Biological monitoring of vaccine take and productive parameters in broilers vaccinated with

Transcription

1 Biological monitoring of vaccine take and productive parameters in broilers vaccinated with immune complex and recombinant vector vaccines against Infectious Bursal Disease (IBD) Luiz SESTI 1, Carlos Kneipp 1, Yannick Gardin, Branko lva 1 CEV Saúde nimal, Paulínia, SP, Brazil CEV Santé nimale, Libourne, France 011 nnual Meeting of the P merican ssociation of vian Pathologists July tlanta, G, US Biological monitoring of vaccine take and productive parameters in broilers vaccinated with immune complex and recombinant vector vaccines against Infectious Bursal Disease (IBD) Luiz Sesti, Carlos Kneipp, Yannick Gardin, Branko lva live Immune Complex vaccine and a recombinant vector vaccine were compared for their biological characteristics of vaccine take and productive parameters from vaccinated broilers. Two () controlled field trials in low IBDV field challenge farms were carried out to monitor the biological characteristics of vaccine take between 35 and 4 days of age (IBD serology / Bursa of Fabricius [BF] weight / lymphoid depletion / BF viral colonization by molecular techniques). In addition, productive parameters of broilers vaccinated with both vaccines were also compared (average slaughter weight, feed conversion, total mortality, daily weight gain). Vaccines were applied via subcutaneous route at 1 day of age. The Immune Complex vaccine induced a significantly more uniform expected biological characteristics of vaccine take as well as a trend for better productivity parameters than the recombinant vector vaccine. Reference: Sesti, L; Kneipp, C; Gardin, Y & lva, B (011) Biological monitoring of vaccine take and productive parameters in broilers vaccinated with immune complex and recombinant vector vaccines against Infectious Bursal Disease (IBD). Proceedings of the 011 nnual Meeting of the merican ssociation of vian Pathologists P, July 011, tlanta, G, US.

2 Objective To compare biological characteristics of vaccine take and productive performance in broilers vaccinated against IBD with either an immune complex () or vector () vaccine. IBD vaccines Immune complex () vaccine (Cevac Transmune IBD) Composed by a live intermediate plus IBDV vaccine strain (Winterfield 51) complexed with specific b against it. Vector () vaccine Composed by a live recombinant Marek s HVT vaccine strain expressing the VP of a classical IBDV (rhvt-ibd).

3 Field trial 1 preliminary survey (end of 009) SP state Brazil (southeast) Small integration company (3.5 million broilers / month) Good biosecurity Very low vvibdv field challenge Materials & Methods broiler flocks 44,640 birds broiler flocks 44,640 birds vaccine Day one - SQ vaccine Day one - SQ Statistics random analysis of variance with Tukey HSD ll-pairwise test at p<0.05 level (Statistix 9.0) Sampling done between 3-35 days of age: Blood (Elisa serology 5 samples per flock) Bursa of Fabricius (BF) o Weight (10 BF) o Histopathology (5 BF) o RT-PCR / RFLP (5 BF)

4 .5 Individual Bursa weight (g) average = 1.08 g average = 1.7 g p< Bursa histopathology BFs lymphoid depletion score 3 1 Lymphoid depletion score in BF (Dr. Fred Hoerr) Lymphoid depletion Score 0-5% % 51-80% 3 >81% No statistical difference between vaccines average =.7 average = 3

5 Elisa Serology (Idexx IBD classic) b titers (lowest/ highest/gmt) No statistical difference between vaccines RT-PCR/RFLP results BF 1 BF BF 3 BF 4 BF 5 1 POS POS POS POS POS POS POS POS POS POS 1 POS POS NEG POS POS POS POS POS POS POS RFLP results flocks = strains detected W51 and G15 strains (local strains) flocks = W51 and G15 strains (no vaccine take = no classical strain s VP)

6 Broiler performance 5 51, ,5 50 Slaughter age (days) Mortality (%) Transmune Vaxxitek Transmune 5.04 Vaxxitek Final weight (kg) ,5 1,5 1 0,5 0 Feed Conversion (kg/kg) Transmune Vaxxitek Transmune Vaxxitek Broiler performance Daily Weight Gain (g) Meat Production / m (kg)

7 Field trial (010) RS state Brazil (south) Medium size cooperative (10 million broilers / month) Medium to low biosecurity Medium vvibdv field challenge Materials & Methods 10 broiler flocks 113,00 birds 10 broiler flocks 113,600 birds vaccine Day one - SQ vaccine Day one - SQ Statistics random analysis of variance with Tukey HSD ll-pairwise test at p<0.05 level (Statistix 9.0) Sampling done between 3-35 days of age: Blood (Elisa serology 5 samples per flock) Bursa of Fabricius (BF; 10 per flock) o Weight (10 BF) o Histopathology (5 BF) o RT-PCR / RFLP (5 BF)

8 Individual Bursa Weight average = 1.3 g Individual BF weight (g) average =.3 g B / 39% > g / 61% 1- g Bursa histopathology =.9 BFs lymphoid depletion score =.4 B Lymphoid depletion score in BF (Dr. Fred Hoerr) Lymphoid depletion Score 0-5% % 51-80% 3 >81% 4

9 Elisa Serology (Idexx IBD classic) = 48 GMT = 1698 B RT-PCR / RFLP results Flocks positive to G3 (W51) = 80% Flocks positive to G9 (Faragher s VP in rhvt) = 80% RFLP results flocks = W51 and G15 strains flocks = Faragher s VP and G15 strains

10 Broiler performance Slaughter ge (days) verage Weight (kg) Feed Conversion (kg/kg) Broiler performance Mortality(%; p<0.10) Daily Weight Gain (g).56 B Production Index

11 Final Comments Vaccination take of both vaccines can be clearly monitored in the field. Broilers vaccinated with the vaccine presented more uniform characteristics of vaccine take. Broiler performance was slightly better for vaccinated broilers in both surveys as normally seen in large data banks in the field. Bursa weight, serology and molecular results clearly indicate that vaccinated broilers are not fully protected against IBDV strains present in the environment (field and/or vaccine strains). These data deny the concept that broilers with larger BFs will perform better and confirm what has been observed in the field worldwide. The use an immune complex vaccine containing an intermediate plus vaccines strain is absolutely safe and presents a greater possibility of allowing better broiler performance than a vector vaccine (i.e., better protection against subclinical challenge). Thanks so much! Luiz Sesti, DVM, MSc, PhD International Technical Manager Ceva Saúde nimal Ltda. Paulínia, SP, Brazil luiz.sesti@ceva.com