Occurrence of Respiratory Affections in Commercial Broiler Chicken Reared in Srinagar (J&K) India

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1 Journal of Veterinary Advances Occurrence of Respiratory Affections in Commercial Broiler Chicken Reared in Srinagar (J&K) India Itoo F. A., Kamil S. A., Mir M. S., Khan H. M., Darzi M. M. and Khan A. A. J Vet Adv 2014, 4(1): Online version is available on:

2 ISSN: MIR ET AL. Occurrence of Respiratory Affections in Commercial Broiler Chicken Reared in Srinagar (J&K) India Itoo F. A., Kamil S. A., Mir M. S., Khan H. M., Darzi M. M. and Khan A. A. Sher-e-Kashmir University of Agricultural Sciences and Technology of Kashmir, Shuhama, Srinagar, (J&K) India. Mountain Reserach Centre for Sheep & Goat Centre for Research on Poultry. Abstract The present study was aimed to study the occurrence of respiratory tract affections in chickens in urban and suburban areas of Srinagar. A total of 186 broiler flocks with flock strength ranging from 374 to 10,000 birds were screened. Clinical history, mortalities and morbid pathology were noted. Studies carried out included evaluating mortality pattern with special reference to clinical and postmortem examination of respiratory involvement, estimation of mortality due to respiratory involvement on the basis of necropsies conducted. Overall mortality recorded was 3.5%, with the flock wise mortality ranging from 1.1 to 20%. Clinical signs observed were dullness, depression, ruffled feathers, nasal exudate, rales, cough, sneezing, dyspnoea, conjunctivitis and swollen head. Necropsy of 5200 carcasses revealed 46.79%, 55.43% and 44.79% occurrence of lesions in trachea, lungs and air sacs respectively. The gross lesions observed in trachea included congestion (28.97%), exudates (26.52%), congestion + exudates (26.16%), haemorrhage (4.76%) and caseous plug in larynx and trachea (13.81%). Lesions observed in lungs included congestion (100 %), consolidation (13%), nodular lesions (6.6%) and urate deposits (3.81%). Air sacs showed cloudiness (67.3%), thickening with fibrinous or caseous deposits (32.69%) and urate deposits (3.06%).The present study revealed that respiratory tract affections constitute an important component of morbidity and mortality among broiler chicken reared in Srinagar and its adjoining areas. Keywords: Broilers, respiratory affections, srinagar. Original Article Corresponding author: Sher-e-Kashmir University of Agricultural Sciences and Technology of Kashmir, Shuhama, Srinagar, (J&K) India. Received on: 01 Mar 2013 Revised on: 25 Mar 2013 Accepted on: 23 May 2013 Online Published on: 29 Jun J. Vet. Adv., 2014, 4(1):

3 OCCURRENCE OF RESPIRATORY AFFECTIONS IN... Introduction Poultry is an essential component of economy and a good source of high quality protein for farmers in temperate northern Himalayan regions of Kashmir. Besides being an integral part of rural backyards, commercial broiler farming is a growing industry in the urban and sub-urban areas. Despite the enormous potentials the poultry industry holds, the inherent nature of production system predisposes birds to various diseases leading to direct and indirect losses in terms of mortality, morbidity with increased maintenance and medication costs, and decreased production i.e. poor weight gain, loss of weight and decreased feed efficiency (Siddique et al., 2008 ; Bell, 2009). Majority of the farms in Kashmir being small and medium scale, the impact of disease is overtly serious. Respiratory tract infections are of paramount importance in the poultry industry because they are a significant component of the overall disease incidence in poultry and have a complex nature (Malik et al., 2004; Roussan et al., 2008; Ahmed et al., 2009). The pathogens which may initiate respiratory disease in poultry include a variety of viruses, bacteria, fungi and parasites. Environmental factors may augment these pathogens to produce the clinically observed signs and lesions. Also, respiratory disease observed in a flock may be a component of a multisystemic disease or it may be the predominant disease with lesser involvement of other organ systems especially the disease like infectious coryza and infectious laryngotracheitis, wherein the disease may be limited to the respiratory system, at least initially (Reece et al., 1986). Respiratory diseases are topic of active research pursuits, because respiratory tract, being open to external environment, falls prey to a combination of various factors (Roussan et al., 2008). Although studies have been carried out in different parts of world including India, there seems to be no report on the systematic study on prevalence and pathology of spontaneously occurring respiratory diseases of poultry birds in Kashmir. Present study was aimed to investigate the occurrence of respiratory tract affections in broiler chickens in urban and suburban areas of Srinagar. Materials and Methods Study Material A total of 186 broiler flocks with strength ranged from 374 birds to 10,000 birds situated in and around the Srinagar area were monitored during the rearing period. Also, poultry carcasses brought for diseases diagnosis to the Department of Veterinary Pathology, Sher-e-Kashmir University of Agricultural Sciences and Technology Kashmir, constituted the material of study. The investigation approach included- farm visits, collecting history from the farmer/farm manager, and postmortem examination. Mortality Pattern Mortality pattern was studied by recording flock strength and mortality of various broiler flocks. Flock association with respiratory affections was recorded as- 1) Negative - with no clinical signs and none of the birds necropsied revealing any respiratory lesions; 2) Primary respiratory affection major cause of ailment is respiratory affection with majority showing respiratory signs/ lesions at necropsy observed only in respiratory organs; and 3) Secondary respiratory affection - respiratory affections as a part of systemic disease/ ailment (with lesions also, in organs other than respiratory system). Clinical Signs The clinical signs were recorded on the basis of information from the farmers and personal farm visits. Specific attention was given to signs with clinical association to respiratory affections viz. nasal secretions/exudates, conjunctivitis, rales, coughing, sneezing, dyspnoea, etc. Occurrence and Nature of Lesions Representative number of carcasses from the mortality in different flocks was necropsied. Systematic examination was carried for lesions in URT, trachea, lungs and air sacs. The lesions observed were recorded. The lesion severity was recorded as mild, moderate and severe. Overall 351 J. Vet. Adv., 2014, 4(1):

