Embryo losses in sheep during short-term nutritional supplementation

Abstract

To test whether a nutritional supplement fed from 6 days before until 15 days after insemination reduces progesterone concentrations and increases embryo losses, Merino ewes were artificially inseminated (Day 0). Control ewes (n = 116) were not supplemented whereas Lupin6 ewes (n = 112) were supplemented with 500 g lupin grain daily for 6 days before insemination, and Lupin6+15 ewes (n = 122) from 6 days before until 15 days after insemination. There were no major differences between treatment groups in progesterone concentrations over the first 17 days of pregnancy. Embryo losses over Days 10-17 were lower in the Lupin6+15 than in the Control and Lupin6 groups, but the opposite occurred from Day 17-30. The concentrations of insulin and IGF-I were higher in Lupin6+15 ewes on Days 5, 12 and 17, compared with Lupin6 and Control ewes, while leptin concentrations decreased by Day 17 in the Lupin6+15 group. We conclude that feeding ewes for 15 days after mating improved embryo survival, which was associated with an increase in the concentrations of metabolic hormones and lower progesterone concentrations. However, the decrease in leptin concentrations promoted by the interruption of supplementation seems be linked to increased embryo mortality up to Day 30.

Reproductive performance in ewes fed varying levels of cut lucerne pasture around conception

“…However, this does not alter the conclusions, since the fetal numbers were similar to lambs born per ewe, indicating fetal numbers were a reliable measure, and the pattern of estimated total embryo retention and partial loss are consistent with the differences in fetal numbers. The small differences in fetal numbers and lambs born per ewe indicates fetal losses after day 60 of pregnancy were small, consistent with other studies which show most losses occur before day 30 (Viñoles et al, 2012).…”

Follicle development, endocrine profiles and ovulation rate in adult Merino ewes: effects of early nutrition (pre- and post-natal) and supplementation with lupin grain

“…The first-wave model is effective in that regard, but the low progesterone concentrations produced by a newly formed and short-life corpus luteum may create an abnormal endocrine milieu (e.g. increased LH pulse frequency) with negative consequences for the development of the pre-ovulatory follicle, the competence of the oocyte and fertility (Sirois & Fortune 1990, Viñ oles et al 2001, 2012, Fierro et al 2011. The development of an alternative approach for synchronising the emergence of waves of follicles during the luteal phase might be useful; therefore, for testing whether changes in the E 2 -FSH feedback loop is indeed an effect of nutrition or a consequence of the 'first-wave' model.…”

Reproductive failure in moose (Alces alces) due to embryonic mortality and unfertilized oocytes

“…Using transrectal ultrasonography after mating, and studying subsequent parturition rates, Gómez-Nieto et al (2011) stated that 13.0 % (6/46) of captive red deer ( Cervus elaphus ) most likely had experienced embryonic mortality. Embryonic mortality and lack of fertilization of oocytes are well-known occurrences in domestic species, e.g., cattle (Diskin et al 2011; Hanly 1961; King 1991), sheep (Cognie et al 1975; Dutt and Simpson 1957; Vázquez et al 2009; Viñoles et al 2012), goats (Armstrong and Evans 1983; Gonz et al 2004; Shelton 1978), pigs (Dziuk 1968; Geisert et al 2007; Soede et al 1994), and horses (Ball et al 1986; Dippert et al 1994; Newcombe and Cuervo-Arango 2011), and underlying causes of may be infectious (bacteria, virus, parasites, fungi) or of genetic, endocrine, and environmental origin (Diskin et al 2011). …”