Estrus detection and estrus characteristics in housed and pastured Holstein-Friesian cows.

This study compared three methods of estrus detection and characteristics of standing estrus between dairy cows kept in cubicle housing and fed a total mixed ration diet (HOUSED treatment) and those kept at pasture with concentrate ration supplementation (PASTURE treatment). The 23 spring-calved Holstein-Friesians in each treatment were monitored by three estrus detection methods simultaneously-visual observations, tail paint and radiotelemetry (HeatWatch)-for 9 wk. Milk progesterone profiles were used to determine the dates of true standing estrus events. All three detection methods had a higher efficiency of estrus detection in the PASTURE treatment than in the HOUSED treatment (P < 0.001), but there was no difference in the accuracy of estrus detection between the two treatments (P > 0.05). Within each treatment there was no difference between the efficiency and accuracy of the three methods (P > 0.05). HeatWatch was as efficient as visual observations at detecting standing estrus events. However, during visual observation sessions all occasions when animals were observed standing to be mounted were not recorded by HeatWatch. More cows expressed sub-estrus events and fewer expressed standing estrus events in the HOUSED than in the PASTURE treatment (P < 0.05). The interval between parturition and the second standing estrus was longer in the HOUSED treatment than in the PASTURE treatment (P < 0.05). All three detection methods were much less effective in the HOUSED than in the PASTURE treatment. This is because all of the detection methods tested relied solely on standing to be mounted and this was reduced in the HOUSED cows. Alternative approaches to estrus detection are needed for cows kept indoors on concrete.