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Swine Breeding, Genetics and Reproduction

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Presentation on theme: "Swine Breeding, Genetics and Reproduction"— Presentation transcript:

1 Swine Breeding, Genetics and Reproduction
Dr. Randy Harp

2 The Stress Report Meat quality is the key to what we are selling
Packers figure out how to identify poor quality and where it comes from Packers are pushing to get leaner hogs, yet not with poor quality Porcine Stress Syndrome (PSS)

3 Two types of PSS genes Napole (RN) and Halothane (HAL)
RN is a dominant allele (RN-) and a recessive allele (rn+) that is simply inherited on one locus The RN- reduces the ultimate pH of the muscle that reduces WHC and increases purge esp. in the ham and loin

4 PSS cont. HAL - is a mutation on chromosome 6 of the pig at nucleotide It increases lean meat content but enhances PSE and PSS. PSS – animal lacks the ability to adapt to stress HAL is inherited also from a single locus and there are two alleles (N normal and n mutant)

5 PSS cont. HAL has three possibilities NN normal Nn carrier
nn mutant (stress positive) DNA probe now can identify all three genotypes 30-50% of carriers will produce inferior muscle pork quality

6 Pork Quality All poor pork quality is not due to HAL only- about 20 % of poor pork quality was negative for HAL Yet, eliminating HAL positive pigs would drastically help the pork quality issues

7 PSS- genetic influence
worst condition is homozygous recessive for HAL and RN produces carcasses that are watery, chewy and undesirable they reproduce at lower rates and often die before they get into the breeding herd heterozygous- don’t show signs but carry the potential for stress

8 PSS either homoz. or heteroz. will cause problems either in transit or at the packing plant Lauren Christian of Iowa State says to mate the carrier sows to totally free boars if you have any stress genes in the herd, look at them as though they are strictly terminal (yet try to stay away from it)

9 PSS Nebraska SPF claims that they were the first to have stress free herds American Yorkshire Club first to take a stand against the stress gene any York boar used for AI or natural had to be test by DNA test and be free in order to be registered Duroc & Chester White Associations were second and third to pass similar rules

10 Birth Defects estimated one out of one hundred has some birth defect
around 150 different known birth defects only 13 % are known to be due to genetics about 13 % due to environmental effects therefore, 75 % unknown

11 if problems pop up, ask four questions:
were the defective pigs sired by the same boar does the condition trace back to one sire, if every litter was effected are the matings due to abnormal inbreeding were the dams afflicted treated similarly during gestation

12 Abnormalties PSS Scrotal Hernia- result from weak muscles around the scrotum frequently occurs at castration recessive gene action is probable cause Umbilical Hernia- belly ruptures or belly busts

13 Abnormalties Atresia Ani- pigs born without an anus
gilts can survive, but boars die Chriptorchidism- Males with one or both testicles retained in the body cavity and the animal is sterile Hermaphrodites- intersexuality among European breeds Underline defects - pin, inverted or blind nipples

14 Abnormalities Tremors- shakers, trembles, myoclonia congenital, shivers, jumpy pig disease Four types of tremors non-heritable: caused by infection of certain hog cholera strains and shows small brains and spinal cords non-heritable- pre-birth infection by a virus such as PRV two type of heritable- recessive gene action with specific breeds

15 Abnormalities Leg defects:
splayleg or spraddle legs- usually rear legs affected truly unknown, but causes considered are choline deficiency, viral infection, etc. small inside toes bent legs

16 Leg Defects cont. polydactyly- mulefoot (presence of only one toe per foot caused by single dominant gene) thickened forelimbs- connective tissue replaces muscle Non-leg defects: Blood Warts- moles or skin tumors Brain hernia- generally lethal

17 Abnormalities Humpback- crooked spine
Hemophilia (bleeders)- mycotoxins caused and by recessive inheritance Rectal prolapse- no genetic influence ( caused by environ. such as coughing, piling, feed ingredients, antibiotics and diarrhea)

18 Principles of Swine Breeding and Selection
Swine testing programs production testing at central test stations or on the farm Performance testing- testing of the individual Progeny testing- testing of the offspring Pedigree selection- using the reputation or records of animals for breeding selection

19 Possible economic important traits for selection
feed efficiency litter size weaned % lean cuts or cutability conception rate 21 day litter weight soundness score ave. daily gain

20 Types of Breeding Crossbreeding: the mating of animals of different breeds. Outcrossing: the mating of relatively unrelated animals within the same breed.

