Trial in­di­cates farm­ers could do with­out an­tibi­otics

Irish Examiner - Farming - - DAIRY SECTOR - Dr Aideen Kennedy, Re­searcher,Tea­gasc, Moorepark Re­search Cen­tre, Fer­moy

Glob­ally, there is con­cern over de­vel­op­ment of an­timi­cro­bial re­sis­tance (AMR). In­ter­est in AMR has in­creased re­cently with the emer­gence of multi-drug re­sis­tant “su­per­bugs”. A num­ber of these “su­per­bugs” rep­re­sent a se­ri­ous threat to hu­man health.

It is es­ti­mated that each year, drug-re­sis­tant in­fec­tions re­sult in 25,000 pa­tient deaths, and cost the EU €1.5 bil­lion in health­care costs.

There is grow­ing con­cern re­gard­ing the im­pact of an­timi­cro­bial use in agri­cul­ture on the emer­gence of an­timi­cro­bial-re­sis­tant bac­te­ria. The ma­jor­ity of an­timi­cro­bials used in dairy cat­tle are ad­min­is­tered via the in­tra­mam­mary route.

In Ire­land, there is wide­spread use of blan­ket dry cow ther­apy (BDCT).

BDCT in­volves ad­min­is­tra­tion of long-act­ing an­timi­cro­bials into all quar­ters of all cows at dry­ing off. Ud­der health has im­proved na­tion­ally, and many an­i­mals are now un­in­fected at dry­ing off, since the es­tab­lish­ment of the Cel­lCheck mas­ti­tis con­trol pro­gramme, the im­proved adop­tion of prac­tices such as B D C T , re g u l a r m i l k i n g ma­chine main­te­nance, and im­proved ud­der hy­giene. In light of such pos­i­tive trends, it has been suggested that BDCT is no longer re­quired, es­pe­cially as con­cerns have been raised that BDCT may lead to an in­dis­crim­i­nate over-use of an­timi­cro­bials.

Thus, a key re­search fo­cus in Tea­gasc is to in­ves­ti­gate mas­ti­tis pre­ven­tion strate­gies that do not rely on BDCT.

Se­lec­tive Dry Cow Ther­apy (SDCT)

Un­like BDCT, where all cows re­ceive an­tibi­otics, se­lected dry cow ther­apy (SDCT) in­volves tar­geted use of an­tibi­otic treat­ment, only in those cows shown to have an in­tra-mam­mary in­fec­tion at dry­ing off.

In quar­ters shown to be un­in­fected at dry­ing off, a teat seal is ad­min­is­tered in­stead. The ad­di­tion of teat seal to a SDCT pro­to­col en­sures that all quar­ters have some pro­tec­tion against new in­fec­tions dur­ing the dry pe­riod. Herd and in­di­vid­ual an­i­mal se­lec­tion is im­por­tant when con­sid­er­ing SDCT. In­di­vid­ual cow milk record­ing is es­sen­tial, to al­low ap­pro­pri­ate se­lec­tion of cows.

Pi­lot Tea­gasc Study

A re­search herd with a bulk milk SCC con­sis­tently un­der 200,000 cells/mL, and less than 2% clin­i­cal case rate in the last three months of lac­ta­tion, with in­di­vid­ual cow milk record­ing data avail­able, was stud­ied in two con­cur­rent years.

At dry­ing off, cows were deemed el­i­gi­ble for in­clu­sion if their SCC had not ex­ceeded 200,000 cells/mL, and they had not pre­sented with a clin­i­cal case of mas­ti­tis through­out the pre­vi­ous lac­ta­tion. El­i­gi­ble cows were ran­domly as­signed to ei­ther Teat

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