Feed is usually the largest single cost of producing milk, often sixty to seventy per cent of the total. A ration with too little energy or protein limits milk. One with too much wastes money.
And the wrong change at the wrong time can make a cow seriously ill.
In this video: how a cow digests, what a ration must supply, forage and concentrate, balancing a feed with the Pearson square, minerals, feeding through lactation, the dry period and calving, feeding when feed is short, and safety. The advice is general and global, with South Asian thumb rules as one example. Your veterinarian and local feeding standards always come first.
A cow can live on grass and straw that people cannot digest at all, because she carries a fermentation vat in front of her true stomach: the rumen. In an adult cow, the rumen and reticulum hold well over one hundred litres. It is kept at about thirty-nine degrees Celsius, with a pH normally around six to seven, and it is packed with bacteria,
protozoa and fungi.
These microbes break down fibre into volatile fatty acids, which supply most of the cow's energy, commonly sixty to eighty per cent. Acetate, high on forage diets, is a major building block of milk fat.
Propionate, higher on grain diets, is her main source of glucose.
The microbes also turn feed protein, and even urea, into their own protein, which the cow digests later.
Chewing the cud matters too.
Rumination produces saliva, more than a hundred litres a day in an adult cow, rich in bicarbonate.
Saliva is the rumen's main buffer against acid. That is why a cow needs long fibre, not only grain.
A balanced ration supplies everything the cow needs in twenty-four hours:
dry matter she can actually eat, energy, protein, minerals, vitamins and, for a ruminant, fibre.
Intake sets the ceiling.
Adult cattle eat roughly two to three per cent of their body weight as dry matter each day, and high-yielding cows more, often three and a half to four per cent at peak. Intake falls with very fibrous feed, heat stress, and around calving.
For fibre, one widely used standard recommends at least twenty-five per cent of the diet's dry matter as NDF, the fibre fraction, with at least nineteen per cent coming from forage.
And never forget water. A lactating cow drinks roughly three to five litres of water for every kilogram of dry matter she eats, plus several litres for every kilogram of milk. In drought, water is often the first limiting nutrient.
A dairy ration is built on a forage base, plus concentrate.
Forage supplies fibre for rumination and a healthy rumen,
and much of the energy when it is good forage.
Concentrate adds energy and protein density.
Know your forages.
Legume fodders, such as berseem, lucerne and cowpea, are rich in protein and calcium.
Cereal fodders, such as maize, sorghum and oats, supply energy.
Wheat and rice straws are low in protein and digestibility,
and rice straw is also high in silica and oxalate. High-yielding cows are commonly fed rations of about sixteen to eighteen per cent crude protein in the dry matter, while moderate yielders on good legume fodder may need little extra protein.
In South Asia, simple thumb rules are widely taught.
Roughage makes up about two-thirds of the dry matter and concentrate about one-third, for moderate yielders.
Then about one kilogram of concentrate mixture for every two and a half kilograms of milk in cows, and for every two kilograms of milk in buffalo, because buffalo milk carries about six to eight per cent fat.
These rules are only a starting point.
They fail with very good green fodder or straw-only roughage, and they do not balance minerals.
To mix two feeds to one nutrient target, use the Pearson square.
Here is the worked example from Laisha's guide.
Maize has nine per cent crude protein, soybean meal forty-four,
and you want a sixteen per cent concentrate.
Subtract across the diagonals.
Forty-four minus sixteen gives twenty-eight parts of maize. Sixteen minus nine gives seven parts of soybean meal. That is thirty-five parts in all, so the mix is eighty per cent maize and twenty per cent soybean meal. Check: zero point eight times nine, plus zero point two times forty-four, is exactly sixteen.
The square balances one nutrient at a time, and the target must lie between the two feeds.
For several nutrients at once, feed mills use least-cost formulation software.
On farm, many dairies feed a total mixed ration, so every bite is balanced.
Minerals are where many rations fail, because forage minerals reflect the local soil.
