mastitis • subclinical ketosis • leptospirosis • abortion • bovine viral diarrhoea • listeriosis • neospora • nfectious • bovine rhino
VET’S VOICE │ MASTITIS
What is the cost of mastitis? Ian Hodge
Mastitis is a costly disease. There is value in achieving better mastitis control –closing the gap – by reducing high somatic cell counts, reducing clinical cases and culling fewer cows. For example if we use the DairyNZ Smart SAMM Mastitis Gap Calculator (which can be found at https://www. dairynz.co.nz/animal/mastitis/tools-andresources/smartsamm-gap-calculator/) we can make the following calculations: If we take a herd of 500 cows, improving the herd somatic cell count average from 200,000 to 150,000, the clinical case rate from 15% to 10%, maintain production at 352,000kg milksolids (MS) and assume a payout of $6, the potential gain in net profit is around $56/cow or $28,000 for the season. This calculation can be broken down into the potential added value of less sub-clinical mastitis ($19,000), of less clinical mastitis ($3000) and of culling fewer cows ($6000). The cost of treatment for a typical single-quarter clinical mastitis infection can be more difficult to determine. If we assume we use three intramammary antibiotic doses (cost about $20), the cost of labour to treat the cow for three days is $20 (one hour), the cost of the milk discard (four days) is $52, and the cost of the reduced production for that cow, as a result of the infection, is $70, which is a 25% reduction in production over a seven-day treatment and withhold period. Total cost $162. This is a best-case scenario. In fact clinical mastitis doesn’t always respond in such a perfect way and the real cost could be as much as $200/ case. In our 500-cow herd example a 10% incidence of calving-associated mastitis during the first two calving months clinical mastitis could cost $10,000 (this includes drugs, labour, discarded milk, reduced production and poor cure rates). Reducing the incidence (number of new cases over time) of mastitis during the spring calving period depends on good dry-period mastitis management. At dry-off some cows will be infected and dry-period antibiotic therapy will resolve a good proportion of these existing intra-mammary infections. It will also reduce the risk of these cows developing mastitis at calving as long as other mastitis prevention practices are addressed. Uninfected cows at dry-off 56
Pure Milk NZ consultant and VetEnt veterinarian Ian Hodge testing milking machine function and risk analysis for mastitis.
can have their teat canals sealed with teat sealants only which can reduce the risk of new mastitis infections for up to 100 days after calving. EFFECT OF DRY-PERIOD MASTITIS CONTROL In the two tables below we can see the effect of dry-period mastitis control practices on clinical case rate during
calving. The first farm decided not to use dry-cow therapy. This farm milks 850 cows and has treated about 97 cases in the first two months of the calving period (11%). This has a cost of about (97 x $200) = $19,400 or $23/cow. The second farm used a well designed dry period management programme including heifer teat sealants. In this case we have 31 mastitis
Table 1. Mastitis case count on Farm 1 (no dry-cow therapy)
Dairy Exporter | www.nzfarmlife.co.nz | March 2017