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Thermal Mechanisms Preventing or Favoring Multiple Ovulations in Dairy Cattle
SIMPLE SUMMARY: 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 m...
Autores principales: | , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
MDPI
2021
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7915362/ https://www.ncbi.nlm.nih.gov/pubmed/33567503 http://dx.doi.org/10.3390/ani11020435 |
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author | De Rensis, Fabio Morini, Giorgio Garcia-Ispierto, Irina López-Gatius, Fernando |
author_facet | De Rensis, Fabio Morini, Giorgio Garcia-Ispierto, Irina López-Gatius, Fernando |
author_sort | De Rensis, Fabio |
collection | PubMed |
description | SIMPLE SUMMARY: 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. ABSTRACT: While cows are predominantly monovular, over the past 30 years the incidence of multiple ovulations and thus twinning has increased considerably alongside milk production. Multiple pregnancies are not desirable as they negatively affect the health of cows and the herd economy. Although causal mechanisms associated with multiple ovulations have been extensively revised, the process of multiple ovulations is not well understood. Recent studies on the thermal biology of the reproductive system have shown how thermal mechanisms may prevent or favor multiple ovulations. This review focuses on this relationship between thermal dynamics and multiple pregnancies. Cooling of the pre-ovulatory follicle is able to regulate ovulation. In effect, pre-ovulatory local cooling of the female reproductive system favors male and female gamete maturation and promotes fertilization. Thermal stress is proposed here as a model of stress. Periods of high ambient temperature affect the processes of pre-ovulatory follicular cooling and multiple ovulations. While the ratio between unilateral and bilateral multiple pregnancies is normally close to one, under heat stress conditions, this ratio may be 1.4 favoring unilateral multiple pregnancies. A ratio approaching unity is here proposed as an indicator of cow wellbeing. |
format | Online Article Text |
id | pubmed-7915362 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2021 |
publisher | MDPI |
record_format | MEDLINE/PubMed |
spelling | pubmed-79153622021-03-01 Thermal Mechanisms Preventing or Favoring Multiple Ovulations in Dairy Cattle De Rensis, Fabio Morini, Giorgio Garcia-Ispierto, Irina López-Gatius, Fernando Animals (Basel) Review SIMPLE SUMMARY: 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. ABSTRACT: While cows are predominantly monovular, over the past 30 years the incidence of multiple ovulations and thus twinning has increased considerably alongside milk production. Multiple pregnancies are not desirable as they negatively affect the health of cows and the herd economy. Although causal mechanisms associated with multiple ovulations have been extensively revised, the process of multiple ovulations is not well understood. Recent studies on the thermal biology of the reproductive system have shown how thermal mechanisms may prevent or favor multiple ovulations. This review focuses on this relationship between thermal dynamics and multiple pregnancies. Cooling of the pre-ovulatory follicle is able to regulate ovulation. In effect, pre-ovulatory local cooling of the female reproductive system favors male and female gamete maturation and promotes fertilization. Thermal stress is proposed here as a model of stress. Periods of high ambient temperature affect the processes of pre-ovulatory follicular cooling and multiple ovulations. While the ratio between unilateral and bilateral multiple pregnancies is normally close to one, under heat stress conditions, this ratio may be 1.4 favoring unilateral multiple pregnancies. A ratio approaching unity is here proposed as an indicator of cow wellbeing. MDPI 2021-02-08 /pmc/articles/PMC7915362/ /pubmed/33567503 http://dx.doi.org/10.3390/ani11020435 Text en © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). |
spellingShingle | Review De Rensis, Fabio Morini, Giorgio Garcia-Ispierto, Irina López-Gatius, Fernando Thermal Mechanisms Preventing or Favoring Multiple Ovulations in Dairy Cattle |
title | Thermal Mechanisms Preventing or Favoring Multiple Ovulations in Dairy Cattle |
title_full | Thermal Mechanisms Preventing or Favoring Multiple Ovulations in Dairy Cattle |
title_fullStr | Thermal Mechanisms Preventing or Favoring Multiple Ovulations in Dairy Cattle |
title_full_unstemmed | Thermal Mechanisms Preventing or Favoring Multiple Ovulations in Dairy Cattle |
title_short | Thermal Mechanisms Preventing or Favoring Multiple Ovulations in Dairy Cattle |
title_sort | thermal mechanisms preventing or favoring multiple ovulations in dairy cattle |
topic | Review |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7915362/ https://www.ncbi.nlm.nih.gov/pubmed/33567503 http://dx.doi.org/10.3390/ani11020435 |
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