Reproduction in Domestic Animals

Reproductive Status Assessed by Milk Progesterone 1174 ng ⁄ ml (31 of 59 of false negatives). Of these, in 24cases smoothed progesterone did not decrease below6ng⁄ ml. This high-progesterone oestrus increasinglyseems to be a real biological phenomenon (Fig. 2). Ofthe remaining 28 false negatives, enlarging the window()3 to + 5 dfo) around oestrus for aligning modeldetected and ratified oestruses by ±3 days of the oestruscaptured 21 cases. Accepting these 21 cases as a matchreduced the number of false negatives to 38 resulting in amodel sensitivity of 93.3%. This sensitivity comparedvery favourably with the sensitivities reported for othermethods of oestrus detection (Firk et al. 2002), evenwhen these methods are used in very favourablecircumstances such as high intensity visual oestrusdetection (85.7% Van Eerdenburg 2006) or after oestrussynchronisation (91.3% for tail paint, 81.4% forpedometers Cavalieri et al. 2003). Only the combinedactivity, milk yield, milk temperature and conductivitymodel of de Mol et al. (1999) had a sensitivity (94%)that matched that for the ratified oestruses. Althoughthis sensitivity was less than the 99% found using theconfirmed oestruses.In addition to enlarging the number of oestrusesaccepted as ‘true’, the profile matching procedure allowsexamination of those cases in which the model indicatedoestrus in the absence of a ratified oestrus, and thusallows calculation of model specificity. There were 171model-detected oestruses (excluding first increases inprogesterone >4 ng ⁄ ml) that did not match a ratifiedoestrus (i.e. false positives). Thus, the model had apositive predictive value (proportion of model detectedoestruses that are true oestruses) of 72.2%[445 ⁄ (445 + 171)]. The total number of progesteronemeasures in the period of oestrus cycling (Status = 1and profile matching weight