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Gonadotrophin-releasing hormone (GnRH) or equine and human chorionic gonadotrophins (eCG and hCG) were evaluated for oestrus/ovulation synchronization (E/OS), as well as the influence of GnRH 5 days post-breeding (dpb) on embryo viability (EV), and progesterone (P4) levels on Day 16 and 30 after laparoscopic AI (LAI) or natural service (NS). Fifty-four lactating/non-lactating Alpine breed goats (average of 3.82±1.2s.d. years of age) of mixed parity were E/OS during the early transitional breeding phase using 12±1 day of 300mg of P4 and 2mL of prostaglandin F2α analogue given at P4 removal. The experiment included a sub-group from a larger study in which a completely randomised design was used. The germane data were arranged as a 2×2×2 factorial. This study focused on goats receiving 120IU of eCG and 60IU of hCG (n=40), or GnRH analogue (n=14) 24h after P4 removal. At 5 dpb, 25 goats received 1mL (IM) of GnRH and the control (n=29) received 1mL of physiologic saline. Goats were time-bred 48h after P4 withdrawal by LAI (n=33) or NS (n=21). Pregnancy was diagnosed at 18 to 24, 30, and 40 dpb by non-return to oestrus, pregnancy-specific protein B, and ultrasound, respectively. EV was evaluated as the difference between pregnancy diagnosis results. Blood serum P4 was evaluated at 5, 16, and 30 dpb. A logistic regression model was used for statistical analysis. Pregnancy rate (PR) for LAI or NS, at 18–24, 30, and 40 days was 73 vs. 76%, 67 vs. 62%, and 64 vs. 67%, respectively (P>0.72). In contrast, when GnRH was used for E/OS, the 5 dpb GnRH influenced EV at 30 days (95 vs. 81%; P=0.06) but not at 40 days (89 vs. 86%; P>0.35), compared with placebo. Similarly, with the exception of PR at 40 days (43 vs. 72%; P=0.05), for the GnRH and eCG/hCG E/OS groups, respectively, PR was not affected (P>0.12) by either E/OS or GnRH 5 dpb or their interaction (P>0.35) at any pregnancy diagnosis (i.e. 18–24, 30, or 40 dpb). Likewise, levels of P4 at 5, 16, and 30 dpb did not affect PR at 18–24, 30, and 40 dpb (P>0.92, 0.71, and 0.11). As shown in Table 1, the level of P4 was not influenced for goats receiving GnRH or placebo at 5, 16, or 30 dpb. The baseline mean P4 blood serum level for goats receiving GnRH 5 dpb differed at 16 but not at 30 dpb (P<0.001). Table 1 Blood serum progesterone (P4, ng mL−1) in response to gonadotrophin-releasing hormone (GnRH) or placebo given 5 days post-breeding Sampling day GnRH Placebo P >1 Mean ±SE Mean ±SE 5 (baseline) 6.2a 0.83 5.7a 0.72 0.66 16 11.7b 1.11 11.0b 1.05 0.65 30 6.2a 0.89 7.6c 0.84 0.26 a–cMean values with different superscripts within a column signify statistical difference for GnRH (P<0.001) and placebo (P<0.02). 1Probability for mean differences in the same row.

