Milk Production Estimator

Avg Lbs per Cow per Year is Annual Production divided by Herd Size, and Annual Production itself scales directly with Herd Size (more cows in the herd means proportionally more lactating cows), so the Herd Size factor cancels out of the division exactly -- only Avg Daily Milk per Cow, Lactation Period, and Dry Period actually move this per-cow figure.

It multiplies Herd Size by the fraction Lactation Period divided by the sum of Lactation Period and Dry Period, so a standard 305-day lactation with a 60-day dry period puts about 83.6% of the herd in active lactation at any time, with the remainder counted as dry cows resting between lactation cycles.

A longer Dry Period lowers the fraction of the herd that's actively lactating at any given time, which directly reduces Daily Herd Production and everything derived from it, including Annual Production, Annual CWT, and Avg Lbs per Cow per Year -- even though no individual cow's daily yield actually changes.

CWT (hundredweight, 100 lbs) is the standard unit U.S. dairy milk is priced and reported in, so Annual CWT converts Annual Production into the units used on a milk-marketing statement or blend-price calculation, making it easier to project gross milk revenue at a given per-CWT price.

It assumes every lactating cow produces exactly Avg Daily Milk per Cow every day of her lactation, when real production actually follows a lactation curve that peaks weeks after calving and tapers afterward, and it doesn't factor in seasonal calving clusters, dry-off timing variation, or herd health and nutrition constraints that limit actual output.