Optimizing Reproduction in Dairy Cattle

1. Optimizing Reproduction in Dairy Cattle

2. Reproductive Management of the Bull

3. Managing Natural Service Sires • About 25% of dairy farms maintain one or more mature bulls • More costly than using only artificial insemination • Kept on the farm to improve pregnancy rates • Can present dangers and health risks

4. Bulls: Age and Intensity of Use • Young bulls shouldn’t be used as heavily as older bulls • Young bulls can service 2-4 cows per week • Old bulls can service up to 12 per week • Younger bulls tend to be preferred • Less dangerous • More likely to be reproductively and functionally sound • Bulls under 1,000 lbs should only service heifers

5. Housing Bulls • Bulls housed with breeding age females • Drawbacks • Dominant bull may prevent subordinates from breeding • Destructive behaviors • Bulls are housed separately, females are brought to bull for breeding • Drawbacks • Heat detection required

6. Fig 25-4. Herd bulls are not only a safety hazard for people, they are hard on facilities as well (Courtesy of Mark Kirkpatrick)

7. Venereal Diseases • Two most important are Campylobacteriosus and trichomoniasis • Ensure health of bull • Through regular testing • Vaccination protocols • Addition of antibiotics to semen

8. Campylobacteriosis • Caused by Campylobacter fetus • Infects bulls penis and prepuce without clinical signs • Destroys fertilized ova • Spontaneous recovery of female occurs 4 months after infection • Abortions may occur • Most effective animal for testing is female

9. Trichomoniasis • Caused by Trichomonas foetus • Presents as infertility with occasional abortions • Clinically may be undistinguishable from campylobacteriosis • Old bulls are most common carriers • Most effective animal for testing is bull • Can be effectively treated • Females can be vaccinated

10. Fig 25-5. Although this bull appears healthy, he will spread trichomoniasis to cows during natural service (Courtesy of University of Illinois)

11. Natural Service (NS) vs. AI Smith et al., 2004

12. Natural Service Issues • Daughter performance • Although the genetics of herd bulls continues to improve, the gap between herd bulls and AI bulls continues to widen • 600 lbs milk (1972) to >1500 lbs of milk (now) • However, in one study, increase of 700 lbs of milk/cow in NS herds • Improved pregnancy rate, shorter calving interval http://dairy.ifas.ufl.edu/dpc/2002/Risco.pdf • Costs are greater for bull maintenance • Safety issues – HUGE!!! • Facility issues

13. Reproductive Management of the Cow

14. Heat Detection and Synchronization of Estrus

15. WATCHING FOR HEATS IS? 1. BORING!!!!! 2. Time consuming (up to 1.5 hrs./day) 3. Tough ** cows only stand for 2-7 seconds at a time - 1% of heat cycle ** need more than one cow to have a “party” – only cows in follicular phase want to play more cows = more estrus activity 4. Everything happens at night

16. Fun Facts • Over 40% of all cows in estrus are missed • 20% of all cows bred are not in estrus • Up to 90% of all estrus activity occurs between 6 pm and 12 noon • 70% between 6 pm and 6 am • Two 30-min detection periods will catch 80% of all cows in estrus • Three periods will catch 90% • For 3 breeding groups, this requires 3-5 hours daily

17. Fig 26-4. Inseminating a pregnant cow breaches the cervical plug, greatly increasing the risk of abortion (Courtesy of Select Sires)

18. Problems with Heat Detection • Even if time is devoted to observe heats, it is still challenging • Multiple groups of animals requiring observation • Two 30-minute observation periods will detect 80% of heats • But that is only for 1 group of animals

19. Fig 26-5. Cows in the follicular phase of the estrous cycle often form sexually active groups with increased mounting activity (Courtesy of Iowa State University)

20. Evaluating Reproductive Performance

21. Factors Driving Reproductive Performance of the Dairy Herd 1. Voluntary Waiting Period 2. Pregnancy Rate on First Cycle 3. Pregnancy Rate on > 1st Cycle 4. Culling Rate

22. Factors Affecting Reproductive Performance of Dairy Herds 1st Cycle Preg Rate VWP 2nd+ Cycle Preg Rate Culling Rate

23. Pregnancy Rate The Percentage of ELIGIBLE Cows that become pregnant every 21 Day Interval equals Heat Detection X Conception Rate

24. Heat Detection Rate 50 cows/ 100 = 50 % 50 Cows Detected in Estrus Conception Rate 18 cows/ 50 = 36% 100 Eligible Cows 18 Pregnancies Pregnancy Rate 18 cows/ 100 = 18 %

25. Survival Curve for Various Pregnancy Rates 50% Preg

26. Assisted Reproductive Technologies

27. Assisted Reproductive Technologies • This term covers many areas • Artificial insemination • Multiple ovulation embryo transfer programs (MOET) • In-vitro fertilization • Cloning • Natural service is no longer the most common approach towards establishing pregnancy in the dairy cow

28. Artificial Insemination • More than 65% of dairy cattle are artificially inseminated • Genetic progress has been phenomenal • AI bulls advancing cows genetics at rate of 250 pounds per year

