Animal Science

1. Animal Science Breeding & Genetics Original Power Point Created by Casey Osksa Modified by Georgia Agricultural Education Curriculum Office June 2002

2. What is Flushing or Conditioning? • Feeding cows, ewes, & sows more generously 2 to 3 weeks before breeding • Feed grain or more lush pastures • Grain: • Cows 3-5# • Ewes 1-2# • Sows 2# • After breeding, return to normal feed

3. Why Flush? • More eggs are produced • Females come in heat more promptly • More certain conception • more uniform timing of birth • 15- 30% increase in lamb and pig crops • Exercise for fat cows, ewes, sows helps

4. Genetics Terms • Heterozygous = two different types of genes (Bb) • Homozygous = two similar genes (BB) • Dominant Gene = trait overpowers others • Recessive Gene = must be accompanied with another recessive gene to express trait • Incomplete Dominance = both traits express themselves

5. Punnet Square • Shorthorn Cattle • R = Red • W = white • RW = roan • If a red bull (RR) is mated to a white cow (WW), what color will the calves be?

6. Punnet Square

7. Punnet Square • If a red bull (RR) is mated to a roan (RW) cow, what color will the calves be?

8. Punnet Square

9. Punnet Square • P = horned • p = polled • If a homozygous horned cow (PP) is mated to a homozygous polled bull (pp), what percent of the calves will be horned, polled?

10. Punnet Square

11. Punnet Square • If a homozygous horned cow (PP) is mated to a heterozygous horned bull (Pp), what percent of the calves will be polled?

12. Punnet Square

13. Punnet Square • Mate an Angus bull that is homozygous black and polled (BBPP) to a red shorthorn cow which is homozygous red and horned (bbpp). • What is the probability that the offspring will be black? Polled? Horned? Black and Polled?

14. Punnet Square Black = 100% Polled = 100% Horned = 0% Black & Polled = 100%

15. Punnet Square • Now mate two of the offspring which are heterozygous for black/red and polled/horned (BbPp) • What is the probability that the offspring will be black? Black Polled? Black Horned? Red? Red Polled? Red Horned?

16. Punnet Square • How do you do a punnet square with multiple genes? • Use all possible gene combinations • BbPp = could be BP, Bp, bP,bp • 4 x 4 grid

17. Punnet Square

18. Punnet Square • Black = 12 out of 16 or 75% • Black Polled = 9 out of 16 or 56.25% • Black Horned = 3 out of 16 or 18.75% • Red = 4 out of 16 or 25% • Red Polled = 3 out of 16 or 18.75% • Red Horned = 1 out of 16 or 6.25%

19. Punnet Square • Mate a heterozygous bull (BbPp) to a homozygous cow (BBPP) • What are the outcomes?

20. Punnet Square

21. Punnet Square • Mate a (BbPp) bull to a (BBPp) cow • what are the outcomes?

22. Punnet Square

23. Punnet Square • What are the chances that a new offspring will be a male (xy) or female (xx)

24. Punnet Square

27. Pregnancy Testing Advantages: • Early warning of breeding troubles (infertile, cystic ovaries) • Rebreed nonpregnant females • Grouping for proper nutrition • More effective use of facilities (parturition) • Guarantee pregnant females for sale

28. Pregnancy Testing Cows • Rectal Palpation • 2 months after removing bull

29. Pregnancy Testing Cows

30. Pregnancy Testing Ewes • Determine open ewes, after 60 days • Determine multiple lambs • Rectal Palpation (hollow plastic rod) • Ultrasonic scanning (light or sound if fetus is present) can’t detect multiples • Intrarectal Doppler (detects fetal heartbeat (130-160)) can’t detect multiples

31. Pregnancy Testing Sows • Ultrasonic detector

32. Pregnancy Testing Mares • Stop of Heat period- 18-20 days after last ovulation • Rectal Palpation - 45 days after mating • Blood Tests : 20 -120 days after mating • Ultrasonography: visual image of reproductive tract, 10 days after mating

