Evaluation of the response to buserelin administered 24 hours prior to artificial insemination in Sarda ewe: follicular dynamics after ovulation

Failure of fertilization and embryo loss during early gestation are major determinants of reproductive efficiency in Sarda ewe. A number of studies have demonstrated that treatment with the GnRH analogue buserelin on day 12 post insemination reduces embryo mortality in cattle and sheep. In response to this treatment, large ovarian follicles (LF) and circulating oestrogens are supposed to decrease; the resulting elevation in progesterone secretion, due to the increased number of active corpora lutea (CL), should facilitate embryo implantation. The aim of this research was to investigate the ovarian effect of buserelin adminstered 24 h prior to A.I. in Sarda ewe

The effect of by-pass linseed oil supplementation on the maternal antioxidant system during the embryo-maternal recognition period in ewes

This study analyzed the effects of dietary supplementation with by-pass linseed oil (LO; rich in α-linolenic acid) on maternal antioxidant systems at Days 14 and 16 of pregnancy in Sarda ewes. This trial used sixteen dry ewes. Eight ewes (CT group) were fed with a control diet without LO, and eight ewes (LO group) were fed with a diet supplemented with LO (10.8 g of α-linolenic acid/ewe/day). Both diets had similar crude protein and energy levels. The experiment included 10 days of an adaptation period and 31 days of a supplementation period. This supplementation period was divided into Period −2 (from Day −15 to −8), Period −1 (from Day −7 to −1; before synchronized mating period/Day 0), Period +1 (from Day +1 to + 7 after mating), and Period +2 (from Day +8 to +15 after mating). Estrous synchronization was induced in all the ewes using an intravaginal sponge (45 mg fluorgestone acetate) for 14 days and equine chorionic gonadotropin (350 UI/ewe) at the end of the treatment. On Days 14 (CT, N = 4; LO, N = 4) and 16 (CT, N = 4; LO, N = 4) after mating, the ewes were slaughtered. Samples of plasma, uterine, and luteal tissues were collected. Thiols, total antioxidant activity (TEAC), superoxide dismutase (SOD) activity, and malondialdehyde (MDA) content were measured. On Day 16, thiol and TEAC in luteal tissues were higher in the LO group when compared with the control one (p < 0.05). Moreover, TEAC was higher for the LO group in uterine tissues on Days 14 and 16 (p < 0.05). SOD activity was higher in the LO group in luteal and uterine tissues on Day 14 and Day 16, respectively (p < 0.001). On Day 16, uterine MDA content was lower for the LO group (p < 0.001). No differences were found between groups at the plasmatic level. However, the by-pass LO supplementation enhanced the analyzed antioxidant parameters in luteal and uterine tissues. In conclusion, these results demonstrate that by-pass LO supplementation exerted a positive effect on antioxidative defenses on maternal structures during the embryo-maternal recognition period in ewes. Thus, this could contribute to improving the maternal environment during the embryo-maternal recognition period in mammals

Circulating Concentrations of Key Regulators of Nitric Oxide Production in Undernourished Sheep Carrying Single and Multiple Fetuses

15 Pág.The aim of this study was to investigate the blood concentrations of L-arginine, asymmetric dimethylarginine (ADMA), symmetric dimethylarginine (SDMA), and L-homoarginine, which are regulators of nitric oxide (NO) synthesis, in single, twin, and triplet pregnancies in ewes undergoing either a dietary energy restriction or receiving 100% of their energy requirements. From day 24 to 100 of pregnancy, the ewes were fed ryegrass hay and two different iso-proteic concentrates fulfilling either 100% of ewes' energy requirements (control group; n = 30, 14 singleton pregnancies, 12 twin pregnancies, and 4 triplet pregnancies) or only 45% (feed-restricted group; n = 29; 11 singleton pregnancies, 15 twin pregnancies, and 3 triplet pregnancies). Blood samples were collected monthly to measure, by capillary electrophoresis, the circulating concentrations of arginine, ADMA, homoarginine, SDMA, and of other amino acids not involved in NO synthesis to rule out possible direct effects of diet restriction on their concentrations. No differences between groups were observed in the circulating concentrations of most of the amino acids investigated. L-homoarginine increased markedly in both groups during pregnancy (p < 0.001). SDMA (p < 0.01), L-arginine, and ADMA concentrations were higher in feed-restricted ewes than in controls. The L-arginine/ADMA ratio, an indicator of NO production by NOS, decreased towards term without differences between groups. The ADMA/SDMA ratio, an index of the ADMA degrading enzyme activity, was higher in controls than in feed-restricted ewes (p < 0.001). Obtained results show that circulating concentrations of L-arginine, of its metabolites, and the ratio between NO synthesis boosters and inhibitors are altered in energy-restricted ewes, and that these alterations are more marked in ewes carrying multiple fetuses.The experimental work was supported by funds from Regione Autonoma della Sardegna—Progetti ricerca fondamentale o di base—L.R. 7/2007—annualità 2013 (CRP 78167).Peer reviewe

