Introduction to Animal Reproduction Class

Intro to Animal Reproduction

1. Animal
Reproduction
Louisiana State University at Alexandria
AGRI 1011 –Intro to Animal Science
Fall 2025 –Section 001X
Pedro H. D. Santos, PhD

2. Why study
reproduction?
•Key driver of livestock productivity (milk,
meat, eggs, offspring).
•Impacts economics (calving interval,
litter size, hatchability).

3. Basic
Concepts
•Asexual vs. Sexual reproduction–livestock = sexual.
•Fertilization–union of sperm & egg → zygote → embryo.
•Gestation–pregnancy length varies by species (cow ~283 d, sow
~114 d, ewe ~150 d, mare ~340 d).
•Parturition–process of giving birth.
•Importance ofreproductive efficiency(open cows, repeat breeders =
$$ loss).

4. Male Reproductive
System
•Organs:testes, epididymis, vas deferens,
penis.
•Function:produce sperm & testosterone.
•Accessory glands:seminal vesicles,
prostate → add fluids.
•Species differences:
–Bull/ram → fibroelastic penis.
–Stallion/boar → musculocavernous
penis.
•Applied:Breeding soundness exams in
bulls (sperm motility, morphology, scrotal
circumference).

5. Female
Reproductive
System
•Organs:ovaries, oviducts,
uterus, cervix, vagina, vulva.
•Function:produce eggs,
support pregnancy.
•Estrous cycle:Proestrus, Estrus
(heat), Metestrus, Diestrus.
•Hormones:estrogen (heat),
progesterone (maintains
pregnancy).
•Signs of estrus in
cattle:mounting, restlessness,
clear mucus.

6. Reproductive anatomy of a dairy cow

7. Species-
Specific
Reproduction
•Cattle:estrous cycle ~21 d, AI widely used.
•Swine:litter-bearing, 114-day rule (“3 mo, 3 wk, 3 d”).
•Sheep/Goats:seasonal breeders (fall estrus).
•Horses:long-day breeders (spring/summer).
•Poultry:no pregnancy; ovulation → egg laid, fertilization in oviduct.

8. Species-Specific Reproduction

9. Reproductive
Technologies
•Artificial Insemination (AI):efficient use of superior sires.
•Estrus synchronization:hormones to manage breeding schedules.
•Embryo Transfer:move embryos from elite donor cows to recipient
cows.
•In vitro fertilization (IVF):fertilization outside body.
•Cloning & genetic engineering:advanced, limited in livestock.

10. Management
&
Applications
•Importance of good heat detection–failure = missed pregnancies.
•Calving/lambing/kidding management:assistance when needed.
•Reproductive health issues:infertility, retained placenta, dystocia.
•Nutritional link:underfed animals have poor fertility.
•Animal welfare:ethical considerations in reproduction (AI,
synchronization, embryo transfer).

11. Heat
Detection
•Why important?Missing estrus = lost breeding opportunity → longer
calving interval → $$ loss.
•Example:
•In dairy herds, every day a cow is “open” (not pregnant) costs
~$3–5.
•Tool:Kamar® heat patches (change color when cow is mounted).
•Modern tech:Activity monitors (Fitbit-like collars) show spikes in
movement during heat.

12. Calving / Lambing /
Kidding Management
•Why important?Most calf/lamb
losses occur at or just after birth.
•Example:
•Signs of normal calving:
water bag, calf feet visible
within 2 hours.
•If no progress =dystocia→
farmer/vet intervention.
•Story:A beef cow with a
large calf (bull sire with big
birth weight genetics) →
higher dystocia risk.

13. Reproductive
Health Issues
•Infertility:Can be caused by uterine infections
(metritis).
•Retained placenta:Common in dairy cows after twins
or difficult calving.
•Dystocia:Difficult birth, especially in heifers or
oversized calves.

14. Nutrition &
Fertility
•Undernutrition:Delayed puberty, silent
heats, poor conception rates.
•Overfeeding:Can also reduce fertility (fat
cows).
•Example:
•“Flushing” ewes/goats before
breeding (short-term high nutrition)
increases ovulation rate → more
twins.
•Louisiana example:Poor-quality
bermudagrass hay → protein
supplement (cottonseed meal)
improves conception in beef cows.
Polizel et. al., 2025

15. Animal Welfare
& Ethics
•AI vs. natural service:AI avoids
transporting bulls, reduces disease
risk.
•Estrus synchronization:Raises
debate — welfare vs. efficiency.
•Embryo transfer:Ethical question =
manipulating nature vs. genetic gain.
•Example:
•Temple Grandin argues welfare
in reproduction means reducing
stress at handling, not avoiding
technologies altogether.

16. Summary
•Male/female anatomy,
estrous cycle, gestation,
species differences,
technologies.
•Which reproductive
technology do you think
has had the biggest impact
on livestock production
and why?

17. See you on Thursday