29. Fig 27-1. A cow is inseminated using frozen semen (Courtesy of Mark Kirkpatrick)

30. Advantages of AI • Increases use of outstanding sires • All producers have equal access • Alleviates danger and expense of keeping a bull • Decreases breeding costs • Helps control diseases • Makes it feasible to prove more sires • Increases pride of ownership • Alleviates distance and time as limiting factors • Increases profits • Daughters of outstanding sires are higher producers

31. Limitations of AI • It requires training • May accentuate damage of a poor sire • Increased number of progeny • May increase spread of disease

32. Insemination Procedures • Semen handling is very important • Exposure to temperatures above -112 degrees F harms sperm • Repeated exposure increases damage • Ice crystals enlarge damaging cell membranes • Maintain over four inches of liquid nitrogen in tank • Check twice a week with a measuring stick

33. History of Embryo Transfer • NOT a new technology • First embryo transfer in Wisconsin in 1943 • First calf in 1951 • First non-surgical calf in 1964

34. Multiple Ovulation Embryo Transfer (MOET) • For ET to be profitable, donor cows must truly be genetically elite • Process is less expensive if several cows can be flushed at the same time • The use of ET for improving the genetic status of a herd is not typically profitable unless some offspring can be marketed at a price that will offset the cost of the transfers

35. Considerations for MOET • Offspring must be valuable enough to warrant costs • $750-1000 per procedure if multiple cows flushed • Over $1500 if single cow flushed • Average 4-5 pregnancies per flush • Average 2 heifer calves per flush • Cost per heifer calf is $150-550 if bulls have no “additional” value beyond sale barn

36. Management Considerations • Donor cows receive 33-37 mg FSH in decreasing doses • No decrease in estrus intensity or duration • Shorter interval from PG administration to estrus --- and more variable • Greater than 12 hour synchrony difference between donors and recipients decreases pregnancy rate • Number of follicles present affect timing of insemination • More follicles results in more CLs, more P4 • More P4 results in faster ova migration • Requires multiple inseminations to ensure fertilization

37. Fig 27-13. Embryo transfer derived offspring and the donor cow from which they originated (Courtesy of Iowa State University)

38. Synchrony • Synchrony between the donor cow and recipients is critical • As little as a 12 hour difference between time of donor and recipient ovulations can reduce possibility of successful pregnancy • Embryos not immediately transferred can be frozen for later transfer • Glycol or glycerol as cryoprotectant • Pregnancy rates slightly lower

39. In Vitro Maturation and Fertilization • Ability to mature or fertilize ova in a culture dish • Infertile or pre-pubertal animals can reproduce • Immature oocytes are aspirated from follicles of superovulated animals • Done by transvaginal ultrasound imaging • These oocytes are cultured for 24 hours • Fertilized by addition of capacitated sperm to the culture media • Cultured further until blastocyst stage is reached

40. Transgenics • Pharmaceuticals • Improved performance • Challenges in controlling expression of transgene (very few express optimally) • Monitor transgenic offspring for optimal expression and clone the successes • Limits practical applications to very profitable options only

41. Patented Animals • April 1987, the US PTO ruled that patents could be issued on genetically engineered animals • Livestock producers pay fees to those who patent these animals • Livestock producers must pay royalties to the patent holder on each generation of patented animals for life of the patent • May be 17 years

42. Cloning • Production of an exact genetic copy • Nucleus of any cell replaces genetic information present in a one-cell embryo • Does not mean clones are phenotypically identical • Cloned calves are currently being routinely produced • Profitability is limited

43. Fig 27-18. Annie, born March 3, 2000, is a clone of a pure-bred Jersey calf (Courtesy of USDA-ARS)

44. Why Clone?? • Reproduce animals with a unique ability • expressed transgene • growth or lactation • Reproduce animals with a unique value • pets, family members • “spare parts” • endangered species • extinct species

45. Challenges for Cloning • Expensive • Inefficient • 692 embryos • 81 blastocysts • 8 pregnancies • 1 live calf • Genetic diversity • Genetic improvement • Developmental problems • embryo • fetus • newborn

46. Challenges at Birth • Placental insufficiency • Gestation length • Birth weight • Signaling for parturition • C-section required • Umbilical cord • Colostrogenesis

47. Challenges After Birth • Pulmonary development • Hypoxic • Acidotic • Hypoglycemic • Thermoregulation • Immune function • Fluid balance • Genetic expression different than “original”

48. Clones • Theoretically identical animals • Genetically they are NEARLY identical • Nuclear DNA identical but cytoplasmic factors and mitochondrial DNA are different • Phenotypically can be quite different • Environmental influences impinge on expression of genes • Altered methylation patterns for ~25% of genes

49. Pregnancy and Parturition

50. Pregnancy • Initiated at conception • Embryo survives on uterine secretions until implantation (day 32) • Cattle develop a cotyledonary placenta • Attaches to caruncles • Risk of pregnancy loss decreases as pregnancy progresses