Ovarian pathophysiology in the sow by Grupo Asís

Presentation brochure ESSENTIAL GUIDES ON SWIN

HEALTH AND PRODUCTION

Ovarian pathophysiology in th sow MarĂa Victoria Falceto Recio

ESSENTIAL GUIDES on SWINE HEALTH and PRODUCTION

Ovarian pathophysiology in the sow

ESSENTIAL GUIDES ON SWIN

HEALTH AND PRODUCTION

Ovarian pathophysiology in th sow María Victoria Falceto Recio

Author: María Victoria Falceto Recio. Format: 17 x 11 cm. Number of pages: 82. Number of images: 59. Binding: paperback, wire-o.

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Ovarian pathophysiology in the sow is the first title belonging to the collection entitled Essential guides on swine health and

production, and it is aimed at veterinarians who must manage and control pig farms day after day, paying special attention to the sow management, which represents one of the most important points in both reproductive as productive success.

Presentation of the book Swine species is the only large farm species that has a large number of offspring, specially since the emergence of hyperprolific lines, which have increased the number of liveborn piglets per litter in the last twenty years. The oestrus cycle of sows is normally 21Â days. Non-pregnant and non-lactating sows and gilts display oestrus or standing heat on a regular basis throughout the year. Hormones significantly affect the reproductive cycle of sows: FSH influences follicular growth, oestrogens are responsible for the typical signs of oestrus, and LH stimulates ovulation, which can be influenced by several factors (age, breed, nutrition). Reproduction represents a key point in the maintenance of the pig sector in terms of production and contributes to the establishment of high levels of swine health. Therefore, it is essential to provide valuable tools to veterinarians about the main challenges related to this topic in order to minimise the impact caused by the most important disorders/diseases at reproductive level. This handbook, written by a renowned specialist in this field, has been developed through a visual and practical approach, using numerous figures that illustrate the ovarian pathophysiology of the sow, and providing the suitable content to the veterinarians so as to tackle this matter successfully.

Ovarian pathophysiology in the sow

The author MarĂa Victoria Falceto Recio Professor of Reproduction and Obstetrics, Faculty of Veterinary Medicine, University of Zaragoza. Subject Coordinator of Porcine in the Degree of Veterinary. Chief of the Reproductive Counseling Service of the Faculty of Veterinary. Co-Director of the Masterâ&#x20AC;&#x2122;s Degree in Swine Health and Production of the Universities of Lleida, Zaragoza, Barcelona and Madrid.

Director of the Magapor Professorship of the University of Zaragoza.

hkeita/shutterstock.com

Secretary of the National Association of Swine Veterinarians (ANAVEPOR) and member of the board of the Association of Swine Veterinarians of Aragon (AVPA) and the Spanish National Association of Scientific Pig Farming (ANAPORC).

Communication services Web site Online visualisation of the sample chapter. Presentation brochure in PDF format. AuthorÂ´s CV. Sample chapter compatible with iPad.

www.grupoasis.com/promo/ovarian_sow

ESSENTIAL GUIDES ON SWIN

HEALTH AND PRODUCTION

Ovarian pathophysiology in th sow María Victoria Falceto Recio

Table of contents 1. Reproductive cycle Reproductive system: parts and functions

Chronology of folliculogenesis in mature sows

Gonads: ovaries

Follicle recruitment: end of dioestrus or weaning in end of lactation period

Tubular part

Follicle selection: pro-oestrus

Copulatory part

Follicle dominance: oestrus

Mammary glands

Hypothalamic-pituitary-ovarian axis and reproductive hormones

Importance of oestrogens: heat Practical application on the farm: how is ideal heat detection?

External factors

What induces the preovulatory LH peak in the follicle?

