Average Daily Gain

Average daily gain is two weighings and a calendar, and its simplicity is both its virtue and its trap. Subtract the initial weight from the final, divide by the days between, and the result projects a feeding period to a target weight, sets a marketing date, and benchmarks the ration. Typical figures run about 1.4–1.8 kg per day for finishing cattle, 0.8 kg for growing pigs, and 0.7–1.0 kg for backgrounded calves on good pasture.

The word AVERAGE is doing quiet work. Gain is not a constant rate: it responds to compensatory growth after a period of restriction, to weather, to a ration change, and to the seasonal march of pasture quality. A single ADG over 120 days smooths all of that into one number, which is what makes it useful for planning and useless for diagnosis. Two herds with identical ADG can have arrived there by completely different paths, and only interim weighings tell them apart.

Gut fill is the largest source of error in any short-period figure, and it is worth more caution than it usually gets. An animal off water and feed shrinks 3–5% of its body weight within hours, and a full animal weighed after a morning at fresh pasture reads high by a similar margin. Over 150 days that noise averages out to almost nothing. Over 14 days it can swamp the signal entirely, and a weighing-to-weighing gain of "zero" in a fortnight frequently means nothing more than that the first weighing was taken off the truck and the second off the feed bunk. Weigh at the same time of day, under the same conditions, and prefer longer intervals wherever the question allows.

Read ADG alongside conversion rather than instead of it. Fast gain achieved with a rich ration may cost more per kilogram than slower gain on forage, and the answer depends entirely on the price of feed against the price of weight. Fast gain also earns something the ratio never shows: fewer days on feed means less yardage, less interest, less exposure to a falling market, and a pen turned over sooner.