Autumn fertility of dairy cows is lower than in winter, although ambient temperatures drop and cows are no longer exposed to thermal stress. For example, in Florida, the autumn conception rate October–November. of Holstein cattle was found to be around 35–40%, compared with above 50% in winter January–March; Badinga et al., 1985..
Conception rates of high-yielding dairy cows in Israel Herd Book data, 1992–1997. drop from 45% in winter to around 20% during the summer, and to 23% and 29% in October and November, respectively. These figures clearly show a delayed influence of summer HS on autumn fertility.