Internal factors

Duration of oestrus and time of ovulation

Factors that influence reproduction

Puberty Reproductive ability What are the characteristics of their reproductive cycle? Follicular dynamics Structures present in the ovary during the reproductive cycle Antral follicles

Practical application on the farm: time of service/insemination

Luteal phase Early dioestrus Late dioestrus/gestation Corpora lutea in the reproductive cycle and gestation

Corpora lutea

Ovulation rate

Corpora albicans

Importance of P4

Hormonal profile

Follicular phase Control of oogenesis and folliculogenesis Endocrine control

Practical application on the farm: use of progestogens to synchronise heat in cycling sows

Luteolysis Practical application on the farm: induction of luteolysis with PG

2. Anoestrus and reproductive seasonality Anoestrus and pseudoanoestrus Summer anoestrus Hormone levels How can a problem of anoestrus be diagnosed on a farm? Differentiation between anoestrus and pseudoanoestrus Ovarian ultrasound scan and P4 determination

Postmortem study of the ovaries Heat induction with gonadotropins Prevention of anoestrus

3. Identification of diseased ovaries Reproductive consequences of abnormal ovarian function Congenital alterations Intersexuality Paraovarian cysts

Acquired alterations Cystic ovarian degeneration Ovarian neoplasms

References Glossary of abbreviations

Reproductive cycle

Ovarian pathophysiology in the sow

Reproductive system: parts and functions

1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16.

7 10

13 14 15

Figure 1. Reproductive system of the sow.

Body of the uterus. Cervix. Uterine horns. Uterotubal junction. Infundibulum (oviduct). Ovary. Mesosalpinx and ovarian bursa. Mesometrium. Isthmus (oviduct). Ampulla (oviduct). Urinary bladder. Vagina. External orifice of the urethra. Vaginal vestibule. Fossa of the clitoris. Vulva.

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RepRoductive cycle

Gonads: ovaries » Functions: » Exocrine: formation and release of female gametes: oocytes.

» Endocrine: production of hormones that regulate sexual traits and reproductive activity in sows.

» Location: lateral margin of the pelvic inlet. » Examination: » Abdominal or transrectal ultrasound scan. » Determination of oestrogens and P4 in blood serum.

01_Reproductive_cycle.indd 5

Tubular part Oviduct » Parts: » Infundibulum. » Ampulla. » Isthmus.

» Functions: » Sperm reservoir after service/insemination. » Sperm capacitation. » They pick up the oocyte during ovulation. » Fertilisation takes place in the ampulla. » They are responsible for embryos transport to the uterus.

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Reproductive cycle

Ovarian pathophysiology in the sow

Bicornuate uterus » Parts: uterine horns (long, narrow and tortuous), body of the uterus (short) and cervix (narrow uterine part and wide vaginal part) with interdigitating pads that close the cervical canal in a zip-like manner.

» Functions: » Reception of the embryo from the oviduct. » Implantation, placentation and development

of gestation until birth. » Production of PG that trigger luteolysis and contraction of the uterine smooth muscles. » The uterine cervix opens and closes depending on the influence of oestrogens and P4.

» Examination: abdominal or transrectal ultrasound scan.

Figure 2. Uterine cervix.

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RepRoductive cycle

Copulatory part » Parts: » Vagina. » Vaginal vestibule. » Fossa of the clitoris. » Vulva: thick labia, rounded dorsal commissure and pointed ventral commissure.

» Functions: » Receives the copulatory organ/catheter during service/AI.

» During farrowing, allows the passage of

Figure 3. External orifice of the urethra.

the foetuses to the exterior. » Allows the passage of urine to the exterior during micturition from the external urethral orifice (located at the limit between the vagina and the vaginal vestibule).

» Examination: » Inspection of the vulva and its secretions. » Observation of the vagina by means of a

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vaginal speculum or an endoscope.

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Reproductive cycle

Ovarian pathophysiology in the sow

Mammary glands » 5-8 pairs of hemispherical mammae with a pointed nipple and two orifices for milk ejection.

» Function: postpartum milk production.

» Mammary examination: inspection, palpation and milk assessment.

Figure 4. Mammae.

