Thermal Mechanisms Preventing or Favoring Multiple Ovulations in Dairy Cattle
Department of Veterinary-Medical Science, University of Parma, Str. dell’Università, 12, 43121 Parma, Italy
Department of Animal Science, University of Lleida, 25198 Lleida, Spain
Agrotecnio Centre, 25198 Lleida, Spain
Transfer in Bovine Reproduction SLu, 22300 Barbastro, Spain
Author to whom correspondence should be addressed.
Academic Editor: Raffaele Boni
Received: 19 January 2021
Revised: 4 February 2021
Accepted: 6 February 2021
Published: 8 February 2021
While cows are usually monovular, the incidence of dizygous twin births has recently increased considerably alongside increasing milk production. Genetic progress and improvements in nutrition and management practices have led to a continuous increase in milk yield and thus also to multiple ovulations and twin pregnancies. Twin pregnancies are undesirable as they seriously compromise the welfare of the cow and herd economy. A better understanding of the processes associated with multiple ovulations should help to reduce rates of twinning. During the stages of the sexual cycle, temperature gradients are established within the ovary and throughout the genital tract. Pre-ovulatory local cooling of the reproductive system favors male and female gamete maturation and subsequent fertilization. In fact, thermal mechanisms may prevent or favor multiple ovulations and thus twinning. The purpose of this review was to update this topic.