By Amber Yutzy
Dairy heifers represent a major investment in a dairy herd’s future genetics, production, and financial welfare. Prevention and treatment of mastitis in all ages of heifers is crucial to your farm’s future profitability. Many times, heifers are forgotten on the farm. They live away from the main farm where they are not cleaned and bedded as often as the milking herd. This can cause huge mastitis issues when they become a productive member of the milking string. Few dairy heifers exhibit clinical signs of mastitis before calving. A S. aureus infection can cause scar tissue to form in the udder which reduces the amount of secretory tissue that can produce milk resulting in 10% less milk in the first lactation. Milk production may be reduced by up to 2000 lbs. during the first lactation for heifers with S. aureus infections leading to huge economic loss for dairy producers (Ruegg, 2011). In a review of heifer mastitis studies, the prevalence of mastitis pathogens recovered from mammary secretions obtained before the first calving ranged from 29% to 74%, while the prevalence of infection at first calving ranged from 12% to 57% (Fox, 2009). Protocols for heifers to improve udder health should be developed with your veterinarian’s input to prevent new infections and to cure existing infections.
Coagulase Negative Staph (CNS) is the most common pathogen recovered from heifers at freshening (S. De Vliegher, L. K. Fox, S. Piepers, S. McDougall, and H. W. Barkema, 2012). This is an environmental bacterium that is known for a high rate of spontaneous cures. Many of these infections disappear within the first week after calving. One study indicated that 41% of mammary quarters had CNS infections between days 1 and 4 post-calving but 46% of those infections had spontaneously disappeared by days 5 to 8 post-calving (Piepers, S., S. De Vliegher, A. de Kruif, C. Opsomer,, 2007). The effect of heifer mastitis on an individual animal is determined by the form of mastitis, the severity of the inflammation, the time of onset of infection relative to calving, cure or persistence of the infection when milk production has started, and the host’s immunity (S. De Vliegher, L. K. Fox, S. Piepers, S. McDougall, and H. W. Barkema, 2012). If your herd is experiencing persistent infections in heifers, developing best management practices to limit long-term effects on milk quality and production is essential.
How does a heifer that is not lactating contract a contagious mastitis causing bacteria? S. aureus is one of the most important and costly mastitis pathogens because it invades deep within the udder tissue causing chronic infections. These chronic infections will greatly reduce milk quality and quantity. S. aureus can be hard to control in lactating herds and infection of dairy heifers usually indicates that many lactating cows are also infected. Many herds have found ways to control mastitis on their farms, but there are still herds that struggle. It is not exactly known how non-lactating heifers develop S. aureus infections, but studies have shown that teat canals of heifer calves can become colonized at very young ages (Nickerson, S. C., W. E. Owens, and R. L. Boddie, 1995). Contagious mastitis organisms live primarily in the udders of infected cows and are spread to heifers when they are fed non-pasteurized milk or colostrum (Roberson, J. R., L. K. Fox, D. d. Hancock, J. M. Gay, and T. E. Besser, 1998). It has been found that ingested milk does not spread pathogens directly from the digestive tract to the udder, but calves most likely spread the pathogens by licking their udder or legs after consuming raw milk. From here the contagious bacteria colonize on the teat skin and eventually lead to infections. Contagious mastitis caused by S. aureus can also spread to heifers during the pre or postpartum period. Freshening pens are often used to house sick cows as well. This can result in contamination of the bedding from sick animals. Mastitis causing organisms can remain infectious for variable periods of time depending on the characteristics of the organism, the type of bedding and the environmental conditions (Ruegg, 2011).
What is the easiest way to control the spread of contagious mastitis bacteria to calves and heifers?
- Pasteurize raw milk that is fed to calves.
- -- Avoid feeding waste milk from cows that are infected with mastitis.
- Use individual stalls for pre-weaned calves.
- Cull calves that suck other calves.
- Do not use freshening pens for sick cows.
- Routinely culture milk from cows that are chronically infected with mastitis.
- -- This will help to identify those in the milking herd that have contagious mastitis.
- Properly handle chronically infected cows to limit the spread of bacteria within the milking herd.
How can you limit the number of heifers that are infected with environmental mastitis causing bacteria? This can be answered in one word, cleanliness. Most risk factors that contribute to the development of mastitis in heifers are related to exposure of heifers to mastitis causing organisms. The hygiene of the environment is important to limit the risk of developing mastitis in heifers. This is true for heifers that are raised on pasture as well as in confinement (Compton, C. W. R., C. Heurer, K. Parker, and S. McDougall, 2007). Heifers can harbor mastitis causing bacteria in their mammary tissue from an early age. Cleanliness is important for udder health from day one of life. Heifers with dirty udders as well as teats that are closer to the ground have been shown to be at a greater risk of mastitis (Ruegg, 2011). This is especially true for infections with environmental pathogens such as Streptococci spp. and Klebsiella spp.
Tips to control environmental mastitis:
- All non- lactating heifers should be housed in an area that is well bedded.
- -- Clean and Dry!
- Non- lactating heifers should be housed in an area that provides significant space for all animals.
- -- Overcrowding causes cleanliness issues.
- Flies should be controlled in all groups of animals on the farm.
- Feeding a well-balanced diet can enhance the immune system.
- Developing routine vaccination protocols can boost immune response.
Combating heifer mastitis takes time and attention. Do not let heifers become the forgotten animals on your farm. These animals are the future of your dairy business and deserve the same attention that the milking herd receives.Source : psu.edu