Milk comes in seasons because an animal gives milk only after it has had young: production peaks in spring when animals freshen after winter, declines through fall as they dry off, and stops or nearly stops in winter unless breeding is staggered. Splitting the herd into two groups that freshen about six months apart, spring and fall, keeps at least one group in milk all year, at a lower total volume than a single peak.
Part of Dairy Production at Scale
The seasonal milk cycle is the yearly pattern of breeding, birth, lactation and dry period that determines when a dairy herd gives milk and when it does not.
Birth Starts The Milk, So The Breeding Date Sets The Supply
The parent article describes the cycle: spring peak when animals freshen after winter calving or kidding, good summer production, a fall decline as animals dry off before winter breeding, and little or no milk in winter unless breeding is staggered. Stagger breeding so some animals freshen in fall and some in spring, and the herd gives year-round milk, though at lower total volume.
Worked Example: Two Cow Groups
Use three standard dairy figures from general knowledge, not from the wiki: a lactation of about 305 days, a dry period of about 60 days, and a cow pregnancy of about 283 days. A cow that gives milk for 305 days and rests for 60 is on a 365-day cycle, so each cow freshens once a year.
- Group A freshens March 1. In milk March through December (305 days ends about December 31), dry about January and February.
- Group B freshens September 1, six months later. In milk September through June, dry July and August.
- Cows in milk by month: January-February, B only (A is dry). March-June, both. July-August, A only (B is dry). September-December, both.
At least one group is always producing. The trough months are those when only one group is in milk: January-February and July-August.
- Breeding date: subtract the 283-day pregnancy from the freshening date. For a March 1 calving, breed 283 days earlier, which is about May 22 of the previous year (283 days is about 9.3 months). For September 1, breed about November 21 of the previous year. A cow therefore has to be rebred about 82 days after calving (365 - 283) to keep the yearly cycle.
Goats Work Differently
Goats are seasonal breeders that naturally cycle in the fall and kid in spring (general knowledge, not a wiki figure), and goat pregnancy is about 150 days, or 5 months. A spring-kidding herd gives a spring peak by default. To stagger a goat herd you need to cheat the season, which is unreliable, so a goat-based dairy is usually planned as a spring-peak dairy: make hard cheese and ghee in the flush and store them for the lean months. See Goat Raising.
What You Need
- A breeding calendar on the wall: dates bred, expected birth, dry-off date
- Feed to match the flush: pasture in spring and stored hay for winter; see Pasture Management and Hay Making
- A way to process the flush: ghee, hard cheese and butter, which turn a perishable spring surplus into winter food
- Birth help available when animals freshen; see Birthing Assistance
Method: Planning The Year
Step 1: Choose the freshening dates for each group. Spring and fall, six months apart.
Step 2: Subtract the pregnancy length to get the breeding date. Record both.
Step 3: Dry off each animal about 60 days before its next birth. Dry-off timing affects the next lactation and the udder’s health at dry-off; see Mastitis.
Step 4: Plan processing around the flush. In spring and early summer make long-keeping products; in fall and winter use the stored products to cover for lower fresh milk.
Common Mistakes
- Breeding everything at once. It gives a huge flush followed by a winter with no milk.
- Counting on one animal for winter milk. She may fail to conceive or go dry early.
- Ignoring feed. An animal on poor winter feed gives little milk whatever the calendar says.
- Forgetting the dry period. An animal needs rest before the next birth; milking straight through reduces the next lactation.
Safety
Freshening is the dangerous week
A freshening cow is protective and unpredictable, and a birth going wrong can kill her and the calf within hours. Do not work alone around calving animals. Milk from the first days after birth is colostrum and goes to the newborn first. Raw milk of any day carries the tuberculosis, brucellosis and listeria hazard until it is pasteurized.
What’s Next
- Learn next: Whey utilization (pigs, gardens) — making use of the flush’s by-products
- Combine with: Scaling & Scheduling — fitting the cycle to labor and storage