title: Reproductive performance in ewes fed varying levels of cut lucerne pasture around conception.
abstract: Elevated intakes of protein and energy may increase embryo mortality, but it is not clear whether fresh lucerne (Medicago sativa) pasture poses a risk. A two-year pen study using oestrous synchronised and artificially inseminated Merino ewes (n=175 in 2013 and 215 in 2014) evaluated whether feeding freshly cut lucerne pasture (mean crude protein 19.7%, metabolisable energy 9.4MJ/kg DM) at maintenance or ad libitum during different periods around insemination altered reproductive performance in comparison with ewes fed a Control diet (mean crude protein 7.8%, metabolisable energy 9.0MJ/kg DM) of pelleted faba bean hulls and oat grain hulls at maintenance. The proportion of pregnant ewes carrying multiple fetuses was reduced (P=0.026) when ewes were fed lucerne ad libitum between days 0 and 17 after insemination compared with the Control diet (0.18 and 0.34, respectively), but not when ewes were fed lucerne ad libitum between days 0 and 7 after insemination (0.22). Reproductive performance, including the proportion of ewes pregnant and the proportion with multiple fetuses, was not different (P>0.05) when ewes were fed lucerne at maintenance between days 0 and 7 compared with the Control diet. While reproductive performance was similar when ewes were fed lucerne at maintenance between 0 and 17 days after artificial insemination compared with pellets at maintenance, fetal numbers per pregnant ewe were reduced by feeding lucerne ad libitum after insemination.
authors.affiliation: School of Animal and Veterinary Sciences, Charles Sturt University, Locked Bag 588, Wagga Wagga, NSW 2678, Australia; Graham Centre for Agricultural Innovation (NSW Department of Primary Industries and Charles Sturt University), Locked Bag 588, Wagga Wagga, NSW 2678, Australia. Electronic address: surobertson@csu.edu.au.
authors.forename: S M
authors.initials: SM
authors.lastname: Robertson
authors.affiliation: NSW Department of Primary Industries, Wagga Wagga Agricultural Institute, Wagga Wagga, NSW 2650, Australia; Graham Centre for Agricultural Innovation (NSW Department of Primary Industries and Charles Sturt University), Locked Bag 588, Wagga Wagga, NSW 2678, Australia.
authors.forename: E H
authors.initials: EH
authors.lastname: Clayton
authors.affiliation: School of Animal and Veterinary Sciences, Charles Sturt University, Locked Bag 588, Wagga Wagga, NSW 2678, Australia; Graham Centre for Agricultural Innovation (NSW Department of Primary Industries and Charles Sturt University), Locked Bag 588, Wagga Wagga, NSW 2678, Australia.
authors.forename: B
authors.initials: B
authors.lastname: Morgan
authors.affiliation: School of Animal and Veterinary Sciences, Charles Sturt University, Locked Bag 588, Wagga Wagga, NSW 2678, Australia; Graham Centre for Agricultural Innovation (NSW Department of Primary Industries and Charles Sturt University), Locked Bag 588, Wagga Wagga, NSW 2678, Australia. Electronic address: mfriend@csu.edu.au.
authors.forename: M A
authors.initials: MA
authors.lastname: Friend
mesh_terms: D000821:Animal Feed / Q000032:analysis*; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D004032:Diet / Q000662:veterinary; D005260:Female; D005298:Fertility; D007315:Insemination, Artificial / Q000662:veterinary; D008098:Litter Size; D000455:Medicago sativa; D011247:Pregnancy; D012756:Sheep / Q000502:physiology*
keywords: Embryo survival; Flushing; Nutrition; Sheep