Back during those thrilling organic days of yesteryear, when men and women like their chickens were omnivores, the farm wife kept a slop bucket underneath the kitchen sink or table and the excess buttermilk, whey, food scraps, mastitus tainted milk, spoiled milk, cladder etc, it all ended up in this slops bucket. Shelled feed corn or corn meal was also often added. This slop was mostly intended for the pigs or fattening hogs but a tin pan full was always poured out in the yard for the hens. They loved it. A careful reading of the guaranteed analysis or ingredient tag will reveal lactose as one of the ingredients in chicken food.
Just as the ingredient list in Mr. Hugh Pipers book on choosing, raising, and showing chickens shows because he listed the nutrient values of various foods that were commonly fed to chickens when his book was first published in London in 1877. Some how chickens survived ingesting poisonous milk for the intervening 138 years.
https://www.gutenberg.org/files/38606/38606-h/38606-h.htm#CHAPTER_XIII
MDCCCLXXVII ?1877?
There is in every
100 lbs. of Flesh-
forming
Food. Warmth-giving
Food. Bone-
making
Food. Husk
or
Fibre. Water.
Gluten,
&c. Fat or
Oil. Starch,
&c. Mineral
Substance
Oats
15 6 47 2 20 10
Oatmeal
18 6 63 2 2 9
Middlings or fine Sharps
18 6 53 5 4 14
Wheat
12 3 70 2 1 12
Barley
11 2 60 2 14 1
Indian Corn
11 8 65 1 5 10
Rice
7 a trace 80 a trace -- 13
Beans and Peas
25 2 48 2 8 15
Milk
4½ 3 5 ¾ -- 86¾
"Barley is more generally used than any other grain, and, reckoned by weight, is cheaper than wheat or oats; but, unless in the form of meal, should not be the only grain given, for fowls do not fatten upon it, as, though possessing a very fair proportion of flesh-forming substances, it contains a lesser amount of fatty matters than other varieties of corn. In Surrey barley is the usual grain given, excepting during the time of incubation, when the sitting hens have oats, as being less heating to the system than the former. Barley-meal contains the same component parts as the whole grain, being ground with the husk, but only inferior barley is made into meal.
Wheat of the best description is dearer than barley, both by weight and measure, and possesses but about one-twelfth part more flesh-forming material, but it is fortunate that the small cheap wheat is the best for poultry, for Professor Johnston says, "the small or tail corn which the farmer separates before bringing his grain to market is richer in gluten (flesh-forming food) than the full-grown grain, and is therefore more nutritious." The "Henwife" finds "light wheats or tailings the best grain for daily use, and next to that barley."
Oats are dearer than barley by weight. The heaviest should be bought, as they contain very little more husk than the lightes*
" (original spelling)