Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)


Animal Science

First Advisor

Herley L. Miller


The postpartum interval is the period of time from parturition until the first postpartum estrus that is accompanied by ovulation. The postpartum interval of the suckled beef cow ranges from 46 to 168 days. A prolonged postpartum interval in the beef cow is of major economic importance in terms of cow productivity. The achievement of a 365 day calving interval requires a calving to conception interval of 80 to 85 days. Since average calving rates to a given service or insemination are only 50 to 60%, the earlier a cow begins to cycle postpartum, the greater the chance of successful conception by this time. There are many factors which influence the length of the postpartum interval. Breed of the dam, heterosis, age of the dam, dystocia, season of calving and photoperiod are a few of the factors contributing to the variation in postpartum interval. Numerous researchers have linked the nutritional state of beef cows to the duration of the postpartum interval. Cows in an adequate nutritional state which results in good body condition prior to parturition, have shorter intervals to first estrus after calving than cows in thin body condition at time of calving. There is increasing information that manipulation of suckling can influence duration of the postpartum anestrous period. In addition, the presence of bulls during the postpartum interval influences the time when cows resume estrous cycles following parturition. The successful management of these factors could result in cows returning to estrus sooner following parturition. Early induction of postpartum estrous cycles in late calving cows or in cows that have long postpartum intervals would be advantageous to the producer. However, evidence that conception rates are higher in cows that have had a postpartum estrous cycle preceeding the time of breeding is conflicting. The purpose of the following literature review will be to examine the various factors that influence the postpartum interval in beef cattle, specifically bull exposure.

Library of Congress Subject Headings

Beef cattle -- Breeding

Beef cattle -- Reproduction



Number of Pages



South Dakota State University