Reproductive Management of Dairy Cows in High Milk-Producing Herds

Abstract

Challenges limiting reproductive efficiency of high milk- producing cows include interrelationships among body condi- tion, dry matter intake, transition from the dry period to lacta- tion, onset of normal estrous cycles, detection of estrus, and embryonic survival. Attention is required to details associated with diet formulation; feed bunk management; cow comfort in free stalls, holding pen, and milking parlor during extremes of temperature and humidity; proper hoof care; milking man- agement and mastitis prevention; control of ovulation and es- trus; and early nonpregnancy diagnosis. Intensive management of transition cows should involve monitoring key metabolic markers using hand-held devices. This should allow early de- tection of illnesses that can be followed by proven interven- tions to alleviate their residual effects. Body condition should be monitored more closely to reduce dry cow and transition problems and prevent prolonged anestrus by maximizing early postpartum dry matter intakes. Cow comfort should be moni- tored more closely to minimize standing time for milking, maximize standing time for estrus and feed intake, and maxi- mize resting time for rumination and more efficient milk syn- thesis. Estrus may be detected using automated techniques such as pedometry, rump-mounted pressure-sensitive radio- telemetric devices, and in-line parlor tests for milk progester- one or estrogen. More highly fertile heifers may be impreg- nated using sexed semen, sexed embryos, or clones to provide more replacement heifers because of declining fertility of lac- tating cows. Strategies to impregnate high-producing cows will require more ovulation control before first and subsequent services without detection of estrus. Because of high rates of embryonic death, more pregnancies may be achieved by using sexed or cloned embryos. Many reproductive technologies used today, including programmed breeding, will be refined and incorporated into the management of cows on fewer dairy farms with more cows per farm. Despite trends for longer lac- tations associated with bST and lesser pregnancy rates, re- newed lactations following parturition will continue to be es-