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Urinary ovarian steroid excretion patterns aligned to the day of peak oestrogen excretion (Day 0) are depicted for this female from 1998 to 2000 (Fig. 8.6). In all years, spontaneous oestrogen excretion increased above baseline by Day —10. In 1998 (the 'control' year when no gonado-trophin treatment was administered), oestrogen concentrations during the 30-day interval preceding ovulation (Days —30 to 0) ranged from 5 to 283 ng mg—1 Cr, with oestrogen returning to baseline by Day +5. In the

Figure 8.4. Faecal (o) and urinary (♦) oestrogen excretion in female SB 473. Values, aligned to day of urinary oestrogen peak (Day 0), were highly correlated (r = 0.87).

20 -10 0 10 20 Day from urinary oestrogen peak

Figure 8.4. Faecal (o) and urinary (♦) oestrogen excretion in female SB 473. Values, aligned to day of urinary oestrogen peak (Day 0), were highly correlated (r = 0.87).

absence of mating or AI, this female nevertheless displayed typical oestrual behaviours, including bleating and chirping. A lordotic tail-up response was observed as urinary oestrogens declined. In this same year, post-ovulatory progestins increased by Day +3 with values from Days 0 through 40 exceeding (p < 0.05) pre-ovulatory concentrations.

In 1999, this same female was treated with FSH and hCG (see Methods) in an attempt to induce oestrus and increase the chance of mating. Despite seven days of FSH treatment (Days —13 to —8), oestrogens did not increase appreciably (see Fig. 8.6b). Therefore, the FSH dose was increased on Day —6, which induced a rapid increase in oestrogen excretion over the next six days (~150 ng mg—1 Cr). On the day of mating (Day 0), hCG was administered, and AI was performed two days later (Day +2). Within five days, a precipitous and sustained 24-day increase in oestrogen production ensued (peak concentrations on Day +19, 5713 ng mg—1 Cr), before oestrogen concentrations declined to pre-treatment levels (Day +33). Urinary progestins increased after mating and remained elevated in a profile that was indistinguishable from that observed in 1998 (see Fig. 8.6a,b). For the 1999 season, this female chirped on Day —15 (before gonadotrophins were given), scent-marked

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