Research Article Volume 2 Issue 4
National Institute of Plant Health Management, India
Correspondence: AMK. Mohan Rao, Sai Viswanatha Residency, MIGH 16, Mehdipatnam, Hyderabad, India, Tel 91 944 065 4555
Received: January 01, 2015 | Published: June 24, 2015
Citation: Rao AMKM, Sakthivel. Role of rodents in poultry environs and their management. J Dairy Vet Anim Res. 2015;2(3):107-114. DOI: 10.15406/jdvar.2015.02.00040
Many poor and middle class farmers in developing countries are taking up poultry since the industry has become a major source of income. Poor quality sheds and their proximity to the crop fields and village habitats result in migration of premise pests like flies, cockroaches, rodents in to the poultry environment contributing to significant losses. Among them rodents take primary share due to their role as pests as well as vectors. They make both qualitative and quantitative losses by feed and egg consumption, losses to the structures, nuisance value causing loss of productivity in the farms. In addition, they transmit dreaded disease like Salmonellosis Pasteurellosis, Mycoplasmosis, Hemorrhagic enteritis, Hymenolepiasis, Capilariasis, and Ascaridiasis to the birds. A Global level review was made on different rodent species responsible for these losses, the characteristic features of major pests. The procedures involved in inspection of the poultry premises and assessing the rodent infestation were spelled out to facilitate planning the rodent management measures. The available management practices of prevention of these unwanted creatures in to the poultry premises along with curative practices viz., using traps and rodenticides were spelled out. It is expected that by managing rodent pests/vectors, both food and health security would be ensured.
Keywords: rodents, salmonellosis, Rattus rattus, Mus musculus, inspection, management
Commercial poultry production is rapidly expanding worldwide to meet the needs of the increasing human population. Further, with the reduced cost and enhanced incomes the per capita poultry meat consumption is increasing. Many poor and middle class farmers in developing countries are taking up poultry to supplement their income and this industry has become a major income source to them. The industry has been growing at 2-3% per year and is expected to continue expansion in the foreseeable future. Global poultry production is anticipated to increase 1.8percent to 106million tonnes in 2013.1 As per Global Production Trends in 2012, the egg production in the world was about 65.5million tonnes and Asia took a share of 38.3million tonnes (58.5%). The egg industry growth from 2000 to 2011 was 2.6per cent per year compared to global growth of 2.3per cent. India, second in egg production in Asia, produced 3.49million eggs during 2011. In India the production has increased from 2million tonnes in 2000 to 3.5million tonnes during 2011 with an average growth of 5 to 6per cent per year.2 This large poultry industry requires extensive housing for the birds to increase the meat and egg production. This intensive production by housing a large number of individuals in relatively small area generates large quantities of wastes (manure, used litter, dead birds) and provides favourable environment for the exponential growth of arthropod and rodent pests. Hence, effective pest management became an essential component for poultry industry. An attempt is made in this review to identify the existing rodent problems as pests as well as vectors transmitting zoonotic diseases, the existing planning strategies and management measures to achieve food and health security.
Poultry pests
Both ecto-parasites and premise pests constitute pest component in poultry environs. The ecto-parasites include mites, lice, fleas, ticks etc. The premise pests include beetles, flies, moths, cockroaches and rodents. Poor quality sheds and their proximity to the crop fields and village habitats result in migration of these pests in to the poultry environs contributing to significant financial losses. The minor pests are attaining often major pest status in high-density large production systems. Among the pests, rodents are the most destructive pests which cause damage directly to the poultry structures by their burrowing nature, gnawing habits and consumption of poultry feed, eggs and chicks. Their indirect impact include contamination of the poultry feed through their urine, faeces and hair. In addition, they also transmit various diseases to poultry birds as well as workers.
Rodent pests: Rodent pests contribute significant losses to poultry farms throughout the world. It is not easy to estimate precisely the losses caused by rodent pests in the poultry situation since both qualitative and quantitative losses occur.3 There is no concerted effort also to estimate the rodent borne losses. As a result precise data on their losses are lacking. An attempt is made to put the available information in this review.