4 MIR ET AL. occurrence of respiratory affections was evaluated as proportion of birds necropsied. Occurrence of individual lesions observed in each organ was evaluated as per cent of carcasses showing respiratory lesions. In case of systemic diseases with respiratory involvement lesions observed in other organs were also studied. Results The overall mortality observed in 186 flocks, with a total of 4, 88,942 birds was 3.5% (17,121 birds). Flock wise mortality ranged from 1.1% to 20%. Clinically birds suffering from respiratory affections were dull, depressed, with ruffled feathers and drooping wings (Fig. 1). Excessive nasal exudate was frequently observed. The exudates were clear and watery to turbid, tenacious and mucoid in nature. Other signs observed included moist or dry rales, coughing, sneezing and dyspnoea. Gasping was observed in some cases, occasionally there was conjunctivitis and in few cases head was swollen. Fig. 1: Broiler chicken of 18 days age suffering from respiratory affection showing depression, ruffled feathers and drooping of wings. Necropsy examination of a total of 5200 carcasses revealed gross lesions in respiratory tract in 33.61% (1748/5200), while 66.38% cases had no respiratory lesions. The occurrence of primary respiratory lesions 21.42% (1114/5200) was significantly higher than the respiratory lesions secondary to systemic ailment 12.19% (634/5200). Lesions were present either individually in trachea, lungs and air sacs, or more than one part of respiratory tract (multi area lesions) were involved simultaneously. In general occurrence of lesions in lungs 55.43% (969/1748) was significantly higher than in trachea 46.79% (818/1748) and air sac per cent (783/1748). Multi area lesions were observed in 39.18% (685/1748) carcasses. Lesions were observed in broiler carcasses throughout rearing period but appeared to be more frequent during later period of rearing. Out of the 818 carcasses showing lesions in trachea, congestion was a predominant finding and was observed in 28.97% (237/818) carcasses, followed by exudate without congestion in 26.52% (217/818); congestion with exudates in 26.16% (214/818); caseous plug in larynx and trachea in 13.81% (113/818); and haemorrhage in 4.76% (39/818). Congestion varied in severity from mild to severe and mucosa invariably revealed swelling and reddish discoloration. Congestion was more sever in birds with primary respiratory affection and occasionally in respiratory disease having 352 J. Vet. Adv., 2014, 4(1):

