Hygienic Milk Production in Animal Husbandry and Dairying

Hygienic milk production refers to the set of practices and sanitary measures adopted from the farm to the processing unit to ensure that milk is obtained from healthy dairy animals, free from pathogenic microorganisms, chemical residues, and physical contaminants, and retains its natural nutritive value and keeping quality.

• Significance: Raw milk is an excellent culture medium for bacterial growth due to its near-neutral pH (6.5 to 6.7), high moisture content, and rich nutrient profile (proteins, fats, lactose, minerals, and vitamins).
• Economic Impact: Clean milk production reduces economic losses through spoilage, prevents milk-borne zoonotic diseases (such as tuberculosis, brucellosis, and Q fever), and fetches better market prices for dairy farmers.
• Bacterial Load Standards: Freshly drawn milk from a healthy udder contains very low microbial counts, but improper handling can rapidly elevate the standard plate count (SPC) and lead to rapid souring and curdling.

The foundation of hygienic milk production begins with maintaining a healthy herd free from infectious and systemic diseases.

• Routine Health Screening: Dairy animals must be regularly screened for contagious diseases such as bovine tuberculosis caused by Mycobacterium bovis, Johne's disease caused by Mycobacterium avium subsp. paratuberculosis, and brucellosis caused by Brucella abortus.
• Mastitis Control: Mastitis is the inflammation of the mammary gland and udder tissue, significantly altering milk composition and increasing somatic cell counts (SCC). It is predominantly caused by contagious pathogens like Staphylococcus aureus and environmental pathogens like Escherichia coli and Streptococcus uberis.
• Quarantine and Culling: Newly purchased animals must be quarantined for at least 30 days. Chronically infected animals that do not respond to antibiotic therapy must be culled to protect the rest of the herd.

Environmental hygiene in the dairy barn and absolute cleanliness of milking equipment are critical to prevent post-secretion contamination of milk.

• Milking Barn Standards: The milking parlor or barn must be well-ventilated, well-lit, and equipped with easily cleanable concrete floors with proper drainage to prevent water stagnation and accumulation of manure.
• Grooming and Washing: Flanks, hindquarters, and udders of dairy animals must be washed with clean potable water and dried with a clean single-use cloth or paper towel before milking to dislodge mud, bedding material, and dung.
• Utensil Hygiene: Milking pails, cans, pipeline systems, and bulk coolers must be constructed of non-corrosive, food-grade materials (preferably stainless steel of AISI 304 grade). Galvanized iron and copper utensils must be avoided as they catalyze lipid oxidation.
• Cleaning Protocol: Utensils must be rinsed with cold water immediately after use, washed with an alkaline detergent solution to remove fats and proteins, sanitized with a chlorine or acid-based sanitizer, and finally inverted to dry.

The actual process of milk extraction and immediate post-milking handling dictate the initial microbial load and shelf-life of raw milk.

• Preferred Milking Method: Full-hand milking (grasping the teat with the whole hand and compressing sequentially from top to bottom) is recommended. Knuckling (pressing the thumb against the teat) and stripping should be avoided as they injure the delicate mucous membranes and teat sphincters, predisposing the animal to mastitis.
• Fore-milking: The first few streams of milk from each teat should be drawn into a separate strip cup and inspected for flakes, clots, or watery consistency, which are early signs of clinical mastitis.
• Teat Dipping: Immediately after milking, when the teat sphincter remains dilated for 15 to 30 minutes, teats must be immersed in an antiseptic teat dip (such as 0.5% iodine or chlorhexidine solution) to prevent entry of environmental pathogens.
• Immediate Cooling: Freshly drawn milk must be strained through a sterile stainless steel wire mesh or cloth strainer and rapidly cooled to 4°C within two hours of milking using bulk milk coolers (BMCs) or farm milk chillers to arrest microbial proliferation.

Milk safety and quality are evaluated through rigorous physical, chemical, and microbiological testing protocols governed by food safety authorities such as the Food Safety and Standards Authority of India (FSSAI).

• Physicochemical Parameters: Cow milk must comply with legal standards of a minimum of 3.2% fat and 8.5% solids-not-fat (SNF), while buffalo milk must contain a minimum of 6.0% fat and 9.0% SNF.
Methylene Blue Reduction Test (MBRT): A standard dye reduction test used to estimate the microbiological quality of raw milk. High-quality milk takes longer than 5 hours to decolorize, whereas poor-quality milk decolorizes in less than 30 minutes.
• Somatic Cell Count (SCC): An elevated SCC exceeding 200,000 cells/mL indicates subclinical or clinical mastitis and reduced milk processing suitability.