Feed loss: Rodents eat poultry feed and they waste and contaminate more than they eat. With a modest estimate of their feed consumption at 10% of their body weight, the rats consume about 25g per day and 9.1kg per year. If that daily figure is converted to a yearly estimate and if as many as 20 rats are present in a rural poultry shed, the annual loss per shed could reach 0.18ton. If the feed costs $175/ton, that cost would be $31.50 or $1.57per rat. Brooks & Fiedler4 estimated similar loss with respect to Norway rat, 8-12per day with 3-4kg per year for Roof rat and 2-3g per day with 0.7 to 1kg per year for House mouse. In big poultry houses and poultries having heavy infestation the feed loss would be much higher. Hamilton5 and Greeves6 reported an annual loss of 23 and 2kg per animal respectively in the case of Norway rat and House mouse. Rats take 10g of feed for day but destroy 10times of feed and poultry birds refused to take such contaminated feed. This refused contaminated food is unaccounted, while taking rodent related losses. The estimate by ICAR Rodent Research Project in India projected the losses as 94 per 1000 birds in Punjab. Chopra7 reported feed loss ranging from 0.05 to 0.14kg in sheds, 0.18 to 6.38kg in feed store and spillage up to 20kg/day in heavily infested poultry houses. In addition to the feed loss, rodents also spoil the feed through their spillage behaviour. Feed spillage losses were never scientifically estimated.
Losses to the eggs: Several studies in India estimated loss was 0.5% in egg production and some time it reaching up to 10% under poor storage conditions. Similarly, the damage to eggs was estimated as Rs. 0.63/100 eggs/day in Punjab.8 In southern Sindh of Pakistan, rats caused a great loss to poultry farmers by attacking over the eggs, young ones and feed of poultry.9
Losses to the structures: Physical damage to the building and equipment is another way rodents can be costly. One of the main characteristic features of rodents is their gnawing habit. Their upper incisors grow perennially at 0.4mm per day. This has led to their acquired habit of gnawing objects in an attempt to arrest the growth of the incisors. This often results in damage to the non-edible items in their habitat. Rodent damage may start as small initially, but quickly develop into a major problem that will be expensive to correct. Due to the gnawing behaviour, even poultry buildings with fibre glass insulated walls are reported to be vulnerable to rodent damage since they attack and make nest in the insulated walls.10 They gnaw the support structures, plastic curtains, egg belts, egg elevators with sponge fingers, and burrowing under walls and concrete.11 They can inflict severe damage to poultry buildings by establishing the burrows through foundation from underneath or making holes on the roofs resulting in water leakage during rainy seasons, gnawing and nibbling of wooden doors, windows etc.
In feed manufacturing units damage to food conveyer belts have frequently reported over the repair and replacement cost up to $15000.3 Some USDA estimates of the actual cost of rats wasting feed and damaging the house and equipment are as high as $25per rat per year. Another potential problem is the danger of fire due to rodents’ gnawing insulation on electrical wiring. Damage to building insulation is expensive, and the chronic energy losses and associated effects on poultry production magnify that expense.12 Operational shutdowns or power failures due to electrical or mechanical malfunctions as a result of rodent damage can cost an operation thousands of dollars and the possible loss of an entire house of birds in only a few short minutes.
Nuisance value: In addition, rodents, especially Rattus rattus and Bandicota bengalensis cause general nuisance for birds in the poultry house due to their noise and movements. This frightens the birds resulting in poor performance.13 The rodents also cause high mortality rates of chicks and production losses. Rats have been known to kill baby chicks and break and eat eggs and frighten birds by their movements or by noises they create. Research has shown that by reducing the rodent population in poultry houses the bird mortality rate can also be lowered.11
Threat as vectors and reservoirs: Rodents serve as vectors and reservoirs of a large number of infectious organisms, of which Salmonella is of particular concern to poultry producers in recent years. Rodents primarily contaminate animal feed in storage areas and feeders through urine and faeces.14 Rodents can transmit about 35 different diseases affecting man and other domestic animals. Rats and mice are linked to poultry diseases such as Salmonellosis, Colibacillosis, Coryza, Pasteurellosis, Mycoplasmosis, Hemorrhagic enteritis, Hymenolepiasis, Capilariasis, and Ascaridiasis.15 The bacterial diseases include Leptospirosis, Fowl Typhoid, Avian Paratyphoid, Salmonellas, Pseudo Tuberculosis, Fowl Cholera, Erysipelas. Viral diseases include New Cattle disease, Ornithosis and Protozoan infections include Toxoplasmosis and Coccidiosis. All these diseases impact seriously in poultry production.16 Disease problems can have serious consequences of a rodent infested poultry house. Diseases caused by Salmonella species and fowl cholera are those of greatest concern to poultry producers. Rodents also carry ecto parasites such as lice, fleas, and mites.