Common deficiencies in grazing and straw-fed cattle around the world include phosphorus, copper, cobalt, selenium, iodine, zinc and sodium. A single generic mineral mixture can oversupply one element and miss another, so area-specific mixtures, made from a survey of local soils, feeds and animals, are better.
Signs to know: phosphorus deficiency causes bone chewing, poor fertility and low intake.
Sodium deficiency causes salt craving and licking of soil. A calcium to phosphorus ratio of about one to one, up to two to one, is generally recommended.
In compounded cattle feed, mineral mixture is usually about one to two per cent, and common salt about one per cent, of the concentrate.
Follow the product label and local advice for the daily amount.
And never give a cattle mineral mixture to sheep: they are unusually sensitive to copper poisoning.
Milk yield rises to a peak at roughly six to eight weeks after calving, while intake rises more slowly and peaks later. So for the first weeks, the cow is in negative energy balance, burning her body fat to fill the gap.
The goals are clear. In early lactation, get intake up quickly, keep the rumen healthy, and supply energy and protein.
In mid lactation, sustain yield and restore condition.
In late lactation, rebuild condition ready for drying off.
How do you know it is working?
Look for steady intake, most resting cows chewing the cud,
dung of porridge-like consistency, stable milk fat and protein, and a loss of no more than about one condition score. The milk test helps.
In early lactation, a fat to protein ratio above about one point four suggests heavy fat mobilisation and a risk of ketosis.
And a herd whose milk fat falls below its milk protein suggests rumen acidosis.
The dry period, usually about forty-five to sixty days, lets the udder regenerate and prepares the cow for calving. Aim for a body condition score of about three to three and a half, on a five-point scale, at calving.
Fat cows eat less after calving, mobilise more fat, and are prone to fatty liver, ketosis, a displaced abomasum and retained placenta. Correct condition in late lactation, not in the dry period.
The three weeks around calving, called the transition period, are when most production diseases strike.
Milk fever is a sudden drop in blood calcium at the start of lactation.
Close-up diets that are low in potassium, with a negative balance of cations and anions, help the cow mobilise calcium at calving.
Ketosis follows severe negative energy balance. Prevent it by avoiding over-fat cows, maximising intake after calving, and using transition diets.
A cow with milk fever needs a veterinarian at once.
Much of the world's cattle, sheep and goats live on crop residues and seasonal grazing, with a lean season every year. When feed is short, prioritise breeding females and young stock, sell unproductive animals early, and feed for survival and maintenance rather than production.
Straw can be improved with urea treatment.
A common recipe dissolves four kilograms of urea in about forty to sixty litres of water for every hundred kilograms of straw.
Spray it on, pack it, and seal it for about three weeks in warm weather, longer in the cold.
Urea-molasses mineral blocks supply nitrogen, energy and minerals as a lick.
And in the long run, silage made in the flush season,
hay, fodder banks and feed reserves are the real answer.
Now, safety. The deadliest feeding mistake is a sudden change. A cow that gets a large amount of grain at once can develop acute rumen acidosis: lactic acid builds up, rumen pH falls below about five, and she may die.
Introduce grain in small steps over one to two weeks, keep enough long fibre, and after drought, refeed starved animals gradually, roughage before concentrate.
Urea is useful but poisonous in excess.
Keep it to about one per cent of the ration's dry matter, mix it thoroughly, introduce it gradually, provide fermentable energy, and never feed it to young calves.
Frothy bloat on lush legume pasture is an emergency.
Watch for moulds and toxins: aflatoxin in badly stored oilseed cakes, nitrate in drought-stressed or heavily fertilised fodder,
and cyanide in young or wilted sorghum. Any drug or feed additive must be used as the label and your veterinarian direct.
To recap.
Feed the rumen, and the rumen feeds the cow: fibre and cud-chewing come first.
Balance intake, energy, protein, minerals and water.
Build on good forage and add concentrate for milk. Use local, area-specific minerals.
Read the cow: cud, dung, condition and the milk test.
Keep cows at the right condition for calving.
And change diets slowly, and handle urea with care.
For more on livestock and every crop, visit laisha.ai. Thank you for watching.
