Growth Performance of Broilers in Experimental Reovirus Infections

Background: The avian reoviruses have emerged to induce various manifestations in chickens. They are associated with disease conditions including malabsorption syndrome, tenosynovitis etc. Reoviruses are an important cause of suboptimum performance in broilers, resulting in poor growth performance. Poultry industry in India is facing a catastrophe due to such infections which go unnoticed in field due to masking of the symptoms by secondary infections and commonly observed nutritional disorders. Aim: To investigate the effect of reovirus infection on overall performance of broiler birds. Material and Methods: The broiler birds were challenged with homologous strains of malabsorption syndrome and tenosynovitis syndrome of reovirus. The growth performance was recorded. Results and conclusion: The growth performance and immune response to NDV did not differ in the birds challenged with tenosynovitis syndrome strain of reo virus as compared to un challenged birds. However, poor live body weight, feed intake, FCR, PE and BPEI and better serum NDV titres were found in chicks challenged with malabsorption syndrome strain of reo virus as compared to the chicks from control group.


Introduction
feeders.The signs of illness may include diarrhoea, catarrhal enteritis, stunted and uneven growth, poor The avian reoviruses were considered to be feathering, hydropericardium, pericarditis, hepatitis harmless in the past.But they have emerged to induce and respiratory signs [7].The farms with such infection various manifestations in chickens.They are associated suffer from heavy economic losses due to higher with disease conditions including malabsorption culling rate, poor feed conversion ratio, reduced and syndrome (MAS), femoral head necrosis, pericarditis, variable body weights at the time of sale.myocarditis, hydropericardium, gastroenteritis, The next important manifestation of reovirus hepatitis, and acute and chronic respiratory syndromes infection is tenosynovitis/viral arthritis (TSS).It is [1,2].Reoviruses are an important cause of suboptimum usually seen in young birds 4 to 7 weeks old but may be performance in broilers [3,4,5].These disease seen in much older chicken also.Though the mortality conditions, many times, go unnoticed in field due to remains less than 6%, morbidity may reach to almost masking of the symptoms by secondary infections and 100% in the infected flocks [7].Economic losses commonly observed nutritional disorders [6].
caused by tenosynovitis/viral arthritis are due to the In affected flock, especially at early ages, a small lameness because of viral arthritis and a general lack number of birds (1-5%) show severely stunted growth of performance including diminished weight gain, and a considerable proportion (10-50%) show variable poor feed conversion and a reduced marketability of growth rate in MAS.All the affected birds do not show the affected birds.the signs of illness but remain active and voracious The present study was aimed to investigate the effect of reovirus infection on overall performance of Feed conversion ratio: The feed conversion ratio broiler birds.
(FCR) for each group was calculated using standard formula.

Materials and methods
Broiler performance efficiency index: The broiler All the necessary permissions from Institutional performance efficiency index (BPEI) was calculated Bio-safety Committee and Institutional Animal Ethics using standard formula [8].Committee had been obtained to carry out the research work.
Protein efficiency: The protein efficiency was calculated based on unit protein consumed to unit body weight Broiler Birds: A total number of 100 straight-run, day gain in each group, separately [9].old and healthy "Vencobb" broiler chicks were obtained from M/s. Venkateshwara Hatcheries Ltd., Immunity: The immune status was recorded by Pune.They were equally divided into four groups (A, estimating serum antibody titres against NDV vaccine B, C and D, n = 25 per group).The birds were reared by Haemagglutination Inhibition Test.under deep litter system following standard and Mortality: Mortality was recorded as and when uniform managemental practices.
occurred and sent for the post mortem examination to Vaccines and Virus: All the vaccines viz.LaSota, the Department of Pathology, Veterinary College, IBD, IB and inactivated IBH vaccine and virulent Udgir, Maharashtra, India.Reoviruses were obtained from M/s. Ventri Biologicals, Statistical analysis: The data obtained on various Pune.The required medicines and supplements were parameters studies during these trials was subjected to purchased from local market.statistical analysis following standard methods [10].Broiler Feed: The broiler feed (starter and finisher)

Results and Discussion
was obtained from M/s. Huma Hatcheries and Breeding Farms, Udgir.
Live Body weight: The data on live body weight of broilers is indicated in Table -1.