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RepRoductive cycle

Hypothalamic-pituitary-ovarian axis and reproductive hormones 4

1 3

Brain

Reproductive system

3. Ovaries: » P4. » Androgens. » Oestrogens.

Hypothalamus: GnRH. 2. Pituitary gland: » FSH. » LH.

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4. Uterus: PG.

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Reproductive cycle

Ovarian pathophysiology in the sow

Factors that influence reproduction Hypothalamus The hypothalamus integrates all the internal and external information 10

External factors

Internal factors

The hypothalamus receives sensory information through the senses:

The hypothalamus receives metabolic and endocrine information:

» Vision. » Smell.

» Tactile perception. » Hearing.

» Reproductive hormones. » Thyroid hormones. » Adrenal hormones.

» Growth hormone. » Prolactin. » Others.

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RepRoductive cycle

Puberty » It appears at 6-7 months of age and indicates sexual maturity and, therefore, the start of the female’s reproductive life. The sooner puberty is reached, the longer her productive life will be and the greater the number of her offspring.

» It will take several weeks for all the gilts in a group to

experience their first heat.

» Factors that influence the time of onset of puberty: » Breed. » Age and weight. » Social interactions: boar effect. » Management: transport, flushing, hormone administration (gonadotropins), stress, etc.

» Body condition. » Health status.

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Figure 5. Boar effect.

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Reproductive cycle

Ovarian pathophysiology in the sow

» At least one heat cycle should be recorded before synchronising a sow with progestogens when gilts are prepared in order to reach the rearing system’s service target. In case of doubt, a uterine ultrasound examination allows the differentiation of a sow that has reached puberty from one that has not (Martinat-Botté, 2003). 12

» If a sow is >8 months old and has not come into heat, it is considered as a case of delayed puberty.

» Attention must be paid to non-detected heats and silent heats!

Figure 6. Sow in heat.

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RepRoductive cycle

Reproductive ability A perfectly developed genital apparatus, normal functioning of the hypothalamicpituitary-ovarian axis, good body condition and no lameness favour the following:

» Cyclicity: ability to return to heat if the sow is not served or does not remain pregnant. 13

» Fertility: ability to become pregnant and gestate offspring to term. » Prolificacy: ability to gestate and farrow a large number of piglets at each farrowing.

» Eutocic farrowing: farrowing without any alterations during the process. » Maternal ability: ability to nurse and look after a litter after farrowing. » Fast return to cyclicity and recovery of fertility after farrowing. » Absence of disease of the reproductive system.

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Reproductive cycle

Ovarian pathophysiology in the sow

Appropriate replacement sows should be chosen as they are the future breeding sows of the rearing system and should reach their seventh farrowing (long lifespan) with good fertility and prolificacy. 14

Figure 7. Lactating sow.

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RepRoductive cycle

What are the characteristics of their reproductive cycle? » Continuous polyestrous female, with 21-day oestrus cycles (18-24 days), except during non-productive times.

Ovarian cycle: 18-24 days 15

» Spontaneous and multiple ovulation: ovulation rate of 8-30 oocytes at each oestrus.

» Biphasic ovarian cycle with a follicular phase during which the synthesis of oestrogens predominates and a luteal phase with dominance of P4.

Follicular phase: 4-6 days Pro-oestrus Oestrus

Luteal phase: 16-18 days Metaoestrus Dioestrus

Figure 8. Phases of the ovarian cycle.

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Reproductive cycle

Ovarian pathophysiology in the sow

Phases of the reproductive cycle:

» Pro-oestrus: period of follicular growth. » Oestrus: period of final maturation of the follicle and ovulation. The sow allows mating/AI. » Metaoestrus (*): period immediately after ovulation with presence of corpora haemorrhagica. » Dioestrus: early phase with functional corpora lutea and maximum production of P4 and late phase with regression of the corpora lutea after luteolysis and decreased production of P4. 16

* Oestrus (days 1-3)

Late dioestrus (days 15-18)

Early dioestrus (days 4-14)

Pro-oestrus (days 19-21)

21 Gestation (114 days)

Figure 9. Phases of the reproductive cycle.