Dynamique folliculaire et niveaux plasmatiques de la progestérone chez la brebis Sarde pendant l’anoestrus saisonnier

L’activité ovarienne pendant le cycle oestrien de la brebis a été décrite et jusqu’à trois ondes de croissance folliculaires ont été observées (Bister et al., 1999 ; Evans et al., 2000). Ce travail contribue à une meilleure connaissance de la dynamique folliculaire et de ses relations avec les niveaux de progestérone plasmatique pendant l’anœstrus saisonnier des ovins

Effect of buserelin administered 24 hours prior to A.I. in Sarda ewes: LH, 17β-oestradiol and progesterone plasma levels

Buserelin administered 24 h prior to A.I. increased ovulation rates in Sarda ewe. This study reports the effect of the same treatment on LH, E2 and P4 plasma levels. After a classic synchronization treatment of oestrous cycles, 24 multiparous Sarda ewes were submitted to A.I. (Day 0) 55 h after sponges removal. On Day – 1 12 ewes (Group T) were given a single i.m. injection of 4 μg/progestin buserelin (Receptal) and the remaining 12 ewes (Group C) acted as control. Blood samples were collected from each subject at 2-h intervals on Days – 1 and 0 (from 8:00 to 16:00 h) and twice on Day + 1 (8:00 and 15:00 h). LH concentration was assessed by ELISA (Reprokit), E2 and P4 by homologous radioimmunoassay. Buserelin caused in T subjects, compared to controls, an increase of LH (Day – 1), a decrease of E2 (Days – 1 and 0) and an increase of P4 concentrations (Day + 1). These differences were statistically significant (P &lt; 0:05). The results are in agreement to our previous observations on follicular dynamics: the higher LH and P4 levels reflected the increased number of corpora lutea and the lower E2 level the decreased number of large follicles

Towards a Sustainable Reproduction Management of Dairy Sheep: Glycerol-Based Formulations as Alternative to eCG in Milked Ewes Mated at the End of Anoestrus Period

This study investigated whether the administration of equine chorionic gonadotrophin (eCG) in a protocol to induce and synchronize ovulations before mating could be replaced by the administration of glycerol-based formulations in milked ewes at the end of their seasonal anoestrus. Forty-eight late-lactation dairy ewes of the Sarda breed were synchronized using sponges impregnated with progestogen and then joined with fertile rams (day (D) 0, ram introduction). From D−4 to D−1, the ewes received by gavage either 100 mL of a glucogenic mixture (70% glycerol, 20% propylene glycol and 10% water; GLU group; n = 24) or 100 mL of water (GON group; n = 24) twice daily. Moreover, on the day of sponge withdrawal (D−1), GON ewes received 200 IU of eCG. There were no differences in reproductive performances between groups. GLU ewes showed higher glycemia (p &lt; 0.001), insulinemia (p &lt; 0.05), plasma glycerol (p &lt; 0.001), triglycerides (p &lt; 0.001) and lower cholesterol (p &lt; 0.001), non-esterified fatty acids (NEFA; p &lt; 0.05) and urea (p &lt; 0.001). Plasma osmolality was higher in GLU but only 4 h after dosing (p &lt; 0.001). Milk yield and milk composition were not affected by the treatments with exception of milk glycerol (p &lt; 0.001) and milk urea (p &lt; 0.001), which were higher and lower in GLU than GON ewes, respectively. In conclusion, the administration of the glucogenic mixture to late lactation dairy ewes at the end of anoestrus period resulted in reproductive responses as good as the ones obtained by the eCG treatment, suggesting that the objective of a sustainable reproductive management of dairy sheep can be successfully pursued

