm, open top 20 cm) up to one month of age and then they were let out for one hour from the beginning of the 2^nd month with 1 hour increase in each subsequent week up to 2 months of age. At night the chicks with the hen were kept in a night shelter, locally called Khacha (base 60 cm,  height 45 cm,  open top 20 cm) approved by PLDP model. The floor space, of day shelter and night shelter was 1.54 m² and 1.13 m² respectively, and was the same for different numbers of (8 to 17) chicks with the hen.

The broody hen was provided with a commercial layer mash feed (100 g/day), restricted for her in a separate feeder, and the chicks with a layer starter feed ad libitum in a plastic feeder. The diet for the chicks contained (manufacturer supplied information) Metabolizable energy 11.9 to 12.3 MJ/kg and crude protein 19%, crude fiber 3%, crude fat 4%, lysine 1%, methionine 0.4%, calcium 1% and available phosphorous 0.45%.

During the feeding time, mother and chicks were confined in separate cages, so as not to share the feeds of one another. After they had been fed completely, the mother was allowed to come into the chicks' shelter, where they could drink clean water together. The allowance of a bird was divided into two, one portion supplied in the morning between 8.00 and 10.00 am and the rest was given in the afternoon between 2.00 and 3.30 pm. The chicks were vaccinated for Newcastle disease at 5 and 20 days and for Gumburo disease at 14 and 28 days of age according to the instructions of the manufacturer. Hen and chicks were examined for health and parasites every week.

Statistical analysis

The recorded and calculated variables were for a 2 (WC) * 4 (ENG) factorial experiment with multiple observations per cell (4 hens per combination) repeated in two periods, analyzed using analysis of variance by GLM procedure of SAS software (SAS , Version 8.2). An analysis of variance was performed to partition variances into: Weight class (WC) of hens, Egg number groups (ENG), Period, WC*ENG and errors for comparison of different variables. When the interaction between WC and ENG was found to be non-significant, the interaction was deleted and finally analysis was performed for WC, ENG and period. Differences for all significant effects were tested using Duncan's Multiple Range Test. Assumptions for the analysis were evaluated using residual plots and Shapiro-Wilks test for normality. A significance level of 5% was used.

Results and discussion

Hatching performance and survivability

In this trial, there was good uniformity in the weight of the broody hens, egg weight, shape index of egg and fertility rate (%) among ENG (Table 1). Although fertility rate was very close to the significant level (P=0.057), this did not affect the hatchability, as true hatchability rate (%) was calculated on fertile eggs. Fertility rate of crossbred Sonali (RIR*Fy) ranging from 83 to 94.4%, almost coincided with the results reported by Kicka et al (1978), who obtained the highest fertility 92.3% in RIR*Fy. Hatchability rate on fertile eggs ranged from 85.8 to 87.4%, whereas Kicka et al (1978) reported 72.2% of hatchability of crossbreds of RIR*Fy. Since RIR and Fayoumi are different breeds, a certain level of heterosis could be expected from their cross. Hatchability was increased by 5 to 20 % in most crosses reported by Byerly et al (1934). Here the shape index of egg was 66%, under the long index, <73% (Kosenko et al 1985) that is 9.6% less than the lower limit of the standard index, which might be a reason for overall reduced hatchability. In Morocco, Benabdeljelil et al (2001) found 64-78% hatchability, incubated by the local 'Beldi' hen weighing about 1.2 to 1.4 kg, a finding that is lower than that of this study. Although both are native chickens, hatchability may vary due to different environments in the countries. Also the weight of the Beldi chicken was higher, but hatchability was lower than in the present study. In this study average hatchability on total eggs set was 76.8±2.44%, which is supported by Rodriguez (2001) in Cambodia, who observed that hatchability in local Khmer hens was 74.5±7.4% from total wt of eggs 441g (10.8 eggs) weighing 41.0 g per egg. However, even though average egg weight was almost the same (41.3 g), egg numbers set were different in our study. The author did not mention weight of the broody hens. There is a tendency to decrease the hatchability with the higher weight of broody hens found in this study of WC1(87.1%) and WC2 (86.6%), where upper weight class hens had apparently a little lower hatchability.

Table 1 shows that 8% more chicks survived in WC1 than in WC2 (P=0.045). A probable explanation is that broody hens of lower weight, may also be at lower age, are more smart, active, run first, and more clever to teach the chicks how to protect themselves from the predators than the hens of higher weight. There was a trend to decrease the survivability with the increased number of chicks, as it is easier to take care of few chicks for mother hens. Only 9% (27 out of 310) chicks died due to various reasons of which 56% (15) were due to predators, 22% (6) to accidents, 15% (4) to nutritional diseases and 7% (2) were beaten. Azizul and Reza (1990) reported the mortality of upgraded birds was 13.63% under village conditions of Bangladesh, which is higher than in the present findings (9%). Semi-scavenging rearing systems may have caused the lower mortality rate in this study. Swan (1999) also agreed that chicken losses due to predators are high in the PLDP areas of Bangladesh. Predation is the ultimate fate of most chicks and growers (Wickramaratne et al 1994). Mongoose was mainly (87%) responsible for killing birds. If bushes or paddy crops were near to the farmer's house, the mongoose hid there and took the chicks away when they came to search for feed. During the crop season farmers should be advised to confine the chicks and give them household wastes, or what they are able to supply in the day shelter. Because loosing the birds by predators is a much greater economical loss than the reduced weight of birds due to lack of food.

Feed Consumption of Broody hens

Broody hens, belonging to different ENG and WC, consumed the same amount of feed (Table 2) during the incubation period. Feed intake was influenced by the 2 weeks interval period of hatching, probably due to variation in temperature and interaction between hen weight classes and egg numbers.

In week 3, it was observed that birds of all ENG and WC increased their feed intake meaning that they spent less time in the nest compared to weeks 1 and 2. This is also justifying the fact that the temperature requirement at the end stage of incubation is less "as the embryo nears full development, the heat produced in its body increases" (Oluyemi and Roberts 1979). An adult laying hen consumes about 115 g whole grain in a confined system (Boorman and Freeman 1979). Broody hens for this study consumed an average of 70 g feed i.e. reduced their feed intake by 40%, which disagrees with the report of Zadworny et al (1988) who found 63% reduced feed intake in Japanese dwarf bantam hens, Chabo.  Weight loss of broody hens was on average 118g (12%) by the end of incubation.

Body weight gain of chicks

Table 3 illustrates that during the last 4 weeks and for the whole period E₁ gained the highest body weight, E₂ and E₃ were intermediate and E₄ the lowest (P=0.027). Body weight gain tends to be lower with an increased number of chicks.