Salmonella is a dreaded disease characterised by acute gastroenteritis in poultries with vertical transmission spreading over generations.3 Umali DV et al.17 have isolated the salmonella bacteria from the faeces of roof rat in Japan.17 The number of salmonella bacilli per faecal pellet was as high as 1 X 108. Salmonella infection of poultry and the resulting contamination of poultry products can result in multi-state outbreaks of human food poisoning, causing symptoms that range from mild nausea to severe illness, and sometimes death in infected persons.18 In terms of economics, total costs associated with human illness caused by Salmonella infection, and those accrued by poultry producers and the food service industry are substantial. Estimates of medical costs and loss of productivity of infected persons range from $983million to $1.4billion annually. Costs to poultry producers include deaths of animals, reduced feed efficiency and a loss of market value from infected products.19
Rodents have been implicated as one of the epidemiological reasons for regional and worldwide increases in egg-associated Salmonella infection.14 Therefore, decreasing animal feed contamination by rodents and controlling rodent populations should be a primary objective of poultry producers.
In order to translate ecological features of rodents into their management, it is necessary to examine the species, biology and management principles in relation to the types of poultry management and housing. The most effective control measures can be planned only if the kinds of rodents are correctly identified. Very few species of rodents, not more than three at any given situation, are responsible for their negative role in poultry environs. Mostly these include Black rat, Rattus rattus, House mouse, Mus musculus and Brown rat, Rattus norvegicus. The available data on country wise major rodent species are in Table 1.
S. No |
Country |
Major Rodent Species |
Source of information |
1 |
Argentina |
R. rattus and M. Musculus |
Fraschina et al. [20] |
2 |
Denmark |
Apodemus agrarius |
Mino et al.[21] |
3 |
Europe |
Rattus norvegicus and Mus musculus |
Mino et al.[21] |
4 |
India |
R. rattus and B.bengalensis |
Sakthivel P [22] |
5 |
Mexico |
R. norvegicus |
Mino et al.[21] |
6 |
Nigeria |
Meriones species and Peromyscus natalensis |
Mino et al.[21] |
7 |
Pakistan |
Rattus rattus, Mus musculus and Rattus norvegicus |
Pervez et al. [23] |
8 |
Taiwan |
Rattus losea, B. Bengalensis and Mus species |
Mino et al.[21] |
9 |
Thailand |
Bandicota bengalensis and B. indica |
Mino et al.[21] |
Table 1 Major Rodent Species in Poultry environs
The poultry environs often have other burrowing rodent species like Lesser bandicoot, Bandicota bengalensis, Larger bandicoot, Bandicota indica, outside the premises. Other rodent pest species were also reported in India and they are minor (Table 2). There is no information existing on the population dynamics of the pest species in poultry environs except for a study in Bengaluru, India.27 However, such study is desirable for an appropriate planning.
Species |
Habitat |
State |
Reference |
R. rattus* |
Live mostly on roofs and feed storage areas |
AP, MP, Haryana, Maharashtra, Punjab, Rajasthan, South India |
Siddique [24] |
M. musculus* |
Live in Feed storage areas. |
Haryana, Punjab, Rajasthan, A.P. |
Christopher et al. [26] Bharadwaj D & Prakash I [28] |
B. bengalensis* |
These make burrows either inside or along the outer periphery of the poultry sheds. |
A.P. Uttar Pradesh, Punjab |
Christopher et al. [26] |
B. indica** |
A.P. Karnataka |
Christopher et al. [27] |
|
M. meltada** |
A.P. Rajasthan; Rajastan |
Christopher et al. [26] |
|
M. hurrianae** |
Table 2 Rodent species found in Poultry farms in India
*Major pest **Rare pest
Planning rodent management
While undertaking rodent pest management, appropriate planning is necessary. The planning includes inspection of poultry environment and assessing rodent pest infestation.