Effet de la Buséréline administrée 24 h avant l’insémination artificielle de brebis de race Sarde: dynamique folliculaire port-ovulatoire et niveaux plasmatiques de LH, de 17 beta oestradiol et de progestérone = Effect of Buserelin administered 24 hours prior to artificial insemination in the Sarda ewe: follicular dynamics after ovulation and LH, 17ß-oestradiol and progesterone plasma levels

La variabilité des résultats de fertilité obtenus après insémination artificielle (IA) programmée chez les brebis synchronisées pourrait être la conséquence de la variabilité du moment de l’ovulation et de la persistance post-ovulatoire de gros follicules (GF). L’application de GnRH ou d’un analogue peut améliorer le taux de fertilité lorsqu’elle n’est pas effectuée trop précocement au cours de la phase folliculaire (Castonguay et al, 1996). Le but de ce travail était de rechercher l’effet de l’administration de buséréline (agoniste de GnRH) 24 h avant I’IA sur l’activité hormonale et ovarienne de la brebis Sarde

Inseminazione artificiale in un allevamento biologico ovino

L’inseminazione artificiale (IA) è alla base del miglioramento genetico di molte specie domestiche. Negli ovini un programma di IA necessita di un trattamento di sincronizzazione del ciclo ovarico con progesterone e PMSG per permettere l’inseminazione a 55h dall’asportazione della spugna senza dover rilevare le manifestazioni estrali peraltro poco apparenti nelle pecore. L’impiego di trattamenti ormonali risulta precluso alle aziende che orientano la loro produzione verso prodotti di qualità come ad esempio quelli biologici. Gli allevatori di tali aziende, perciò, si trovano nell’impossibilità di poter partecipare a programmi di miglioramento genetico. L’obbiettivo di questo lavoro è di valutare l’applicazione della IA in un’azienda biologica senza far uso di ormoni

Administration of glycerol-based formulations in sheep results in similar ovulation rate to eCG but red blood cell indices may be affected

15Pág.The objective of this study was to investigate the metabolic and osmotic effects of different doses of glycerol or a glycerol - propylene glycol mixture in Sarda sheep with the aim to identify those able to beneficially modify ewe's metabolic status without harmful changes in red blood cell (RBC) indices. Thereafter, the selected doses were tested for their effects on ewe's ovarian activity during an induced follicular phase and compared to the effects of a hormonal treatment with equine chorionic gonadotrophin (eCG).This study was financed by a doctoral grant from the Italian Ministry of Education, University and Research (Programma Operativo Nazionale Ricerca e Innovazione 2014–2020 - CCI 2014IT16M2OP005 - Fondo Sociale Europeo, Azione I.1 “Dottorati Innovativi con caratterizzazione Industriale). The funding institution financed laboratory analysis, the dietary treatments, and FDS. The funding institution had no role in the design of the study; in the collection, analysis, and interpretation of data; or in the writing of the manuscript.Peer reviewe

Postnatal pituitary and follicular activation: A revisited hypothesis in a sheep model

The importance of postnatal pituitary activation as regards female reproductive development is not yet understood.By taking advantage of the experimental model developed in a previous study, i.e. ewe lambs expressing markedly different ovarian phenotypes at 50 days of age, we design this study to determine whether differences found in ovarian status during the early prepubertal period are due to different patterns of postnatal pituitary activation, and to assess whether these differences have long lasting effects on subsequent reproductive performance. Results showed that ewe lambs with high antral follicle count (AFC) at 50 days of age had significantly lower plasma follicle stimulating hormone (FSH) concentrations and higher anti-Mullerian hormone (AMH) concentrations during the first 9 weeks of age compared with low AFC ewe lambs (p<0.0001). With a longitudinal experiment we showed that a high AFC in the early prepubertal period is associated with consistently higher AMH concentrations and number of antral follicles up to the post-pubertal period, and with higher pregnancy rates in the first breeding season. In addition, the effect of age in decreasing AMH concentrations was more marked in the low AFC group. Results of the present study demonstrate that ewe lambs undergo different patterns of postnatal pituitary activation. A high AFC at 50 days of age indicates an advanced phase of ovarian maturation, which was accompanied by constantly higher AMH concentrations up to the post-pubertal period, a greater ovarian response to FSH stimulation and by higher pregnancy rates at first mating, as compared with the low AFC group