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Olivera-Muzante J.,Area de Produccion y Sanidad Ovina | Gil J.,Area de Teriogenologia | Fierro S.,Area de Produccion y Sanidad Ovina | Menchaca A.,Institute Reproduccion Animal Uruguay

The objective was to improve the reproductive performance of a prostaglandin (PG) F 2α-based protocol for timed artificial insemination (TAI) in sheep (Synchrovine®: two doses of 160 μg of delprostenate 7 d apart, with TAI 42 h after second dose). Three experiments were performed: Experiment 1) two doses of a PGF 2α analogue (delprostenate 80 or 160 μg) given 7 d apart; Experiment 2) two PGF 2α treatment intervals (7 or 8 d apart) and two times of TAI (42 or 48 h); and Experiment 3) insemination 12 h after estrus detection or TAI with concurrent GnRH. Experiments involved 1131 ewes that received cervical insemination with fresh semen during the breeding season (32/34 °S-58 °W). Estrous behaviour, conception rate, prolificacy, and fecundity (ultrasonography 30-40 d), were assessed. In Experiment 1, ewes showing estrus between 25 and 48 h or at 72 h after the second PGF 2α did not differ between 80 and 160 μg of delprostenate (73 vs 86%, P = 0.07; and 92 vs 95%, P = NS, respectively). Conception rate and fecundity were lower (P < 0.05) using 80 vs 160 μg (0.24 vs 0.42, and 0.27 vs 0.47, respectively). In Experiment 2, giving PGF 2α 7 d apart resulted in higher (P < 0.05) rates of conception (0.45 and 0.51) and fecundity (0.49 and 0.53) than treatments 8 d apart (conception: 0.33 and 0.29; fecundity: 0.33 and 0.34) for TAI at 42 and 48 h, respectively. In Experiment 3, rates of conception, prolificacy and fecundity were similar (NS) between Synchrovine® with TAI at 42 h (0.50, 1.13, and 0.56) and AI 12 h after estrus detection (0.47, 1.18, and 0.55), and Synchrovine® plus GnRH at TAI (0.38, 1.28, and 0.49). However, all TAI treatments had lower (P < 0.05) prolificacy and fecundity compared to AI following detection of spontaneous estrus (1.39 and 0.83, respectively). In conclusion, the Synchrovine® protocol was: a) more successful using 160 vs 80 μg delprostenate; b) more successful with a 7 d than 8 d PGF 2α interval; c) similarly effective for TAI versus AI 12 h after estrus detection; and d) not improved by giving GnRH at TAI. © 2011 Elsevier Inc. Source

Vinoles C.,Lana | De Barbieri I.,Lana | Gil J.,Area de Produccion y Sanidad Ovina | Olivera J.,Area de Produccion y Sanidad Ovina | And 3 more authors.
Animal Production Science

To evaluate the impact of feeding rams for 14 weeks with legumes and supplement on their clinical, behavioural and endocrine responses, 32 Merino rams, 17 months old, were allocated to four groups (n = 8). The 2×2 factorial arrangement evaluated the pasture type (IP, improved pasture; NP, native pasture) and the effect of feeding (+S) or not (S) feeding a supplement. Every 2 weeks liveweight, scrotal circumference and serving capacity were evaluated and blood samples taken to measure the concentrations of metabolites and metabolic hormones. Grazing behaviour was evaluated every 4 weeks. Rams grazing IP (61.8±0.7 kg) were heavier than those grazing NP (59.6±0.7 kg; P<0.05), and +S rams (61.8±0.7 kg) heavier than S rams (59.3±0.6 kg; P<0.05). Compared with rams from the IP+S, IPS and NP+S, rams grazing NPS lost weight (P<0.001) during the experiment. The scrotal circumference was larger in IP+S (30±0.4 cm), I-PS (30±0.4 cm) and NP+S (31±04 cm) than in NPS (29±0.4 cm; P<0.001). Only in rams from the group NP+S was a significant increase in scrotal circumference observed during the trial (P<0.05). The supplement tended to maintain the mating potential elevated towards the end of the experiment (+S: 74.3±5.4 and S: 61.7±6.3 ewes/ram; P = 0.07). Supplemented rams were less frequently seen grazing (47±3%) than non-supplemented rams (57±4%; P = 0.09). Rams grazing IP ruminated more frequently (13±2%) than those grazing NP (9±2%; P<0.001). Events such as lying down, playing, self-grooming and drinking water were more frequent in supplemented (36±2%) than non-supplemented rams (30±2%; P = 0.09). The supplement increased the concentrations of insulin and glucose and decreased the concentrations of non-esterified fatty acids, albumin and urea (P<0.05). IP increased the concentrations of insulin-like growth factor-I, protein, albumin and urea and tended to increase the concentrations of insulin. We conclude that feeding Merino rams a high plane of nutrition reduced the frequency of grazing events and stimulated a long-term improvement of the metabolic status, evidenced by an increase in liveweight and scrotal circumference, with relevant implications for their mating potential. © 2012 CSIRO. Source

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