Feedback: Why fresh cow milk becomes acidic

CAUSES OF ACIDITY IN MILK

What is the relationship, if any, between cows eating napier grass that is finely chopped by the chuff cutters, their inability to chew cud after eating the fodder and the end result being production of acidic milk?

How is it that finely chopped forage causes acidity in a cow’s rumen? 

What should one do to deal with that and provide quality milk to the market?

In my area, our dairy cooperative is rejecting farmers’ milk on this ground. It’s quite “funny” because you take your milk in the morning and it’s accepted and when you deliver afternoon produce, it’s rejected.

Grace Njenga

Major feed digestion in ruminants takes place in the rumen, with the aid of rumen micro-flora (bacteria, protozoa and fungi).

Growth of these micro-organisms requires a balanced feed ration (could be both concentrates and forage). These micro-organisms regulate fermentation process in the rumen.

Bacteria regulate the level of methane, carbon-dioxide and hydrogen, resulting in the influence of the rumen pH. Rumen pH influences microbial population and level of volatile fatty acids (acetic, propionic, butyric, isobutyric, valeric, isovaleric, and traces of various other acids).

Acetates are essential in the synthesis of milk fats. Propionate is used in milk sugar synthesis. Milk sugars influence the milk density (lactometer reading; a platform test).

Therefore, milk compositions checked by milk processors are influenced by the feeds the cows are given. On the other hand, before you conclude that the acidity of the milk is because of the feeding, remember handling of the harvested milk is also key in high quality milk production.

The sanitary procedures applied to equipment and the udder and storage and time taken for milk to reach the collection centre or the cooperative all matter. Milk will only maintain its high quality for two hours after milking without refrigeration, thereafter, exponential microbial multiplication sets in.

These micro-organisms use milk sugar, lactose as a substrate. Lactic acid, which lowers the pH of the milk is the product of this process.

Such milk is rejected by milk processors because it cannot withstand the high heat treatments, instead it clots. Alcohol (68-72 per cent) is used in alcohol test to check if the milk protein is stable.

Poor quality milk will clot on this test and will be rejected. The solution here is to maintain high levels of hygiene.

Godfrey Were Juma,
Department of Dairy, Food Science and Technology, Egerton University.

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BEST CHICKEN HOUSE

I have been accumulating Kienyeji hens for the last three months and I have put them in a makeshift structure. Two of my hens are sitting on 15 eggs each and I feel I am ready to take in more hens.

I would like to invest in a modern structure as I have space and savings. Please send me a modern plan. Should my house face East or West?

Cate Nyawira

If you intend to construct the house in an area that is hot, the long axis (length) of the house should run from east to west and the sides (width) should face north-south to prevent direct sunshine from reaching the house.

However, if it is in a cold area it is desirable to construct the houses facing south or south-east to get maximum sunlight.

Sophie Miyumo, Department of Animal Sciences,

Egerton University.

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GROWING AND ADDING VALUE TO TOMATOES
I want to grow tomatoes in Meru and go further and add value to make paste. I am seeking advice on this venture.
Jediel Muthuri

With red tomatoes, it is easy to make preserves that can be used to make red sauces and soups all-year-round, even when there are no more fresh tomatoes in the market. 

To start, the tomatoes first need to be peeled by dipping gently into boiling water for 30 seconds. The tomatoes should, therefore, be taken out of the cooking pot as quickly as possible with a sieve.

They should be plunged immediately into cold water for a few minutes to loosen the skin. The tomatoes should be completely peeled without leaving any skin on them.

Extraction of the pulp is done by putting the tomatoes into a device called an extractor, which separates the pulp from the seeds.

If there is no extractor available, you can also cut the tomatoes into smaller parts and squash them. Thereafter, put the squashed tomatoes through a sieve and repeat this a number of times to help crush the pulp and maximise the yield.  

When all the pulp is collected, pour it into a cooking pot, which is then placed on the fire for what is called pre-heating. It must simmer without ever boiling.

Preservation jars must be prepared by washing with hot water. A small spoonful of lemon juice, without pips, should be put into each clean, empty jar. 

After pre-heating, tomato pulp should be placed into the jars. The jar must not be filled right to the top, leave about one to two fingers wide of air underneath the lid to prevent the jars from bursting during sterilisation.

The lid should then be sealed tightly. The jars with the pulp should be sterilised in a pot of boiling water for 45 minutes.

Keeping the tomato preserves should be done in a cool dry place. But once the lid has been unscrewed, the tomatoes won’t keep long: they must be used the same day. So open the jar only when the user is ready to use the peeled tomatoes paste preserve.

Caroline Makau,
Department of Dairy, Food Science and Technology, Egerton University.

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GETTING RID OF MOLES
How do I get rid of moles from my farm? The pest has systematically destroyed my bananas, sugarcane, cassavas, potatoes and of late, it has been disappearing with young beans and maize plants underground.

I have tried trapping but this has not helped much yet I pay Sh50 for every catch. It seems as if some travel underground from neighbouring farms and complicate matters.

At one time I tried the fish poison bean, but to no avail.

Tom Ogola, Kisumu.

Mole management is a continuous process and should be extended to the adjacent farms.

This is because moles have high reproductive rate and are highly migratory through a system of tunnels they make, and, therefore, controlling them on your farm without the corresponding efforts from the adjacent farms may not yield much.

There are several approaches that have been recommended for controlling moles. Some of the approaches may be cumbersome, costly and uneconomical for the farmer.

However, trapping and killing the moles using harpoon-type traps that are strategically placed on the paths/tunnels can reduce the moles.

Alternatively, poison rodent baits/rodenticides placed in the tunnels can be used to kill them.

Sylvans Ochola,
Department of Crops, Horticulture and Soils, Egerton University.