Mastitis and Milk Quality: Working Through Late Lactation, Dry Off, & Back to Kidding.

 By Jennifer Bentley - Iowa State University.

 Milk quality and mastitis are always challenges for goat producers but late lactation accentuates this. Many understand the challenges of early lactation with the demand for milk production for commercial use or feeding multiple kids and meeting that demand nutritionally.

There are three major reasons why increased risks occur in mid to late lactation:  
• Breeding season brings hormonal shifts with estrus that lead to slight immune suppression (and all does are here at once)
• Late lactation means less milk and udder pressure, so lower flushing effect of organisms unless proper milking stimulation and practices are followed
• Reduced appetite and increased aggressive behaviors (stressors) during breeding season, especially if bucks are introduced amongst the whole herd. Some of these are inevitable but others can be addressed with enhanced best management practices.

Defining a milk quality problem is a priority no matter the stage of lactation. Certainly, active aggressive surveillance and identification of clinical mastitis through examining milk, udder conformation and abnormalities, and overall animal health are crucial. But most mastitis is subclinical, or unseen so use of tests like culture (infections), or somatic cell counts (SCC) (electronic or CMT doe side) are essential.

The California Mastitis Test (CMT) is a simple method used on to first evaluate milk quality. CMT works by mixing milk with detergent that coagulates somatic cells, forming a gel reaction. The more somatic cells, the greater gelling. CMT scores range from 0-3 representing somatic cell counts of 0 to over 10 million. (refer to Table 1. California Mastitis Test scoring system in goats, Schalm, 1971).

Most producers who screen their does look and usually only define mastitis by does that gel the paddle the worst (thick grape jelly consistency). While this is a problem doe, that jelly represents a clinical mastitis of over 10 million SCC. However, there are many does that are subclinical making it more difficult to detect. Using the CMT paddle, it can be detected by gel moving a little sluggishly but still moving. This represents SCC > 1 million and still a problem doe with mastitis.

This tool helps to define where the infection may be occurring (early, mid, late lactation or around kidding).

Using these results can help to understand and possibly culture problem does, define solutions to keeping does healthy, and developing strategies to address high SCC and infected does.

Cultures are useful, especially in defining if mastitis is contagious or not, as well as directing prevention and treatment strategies. Some does may have contagious mastitis, for example Staph Aureus, so identifying and eliminating these does or minimizing their spread at milking is critical. Remember the hands of the person milking can be the vector for spreading Staph aureus. Gloves need to be worn so they can be sanitized after handling infected goats.

Most other organisms, namely, streps & coliforms are environmental. These organisms can come from bedding, feces, water, or from skin. Commonly found is a skin bacteria, Staph Epidermitis, often identified as a “coagulase negative staph” (CNS) on culture reports to differentiate it from Staph aureus, a “coagulase positive Staph”.  It is treatable if identified early.

Strategies to address milk quality or mastitis risks should be year-round but enhanced during late lactation, as somatic cell counts can be high towards the end of lactation:
• Clean, dry environment focusing on reducing germ load.
• Proper nutrition to enhance immunity; when feed consumption decreases, milk production will follow.
• Heat stress can depress feed intake and lower milk production; keep does cool during the hot months.
• Keep fresh, clean water available always.
• Proper milking practices: stimulation times for effective, cleaner milk out.
• Pre and post milking sanitation including teat dipping and drying to reduce organism load, improve teat skin, improve milk out stimulation, and reduce overall mastitis risk.
• After pre-dipping, stripping teats of the first milk is a good practice to remove high somatic cells. It is also a good way to check the milk for signs of clinical mastitis; flaky, chunky, stringy, or discolored.
• Using single use paper or cloth towels ensures that each doe gets a clean towel for wiping teat ends.
• Keep doe standing for at least 30 minutes after milking to allow for the teat end to close and limit bacteria from entering the teat gland. Access to fresh feed immediately after milking is one way to keep them standing before going to lie down.
• When drying a doe off prior to kidding, monitor doe closely for signs of mastitis and intramammary infection; balancing feed intake to decreasing milk production.
• If administering a dry doe treatment intramammary, practicing good clean hygiene techniques.
• Body condition of does at dry off and proper management practices during the dry period are critical for a successful next lactation. Proper body condition (not thin or heavy) is critical and should be maintained during dry period.
• Proper nutrition, clean environments, and excellent ventilation. Work with nutritionists on extra needs of does with twins or greater.

At the time of kidding, all management practices still apply; nutrition, environment, and milking practices to optimize doe milk flow and reduce infection risks. Within a week of kidding, consider using the CMT, to evaluate all does for milk quality. It is important that this first milk known as colostrum mixes thoroughly with the CMT solution before interpretation. Monitoring milk quality will allow for bulk tank limits of SCC to be met, earlier detection and identification of mastitis, and overall dairy goat health. Work closely with your veterinarian on appropriate therapies; consider only treating positive CMT or problem udder halves to reduce costs and risks.

Milk testing is another way to help monitor milk quality. The Dairy Herd Improvement (DHI) Association allows for monthly data collection of individual does for somatic cell counts, milk fat, protein, and production. Keeping records is a good way to monitor individuals as well as overall herd health. Seasonal, feed, or management trends can quickly be assessed with routine monitoring.

Management changes can impact milk production and quality very quickly.