NUTRITION ▶▶▶


Quality minerals for improved udder health


Mastitis is an inflammation of the udder, usually caused by the invasion of bacteria through the teat canal. It can also be attributed to mycoplasmal, fungal or algal infections; mechanical trauma (such as teat injuries); thermal trauma and toxins. The inflammation consists of white blood cells (leukocytes, or somatic cells) released into the mammary gland in response to the invasion, where there is a local battle.


BY DR MARIA AGOVINO, EUROPEAN RUMINANT ON-FARM MANAGER, ALLTECH T


hese bacteria multiply and produce toxins that cause injury to milk-secreting tissue and various ducts throughout the mammary gland. The white blood cells also release toxins, engulf bacteria and


cause temporary local destruction of the tissues. The elevated somatic cell count (SCC) is a measure of the degree of inflammation in the udder.


Underestimated cost Mastitis is considered to be one of the costliest dairy cattle diseases. The losses associated with mastitis are often under- estimated at farm level because many go unseen, such as re- duced milk production and lower herd growth potential, which can impact expansion. Multiple factors contribute to mastitis and SCC, ranging from environmental issues to the milking procedure to poor immune system function. Bacteria are generally the cause of most mastitis cases, originating from already infected udders, replacement animals coming onto the farm and the environment, including cubicle bedding, manure and poor milking hygiene. Promoting udder and teat integrity goes a long way toward reducing the risk of infection. Ensure good hygiene during and after milking (for example, using teat dip or spray), make sure the milking machine is functioning correctly (for exam- ple, not leaving the clusters on for longer than necessary) and keep udders clean. Disinfecting teats and scoring udders for hygiene is also essential for reducing the pathogenic load during the milking routine. If cows are consistently entering the milking parlour with dirty udders and teats, then the housing and management systems need to be improved.


16 ▶DAIRY GLOBAL | Volume 7, No. 1, 2020


Alternatives to antimicrobials Most antibiotics used in dairy herds are related to udder health, of which a large proportion are dry-cow products. However, concern has risen over conventional antibiotic treatments of mastitis due to the global emergence of multi- ple antibiotic-resistant bacteria. Because of this, it is now essential to focus on preventive strategies instead. Preventive dry cow therapy, to treat all teats on all cows, can no longer be considered prudent. Successful udder-health management should aim to minimise antimicrobial use. A study showed that herds participating in a veterinary herd health management programme and herds selectively drying off cows used fewer antimicrobials compared to herds not participating in such a programme or applying blanket dry- cow therapy (Stevens et al., 2016). There are useful screening tools available that perform real-time diagnostics to make se- lective dry cow therapy a practical approach, where only high-risk quarters are ultimately dry cow treated. Internal teat sealants are an adequate alternative to antibiot- ics for preventing low SCC cows from becoming infected dur- ing the dry period (Cameron et al., 2014; Cameron et al., 2015; Rupp and Boichard, 2003). Alternatives to internal sealants are external teat dips, which protect against new infection by covering the teat end with a disinfectant. However, these need to be reapplied frequently. Many breeding programmes include genetic selection for mastitis resistance; yet, only a small part of the solution for good udder health is found in the breeding programmes (Rupp and Boichard, 2003). Development of vaccines to prevent or control mastitis is an important goal. Coliform mastitis control has made good pro- gress through mutant gram-negative vaccines. Development of an effective Staphylococcus aureus vaccine is an ongoing research objective


Role of minerals Trace minerals play key roles in many enzyme systems, pro- tein synthesis, carbohydrate metabolism and antioxidant sys- tems, as well as immunocompetency. Therefore, an essential component of a mastitis control programme is to support im- mune function, which can be achieved through improved nu- trition, vaccination and the removal of potential immune sup- pressors. Udder health and immune function are influenced by the mineral status of the animal, in particular, trace


PHOTO: KOOS GROENEWOLD


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