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RepRoductive cycle

Follicular dynamics The sow does not have waves of follicle development; her antral follicles develop continuously until ovulation. The follicles which do not ovulate are atretic.

Oestrus cycle (days)

Follicular development

21 Oestrus

Terminal follicular growth

Antral follicles

Luteal development

Progressive corpora lutea

Figure 10. Follicle and luteal dynamics (adapted from Hafez, 1987).

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Regressive corpora lutea

Corpora albicans

Scale

5 mm

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Reproductive cycle

Ovarian pathophysiology in the sow

Structures present in the ovary during the reproductive cycle Antral follicles 2 7

Transparent, fluctuating and filled with follicular fluid in the follicular antrum. Oestrogens are produced in these follicles.

Table 1. Follicular size. Follicle Very small Size (mm) <2

Small 2-3

Medium 4-6

Large 7-12

1. 2. 3. 4.

Mesovarium. Superficial epithelium. Follicles. Ovulation.

5. Corpora haemorrhagica. 6. Corpora lutea. 7. Corpora albicans.

1 cm

Figure 11. Follicles.

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RepRoductive cycle

Corpora lutea After ovulation, the corpora lutea go through three stages.

Corpora haemorrhagica

Progressive corpora lutea

Hard to the touch, with a liver-like colour and a clot with dense material in their interior. They start to produce P4.

Hard to the touch and bright pink; when they are cut transversally, it is possible to observe a smaller clot. They produce the maximum amount of P4. There are small and medium follicles in the ovary.

b Figure 12. (a) Whole corpora haemorrhagica and (b)Â cross-section. Figure 13. Progressive corpora lutea.

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Reproductive cycle

Ovarian pathophysiology in the sow

Regressing corpora lutea Hard to the touch and pale pink coloured; no clot is observed when they are cut transversally. P4Â production decreases. 1 cm

Figure 14. Regressing corpora lutea. 20

Corpora albicans Hard to the touch and yellow or white coloured. They do not produce P4.

Figure 15. Corpora albicans. Growing follicles are also presented.

1 cm

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RepRoductive cycle

Hormonal profile Ovulation

Ovulation

Oestrus

8 10

20 5

4 10

FSH (ng/ml)

E2 (pg/ml)

LH (ng/ml)

Days

P4 (ng/ml)

PGF2a (ng/ml)

Figure 16. Hormonal concentrations in blood during the sowâ&#x20AC;&#x2122;s oestrus cycle (adapted from Laing et al., 1991).

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Reproductive cycle / Follicular phase Spermatogenesis

Ovarian pathophysiology in the sow Oogenesis

One spermatocyte I (2n) First meiotic division

End of first meiotic division (pre-ovulatory follicle)

Two spermatocytes II (n) Second meiotic division

End of second meiotic division (after ovulation)

Four spermatids (n) Maturation

Figure 17. Spermatogenesis and oogenesis in swine.

One oocyte II (n): arrest in metaphase of second meiotic division and expulsion of the first polar body.

Fertilisation by the sperm and end of second meiotic division. Expulsion of the second polar body.

Degeneration of the polar bodies

Four spermatozoa

One oocyte I (2n): arrest in prophase of first meiotic division.

Zygote (2n)

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RepRoductive cycle / FolliculaR phase

Control of oogenesis and folliculogenesis Preantral follicles only depend on intraovarian factors (growth factors) and are independent of the gonadotropic control by the pituitary gland. Once the follicular cavity (antral follicles) is formed, follicular growth and maturation also depends on the secretion of the gonadotropins FSH and LH by the anterior pituitary gland, that is, on the balance of the hypothalamic-pituitary-ovarian axis. Insulin and other hormones (prolactin, growth hormone and thyroid hormones) also participate in this balance.

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