How does cow-calf association inhibit the onset of estrous cycles after calving?

Abstract

The "suckling response" maintains anestrus in beef cows for about 40 to 60 days postpartum. The suckling response remains intact in mastectomized cows, so stimulation of the inguinal area, and not milk flow or teat stimulation, must be part of the response. Cow-calf recognition is part of the suckling response because suckling by cross-fostered calves after nose-to-nose contact followed by suckling of an alien calf does not prevent cycling. We believe the suckling response involves a cow recognizing her own calf, followed by the calf stimulating her inguinal area. It may be possible to initiate estrus by simply blocking the cow's recognition of her own calf.