The Ewe
DAYS 0–7 > Greatest risk of embryo loss due to heat and humidity stress

DAYS 30–90 > Critical period for placental and mammary gland development. Reduced fetal growth, birth weights, vigor, and lower milk production result from poor nutrition at this time. Macro- and micro-mineral supplementation is vital. Impairment cannot be made up for later.

DAY 60 > Booster vaccination (following pre-breeding vaccine) protects ewe against chlamydiosis and vibriosis abortions

DAYS 100–BIRTH > Nutritional demands of fetuses place greatest demand upon ewe

DAY 120 > Vaccination against respiratory, clostridial diseases and tetanus stimulates high level of antibodies in colostrum, (forming by about day 136). Periparturient rise of internal parasite egg production: deworm to protect lambs.

DAY 150 or BIRTH > Colostrum production ceases; 24–36 oz available to lambs.

AFTER BIRTH
DAYS 21–28 > Maximum milk production attained. Maximum production requires maximum nutrition. Feed best hay, match grain amounts to number of nursing lambs.

DAY 60 > Many ewes producing less than half of the amount of milk they produced at peak production.

The Lambs

Gestation
DAYS 20–24 > Embryos implanted in uterine wall

DAY 35 > First primary fiber follicles form

DAYS 60–63 > Most primary fiber follicles formed; lateral primary follicles begin to form

DAYS 90–100 > Secondary wool follicles begin forming

DAYS 100–BIRTH > 70% of fetal growth occurs

DAY 120 > Fetal lambs immunocompetent: capable of forming some antibodies

BIRTH > Antibody-rich colostrum (received within 24 hr of birth) provides passive immunity for up to 10 weeks; primary follicle fibers shed

AFTER BIRTH
DAYS 7–14 > Lambs begin eating creep feed; some rumen function by day 14; 250% increase (from birth) in growth/maturity of secondary follicles

DAYS 28–42 > Lambs convert from high-milk, low-feed to low-milk, high-feed diet

DAYS 42–56 > Rumen becomes fully functional; lambs vulnerable to coccidiosis (add coccidiostat to feed)

DAY 60 > 75% of secondary follicles growing fiber; lambs vulnerable to high parasite loads (deworm)

DAY 70 > Disease immunity of lambs, gained by colostrum, depleted (vaccination vital)

DAYS 91–98 > In vaccinated lambs, antibody titers peak; booster of vaccine at this period “confirms” to immune system that antibody production is important

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