Nguyen Quang Suc, Dinh Van Binh, Le Thi Thu Ha and T R Preston1
Goat and Rabbit Research Centre, Sontay, Vietnam
Abstract
This paper reports the results of a preliminary experiment to test the hypothesis that a system of underground shelters would be a way of improving the environment of the rabbit, as compared with conventional raised cages, and thus make it possible to increase productivity in a tropical climate. The study was done with the cooperation of 30 small scale farmers in Ha Tay and Hai Hung provinces in North Vietnam.
All the performance parameters were significantly improved in rabbits housed in the underground shelters compared with the cages. The does in underground shelters were 8% heavier after 2 months in the experiments, they gave birth to 9% more offspring and weaned 36% more than those in cages. Survival rate to weaning of the offspring in underground shelters was improved from 69 to 86%. Parturition interval was reduced from 77 to 49 days.
During the growing-fattening phase, the rabbits in underground shelters were 17% heavier after 1 month and 20% heavier after 3 months with average growth rates that were 23% greater.
It is concluded that the underground shelter system of housing is especially suitable for rabbit production for small scale farmers in tropical regions.
Key words: Rabbits, underground shelters, cages, environment, reproduction. growth, tropics
1 Finca Ecologica, University of Agriculture and Forestry, Thu Duc, Ho Chi Minh City, Vietnam
Introduction
Rabbit breeding is practised almost all developing countries and contributes to family nutrition and economy, though the availability of a source of animal protein, as well as through extra income by scale of animals. Rabbit production has been developing in Vietnam with the conventional system of cages raised above the ground. The major constraints of this housing system are low reproduction due to high temperature in summer (30–35°C) and high mortality of the offspring due to cold (12–15°C) and wet weather in winter. The suitable ambient environment for rabbit production in Vietnam is a temperature range of 18–28°C and humidity between 80 and 86% (Nguyen Quang Suc 1985).
The greatest disadvantage of the cages system is that the rabbits are exposed to high temperatures during the hot season. The impact of temperature rabbits has been studied by various authors. Lebas et al (1986) noted that high temperature affects spermatogenesis, reducing the volume and concentration of ejaculates and also affects sperm motility after 8 hours at 36°C or 14 days at 30°C. High temperature also affects growing rabbits negatively due to reduced rates of liveweight gain caused by the reduction in feed intake. When rabbits are raised at 18–20°C they can reach a live weight of 3 kg by 112 days whereas at 30–31°C they only reach 2.5 kg (Lebas et al 1986).
It has been proposed that the system of under ground shelters, developed by Finzi and Amici (1991), would be a way of modifying the immediate environment of the rabbit and thus make it possible to increase productivity in a tropical climate. This paper reports the results of a preliminary experiment to test this hypothesis carried out on small scale farms in Ha Tay and Hai Hung provinces in North Vietnam.
Material and methods
Treatments, design and feeding
Thirty farmers, who traditionally raised rabbits, were chosen to implement the experiment which consisted of a comparision of some form of underground shelters versus the conventional system of raised wire cages. Each farmer was asked to keep 3 females and 1 males for the observation of reproduction and lactation and 5 weaned rabbits for fattening on each of the two housing systems. The feeding system was the same for both types of housing and consisted of free access to a molasses block, by-products from the kitchen as available (eg: Banana peel, Jackfruit, soya bean residue), grasses (Mostly guinea grass) and tree leaves (from Trichantera gigantea, mulberry, Leucaena leucocephala and bamboo). The experiment began in January 1996 and continued until November 1996.
A more detailed study of the effects of the housing system on temperature and humidity was done between 5 and 15 July 1996 at the experimental farm of the Goat and Rabbit Research Centre, where the same treatments as on the farms were applied.
Housing System
Conventional:
The most widespread housing system in Vietnam is the one which utilizes hutches or cages. This was introduced during the colonial period and imitates the hutch models which were developed during the first phase of intensification of rabbit production, and were later superseded by the wire net cages presently employed in large scale operations world wide.
Alternative systems:
Free range
The free range system is obviously the most simple since it respects the rabbit's natural living
conditions. In a small group (1 buck and 3–5 does) the rabbits will reproduce without leaving
the area if feed and water are regularly supplied and they are kept under control by some form of
periphery fence.
Underground Shelter
The underground shelter is based on the
premise that rabbits under naturals conditions
live in underground “burrows” dug out from
the soil. This can provide a better
environment for the rabbits especially if they
are free to move in and out according to the
climatic conditions. The stimulation of such
Aburrows@ can be done by making a shelter
above or under the ground using stones,
bricks, clay or concrete, which can be covered
by earth. With this system rabbits can choose
the place to make their nest for giving birth.
