Abstract
Full signalling of oestrous behaviour is vital for proper timing of AI and good reproductive performance, currently jeopardized by shorter observations of oestrus behaviour. Alternative indicators including progesterone (P(4)) recordings on-farm are tested. Oestrous intensity of 37 heifers (H) and 30 1st-parity dairy cows (C(1)) either Swedish Red (32) or Swedish Holstein (35) with high genetic potential for milk production, was studied in relation to AI. P(4)-levels in blood or milk were monitored on-farm at 0, 7, and 20 d post-AI with a portable ELISA reader (eProCheck(800)). Avoidance distance and body condition were scored at day 7, and pregnancy diagnosed by P(4) (day 20) and trans-rectal palpation (day 50). More heifers (46%) than C(1)-cows (10%) showed standing oestrus (strongest intensity, P < 0.05), leading to higher pregnancy rate at d50 (72% versus 37% for C1, P < 0.01) and calving rate (H: 64%, C1: 33%, P < 0.05). Avoidance distances were short (<1 m), reflecting good human-animal interaction. Visually-recorded standing oestrus yielded 4.8 fold higher odds of pregnancy, respectively 4.6-fold higher odds of calving. On-farm P4-recordings had complementary value yet less accuracy. Intensity of oestrus signalling relates to animal well-being, reflected in pregnancy-to-term being a good indicator for optimal welfare in high-producing dairy cattle.