5 OCCURRENCE OF RESPIRATORY AFFECTIONS IN... multisystemic involvement like New castle disease. Nature of the exudate varied from mucous to caseous. Exudates in younger birds generally was catarrhal, whereas the cases associated with ascites or severe colibacillosis, revealed large quantities of dirty copious exudate filling the lumen of trachea. In cases with concurrent congestion and exudates the nature and severity of either condition varied from case to case. In most cases, exudates was sanguinous, while it was caseous in primary respiratory disease (Fig. 2). Caseous plugs were creamy to cheesy pilings, partially or completely occluding the lumen. Fig. 2: Trachea of chicken revealing congestion of mucosa and presence of caseous exudates. Lung lesions, observed in a total of 969 carcasses, were invariably associated with varying degrees of congestion (100%). The congestion was severe in per cent (423/969) cases, mild in per cent (273/969) and moderate in per cent (270/969) cases. Congestion was mostly bilateral and in mild to moderately affected cases lungs appeared darker than normal. Severely congested lungs appeared moist, oedematous and voluminous, and exuded blood tinged fluid on incision. Other lesions observed included consolidation 13% (126/969), nodular lesions 6.6% (64/969), and Urate deposits in 3.8% (37/969) cases. Consolidation ranged from patchy to diffuse, usually unilateral and associated with moderate to severe congestion. In cases with bilateral consolidation, lungs were enlarged. Few cases also revealed dark brown to blackish discolouration, along with hepatization of lungs and were heavier than the normal (Plate-3 C). Nodular lesions were associated with aspergillosis. The nodules were yellowish, caseous and varied in size from lentil to gram. These nodules at times were studded deeply in tissue thereby distorting its shape. The extent of involvement was from few discrete lesions involving part of lung to complete involvement of both lung lobes (Plate-4A). The nodules generally extended into air sacs and other visceral organs in most of the cases. Urate deposits on lungs appearing as diffuse to sparsely sprinkled chalky white masses, were seen as part of visceral gout. 353 J. Vet. Adv., 2014, 4(1):

6 Grossly lesions observed in air sacs included cloudiness in 67.3 (527/783), thickening in 32.69% (256/783) cases, and Chalky white urate deposits sprinkled on surface 3.06% (24/783). In a few cases of aspergillosis, yellowish nodules were observed on the surface of air sacs. Abdominal air sacs were most frequently and severely affected. Most of these cases were associated with lesions in the lungs and the trachea. Thickening of air sacs was usually associated with presence of fibrinous or caseous exudates and were associated with severe cases of colibacillosis or ascites. Discussion Mortality of birds in poultry production facilities represents a major economic loss for poultry producers and the integrators. Varying mortality rates have been reported from different places. The mortality observed in this study is in concordance with report from India and abroad. Mortality up to 4 per cent in broilers has been reported by Tabler et al., (2002). Joshi et al., (2004) reported 4.38 per cent mortality in ten broiler farms with a total strength of 68,378 birds, in and around Anand district of Gujarat state. Bhende (2006) also, reported an average mortality of 4.55 per cent in large broiler farms and 5.63 per cent in medium broiler farms in Karnataka. However higher mortality 34.9 per cent has been reported by Saleque et al., (2003) in broiler in Bangladesh. At the broiler farm, the weekly mortality rate changes through time. Heier et al., (2002) reported the average weekly cumulative mortality of 1.54 during the first week and 0.48% a week during the remainder of the grow-out period, while Behra et al., (2009) reported 47% and 26% mortality in first and second week, respectively, in and around Bhubaneswar. The differences in the mortality rate reported by various workers as well as that observed during this study may be attributed to multiple reasons. While the geographical area and period under investigation constitute the major variants, the management practices at the farm and design of study also, has great impact on the observed mortality. Besides the disease outbreaks greatly modify the overall mortality rate at a given point of time. In addition to the above-mentioned causes of MIR ET AL. broiler mortality, several other factors may also influence mortality rates. Genetics, sex of bird, health and immune status of breeder flock, hatchery sanitation, longer grow out periods, and degree of on-farm culling may all affect mortality within a normal range when acute mortality does not result from temperature stress or disease (Tabler et al., 2002; Yassin et al., 2009). Environmental stress and sudden death syndrome have been recognized as important cause of early mortality among broilers (Aengwanich and Simaraks, 2004). Chick mortality is used as one of the indicators of the occurrence of welfare problems (European Union, 2007). Achievement of low mortality rates serves as guides to good management practice. At a broiler farm, the daily cumulative mortality rate in at least 7 consecutive flocks should be below 1% + 0.6% x slaughter age of the flocks per day (Yassin et al., 2009) and higher mortality rates warrant critical evaluation. The respiratory involvement is usually observed early in its course because of its prominent overt effects which are easily discernable through visual and auditory examination. Further, interference with breathing has immediate effects on all systems resulting in signs of generalized weakness and depression. However, the signs observed are either non-specific with respect to the nature of respiratory ailment or at least occur in a group of related diseases. Nasal exudate is frequently observed due to high ammonia levels, in infectious coryza and fowl cholera. However, it is also observed in ND, IB, ILT, Avian influenza-a, and Vit. A deficiency. Rales, coughing, sneezing and dyspnoea indicate respiratory impediment or irritation. They are frequently observed in ILT, but also in IB, ND, aspergillosis, and vit-a deficiency. Conjunctivitis and swollen head occurs in infectious coryza, and Mycoplasma infection (Saif et al., 2003). In this study per cent broiler birds necropsied showed lesions in the respiratory tract and ranged from to per cent. The observations correlate well with the clinical picture and flock mortality observed with respect to respiratory affections. The incidence of respiratory affections during early period of rearing is comparatively low which has been attributed partially to maternal immunity (Heller et al., 1990) 354 J. Vet. Adv., 2014, 4(1):