Inspection of poultry environment
The first step is to conduct a visual inspection of the premises. The purpose of inspection is to determine whether a current or potential rodent infestation exists at a specific location, if so areas of their infestation, routes through which they could establish. Rodent sightings, droppings, tracks, burrows, pathways, fresh gnawing marks, and dead rodents offer the information of their presence. The first line of attack on rodents is preventing their entry inside the structures. The inspection covers garbage dumps, drainage channels, pipes, holes, burrows, electrical or telephone wires, gaps between door and the floor, ventilators, exhaust ducts, water pipe lines and overhanging tree branches on the structures.
The standard Inspection procedure is to:
Rodent infestation measurement
The infestation of rodents could be assessed based on
Visual sighting: The first step in rodent control in poultry is to determine the extent of infestation which can be detected by sighting, droppings, tracks, burrows, pathways, egg damage, fresh gnawing and dead rodents. If the rodents are repeatedly seen in during day time it indicates high infestation.
Trapping method: In situation like storage godowns the rodent species like Musculus and R. Rattus are non-burrowing rodents. They hide in between the stacks and cracks and crevices and make damage to food grains. Under such situation the assessment rodent population can be done by suing trapping index method. There are two ways of determining the trapping index.32
There are two methods for evaluation of the rodent population through trapping –
Single catch traps are laid in the poultry in trap line/grid methods for continuously three nights and the trapping index is computed as follows:
where M=total number of rodents trapped; n = number of traps used in a trap line; t=number of nights
In the CMR Method, the rodents trapped each night are marked and released, and a second trapping is undertaken 1–2days after the first trapping, which may include some marked rodents as well. The population size may be calculated as proportion of marked ones with new ones as follows:
where N=population size; M=number trapped in the first trapping; n=total number trapped in the second trapping and m=number of rodents re-trapped in the second trapping. This method is mostly not practised since farmers do not permit releasing the trapped rats.
Tracking Index: Tracking is one of the simple methods used for assessing rodent incidence. Generally, talcum, chalk or fine sand are used to track of rodent activity in indoor condition,33 but these materials may cause adulteration of the feed and is drifted with air. The study made by Rao et al.,34 have standardised the tracking method with the natural colouring material. Alcohol with colour powder was found to be the best one when compared to other products and it gives the clear foot prints (Figure 1). Vinyl tiles (30X15cms) were treated with different tracking materials like turmeric, colour powder, stamp pad ink, charcoal powder applied with alcohol slurry (to avoid the drifting) for generating clear foot prints. Tracking material, when applied as thin film in the middle area (10x15cm) of the tiles, leaves foot prints of moving rodents. Such tracking tiles with the foot prints can be considered as positive and without foot prints as negative. Even rodent species also could be identified based on nature of foot prints. The tracking index (T.I.) can be calculated using following formula:
Live Burrow Count Method (LBC): This method is based on the active (live) burrows of rodents around the poultry premises. The species like Bengalensis leave fresh excavated (scooped) soil as small pebbles at the main entrance.35 Since these bandicoots are solitary in living, number of active burrows indicate approximate rodent incidence in the area. This is a feasible method to estimate the burrowing rodent population in poultry environs. Other burrowing rodents like B. Indica and Tatera indica make their burrows near wet or dry conditions, especially in poultry manure and the ground below the slabs and along the walls outside.
Since poultry growers are unaware of the severity of rodent infestation and its impact on poultry and public health, the issue of rodents is rarely paid attention. Effective rodent control in and around the poultry houses involves both preventive–sanitation and rodent proofing; and curative measures with population reduction.12
Sanitation
Clean premises discourage rodents to inhabit in any area. Sanitation through maintenance of sheds, surroundings and equipment clean, removal of weeds, garbage, and waste material around the premises prevent the rodent infestation.16 The trees and other planting materials in and around the poultry house must be removed to reduce rodents harbouring the area. The sheds should be sanitized to minimize the risk of disease to incoming flocks of birds. The poultry house should not have proximity to residential houses to avoid unsanitary conditions. Proper storing of poultry feed is essential since rodent infestation is always high at storage level. The feed should be stored inside the storage bin or bags are properly stacked on wooden pallets. Debris such as old equipment, old boards, etc., affording rodents hiding or nesting place should be removed. Maintain at least a 3-foot space around the perimeter of the poultry house that is free of bushes and trash.
