Dairy Technology I – SS3 Livestock Farming Lesson Note (Second Term)

Dairy technology is the science of producing, handling and preserving milk, from the cow’s udder to the customer.

Behavioural objectives

By the end of the lesson, students should be able to:

1. define dairy technology;
2. state the three things a farmer must focus on to get a high milk yield;
3. describe the hygiene rules for the milker, the animal and the equipment;
4. outline the steps for handling milk after milking;
5. name the physical, chemical and biological contaminants of milk, with examples.

What is dairy technology?

Dairy technology is the science of milk, the “first food of life”, covering everything from milking to the customer’s table.

• Breed: the type of cow kept for milk.
• Feeding: the pasture, water and concentrates the cow eats and drinks.
• Comfort: shade, ventilation and calm handling.
• Hygiene: cleanliness of the milker, the animal and the equipment.
• Handling after milking: straining, cooling and storing the milk.

Why does dairy matter in Nigeria?

• Imports: much of the milk sold in shops is made from imported milk powder.
• Local cattle: local cows such as the Bunaji (White Fulani) can supply fresh milk if well managed.
• Local products: fresh milk is used to make nono, fura da nono, cheese (wara) and yoghurt.

What is milk made of?

Milk is a liquid food made in the cow’s udder, and it contains water and several nutrients.

• Water: the largest part of milk.
• Fat (butterfat): gives energy and is used to make butter and cream.
• Protein: for growth and repair of the body; casein is the main milk protein.
• Lactose: the milk sugar, which gives energy.
• Minerals and vitamins: calcium for bones and teeth, and vitamins such as A and B.

What are the common dairy cattle breeds?

Dairy cattle in Nigeria are either local (zebu) breeds or exotic breeds brought from temperate countries.

How can a farmer increase milk production?

A farmer increases milk yield by improving three things: the breed, the nutrition and the comfort of the cow.

The “mother” (breed)

• Genetic ability: some cows are naturally better at making milk.
• Crossbreeding: crossing tough local breeds with the Holstein-Friesian can raise the litres a cow gives daily.

Nutrition

• Pasture: good-quality grass and legumes, or hay and silage in the dry season.
• Clean water: available at all times, because milk is mostly water.
• Concentrates: feed rich in energy and protein, such as maize offal and groundnut cake.

Comfort

• Shade and ventilation: a stressed or hot cow gives less milk.
• Gentle handling: rough treatment makes the cow hold back her milk.
• Regular milking times: the cow gets used to a routine.

What are the rules of hygiene in clean milk production?

Hygiene in milk production means keeping the milker, the animal and the equipment clean so that germs do not enter the milk.

• Why it matters: milk is warm and full of nutrients, so bacteria grow quickly in it.

The milker (the person)

• Health: the person milking must be healthy, with no cough or skin infection.
• Hands and nails: wash hands with soap and keep nails short.
• Behaviour: no smoking or eating while milking.

The animal

• Washing: wash the udder and teats with warm, clean water and dry them with a clean cloth before milking.
• First squirt: discard the first milk from each teat into a separate cup, because it often contains the most bacteria.

The equipment

• Containers to avoid: rusty buckets and scratched plastic buckets, because scratches hide bacteria that soap cannot reach.
• Best containers: stainless steel, or aluminium without seams, because they are easy to sterilise.
• Cleaning: wash after every use, rinse well and dry before the next milking.

How should milk be handled after milking?

Milk is handled after milking by straining, cooling and storing it quickly to slow down spoilage.

• Why speed matters: in warm weather, fresh milk left uncooled can turn sour within a few hours.
• Cause of sourness: bacteria change lactose into lactic acid.

1. Straining: pass the milk at once through a clean, fine cloth or milk filter to remove hair, dust and dirt.
2. Cooling: cool the milk to 4°C as fast as possible, because bacteria grow slowly in the cold. Without a refrigerator, stand the container in a bowl of cold, flowing water.
3. Storage: keep the milk covered in a cool, dark place, away from strong-smelling items such as onions or kerosene. Milk absorbs smells.

What are the common milk contaminants?

There are three types of milk contaminant: physical, chemical and biological.

Physical contaminants

• Examples: hair, dung, flies and dust.
• Control: clean the udder, keep the milking area clean and strain the milk.

Chemical contaminants

• Examples: traces of soap from poor rinsing, and antibiotics if the cow was recently treated for sickness.
• Control: rinse equipment well and follow the withdrawal period after treatment.

Biological contaminants

• Examples: bacteria such as E. coli and Salmonella, which can cause food poisoning.
• Control: hygiene of the milker, animal and equipment, and quick cooling.

What are the stages of quality milk production?

Quality milk production has three stages: pre-milking, milking and post-milking.

Class discussion

1. The “smell test”: Why does milk from some local markets smell like smoke or cowshed? What part of the hygiene steps did the farmer likely miss?
2. Problem solving: If a dairy farmer in a rural area has no electricity for a fridge, what are two “low-tech” ways to keep milk from spoiling before the morning bus arrives to take it to the city?

Evaluation

1. Define dairy technology.
2. State three things a farmer must focus on to get a high milk yield.
3. Why should the first squirt of milk from each teat be discarded?
4. List the three steps for handling milk after milking. To what temperature should milk be cooled if a refrigerator is available?
5. Name the three types of milk contaminant and give one example of each.

Assignment

Observation: Visit a local “Fura da Nono” seller. Observe how they handle the milk. Based on today’s lesson, what is one thing they are doing well, and one thing they could improve?