The Oestrous Cycle of the Cow. A photographic atlas. UPDATED EDITION

PRESENTATION

BROCHURE

The Oestrous Cycle of the Cow A photographic atlas

Manuel Fernรกndez Sรกnchez

UPDATED

edition

The Oestrous Cycle of the Cow

The Oestrous Cycle of the Cow A photographic atlas

A photographic atlas

Manuel Fernández Sánchez

UPDATED

edition

UPDATED EDITION

This book helps the reader to interpret the reproductive status of the cow using an outstanding selection of photographs with an eminently practical focus. The carefully chosen images let the reader visualise what they are touching during an examination, and describe the more basic procedures, such as rectal palpation or artificial insemination. It also highlights the importance of using oestrus synchronisation protocols in routine reproductive practice.

TARGET AUDIENCE:

✱ Production animal vets. Cattle ✱ Production animal technicians ✱ Veterinary students FORMAT: 22 × 28 cm NUMBER OF PAGES: 328 NUMBER OF IMAGES: 673 BINDING: hardcover

RETAIL PRICE

€75

Author MANUEL FERNÁNDEZ SÁNCHEZ Veterinary sciences graduate of the University of Zaragoza, Spain. He currently coordinates nutrition projects, and specialises in analysing data generated on farms through various online initiatives. He is the webmaster of consuvet.com and the creator of www.cowsulting.com, www.recetaveterinaria.com, and www.cowculations.com.

KEY POINTS:

➜ Includes many visual materials that are of great educational value. ➜ Relates reproductive success to successful production, and describes basic procedures such as rectal palpation and artificial insemination. ➜ Helps the reader create a decision tree that will help them diagnose the reproductive stage of the cow being examined.

The Oestrous Cycle of the Cow

Presentation of the book For proper reproductive control, routine examination of the bovine reproductive tract challenges the veterinary professional to draw a comparison between the structures that they palpate during examination and those that really exist. For that purpose, this book includes an amazing selection of photographs of the oestrous cycle of the cow that will help the reader to determine the cow's reproductive stage by palpation.

It also provides detailed descriptions of the main synchronisation protocols that are typically used for reproductive control on farms, from a practical perspective. This clear educational material helps readers to understand and appreciate these protocols and the reasons why they can fail.

Readers who are unfamiliar with bovine reproduction will be able to review basic techniques, such as rectal palpation and artificial insemination, and learn about the importance of reproductive success, which leads to successful production. Expert readers will be able to see images of what they are really palpating in examinations.

The author Manuel Fernández Sánchez Manuel Fernández Sánchez is holds a degree in veterinary medicine from the University of Zaragoza, Spain. For over 30 years, his professional career has always been related to the world of ruminants, from his training in Bristol, Belgium, and Scotland to his current position as a nutrition and reproduction technician in the Spanish region of Galicia.

He started at the National Association of Rasa Aragonesa Breeders (ANGRA), where he developed genetic improvement and reproduction programmes for meat sheep, and also worked in the Spanish region of Asturias on reproductive control and milk quality in cattle.

This professional experience in a wide range of business sectors, combined with his experience from clinical practice and from providing consultancy services in the field of dairy cattle reproduction has given him a broad view of veterinarians’ needs when it comes to resolving reproductive issues.

He currently works in Galicia coordinating nutrition projects, and he specialises in analysing data generated on farms through various online initiatives. He is the webmaster of consuvet.com and the creator of www.cowsulting.com, www.recetaveterinaria.com, and www.cowculations.com.

This atlas of images is the fruit of his labour, and brings together the work of a practitioner who knows what it means to face real problems in the field.

Table of contents How to use this book 1. The reproductive tract of the cow Morphology, structure and function Position Reproductive organs of the cow Anatomy of the ovary Anatomy of the oviduct Anatomy of the uterus. Horns and body Anatomy of the uterus. Cervix Function of the ovary Hypothalamic-pituitary axis Relationship between production and reproduction Examination of the reproductive tract by rectal palpation Artificial insemination

2. Oogenesis, follicular development and dynamics Oogenesis Follicular development Follicular dynamics Synchronisation protocols

3. Recognising structures Guide to identify ovarian structures General evaluation of the cycle Recognising ovarian structures

4. The puerperium 5. Pregnancy diagnosis by palpation 6. Ovarian and uterine disease Ovarian cyst Follicular cyst Luteal cyst Persistent follicle Post-partum anoestrus Metritis Mummified foetuses Embryonic reabsorption Other processes