Oestrus and ovulation synchronization (E/OS) regimens for fixed-timed breeding are useful when consistently eliciting ovulation. Early synchronization in the reproductive season promotes unreliable oestrus behavioural and physiologic response due to insufficient ovarian priming. In ruminants, equine (eCG) or human chorionic gonadotrophin (hCG) has FSH bioactivity or elicits ovulation, correspondingly. Hence, 120 and 60IU of eCG and hCG, respectively, are included in goat E/OS regimes. This experiment addresses the time when eCG/hCG (CG) is given relative to progestagen (P4) withdrawal and its effect on oestrus and ovulation. Fourteen non-lactating, Alpine breed goats, ranging from 1 to 6 kiddings, averaging±s.d. 3.9±2.0 years of age, and 56.3±5.0kg of bodyweight (BW), and body condition score (BCS) of 2.6±0.2, were evaluated early in the transitional reproductive phase (12h daylight:12h darkness). E/OS was accomplished with 12 day of P4 (200 mg) exposure by intravaginal insert. Three treatments were evaluated: Traditional (T; n=4) did not receive CG and served as the control group; early (E; n=5) received CG 24h before P4 removal; and reverse (R; n=5) received PGF2α 24h before P4 withdrawal as well as CG concurrent with P4 withdrawal. Oestrus response to E/OS was evaluated 24h after breeding using epididymectomized bucks. Ovaries were scanned by transrectal ultrasound (Aloka SSD-500V/7.5-MHz linear array probe) for 4 consecutive days starting with the first i.m. injection of 1.0mL of PGF2α or 1.5mL of CG. Images were digitized (MediCapture™) for later morphometry. The absence of effect (P>0.05) from concomitant variables age, BW, BCS, and parity was ascertained using a logistic regression model (JMP/SAS v15; SAS Institute Inc.). Ovulation, defined as the disappearance of the largest (>7mm) preovulatory follicle on a subsequent observation, was 100, 80, and 100%; and the average±s.e. number of ovulations per goat was 2±0.41, 1±0.32, and 1.3±0.49 (P>0.05). Table 1 summarises follicular size documented of 122 observations of ovulatory areas. Graafian follicle location was not different for left or right ovaries (P>0.05). Oestrus behavioural response to each E/OS treatment (T, E, or L) up to 24h after P4 removal was 50, 80, and 80% (P>0.05), respectively. In summary, oestrus response and ovulation were not affected by the variables studied. In this experience the timing of CG was not relevant. Table 1. Mean diameter (±SE; mm) of nonovulatory and preovulatory follicles on left (L) and right (R) ovaries E/OS protocol Non- and preovulatory Nonovulatory Preovulatory L R L R L R Traditional 6.4±0.6 5.5±0.6 4.8±0.4 4.5±0.4 7.7±0.4 8.9±0.3 Early 5.2±0.3 5.5±0.4 4.9±0.2 4.4±0.3 8.4±1.2 8.1±0.2 Reverse 6.6±0.5 5.3±0.6 5.1±0.4 4.4±0.5 8.7±0.3 8.1±0.2 Overall 5.7±0.19 4.7±0.14 8.3±0.14

The objective of the study was to determine effects of the nutritional plane before breeding on performance of different hair sheep breeds. Twenty-five Dorper, 27 Katahdin, and 32 St. Croix ewes with initial BW of 65.6, 65.7, and 54.3 kg (SEM=1.95) and body condition score (BCS; 1–5) of 3.35, 3.29, and 3.09, respectively, consumed wheat straw ad libitum for 11 wk before breeding. Ewes of each breed were divided into four groups, with two groups per nutritional plane (NP). Ewes on a low NP (Low-NP) were supplemented with 0.16% BW (DM) of soybean meal (SBM) and ewes on the high NP (High-NP) received 0.8% BW (DM basis) of 0.25% soybean meal and 0.75% ground corn. Ewes were divided into two groups for estrus synchronization. Four rams of each breed were used, two for the first 17 d of breeding and the other two from d 17 to 34. Conception and embryo mortality were determined by ultrasound imaging at 25 and approximately 40 d post-breeding. Average daily gain and BCS change were similar among breeds, but both were greater for High-NP vs. Low-NP (ADG: 57 vs. -4 g, SEM=8.1; BCS change: 0.22 vs. -0.02, SEM=0.041). Wheat straw DMI was greater (P = 0.01) for Low-NP than for High-NP (2.02 and 1.58% BW, respectively; SEM=0.042) and for St. Croix than for Dorper and Katahdin (P = 0.04; 1.96, 1.68, and 1.74% BW, respectively, SEM=0.060). There were no differences in the number of services or conception (P > 0.05), and no embryo mortality was noted. In conclusion, NP did not influence reproductive performance assessed early after breeding despite differences in ADG and BCS change. This may be due to moderate initial BCS and increased straw intake by Low-NP ewes.