title: Causes of declining fertility in dairy cows during the warm season.
abstract: In the Northern Hemisphere, from June to September and in the Southern Hemisphere from December to March, there are periods of reduced fertility (sub-fertility) in dairy cows that are described as summer infertility. Several factors contribute to sub-fertility during this time, such as ambient temperature, humidity and photoperiod. During the warm season there is a reduction in feed intake that may compromise the energy balance of the cow and/or induce an imbalance in the activity of the hypothalamo-hypophyseal-ovarian axis. These factors reduce the reproductive performance of the cow and compromise the quality of oocytes, embryos and corpora lutea. This paper reviews current knowledge on the metabolic and endocrine mechanisms that induce summer infertility and describe their effects on follicle, oocyte and embryo development in dairy cows.
authors.affiliation: Department of Veterinary Medical Science, University of Parma, Italy. Electronic address: fabio.derensis@unipr.it.
authors.forename: F
authors.initials: F
authors.lastname: De Rensis
authors.affiliation: Transfer in Bovine Reproduction SLu, 22300 Barbastro, Spain.
authors.forename: F
authors.initials: F
authors.lastname: Lopez-Gatius
authors.affiliation: Department of Animal Science, University of Lleida, Agrotecnio Center, Lleida, Spain.
authors.forename: I
authors.initials: I
authors.lastname: García-Ispierto
authors.affiliation: Department of Veterinary Medical Science, University of Parma, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Morini
authors.affiliation: Department of Comparative Biomedical Sciences, The Royal Veterinary College, Herts AL9 7TA, UK; The Institute of Agriculture, University of Western Australia, Crawley 6009, Western Australia, Australia.
authors.forename: R J
authors.initials: RJ
authors.lastname: Scaramuzzi
mesh_terms: D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000209:etiology*; D004435:Eating; D047108:Embryonic Development; D004734:Energy Metabolism; D005260:Female; D018869:Heat-Shock Response; D006358:Hot Temperature; D007247:Infertility, Female / Q000209:etiology / Q000662:veterinary*; D017440:Photoperiod; D012621:Seasons
keywords: Dairy cow; Estrus; Fertility; Warm season