Recommended reading & references

Plaza Antonio Beltrán Martínez, 1 Centro Empresarial El Trovador planta 8, oficina 50002 Zaragoza, España

■

+34 976 461 480

The Oestrous Cycle of the Cow A photographic atlas

Manuel Fernรกndez Sรกnchez

UPDATED

edition

THE OESTROUS CYCLE OF THE COW. A PHOTOGRAPHIC ATLAS

Synchronisation protocols The aim of this book is to facilitate understanding of the cow’s reproductive cycle. Knowledge of the oestrous cycle and the hormones involved in it is essential to achieve this.With the information provided, readers will be able to locate and describe the ovarian structures and distinguish why they are present so as to determine what stage of the cycle these structures are in.

An adequate reproductive rate can be maintained without using heat synchronisation, but this requires: The recovery of reproductive function, based particularly on adequate management of feeding in the peripartum.

■ A very effective heat detection system so insemination can be perfomed in time. The system may be based on visual detection by operators or on automatic systems (pedometers, activity meters, etc.).

■

The pregnancy rate in a herd is influenced by the following: ■ Transition from dry period to lactation.

■ Dry matter intake.

■ Body condition.

■ Normal start of cycles.

■ Heat detection.

■ Fertility.

■ Embryo survival.

Key points in reproductive control

Understanding reproductive physiology

Recognition of diseases

Diagnosis and evaluation of structures

Choice of the most appropriate treatments

Identification of structures

Selection of synchronisation protocols

Adapted from Fernández Sánchez, 2016.

FIGURE 1. With the development and widespread use of ultrasound in cattle, diagnosis and treatment efficiency have increased.

42

OOGENESIS, FOLLICULAR DEVELOPMENT AND DYNAMICS

Heat detection is usually a bottleneck that is difficult to overcome on dairy farms and, when the adequate levels of accuracy are not reached, it is usually a factor causing a lot of frustration to farmers. To solve this problem and avoid the cost of days open (days when the cow is not pregnant), heat synchronisation and resynchronisation protocols have been designed.

Eliminating dependence on heat detection also allows better work organisation when handling batches of cows. All this has led to widespread use of synchronisation protocols, especially on more intensive farms.

These synchronisation protocols act on the following: ■ The follicular development phase.

■ The time of regression of the corpus luteum.

■ The time of ovulation.

Synchronisation protocols can be applied by farmers, but technicians are those who must know the underlying principles for their use and why one protocol is more suitable than another on a farm. It is equally important, if they do not work as intended, to know why.Therefore, the person responsible for heat synchronisation on a farm should be the veterinarian.

Hormones involved All protocols use synthetic hormones and will cause a group of cows to come into heat at the same time so as to schedule insemination.

As in humans, visual, olfactory, and tactile nerve perceptions influence cows and direct impulses from the involved organs (hypothalamus and pituitary gland) to the target organs (ovaries and uterus). This is the hypothalamic-pituitary-gonadal axis, where hormones act as chemical mediators that trigger the cascade of events described earlier in this book.

So far this appears to be easy, but the complication occurs due to the multiple interactions with the hypothalamus and its releasing factors. For instance, reproductive diseases are associated with disorders in hormone receptors in target organs. Therefore, all hormones are not equally efficient in all cows, as there are factors dependent on the individual, such as the poor metabolic adaptability of hypothalamic structures: ■ In general, any change in a cow’s metabolic profile alters hypothalamic function (changes in vitamin, mineral, glucose levels in blood, etc.).

■ External stimuli that activate or inhibit structures, e.g.: ■ Photoperiod outside the ideal ratio (light/dark ratio =1).

■ Caloric stress outside the optimum range (3-24 degrees).

■ Other causes of stress: hunger, thirst, movements and transport, changes in routine management (milking time, hierarchies, changes in feeding time, etc.).

43

THE OESTROUS CYCLE OF THE COW. A PHOTOGRAPHIC ATLAS

Reproductive success therefore depends on two essential factors: ■ The establishment of balanced and above all stable rations over time so that no significant metabolic changes occur.

■ The provision of animal welfare, trying to minimise changes in management practices.

Emergence of protocols over time Although methods for synchronising heat already existed before the 1980s, it was during that decade that prostaglandins began to be used. Progesterone use should not be forgotten (Fig. 2).

1980

1979

FDA approved use of PGs in cattle

1985

1990

1986

1995

Discovery of follicular waves

1980

1995

Ovsynch protocol published

1990

Directed reproduction system

GnRH+PGF protocol published

2000

2005

2010

2001

Presynch Ovsynch protocol published

2003

Resynch comparative protocol published

FIGURE 2. Timeline of main synchronisation protocols.