Challenge studies:
The results revealed no significant difference in Experiment 1 (TSS): Fifty, day old susceptible live weights up to the age of 3 days.The chicks chicks were equally divided into two groups, group A th challenged with homologous strain of tenosynovitis and group B. On 46 day of age, group B was challenged syndrome reo virus (Group B) showed non-significant 4 with 0.1 ml of 10 TCID (per bird) of tenosynovitis 50 difference in body weights throughout the observation syndrome strain of Reovirus via left intra-foot pad period of 60 days when compared with control group A. inoculation.The group A was kept as unchallenged The chicks from group D showed significantly control.The birds were further observed for 14 days lower weight gain after challenged with homologous after challenge.strain of malabsorption syndrome reo virus when Experiment 2 (MAS): Fifty, day old susceptible compared with control group C. The uneven growth chicks were equally divided into two groups, group C rate and live weights were recorded in group D after and group D. On third day, group D were challenged challenge.In control group C the growth was found to 4 with 0.1 ml of 10 TCID (per bird) malabsorption 50 be uniform with increasing trend in body weight.syndrome strain of Reovirus via intra-muscular route.
Feed Intake: The overall feed intake of the broiler The group C was kept as unchallenged control.The chickens throughout the experiments has been presented chicks were observed daily for 24 days after challenge.in Table-2.

Growth Performance:
In experiment 1, the feed intake did not differ in Live Body weight: The birds from each group were the birds challenged with tenosynovitis syndrome weighed individually on day 3, 14, 21, 28 (Group A, B, strain of Reovirus (group B) as compared to birds from C, D) and 35 and 60 (Group A, B).Mean live body control group (group A) throughout observation period.weight (g/b) was computed.
However, the results of experiment 2 indicated that the feed intake was reduced in chicks challenged Feed Intake: Measured quantity of feed (g/b) was with malabsorption syndrome strain of Reovirus offered to the birds of each group and the left over feed (group D) as compared to the chicks from control was recorded after completion of the experiment.The group C. difference between the feed offered and the left over feed was recorded as actual feed intake.
Feed conversion ratio: The feed conversion ratio (FCR) for each group has been presented in Table-2.
Reovirus (group D) as compared to the chicks from In experiment 1, the FCR did not differ in the control group C. birds challenged with tenosynovitis syndrome strain In experiment 1, the immune response to of Reovirus (Group-B) as compared to birds from Newcastle disease virus vaccine did not differ in the control group (Group-A) throughout observation period.
birds challenged with tenosynovitis syndrome strain However, the poor FCR was recorded in chicks of reo virus (group B) compared to control birds challenged with malabsorption syndrome strain of (group A) up to the age of 60 days.

Reovirus (Group-D) as compared to the chicks from
The results of trial 2 indicated better serum NDV control group C. titres were recorded in group D as compare to group C up to the first 27 days of their age.Broiler performance efficiency index: The broiler performance efficiency index (BPEI) has been Mortality: No mortality was recorded in any group presented in Table -2.throughout the experiment.In experiment 1, the BPEI did not differ in the During the present investigation, all birds birds challenged with tenosynovitis syndrome strain inoculated with Reovirus were developed the disease. of Reovirus (Group-B) as compared to birds from It indicated that the birds are most susceptible to avian control group (Group-A) throughout observation period.
Reovirus infection at a young age [11].The Reovirus However, the poor BPEI was recorded in chicks infection is suggestive of suppressive factors [12].challenged with malabsorption syndrome strain of Though the vaccine strains of Reovirus differ from Reovirus (Group-D) as compared to the chicks from field strains, majority of strains are virulent [13,14].control group C.
Investigators documented anaemia, nonuniformity and poor performance that had reportedly occurred in Protein efficiency: The protein efficiency (PE) has several successive grow-out flocks on a commercial been presented in  broiler due to this infection [15,16].Avian Reoviruses In experiment 1, the PE did not differ in the birds are an important cause of economic losses in challenged with tenosynovitis syndrome strain of commercial poultry [17].

Reovirus (Group-B) as compared to birds from control
The GI tract has the most extensive exposed group (Group-A) throughout observation period.
surface in the body, and a wide variety of factors However, the poor PE was recorded in chicks associated with diet.Infectious disease agents like challenged with malabsorption syndrome strain of

Table - 1
. Body weight of broiler chicken throughout the experiments.The chicks infected with malabsorption syndromeArkansas Cooperative Extension Service -Division of strain of Reovirus showed poor growth performance.thestudy.MBK recorded the data.SPA 10.Snedecor CW, Cochran WG.,(1994).Statistical th analyzed the data.SPA and SJM drafted and revised methods (6 edn).Lowa State Univ.Press Anes, USA.11.Dana Goldenberg, Avishai Lublin, Ezra Rosenbluth, the manuscript.All the authors read and approve the E. Dan Heller, Jacob Pitcovski.(2011).
such that birds had easy access to food and water.However, the birds from challenged with tenosynovitis 8.Ali Mervat A. (1999).Effect of probiotics addition to syndrome strain of Reovirus showed no significant broiler rations on performance and some blood difference in growth performance.constituents.Egypt.Poult.Sci.J., 19: 161-177.9. Persia M. E., C. M. Persia, M. Schang and J. Azcona.Author's contribution (2003).Nutritional evaluation of dried tomato seeds.SPA designed and conducted the study.SJM and DMB Poultry Science associated,141-146.managed Differentiating infected from vaccinated animals, and