Rodent proofing
The basic philosophy of rodent proofing is elimination of all rodent entry points as per the inspection made. In most cases, it is often cost prohibitive, but rodent proofing needs to be undertaken in all feasible areas for long term maintenance of rodent free poultry premises.16 In addition all the storage areas need to be made rodent proof. Other measures could be:
Curative measures
Where rodent proofing isn’t practical, other techniques of rodent control need to be considered. In spite of measures taken for prevention of rodent entry into the poultry structures, sometimes they may enter inside through feed bags or any other source. In such an eventuality they need to be managed. The methods which are in vogue include trapping and chemical application. The methods like biological control or ultra-sonic devices will not yield desirable success in poultry environs.
Trapping:
Trapping is an effective, quick, and economical control approach to
Traps are used in situations where baits may pose a hazard. Rodents will not travel far from their normal activity areas and hence more numbers of traps should be placed. Trapping is more effective where a rodent population is high. There are different types of traps used to control the rodents in poultry. They include non-poisonous sticky (glue) traps and mechanical traps.
Multi-catch traps are designed to repeatedly catch several numbers of rodents with one setting and the scent from the captured rodents entices others to the trap (Figure 3). However, these traps are expensive. Also, the captured rodents should be killed by drowning them in to water for 5minutes. Releasing captured rodents outside is not a solution, since they will quickly find a way back into the structure. Traps must be checked regularly to prevent the captured rodents from starving or dying of thirst and creating an odour problem.
Other types of traps can also be used. One of the inexpensive and eco-friendly indigenous trap - Palmyrah basket kill trap is made up of bamboo was evaluated in poultry sheds (Figure 4). The trap was found to be effective against the R. Rattus and B. Bengalensis. Total 21,827 rodents were trapped during January 2011 to 2013 in the poultry premises around Hyderabad, India (Table 3).
Year |
Total Trap Nights |
R. rattus |
B. bengalensis |
Overall Rats Trapped |
Overall Trap Index |
||
Number of Rats Trapped |
Trap Index |
Number of Rats Trapped |
Trap Index |
||||
2011 |
29200 |
7257 |
0.24 |
604 |
0.02 |
7866 |
0.26 |
2012 |
18200 |
4738 |
0.26 |
899 |
0.04 |
5637 |
0.3 |
2013 |
32400 |
7286 |
0.22 |
1028 |
0.03 |
8324 |
0.25 |
Combined |
79800 |
19281 |
0.72 |
2531 |
0.09 |
21827 |
0.81 |
Table 3 Trap index data of rodent species trapped from Palmyra basket trap in poultry farm during January 2011-December 2013
Chemical control
Use of rodenticides is the most common, expedient and humane method to control pest rodents and became a normal practice for rodent management strategy in most parts of the world.3 They have greater scope in large-scale control operations, since a mixed population of several species are encountered in the poultries. Many rodenticides in different formulation have been tested and being used throughout the world. Although both acute (fast acting) and chronic (slow acting) rodenticides are available, only chronic ones are desirable in poultry premises due to hazard of accidental or secondary poisoning. The chronic rodenticides in most of the countries are anticoagulants and act on multiple feeding or death is delayed. This will prevent possible non target animal mortality.
The poultry industries suffer from the rodents that cause economic losses to the poultry growers throughout the world. Looking at the economic loss caused by rodents in poultry sector by rodents, it is quite essential to create awareness among the poultry farmers and motivated to take up rodent control in an integral way as envisaged above for food and health security of the World. Integrating the preventive measures with cleanliness and structural improvements coupled with trapping and baiting with different rodenticides are the important tool for the management of rodents. At the same time safe and judicious use of the rodenticides will avoid secondary or accidental toxicity to the non-target animals.
The authors are grateful to the Director General for encouragement.
Author declares that there is no conflict of interest.
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