Comparing Milk and Milk Powder
Question yesterday at our meeting on Alweston Farm, Alweston, Sherborne, Dorset:
"Last year I changed from feeding milk powder to feeding milk. My calves are doing much better on the milk. Why is that?"
Details that came out were that she had been feeding a high quality milk powder that was, as she could recall, 20%protein and 18%oil (fat). It was mixed at the label rate of 100g powder makes 1 litre and she was feeding 4 litres a day [ you and I can figure this out = total dry matter per day was 400g.]
The milk she fed was a somewhat inconsistent 50:50 blend of tank milk [she was getting paid for 3.0% protein and 4.0% fat, probably about 13% solids] and milk of an unknown composition from fresh cows whose milk was not ready to sell. A reasonable guess on this blend might be 15% solids, 3.4% protein and 5% fat. She continued to feed 4 litres volume daily. At 15% solids 4 litres a day equals 600g dry matter daily (4 litres =4000g, 4000 x .15 = 600g d.m.)
On a dry matter basis we can estimate this 3.4% protein, 5% fat milk to equal 23% protein and 33% fat. [.034/.15=.23x100=23%; .05/.15=.33x100=33%]
So let's compare intakes:
Milk powder: 400 grams total dry matter, 72g fat (400 x .18 fat)
Milk: 600 grams total dry matter, 198g fat (600 x .33 fat)
Back to her question: "My calves are doing much better on the milk. Why is that?" Recall she was feeding equal liquid volumes of both reconstituted milk powder and whole milk.
Dry matter intake drives growth. Feed more dry matter a calf grows more rapidly.
Milk fat is the major source of energy for a young calf. With enough protein as well, feed more highly digestible energy a calf grows more rapidly.
The group discussion then launched off on procedures for feeding milk powder with everyone agreeing that mixing powder at 100g/litre was really wrong. And, most of the farmers present fed more than 4 litres a day, especially in cold rainy weather which seems to have been a continuous state since last July.
Have a good day.