Reproductive Management of the Cow Herd

Basic Bovine Reproductive Facts Puberty at 6 to 12 months of age Estrous cycle is 21 days + 3 days Standing heat or estrus is 12 to 18 hrs. Ovulation occurs after estrus. Gestation period is 285 days + 5 days

GOALS To achieve a high conception rate in a relatively short breeding season. 60 to 90 day season is ideal. Calves that are uniform in age are easier to manage and market. To retain cows in the herd for a long time and thus reduce the number of replacements Normal replacement rate is about 20%

Natural Service In commercial beef herds, most of the mating is via natural service. Bulls are with the cows 24 hours per day and do all heat detection. With natural service, a relatively large volume of semen is placed in the vagina during standing heat.

Artificial Insemination Used primarily in seedstock herds and well managed commercial herds. Usually consists of 1 or 2 AI services followed by a “cleanup” natural service sire. Heat detection is labor intensive. A relatively small volume of semen is deposited in uterine horn at end of estrus. Cows detected in heat in a.m. are bred in p.m. and vice versa.

Heat Detection Frequent observation. “Gomer” bulls that have been vasectomized Fitted with chin-ball marker Penal deviation prevents disease transmission Cull cows that have been injected with testosterone. Pressure patches on rump.

Estrus Synchronization One injection PGF with 10 day breeding Two injection PGF programs MGA/PGF Synchro-Mate-B program GnRH/PGF – “Select Synch” Co-Synch

Embryo Transfer Used primarily in seedstock herds to generate increased numbers of progeny from superior “donor” females. Progeny must have superior economic value to make system cash flow. Lesser value “recipient” females are synchronized to match estrous cycle of donor.

Embryo Transfer (continued) Donor cow is super-ovulated and then mated at estrus. Embryos are recovered (“flushed”) from the donor 7 days after estrus. Embryos can be transferred to recipients or frozen for future transfer. Approximately four pregnancies are generated per flush.

Calving Season Management Heifers should be bred to begin calving about 3 weeks prior to the cow herd. Allows for a longer postpartum interval before rebreeding. Permits crew to check heifers early in season. Be prepared to assist as needed. Abnormal presentations Heifers may require more assistance than cows

Processing Newborn Calves Get colostrum into calf within a few hours after birth. Iodine navel to prevent navel ill. Inject with Bo-Se and Vitamin AD&E. Intranasal vaccine for IBR, BVD & PI3 Scour vaccine (E. coli and Rota-Corona viruses). Identify (tattoo and ear tag).