Manipulation of the broody period to increase egg production of indigenous hens under rural conditions in Bangladesh

Manipulation of the broody period to increase egg production of indigenous hens under rural conditions in Bangladesh

Indigenous hens started to lay eggs at 190-200 days with an average of 3.5 clutches of 12.5 eggs each. After each clutch the hens brood on the eggs for 3 weeks, the eggs hatch and the chicks are reared to 9 weeks of age. The hen then commences to lay another clutch with an average interval of 9.3 weeks and during the 240 days of the present study period the birds produced 42 eggs/hen. When a management intervention was made and the chicks were confined at 4 weeks of age the hens reduced the interval between the broody periods from 9.3 to 5.5 weeks and increased the number of clutches from 3.5 to 5.0, producing 60 eggs during the 240 days' study period, which is an increase of 18 eggs per hen (43%).

KEY WORDS: Bangladesh, indigenous breeds, laying hens, scavenging, broody period, egg laying rate, manipulation of nursing system

In rural Bangladesh mostly indigenous hens are kept. They have evolved from the Indian Red Jungle Fowl and their production is low. This may be due to the pronounced instinct of brooding and a long period of nursing baby chicks.

The endocrine basis of both incubation and brooding has been well reviewed by Eisner (1960) who determined the genetical variation in parental behavior and methods of inducing and reducing the broody periods.

The objective of the present study was to investigate the possibility of increasing egg production by reducing the period of brooding and thereby increase the number of laying days.

The study was carried out in a village near the Bangladesh Livestock Research Institute. Sixty four local birds were identified as layers by the method described by Nesheim et al (1979) and were individually wing-banded. Thirty two layers were kept as control without any interference in the traditional management practice; for the other thirty two layers the reduction of the nursing period was manipulated by placing the 4 weeks-old chicks under a traditional bamboo structure to separate them from the mother hen for 3 days. However, they were returned to this confinement for four weeks for supplementary feeding. During this period they were provided with broken rice, wheat and fresh water ad libitum. No vaccination program was used during the period under observation.

According to previous observations, indigenous hens in the rural scavenging system, start to lay at 190-200 days with 3.5 clutches of 12.5 eggs each and an average egg weight of 39 g. After each clutch the hens brood for a period of three weeks and they hatch chicks with an average weight of 27 g. The chicks are reared by the mother hen for about 9 weeks until they can look after themselves. The hen then commences to lay another clutch.

In the village study, the average interval between the broody periods without any interventions was found to be 9.3 weeks (Table 1) and the group of hens in the traditional system of nursing produced 42 eggs/hen during the 240 days that observations were made. When an intervention was made and the chicks were separated at four weeks of age, the mother hen was observed to enter a dispersal stage for three days after which she started to feed independently without paying attention to the chicks. At this stage chicks were freed from confinement. After five days the hen started to lay a new clutch and thus the interval between the broody periods was found to be 5.5 weeks. The average number of clutches during the 240 days of observation was found to be 5.0.

Table 1 Influence of system of chick rearing on egg production and intervals between brooding

System of nursing	N1 of hens	Avr Wt (g)	No clutch /hen	Interval Broody period (weeks)	Total number eggs/hen

Traditional	32	890	3.5b	9.3a	42b
Confinement from 4 wks	32	910	5.0a	5.5b	60a

a,b: values within a column with no common superscripts are significantly different (P<.05).

The number of clutches by the traditional system is about 3.5, but after reducing the nursing period it increased significantly (P:0.05) to 5 clutches/hen. Egg production of indigenous hens under the traditional rural system was 42 eggs/hen during the 240 days of the observation period, but after separating the chicks from the hen at 4 weeks of age and reducing the interval between the broody period from 9 to 5 weeks the number of eggs laid per hen was found to be 60, which is an increase of 18 eggs per hen during the 240 days of observation (43%). In other words, the laying percentage was increased from 18 to 25%, which is the performance observed by two exotic breeds in another study (Sazzad 1992).

Eisner E 1960 The relationship of hormones to the reproductive behavior of birds referring especially to paternal behavior: a review. Animal Behaviour 8:155-179

Nesheim M C, Austic R E and Card L E 1979 Poultry production. Lea and Febiger pp86-91