Use of prostaglandins Prostaglandin (PG) is a lipid compound derived from fatty acids.

Characteristics ■ The administration of both natural PGs and their synthetic analogues (alpha-prostol, cloprostenol, fenprostalene, luprostiol, etc.) induces regression of a mature corpus luteum in the ovary, thus inducing and synchronising heat.

■ This effect does not occur in the first 5 days of life of the corpus luteum or at the end of the cycle (Fig. 3).

■ Therefore, if the cow does not come into heat with one injection, PGs should be re-administered at intervals of 7, 11, or 14 days (Fig. 4). The 14-day interval appears to provide the best response.

44

2008

Ovsynch56 protocol published

2009

Double Ovsynch protocol published

OOGENESIS, FOLLICULAR DEVELOPMENT AND DYNAMICS

■

■ ■

When PG is injected in cows in dioestrus, these come into heat after 2-7 days, though most will do so after 3-5 days.

It is recommended that cows are inseminated at detected heat after treatment.

A disadvantage is that it does not work in cows in anoestrus or non-cycling cows.

When to use it ■ Its success depends on the presence of a corpus luteum.

■ A veterinarian is required to check for a functional corpus luteum.

■ The onset of heat may vary from 2 to 7 days after PG administration depending on the maturity of the dominant follicle at the time of the injection.

1

21

2

Formation of the corpus luteum

3

5

18

9

20

4

1

Regression of corpus luteum

17

6 9

15

8

16

7

10

11

12

13

14

Functional corpus luteum FIGURE 3. Oestrus and ovulation.

PG

PG Oestrus

7-11-14 days

PG Oestrus

TAI (80 h)

7-11-14 days

FIGURE 4. Use of prostaglandins for timed artificial insemination (TAI).

45

THE OESTROUS CYCLE OF THE COW. A PHOTOGRAPHIC ATLAS

Possible errors ■ A functional corpus luteum is not present.

■ Not all cows come in heat at the same time: assuming that prostaglandin is injected on the days when luteolysis occurs (days 6-16 of the cycle), the days elapsed until the cow comes into heat will depend on follicular development at the time of PG administration, since PGs control corpus luteum regression but do not act on follicular growth (Fig. 5).

PG

2-3 days

Oestrus

Progesterone

PG

4-5 days

Oestrus

Progesterone

FIGURE 5. Onset of oestrus after administration of prostaglandins depending on follicular development.

Discovery of follicular waves Knowledge of follicular dynamics led to advances in the development of new synchronisation systems.

The advent of ultrasound revolutionised monitoring of reproductive biology and promoted the extended use of synchronisation protocols.

46

OOGENESIS, FOLLICULAR DEVELOPMENT AND DYNAMICS

GnRH+PG This protocol involves the use of gonadotropin-releasing hormone (GnRH) in combination with prostaglandins.

Characteristics ■

On day 0, GnRH is administered: ■ ■ ■ ■

■

It induces a LH surge.

It causes ovulation or luteinisation of large follicles.

It synchronises the recruitment of new follicular waves.

It synchronises the development of follicular waves.

On day 6, PG is administered: ■

■

Several studies (Twagiramungu, 1990) have reported a better synchronisation of oestrus when GnRH is administered 6-7 days before PGF, when compared with the use of prostaglandins alone.

Heat is detected, followed by artificial insemination (EDAI).

When to use it ■ This is the same scenario as for the use of prostaglandins.

■ It synchronises the cycle in 70-80 % of cows (on the premise that cows are cycling) at a 4-day interval without detriment to their fertility rate.

■ Administration of GnRH eliminates large follicles causing their ovulation or atresia and induces the emergence of a new follicular wave 3-4 days after treatment (at any time during the cycle).

■ The precision in the onset of heat and fertility rate achieved is due to the selection of a follicle that will ovulate after prostaglandin-induced luteolysis 6 days after treatment.

Possible errors ■ The fate of the selected follicle after treatment (ovulation or atresia) depends on the degree of luteolysis induced by the injection of prostaglandins. When the degree of luteolysis is complete (blood progesterone <1.0 ng/ml), as usually occurs in most cases, ovulation of the dominant follicle takes place, signs of heat appear and oestrogen levels (E2) subsequently decrease (Twagiramungu, 1994).

