Development of improvised housing system for commercial rearing of broiler rabbits

V Ramesh Saravana Kumar, K Sivakumar, D Anandha Prakash Singh, V Ramesh, J Muralidharan and K Viswanathan

Department of Livestock Production and Management
Veterinary College and Research Institute, Namakkal-637 002, Tamil Nadu, India
lpmramesh@yahoo.co.in

Abstract

Conventional ground level rabbit sheds are common in India. Structural details of a conventional improvised ground level rabbit shed and improvised raised platform shed were furnished. The temperature, relative humidity and air velocity in the indoor atmosphere of both sheds were measured and compared with outside atmosphere.

The mean maximum temperature inside the raised platform is 1.3ºC more than conventional ground level house, but the advantage of more air movement help to keep the house comfort to rabbits. Raised platform rabbit house should be surrounded by sufficient trees to reduce indoor maximum temperature in tropical semi-arid climate.

Key words: microclimate, rabbit, raised platform

Introduction

In India, rabbit rearing has attracted farmers since the last ten years. Broiler rabbits must be considered as an important contributor to assure food security because of the ability of the species to produce when only some vegetable resource is available (Finzi 2000). The ever growing demand for meat helps the rabbit industry to grow further and further.  Though it has not made an impact in the meat industry in India, the chances of popularizing rabbit meat still exist. At least 82% of the world’s production of rabbit meat occurs in developed countries (Lebas et al 1986).  Colin and Lebas (1996) carried out a survey on world rabbit meat production and reported that India has 36700 females producing 750 tonnes of rabbit meat with a per capita consumption of 90 g. In the modern production systems of livestock, rabbit rearing is still kept under traditional pattern.  Even though there are many commercial advantages in conventional system, the large scale commercial rabbit rearing needs improvement in housing. In the conventional housing system, rabbits are kept in hutches where either cages or litter floor systems are in vogue. The cage system of rearing replaced floor system in the late 1990’s. The cages are erected on wooden poles, steel bars and on stones.  In some situations cages are hung from the roof also.  There are both positive and negative attitudes for the conventional ways of rearing rabbits. The major constraints of this system are low reproduction due to high temperatures in summer (30-35 ºC) and high mortality of the offspring due to cold (12 -15 ºC) and wet weather in winter. The suitable environment for rabbit production in Vietnam is a temperature range of 18 – 28 ºC and humidity between 80 and 86 % (Nguyen Quang Suc 1985). While reviewing the information available on housing systems for rabbits, not many changes were tried or introduced in India. 

Materials and methods

Two types of rabbit housing systems were used for this study. They were established in Veterinary College and Research Institute, Namakkal, Tamil Nadu, a constituent unit of Tamil Nadu Veterinary and Animal Sciences University, Chennai, Tamil Nadu, India. These rabbit units are being utilized for academic, research and extension purpose. These units are capable of supplying breeding rabbits to farmers, slaughter house of this institute and research needs as well.

Location description

Namakkal district is in the north western region of Tamil Nadu. It is a small district located at 11º09’42.1” N latitude and 78 º09’39.7” E longitude with mean annual rainfall of 760mm.  The average daily maximum temperature varies from 26 ºC during December to 46 ºC during May.  The average daily minimum temperature varies from 15ºC during January to 25ºC in April.  March to June forms the hot season and the hottest months are April and May, though summer showers are quite possible.  The highest maximum temperature registered its maximum (46 ºC) over 10 years on April 18, 1998.  The minimum relative humidity (RH) ranged from 23% to 45% in March, where as the maximum RH ranges from 42% in February to 92% during March.

Conventional rabbit houses

At present, in Tamil Nadu state, thatch roofed (65%) and tile roofed (35%) rabbit houses are common.  The floor is earthen (100%) and almost all the farmers adopt cage rearing.  The cages are of various dimensions and size allowing 0.28 m² per adult.  The cages are erected on wooden poles or iron angels at a height of 0.6 m.  Normally 2 or 3 rows of double sided cages are in use.  The height at ridge normally varies from 3.65 to 4.87 m and at eaves the sheds are 2.13 to 2.74 m high.  The distance between top of the cage and eaves varies from 1.06 to 1.37 m, allowing favourable cross ventilation.  The portion of the floor at the bottom of the cages needs sweeping at least once in 48 hours to remove the faecal materials.  The urine get absorbed into earth thus controls ammonia build up.  The details on microclimatic parameters including ventilation rate and light intensity are not available, since there was no organized work conducted on this subject in this area.

Improvement in housing

The need for improvement in housing system was felt when farmers started recognizing rabbit meat as one of the good quality meat.  This awareness was first created among the veterinary students of this institute.  The increasing meat demand from the students indicated that the consumers were satisfied with rabbit meat.

