Preface

This book, Animal Reproduction in Veterinary Medicine, targets a broad audience: veterinarian students, academics, veterinary practitioners, and even the general community. Through time, reproduction has been increasingly foreseen as critical for livestock production. Different environmental stimuli, together with genetic improvement, has driven an increase in the production levels, as well as raising new challenges in cattle reproduction, with the increased number of reproductive failures, that is not always easy to solve. Veterinarians and farmers have to deal daily with reproduction issues and struggle to correct infertility and improve the reproductive fitness of ruminant species worldwide.

Reproductive problems may present with multiple causes for a single symptom, challenging the practitioner to keep up with the ever-growing information published on different aspects of animal reproduction, from the physiology to the technology, passing through the therapeutics and new diagnostic tools. Diagnosis is not always easy, and the therapeutic approach may be tentative. In some situations, the physiologic and immunological mechanisms retain the ability to respond to aggressive treatment, and some empirical approaches to master reproductive processes still lack published support.

Many researchers across the globe contributed to this book. Herein the reader can find new information on various aspects of animal reproduction: the estrous cycle in ruminants, the manipulation of the cycle and synchronization of ovulation in ruminants, the clinical management of the Lidia breed, optimizing piglet survival and sow reproductive health, the primary physiological mechanism regulating reproduction and clinical endocrinology in ruminants and mares, pheromones to stimulate sow reproduction, some clinical aspects of the reproductive function, mastitis, milk production, calf-sex influence on bovine milk production and reproductive toxicology in veterinary medicine. When readers and stakeholders provide new feedback on this present form of the book, we hope this will be the drive to add new chapters to a book series.

**II**

**Chapter 7 133**

Milk Production and Mastitis **147**

**Chapter 8 149**

**Chapter 9 171**

**Chapter 10 183**

**Chapter 11 211**

Reproductive Toxicity **235**

**Chapter 12 237**

Current Status of Antimicrobial Resistance and Prospect for New Vaccines

Induction and Synchronization of Estrus *by Prasanna Pal and Mohammad Rayees Dar*

Control and Prevention of Mastitis: Part Two

against Major Bacterial Bovine Mastitis Pathogens

Calf-Sex Influence in Bovine Milk Production *by Miguel Quaresma and R. Payan-Carreira*

Reproductive Toxicity of Insecticides *by Mehtap Kara and Ezgi Öztaş*

**Section 4**

Bovine Mastitis: Part I *by Oudessa Kerro Dego*

*by Oudessa Kerro Dego*

*by Oudessa Kerro Dego*

**Section 5**

**Faruk Aral** Independent Researcher

#### **Rita Payan Carreira**

Department of Veterinary Medicine, MED - Mediterranean Institute for Agriculture, Environment and Development, ECT, Universidade de Évora [Pole at Mitra], Évora, Portugal

#### **Miguel Nuno Pinheiro Quaresma**

Animal and Veterinary Research Center (CECAV), Universidade de Trás-os-Montes e Alto Douro, Vila Real, Portugal

**1**

Section 1

Reproductive

Physiology and Clinical

Endocrinology

Section 1

Reproductive Physiology and Clinical Endocrinology

**3**

**Chapter 1**

Mares

**Abstract**

**1. Introduction**

of the fetus and premature delivery [3].

Physiological and Clinical Aspects

Estrous Cycle and Pregnancy in

The use of advanced reproductive endocrinology can generate important economic benefits for equine breeding farms. Pregnancy in the mare involves considerable endocrine changes, which can be explained in part by the development of different structures such as embryonic vesicles, primary and secondary CL, endometrial cups and development of fetoplacental units. Both the pregnant mare and the fetus adapt to this development with unique mechanisms, such as alterations in the maternal endocrine metabolism and hormonal feedback. Since the ability to produce a viable foal is critical for the broodmare, the maintenance of the gestation implies almost a year of physiological effort. Therefore, the joint knowledge of basic reproductive science and current clinical endocrinology allows veterinarians and breeders to be better positioned to achieve their objectives. This chapter reviews normal and abnormal endocrine patterns during the equine estrual cycle, pregnancy. We also consider hormonal evaluation related to placentitis, abortions, recurrent pregnancy loss, and premature deliveries. Also, several aspects associated with endocrinological control of the reproductive cycle, ovulation, parturition,

high-risk mare, and hormone supplementation will be developed.

The gestation in the mare begins with the fertilization of the ovum, then the implantation of the blastocyst in the uterus followed by the development of the placenta and fetus until delivery. Therefore, gestation is a dynamic and coordinated process involving systemic and local changes in the mare that support the supply of nutrients and oxygen to the fetus for growth and development in the uterus [1]. In part, these changes occur through the secretion of hormones in the placenta, which in turn interact with each other and exert extensive effects on maternal tissues during gestation [2]. These endocrine changes in maternal physiology adaptations to gestational status result from modifications in the maternal environment of steroids such as progesterone (P4), estrogens, androgens, and other hormones such as relaxin and prostaglandins (PG). However, an inadequate adaptation of maternal physiology can lead to gestational complications, such as restriction or overgrowth

**Keywords:** estrous, clinical endocrinology, mare, pregnancy

of the Endocrinology of the

*Katy Satué and Juan Carlos Gardon*