33. Multiple Births • Percent Twins: • Beef .5% • Dairy 2% • Sheep 20-60% • Horses 1.5% • Twins not desirable in most other than sheep, triplets undesirable in sheep

34. Freemartin Heifers • Sterile heifers that are born twin with a bull • 85% of twin births with both sex • Fetal circulations fuse, male hormone circulates into female, interferes with normal sex development • Can examine vagina of heifer to determine if freemartin (1/3 as long)

35. Expected Progeny Difference (EPD) • Breed Specific (can’t compare epd’s of different breeds) • Expressed as + or - • Birth Weight in pounds • Weaning Weight in pounds at 205 days • Yearling Weight in pounds at 365 days • Maternal Influence (milking ability) pounds of weaning weight produced by daughters

36. Expected Progeny Difference (EPD) • Direct Calving Ease, size & shape of calf • Maternal Calving Ease: size, internal structure, uterine environment of female • Gestation Length in days • Yearling Height in inches • Scrotal Circumference in centimeters

37. Expected Progeny Difference (EPD) • Carcass weight in pounds • Marbling in USDA marbling degrees • Ribeye area in square inches • Fat Thickness in inches

38. Expected Progeny Difference (EPD) Sire BW WW YW Milk A 4.9 12.2 13.2 -3.0 B 4 0.2 3.5 9.0 C 3 0 5 13.0 • Want to increase milk production? • Want to reduce birthweight? • Want to increase rate of growth?

39. Crossbreeding • mating of animals of different breeds • can increase productivity • produce animals with combination of traits • foundation stock for new breeds • introduce new genes quicker than in purebreds

40. Hybrid Vigor • or Heterosis • biological phenomenon which causes crossbreeds to outproduce the average of their parents

41. Complementary • the advantage of a cross where two or more traits complement each other • good quality of breed A and a different good quality of breed B combine in the offspring • qualities complement each other

42. Factors Affecting Crossbreeding Advantages • To achieve 15=-25% immediate increase in yield per female, depends on: • Making wide crosses =wider heterosis • Select complementary breeds • Use high performance stock • Sound Crossbreeding Program: use crossbred females • Tap Purebreds: to renew hybrid vigor

43. Two-Breed Cross • Purebred Bulls X Purebred Cows of another breed • Angus X Hereford = Black Baldies • 8-10% increase in weaning weight • Does not use a crossbred cow

44. Two-Breed Backcross • or Crisscross • Breed A X Breed B = Crossbred calves • Crossbred X Breed A or B • Charlais Bull X Hereford Cow = Cross • Cross X Charlais • Yields 67% of maximum heterosis

45. Three Breed Rotation Cross • 3 Breeds (Hereford, Brahman, Charolais) • Crossbred females bred to purebred bull of breed A • Resulting cross mated to purebred bull of breed B • Resulting cross mated to purebred bull of breed C • Repeat rotation • 87% of maximum heterosis

46. Three Breed Fixed Cross • Crossbred cows mated to Purebred bull of breed C • All calves sold • Purchase crossbred cows • 100% of maximum heterosis

47. Breeding Programs • Selection of breeding stock is critical • Look at all traits, not just one or two • Purebred bulls • Be objective

48. Heat Detection • Producers miss 25-50% of heat periods • Delays calving by 30-40 days • Loss of income: $40 in dairy, $20 in beef • Chin-Ball Marker: marker attached to bottom of a halter of a surgically altered teaser bull (Gomer) • Heat-Mount Detector: fabric with ink-filled capsule, pressure breaks capsule

49. Heat Detection • Pen-O-Block: plastic tube placed within bull’s sheath, held by stainless steel pin • Allows bull to mount cow, mechanically impossible to breed • Vasectomized Bull: can transmit disease

50. Manipulating Estrous • Artificial Lighting: ewes, mares, fowl • Lengthen days, then shorten to simulate natural breeding season • Hormones: • Progestagens: mimics pregnancy, feed, inject, implant, for 14-20 days, when removed, cows cycle 2-8 days later • Prostaglandins: single dose injection, 90 hours later = estrous