An old conventional type, Mangalore tile roofed, mud floor, deep litter poultry shed was converted into rabbit shed under cage rearing.  Cages were erected on wooden poles and some cages were hung from the ceiling.  The menace of rats, bandicoots and other predators caused considerable loss in the beginning.

Later, the conventional shed (Shed I) was finished with cement concrete floor and the cages were erected over pillars.  Another modern raised platform shed was also constructed.  The structural details of both these sheds were discussed along with the results of microclimatic variables after subjecting them to test of hypothesis, as suggested by Snedecor and Cochran (1989).

Result and discussion 

Shed I – Ground level house

The dimensions of various structures were furnished in Table 1.

This shed (Figure 1) measuring 27.15 m length and 6.45 m was constructed at the ground level giving 0.6m side wall on two sides (length wise) and a complete wall on eastern and western sides to bear the weight of the roof.  The east to west orientation prevented direct sun rays into the building and facilitated good ventilation.  The sides were closed with chain link (0.05 m X 0.05 m – 2.5 mm size) which is quite cheap, durable and prevent spider web accumulation.  The entries of wild birds were prevented at the eaves.  The floor was finished with cement concrete through out the shed (Figure 2) except at the bottom of all cages, where a pit (width 0.95 m) was dug for a depth of 0.6 m and the floor of the pit is left earthen to absorb urine and spilled water from the cage. 

The droppings were collected in the pit and it becomes no need to clean the droppings daily as in the old system.  The pit when filled (normally it fills by 2 months) was emptied after just by lifting the cage.

The cages were just rested on permanent brick pillars (23 cm x 23 cm) standing at a height of 0.6 m from the ground level (Figure 2).  The distance between two pillars was kept as 1.35 m.  The passages were measured 0.92 m at the sides and 2.17 m in the center.  The central passage was wider since the shed was supported by “cut stone pillars” at the ridge in the centre of the shed.  The pits at the bottom of the cage were provided with a 5 cm tall “brim walls”, for preventing entry of wash water into the manure collection pit.  Sufficient numbers of trees were established as wind breaks.  The microclimatic details of the shed were furnished in the Table 2 and 3.

From the tables it could be evident that the temperature was lower in shed I than in raised platform shed.  Even though shed I was tile roofed, the advantage of green cover around the shed helped to keep the temperature lower than raised platform shed. But in summer tile roof conduct more of heat inside the building.  To overcome this stressful event, water sprayers were useful neglecting little increase in relative humidity.  The cost of construction (Rs. 750.00/head) was very reasonable and this housing system can be recommended to the field.

Shed II - Improvised raised platform

The modern concept in housing started with elevated or raised platform.  The advantages claimed are

i)                    good light

ii)                   good ventilation

iii)                 ammonia free air

iv)                 clean indoor atmosphere. 

The widespread adoption of this system reflects the successful advantages of the new system. 

Ramchurn (1979) reported that a mortality of 80% at the University farm and in the villages of Mauritius, which led to a dramatic drop in the rabbit population. He also believed that poor housing was a contributing factor. In rabbit keeping, though there are only little drawbacks in the conventional housing system, a new raised platform rabbit house was established (Figure3 and 4) in Veterinary College and Research Institute, Namakkal to study its advantages for broiler rabbits. 

This modern shelter was constructed a cost of Rs. 4.0 lakhs.  The structural details are provided in the Table 1. The plinth area of 147.17 square meter (20.3 x 7.25m) accommodates nearly 200 parents or 100 parents and their followers.  The floor was constructed at 1.5 m height from the ground all round.  The litter materials, wasted forage and urine are self collected to the ground through a 1.3 m wide opening below all the cages.  This building had no side wall.  Sides are enclosed with 0.05 m X 0.05 m chain link on length wise and closed solid walls up to the ridge on the wide side in the east and west of the building.

The structures are totally rodent proof with a projecting platform of 0.6 m wide and the steps were kept 0.6 m away from the building.  The roof is gable type with continuous ridge opening (Figure 5) to facilitate upward movement of foul air.  Three rows of cages are kept with four passages.   

The outer two passages (A and D) are kept wider (1.45m) than inner (B and C) passage (0.85m).  The stands (0.6 m height) are carrying the cages and the cages are top open type.

Microclimate

The design of rabbit housing is governed by the behavioural characteristics of the animals and their reactions to environmental temperature and humidity. Rabbits use three devices to modify their heat regulation, they are i) general body position, ii) breathing rate and iii) peripheral temperature (ear temperature). These systems work between 0 ºC and 30 ºC. But when temperatures reach 35 ºC or more, rabbit can no longer regulate their internal temperature and heat prostration sets in. The type of housing provided should bring down the temperature within the above range irrespective of high temperature outside (Lebas et al 1986).   

