U.S. Department of Agriculture: Agricultural Research Service, Lincoln, Nebraska


Date of this Version


Document Type



Published in Beef Research Program Progress Report, No. 4, Part 2 (May 1993)


Reproduction is a major component of production efficiency for a cow-calf system. Failure of a cow to conceive is the most important factor reducing net calf crop. The interval from parturition to estrus, or postpartum interval, greatly influences the chances of a cow becoming pregnant during a restricted breeding season. Breeds can differ in length of postpartum interval and further, postpartum interval is influenced by numerous environmental factors including nutritional value of available feedstuffs. Inadequate energy availabilityincreases postpartum interval in suckled beef cows, but energy requirements differamong biological types. The level at which energy begins to limitreproductive performance may not be constant for all biologicaltypes of cattle. The objective of this study was to test the effects of biologicaltype and daily metabolizable energy availability on length of postpartum intervalof mature beef cows.