Young females, sentinels of viral circulation in beef cattle herd Results of BVD monitoring in Cher & Loir-et-Cher PSAl
Objective • To develop a general monitoring tool like in dairy herd • No additionnal constraint for breeders : ⇒ Requires only prophylaxis blood samples • Low cost: => Pooled blood serum
Device development • Thesis of Benjamin SAUTEREAU (NANTES 2005) in Cher department. • Test = Elisa p80 LSI : – Antibodies witnesses of viral multiplication ; – Only 1 vaccinal crosstalk : Mucosiffa (/mucobovin); • Objective = to find a representative sample of the herd. – Comparative study : herd seroprevalence vs. age group seroprevalence – Test used out of instruction for use : exploitation of the raw results of inhibition percentage
Device development • Pools of 5 blood serums are too sensitive and doesn’t represent the group’s seroprevalence.
Device development • Serologies on pools of 20 blood serum, sampled within the whole herd are not correlated to herd seroprevalence
Device development • Serologies on pools of 20 blood serum are correlated in intragroup seroprevalence (age group)
Device development • For big herds, serological results on young animals (1 year-old heifers) are not a good indicator of BVD’s circulation in the rest of the herd (breeding in a separate group).
Device development • Serological results of 3 years-old heifers (G3 = 24-36 months) are a good indicator of herd seroprevalence. Seroprevalence/G3 > 60% � Herd seroprevalence > 55% ⇒ G3 are sentinels of viral circulation ! (linked with presence of IPI animals or several transitory viremic animals)
Raw results of screening Distribution of inhibition percentages classes of pooled blood samples of Loir-et-Cher beef cattle herds => Threshold determination to discriminate both populations with our results Distribution of inhibition percentages of pooled blood samples of Loir-et-Cher beef cattle herds
Raw results of screening ⇒ Both populations are more difficult to discriminate, many « intermediate » situations. ⇒ Representative of an high prevalence «open» system . By inhibition percentage classes 700 600 500 400 300 200 100 0
Multiannual evolution ⇒ Best segregation of populations and higher «favorable» proportion. ⇒ Effect of control plans (since 2006). (we hope)
Multiannual evolution => Stability of the distributions (low farm density), thus stability of chosen thresholds
Thresholds (re)validation Agrees with B Sautereau’s Thesis (ENVN 2005 – GDS18) 2 65% 1 35% 0 ⇒ Implementation of a rating system 0/1/2 (ABD in Cher).
Obstinacy of ratings Distribution livestock/rating Evolution rating « 0 » Evolution rating « 2 » ⇒ Implementation of a monitoring system, in order to decrease the variations of intermediate rating = sequences 0/1/2 such as BVD monitoring in dairy herds
Comparison of dairy and beef cattle device séquence Statut commentaire 2013 000 A non infecté récemment 100 A non infecté récemment A B C D E 010 A non infecté récemment A 61% 1% 001 A non infecté récemment 2 011 B infection limitée (stoppée ?) 0 3% 1% 1% B 111 B infection limitée (stoppée ?) 012 B infection limitée (stoppée ?) 0 C 1% 1% 112 B infection limitée (stoppée ?) 9 021 B infection limitée (stoppée ?) D 9% 2% 121 B infection limitée (stoppée ?) 101 B infection limitée (stoppée ?) E 5% 1% 16% 210 B infection limitée (stoppée ?) 110 B infection limitée (stoppée ?) 211 B infection limitée (stoppée ?) 002 C séroconversion ? 2013 102 C séroconversion ? A B C D E 222 D contaminé 122 D contaminé A 83% 2% 1% 212 D contaminé 2 221 D contaminé 0 B 3% 2% 1% 022 D contaminé 020 E cas particuliers 0 1% 1% C 201 E cas particuliers 9 120 E cas particuliers D 2% 2% 202 E cas particuliers 200 E cas particuliers E 2% 220 E cas particuliers
Costs and Feasibility Loir et Cher Cher Feasibility : Realization on prophylaxis blood samples (no additional intervention of the veterinarian). « Mass programming » DAP / DAI in Sigal. = AUTOMATIC (1 minute programming / year) Results out of Sigal (specific informatic Results out of Sigal (specific informatic data exchange) and out of prophylaxis data exchange) reports Cost : 12,5 € / livestock /year (8 € for dairy Cost : 14,7 € / livestock /year herds)
Prospects Loir et Cher Cher Preservation of the alert device Preservation of the devices: Implementation of a personnalized BVD - «targeted assanation» ; assessment - personnalized BVD assessment. Be capable of establishing statutes Non_IPI on the basis of these epidemiological criteria, such as for the dairy livestocks of the CDC ACERSA: Females > x months in " Super A " (AAAA) (research needed)
Conclusion • A simple and low cost device for BVD monitoring in beef cattle herds • Adaptable (and needs to be adapted) to the epidemiologic situation. • Exploitable as a guarantee criteria : further investigations needed
Aknowledgments • Daniel Parizot • Benjamin Sautereau • Rémi Vermesse • Esthel Thieri-pigé Contact : serge.nouzieres.gds41@reseaugds.com
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