The temperature, relative humidity and air velocity in the indoor atmosphere of both shed I and shed II were measured (Table 2) and compared with outside atmosphere (Table 3). From the tables it can be seen that the mean temperature did not differ significantly between the sheds. The maximum temperature was more in shed II and the minimum temperature was more in shed I.  This might be due to quick heating in the forenoon in shed I and in the nights the ground radiation temperature did not reach the raised platform. The vice versa must be possible in shed I. The relative humidity is significantly (P<0.01) lesser in shed II than in shed I. Better air movement in shed II might have removed the moisture content both in the forenoons and afternoons.

The ideal relative humidity of an indoor rabbitry is under 75% at a temperature of about 16 ºC.  This is materially impossible to maintain such ideal microclimate unless there is a special control.  Thus the next best alternative to ensure that the relative humidity should not be higher than that of the outside air by more than about 5%, and the temperature should not differ from that outside by more than about 5 ºC.  Usually it is preferable to have both temperature and humidity lower inside the rabbitry than outside, except in cold weather (Sandford 1996).  But, in the present study, the construction method reduced (P<0.05) the mean temperature only by 0.9ºC in shed II, whereas such significant difference was not noticed in shed I (Table 3).  The RH was more in both the sheds than outdoor RH.  This might be due to the availability of green ‘hedge lucerne’ and ‘mulberry’ available around the sheds.  Hence under tropical semi arid climate, the requirement of microclimate recommended by Sandford (1996) for indoor temperature and relative humidity may not be hold good.

Ventilation

In the open sided (both sides open) farm system, natural ventilation is easily achieved, which is essential for the removal of noxious gases, pollutants, moisture, dust and heat.  Morisse (1981) recommended an air speed of 0.30 m/sec to 0.40 m/sec at a temperature of 22 to 25 ºC in France.   In the present case, raised platform house (0.67 m/sec and 0.81 m/sec) had better air velocity than conventional house (0.61 m/sec and 0.78 m/sec) both in the forenoon and afternoon.  Though the maximum temperature (33.2ºC) inside the raised platform house was 1.3ºC more than ground level house (31.9ºC) the benefit of better air movement (0.67 m/sec) in the forenoon helped to keep the rabbits in a comfortable environment.

Conclusions 

• Conventional mud floor sheds shall be finished with cement concrete floor for cleaner environment.
  
  
• In tropical semi arid climate, the shed shall be surrounded by sufficient trees or green cover.
  
  
• Raised platform sheds are beneficial for rabbits in terms of better air movement, lower minimum temperature and protection from predators.
  
  
• In tropics, the indoor temperature and relative humidity shall be conveniently less than the outdoor. 

Acknowledgements 

The authors are thankful to the Dean, Veterinary College and Research Institute, Namakkal and The Tamil Nadu Veterinary and Animal Sciences University, Chennai – 600 051 for providing all facilities and funds for the construction of the new shed.

References 

Colin N and Lebas F 1996 Rabbit meat production in the world. A proposal for every country. 6 th World Rabbit Congress, Toulouse, France, 9-12 th July, WRSA 323-330

Finzi A and Amici A 1991 Traditional and alternative rabbit breeding systems for developing countries. Revista di Agricoltura Subtropicale e Tropicales. Anno LXXXV No: 1: 103-125

Lebas F, Coudert P, Rouvier R and Rochambeau H de 1986 The rabbit; husbandry, health and production. FAO Animal Production and Health Series, No 21 http://www.fao.org/docrep/t1690E/t1690e00.htm

Morisse J P 1981 (quoted in) Lebas F, Coudert P, Rouvier R and Rochambeau H de 1986 The rabbit; husbandry, health and production. FAO Animal Production and Health Series, No 21 http://www.fao.org/docrep/t1690E/t1690e00.htm

Nguyen Quang Suc 1985 The disease situation of improved New Zealand White rabbits raised in Vietnam. Publication of The Animal husbandry Research Institute, Hanoi

Ramchurn R 1979 Improved housing conditions for rabbits. Tropical Animal Production 4 (3): 223-231 http://www.utafoundation.org/TAP/TAP43/4_3_3.pdf

Sandford J C 1996 The domestic rabbit. 5 th Edition. Alden press limited, Oxford.

Snedecor GW and Cochran WG 1989 Statistical Methods. 8^th Edition, Iowa State Press, Ames, Iowa, USA. pp.254-268

Received 25 August 2007; Accepted 1 June 2008; Published 3 October 2008

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