7 OCCURRENCE OF RESPIRATORY AFFECTIONS IN... providing some degree of defense as well as early deaths preventing development of grossly discernable lesions in respiratory tract. Although, the vaccinations against important diseases do prevent outbreaks of fulminating diseases in later life, they do not provide total protection against development of subclinical lesions. Further, the bird s immune system responds through acute inflammation and if this local inflammation causes only mild damage, the respiratory tract recovers in 7-10 days. In this respect, the trachea and bronchi have good repairing capacity followed by parabronchi, while lungs have poor healing capacity (Nighot et al., 2002). Also, after 3rd week broiler birds are under high production stress increasing generalized predisposition to disease as well as causing production diseases like ascites which are associated with severe respiratory involvement (Decuypere et al., 2000). The occurrence of respiratory tract lesions is much higher than earlier reports. Timurkaan et al., (2008) carried out a slaughterhouse study and reported 1.27 per cent occurrence of gross lung lesions. The observed discrepancy may be attributed to the fact that only naturally dead birds having history of respiratory ailments were included in present study. Gross lesions observed in trachea of broiler carcasses during present study varied in their nature and severity. The differences could be attributed to stage of disease progression and nature of ailment. Tracheal congestion is the first and foremost response to aerosol irritants and infections. Atmospheric ammonia in poultry facilities has long been recognized as a significant environmental problem in chicken (Beker et al., 2004). The concentration of ammonia may rise markedly in poorly ventilated houses where it may exceed 200 ppm (Carlile, 1984). Ammonia levels as low as 20 ppm for extended periods damages tracheal mucous membrane impairing mucus flow and tracheal ciliary action. (Al-Mashhadani and Beck, 1985). The condition is usually complicated by secondary infections such as Newcastle disease and Escherichia coli infections (Saif et al., 2003) besides predisposition to metabolic disturbances like ascites, with multisystemic involvement (Beker et al., 2004). This is in concurrence with the observation that severity of lesions observed was more with primary respiratory affection and in respiratory disease with multisystemic involvement like New castle disease. Moderate irritation of mucous membrane causes grossly visible congestion and/or increased fluidy mucous. In more severe and complicated cases exudate may be copious, dirty or much viscous and mucous membrane may present haemorrhages. Excess mucus in the trachea is observed in IB (Ignjatovic and Sapats, 2000; Cavanagh and Naqi, 2003), while severe hemorrhages and mucus plugs have been regarded as characteristic lesions in ILT (Sellers et al., 2004). In the present study no attempt was made to isolate the causative agent and hence the role of viral pathogens in causation of lesions in trachea cannot be ruled out. The pattern of lung lesions observed in present study is in concurrence with earlier reports (Timurkaan et al., 2008). Aengwanich and Simaraks (2004) observed that congestion, oedema and hyperaemia of lung were consistent finding in broilers under heat stress. Lungs having slow recovery power, when compared with other parts of respiratory tract, are apt to develop progressive lesions. While congestion is the immediate response to an irritant, consolidation reflects chronic progressive or severe nature of the irritant. Such lesions have been associated with a myriad of respiratory affection notably atmospheric ammonia and dust, colibacillosis, salmonellosis, ND, ILT, and ascites (Harish et al., 2005; Saif et al., 2003). Air sac lesions in broilers have been regarded characteristic for Mycoplasma and E. coli infection (Levisohn and Kleven, 2000; Marius Dwars et al., 2009; Lutful Kabir, 2010). Lesions have also been observed in Haemophilus paragallinarum (Droual et al., 1990). It has been observed that the caudal group of air sacs is most prone to infections while the cranial group of air sacs is less often affected. This has been attributed to the fact that all of the gas inhaled must pass through paleopulmonic parabronchi prior to reaching the cranial air sacs, resulting in the trapping and removal of most foreign particles. On the other hand, the gas that enters the caudal group of air sacs passes only through over-ventilated neopulmonic parabronchi (Scheid et al., 1989) or directly into these air sacs 355 J. Vet. Adv., 2014, 4(1):

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