Mastitis in heifers

From national and overseas surveys, as well as from local feedback, we know that mastitis in heifers is a common and frustrating problem. In addition, mastitis is associated with significant economic loss due to treatment costs, short and long-term production losses, reduced fertility and increased risk of culling.

High costs of heifer mastitis

A nationwide study shows that costs due to heifer mastitis average $197 for every first case, and $2020 for the average 340-cow herd. Mastitis in heifers is common. Almost all clinical cases occur within 7 days of calving and the bacteria isolated usually come from the environment. Recent research has helped to understand this common and frustrating problem, given some practical methods to control it, and for the first time, an accurate estimate of its economic costs and benefits of prevention.

In the 2008/09 season, a survey involving 40 herds from 4 dairying regions of NZ, has sought to better define the costs of this disease and to provide farmers with cost-benefit budgets for different control options. Data were collected on the number of cases on each farm, costs due to extra time involved in managing and treating these heifers and purchasing additional replacements because of culls and deaths following cases, and losses due to discarded milk and lost production in the current and following season. These are shown separately in the graph below assuming a $5.50 per kg MS payout, $750 difference between cull and replacement heifer, and $17.50 per hour labour cost.

The cost of treatment ($51) is only a quarter of the total cost because of ‘hidden' losses and costs. Each case of heifer mastitis required only 1 minute per milking or 12 minutes per case to manage for the duration the animal was having milk withheld from supply, meaning the labour costs per case are low ($3). However, most farmers will know that frustration and worry over mastitis can't easily be defined by a dollar value.

So what factors increase the risk of clinical mastitis in heifers?

At a herd level ... those herds with

• higher average milk solid (MS) production per cow
• more cows per milker
• a single milking mob (ie cows and heifers run together after calving)
• high stocking rate (>3.3 cows/ha)
• higher proportion of cows with clinical mastitis
• high usage of standing off and/or feed pads

can be expected to experience a higher incidence of clinical mastitis in heifers.

At heifer level ... the risk factors for clinical mastitis have been identified as

• presence of infection before calving
• udder oedema/swelling
• teats being closer to the ground
• Friesians compared to Jerseys
• dirty udders

The issue remains the subject of considerable NZ and international research and the prevention strategies that have emerged from this include medical interventions and management options. The medical interventions are:

The infusion of Teatseal into the udders of maiden heifers 4 weeks before the planned start of calving. Published data indicate the overall risk of clinical mastitis can be reduced by 25% and subclinical infections by 57% and the data for reducing the risk of mastitis due to Strep uberis are even more impressive. The experience of local herds using Teatseal has been very positive with outstanding results in some herds and as such, this is the option Totally Vets is currently recommending. 

The use of a dose of injectable penicillin either within 7 days of the expected calving date or on the day of calving. The former option (within 7 days) is more difficult to achieve from a management point of view but will give better results. The disadvantages of these options are the increased risk of antibiotic residues and that the results are not as good as when compared to Teatseal.

Other management tools available to reduce heifer mastitis around calving or to minimise the immediate and long-term impacts of infection include:

• teat spraying 2-3 times per week before calving
• training heifers to the milking shed
• running a separate heifer mob and calving them down in ‘clean' paddocks
• pre-milking heifers that are dripping milk
• managing body condition scores so that heifers calve in condition score 5-5.5 (not higher)
• identifying environmental ‘hot spots' (eg feed pads, races, common gateways, etc)
• screening all heifers (and cows) with a ready-to-use mastitis test (RMT) paddle on the 4th day after calving. Heifers scoring as a 3 on RMT should be treated and any borderline cases withheld for a further period and retested daily until a final decision is made. (Cows with a high score are treated depending on age and previous history). Any clinical cases detected at this time will be treated as per normal.

Unfortunately, there is not a ‘one size fits all' solution for calving mastitis. The good news is that our understanding of this complex disease process is expanding rapidly. Talk to your Totally Vets veterinarian about strategies for reducing mastitis, improving milk quality, and increasing milk yield that could have a place in your operation.