■ However, when luteolysis is incomplete (progesterone >2.0 ng/ml), heat is not achieved because oestrogen levels are maintained and the dominant follicle becomes persistent. It occurs in 10-20 % of cows.

■ Low progesterone levels for prolonged periods are associated with increased frequency of LH pulses, inhibition of preovulatory LH surge induction and development of persistent follicles (Roberson et al., 1989; Savio et al., 1993; Stock and Fortune, 1993; Sanchez et al. 1995).

■ Thus, errors in the use of this protocol are more often due to incomplete luteolysis after prostaglandin administration than to a lack of follicular development after GnRH administration (Twagiramungu, 1994).

47

It synchronises the cycle in 70-80 % of cows at a 4-day interval without detriment to fertility rate.

Errors in the use of this protocol are mainly due to incomplete luteolysis after prostaglandin administration.

THE OESTROUS CYCLE OF THE COW. A PHOTOGRAPHIC ATLAS

Ovsynch Soon after its development, the Ovsynch protocol (Fig. 6) became the standard protocol and a large number of modifications were made to it in search of the best time to implement it.

All these modifications may have caused confusion among technicians and livestock farmers. Therefore, careful attention should be paid to the original protocol in order to understand its variations.

Characteristics ■ Day 0: GnRH is administered to induce ovulation and promote the formation of a new corpus luteum and a new follicular wave (thus making the cow start a new cycle).

■ Day 7: PG is administered and causes the new corpus luteum to regress.

■ Day 9: A second dose of GnRH is administered to induce ovulation of the new follicle 16 to 24 hours later.

GnRH

PG 7 days

48 h

Spontaneous or GnRHinduced luteolysis

Ovulation/luteinisation and development of a new follicle

GnRH

TAI

16 h

Synchronisation of ovulation

FIGURE 6. Ovsynch synchronisation protocol.

When to use it ■ The ideal day to start the Ovsynch protocol is around day 6 (5-10) after the onset of heat (Fig. 7).

Possible errors Ovsynch may fail if it is applied to cows regardless of their reproductive status. Because the protocol can be initiated on any day of the oestrus cycle, there may be no ovulation with the first GnRH administration: ■ If cows are at an early stage of follicular development (in any follicular wave), granulosa cells do not possess sufficient LH receptors to respond to the first GnRH injection (Fig. 8).

■ If the protocol is initiated in the final stages of the oestrous cycle, spontaneous luteolysis may occur before PG administration (Fig. 9).

48

OOGENESIS, FOLLICULAR DEVELOPMENT AND DYNAMICS

Ovsynch

P4 plasma concentration (ng/ml)

8

6

4

P4

2

0 0 GnRH

7 PG

10

9 GnRH

Timed artificial insemination

Days since oestrus Adapted from Fernández Sánchez, 2018.

FIGURE 7. Correct synchronisation of Ovsynch treatment: cycle day 6 = treatment day 0 (selection phase: first follicular wave).

GnRH

GnRH F

CL

0

F

≈ 30-40 % of cycle

CL

Ov

-10

21

Day of oestrous cycle Adapted from Vasconcelos et al., 1999.

FIGURE 8. Lack of ovulation with the first administration of GnRH.

49

THE OESTROUS CYCLE OF THE COW. A PHOTOGRAPHIC ATLAS

PG

GnRH

7 days

≈ 50 % of cycle P4

✘

0

-10

Ov

21

Day of oestrous cycle Adapted from Vasconcelos et al., 1999.

FIGURE 9. Spontaneous luteolysis before PG administration.

The efficacy of Ovsynch It is mainly based on: ■

Ovulation caused by the first injection of GnRH.

■

Luteolysis caused by the administration of PG.

■

Ovulation caused by the second administration of GnRH.

If any of these assumptions do not occur, the conception rates will decrease substantially.

Other Ovsynch-based options One of the first questions that arose when farmers started using the Ovsynch protocol was whether there would be any difference in the conception rate (CR) if FTAI (fixed-time artificial insemination) was used at different times after the second GnRH administration. Different variations therefore began to appear.

FTAI 8, 16, 24, or 32 hours after the second GnRH dose ■

■

■

Initial results showed that cows inseminated 16 hours after receiving the second dose of GnRH had the best conception rate (CR).

More data are available today on these protocols and there appears to be no difference in CR when cows are inseminated 16 or 24 hours after receiving the second dose of GnRH. Similarly, cows that are inseminated and administered the second GnRH injection at the same time (Cosynch) generally have a lower CR than cows inseminated 16 or 24 hours after this injection (classic Ovsynch) (Fig. 10).

50

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