They can also modify the shelter by “digging”
to enlarge or lengthen the “burrow”.
Integreated free range and underground
The integration of the underground shelter
and limited free range appears to be the
most feasible way for implementing an
improved housing system at household
level. This was the housing system chosen
for the experiment.
Table 1: Mean values for parameters of reproduction and growth of rabbits housed in cages or in underground shelters in small scale farms
Cages | Under-Ground | SE/Prob. | |
Liveweight of doe, g | |||
Initial | 1652 | 1659 | ±20.9/NS |
Final | 2,137 | 2,310 | ±11.2/0.001 |
Litter size at | |||
Birth | 5.57 | 6.09 | ±0.17/0.04 |
Weaning | 3.84 | 5.21 | ±0.22/0.001 |
Parturition interval, d | 77.2 | 48.6 | ±3.9/0.001 |
Weight of growing rabbit, g | |||
1 month | 306 | 360 | ±3.9/0.001 |
2 month | 891 | 1,055 | ±5.3/0.001 |
3 month | 1,365 | 1,639 | ±6.5/0.001 |
Gain | |||
1–3 mth, g/d | 17.7 | 21.3 | ±0.095/0.001 |
Table 2: Mean values for temperature and humidity in cages and in underground shelters at 00.70, 13.00 and 19.00 hours during 10 days period
Day | Temp°C | Humidity, % | ||
Grnd | Cage | Grnd | Cage | |
1 | 28 | 32 | 65 | 60 |
2 | 30 | 35 | 65 | 62 |
3 | 28 | 30 | 76 | 72 |
4 | 26 | 28 | 86 | 80 |
5 | 26 | 30 | 83 | 83 |
6 | 26 | 30 | 82 | 72 |
7 | 26 | 30 | 82 | 74 |
8 | 26 | 30 | 83 | 76 |
9 | 27 | 32 | 84 | 83 |
10 | 27 | 31 | 83 | 80 |
Measurements
On all farms the following performance data
were recorded:
On the experimental farm, the ambient temperature and the humidify were recorded daily at 7.00, 13.00 and 19.00 hours in the cages and in the underground shelters over a 10-days period from 5 to 15 July.
Results and discussion
Effect of housing systems on
reproduction and growth of rabbits
The results from the on-farm trails are presented in Table 1. All the performance parameters were
significantly improved in rabbits housed in the underground shelters compared with the cages. The
does in the underground shelters were 8% heavier after 2 months in the experiment, they gave birth
to 9% more offspring and weaned 36% more than those in cages. Survival rate to weaning of the
offspring was improved from 69 to 86%. The decrease in the parturition interval from 77 to 49
days, in favour of the underground shelter is of major economic importance.
During the growing-fattening phase, the rabbits in underground shelters were 17% heavier after 1 month and 20% heavier after 3 months with average growth rates that were 23% greater.
It was not possible to obtain detailed records on feed intake but most of the farmers observed that the rabbits in the underground shelters are more than those in cages. More precise experiments are needed to confirm this aspect.
Table 3: Effect of housing on temperature and humidity (mean values)
Cage | Grnd | Diff | SE/Prob | |
Temp°C | 29.4 | 25.9 | 3.8 | ±0.33/0.001 |
Humidity, % | 75.9 | 80.4 | 4.75 | ±0.99/0.001 |
Effect of housing systems on temperature and humidity
The results of the study on temperature and humidity during a 10-day period in July in the two housing systems are shown in Tables 2, 3 and 4. Ambient temperature on average was 3.8°C lower (P=0.001) and humidity was 4.75% higher (P=0.001) in the underground shelters compared with the cages. It seemed that these mean differences were maintained throughout the day from 07.00 to 19.00 hours (Table 4).
Table 4: Mean values for temperature and humidity during the day in cages and underground shelters
Temp°C | Humidity, % | |||
Cage | Grnd | Cage | Grnd | |
07.00 | 29.6 | 25.7 | 77.6 | 81.5 |
13.00 | 30.5 | 26.9 | 74.2 | 78.9 |
19.00 | 28.2 | 25.2 | 76.0 | 80.8 |
Conclusions and recommendations
Acknowledgments
This study was financed through a “Letter of Agreement” with the Animal Production and Health
Division of FAO. The authors are grateful to Dr Manuel Sanchez, FAO, Rome and to Dr A Finzi
of the Rabbit Research Centre, Animal Husbandry Institute, University of Viterbo, Italy, for their
suggestions and advice.
References
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
Nguyen Quang Suc 1985 the disease situation of improved New Zealand White rabbits raised in Vietnam. Publication of the Animal Husbandry Research Institute, Hanoi.