21 Types of Breeding cont. Inbreeding: production of offspring from parents more closely related than the average of a population. Line breeding: a form of inbreeding in which an attempt is made to concentrate the inheritance of some ancestor in the pedigree.

22 Principles of Swine Breeding and Selection
Breeding Program- a designed system of management to make genetic improvement Basic steps establish goals determine economic traits utilize records evaluate performance stick to your program

23 Principles of Swine Breeding and Selection
Factors that determine to include in a selection program eonomic value heritability genetic relationship with other traits ease of measuring

24 Heritability Estimate
Heritability estimate: hereditary variation due to additive gene action. effects the rate of improvement low heritability lends to slow rates of improvement high heritability estimates yields faster rates of improvement

25 Heritability Estimates for economical important traits
Rate of Gain -days to 230 35% Feed Efficiency 30% Litter size 15% Loin eye Area 50% Ave. Daily Gain 40% Litter Weaning Wt. 15% Carcass length 60% Backfat

26 Terminology Prepotency: the amount that an offspring looks like the parent. Nicking: when genes of the dam and sire complement each other. Heterosis: the improvement that the offspring has over its parents.

27 Selection Systems Tandem- looking at intensifying on one trait at a time Independent Culling- using minimal criteria to select for two or more economic important traits Selection Index- using the combination of two or more economic important traits by observing an index to make selections for breeding

28 Selection Differential
definition- the difference between animals selected to be parents and the average of all animals in the herd for selection for a specific trait S. D. = ave. of animals selected minus the ave. of all animals X heritability

29 Example of selection differential for Feed Efficiency
selected females and males at 3.1 # of feed / # of gain ave. of parents = 3.0, herd ave. was 3.3 diff. is .3, whereas heritablity = .35 therefore, .3 X .35 = .105 gain from selection $$$ ???? # = 200 # gain = 600 # of feed

30 Expected Progeny Differences - EPD’s
a prediction of the progeny performance of an animal compared to the progeny of an average animal in the population, based on all information currently available. do not cross compare handout from Duroc Swine Registry

31 Swine Reproductive Anatomy & Physiology

Organ- any part of the body having a special function Gland- an organ that produces a specific product Endocrine- a gland that secretes discharges directly into the blood Exocrine- a gland which discharges its secretions through a duct

33 Reproductive Function & Hormones in the female are influenced in response to:
Nutrition Disease Lactation Length Parity Housing Genetics Age Season Stress Body Condition Management

34 Reproduction Depends Upon Hormonal Interaction and Responses:

35 Reproduction in Female Pigs is Cyclic
Estrus Estrus Estrus

36 Estrous Cycle

37 The Hypothalamus Nutrition Genetics Season Age & Weight Secretes GnRH
(Gonadotropin Releasing Hormone) in response to: Nutrition Genetics Season Age & Weight

38 The Pituitary Secretes gonadotropins in response to GnRH
FSH Follicle Stimulating Hormone LH Luteinizing Hormone Source of OXYTOCIN (PG600 like)

39 Reproduction Depends Upon Hormones:
GnRH Estrogen & Oxytocin Progesterone, LH & FSH

40 Reproductive Hormones
Estrus LH Causes ovulation Estrogen Induces estrus) Progesterone Prevents estrus

41 The Reproductive Tract
Uterus Oviduct Ovary Cervix Bladder Vagina Vulva

42 Swine Female Repro Tract

43 The Vagina The organ for copulation (mating)
pH unfavorable to sperm & microbes

44 The Cervix Mucus source has 5 interdigitating pads
protects fetus when closed

45 The Uterus the site of embryo and fetal development
Prostaglandin production prostaglandins

46 The Oviducts catch egg site of fertilization leads to uterus

47 The Ovary Has numerous follicles- -which contain eggs & hormones


49 Tract Comparisons

50 Embryonic Position in the Uterine Horns

51 Reproductive Function & Hormones in the boar are influenced in response to:
Age Nutrition Disease Housing Genetics Season Body Condition Stress Management

52 Hypothalamus Gland GnRH

53 Pituitary Gland The Pituitary responds to GnRH production FSH & LH

54 Testes FSH & LH The testes respond to FSH & LH presence by beginning
spermatogenesis. FSH & LH

55 Reproduction Depends Upon Hormonal Interaction and Responses:



58 Male Hormone Production
Androgens Testosterone, Estrogens Ingibins

59 The Hypothalamus Nutrition Genetics Season Age & Weight Secretes GnRH
(Gonadotropin Releasing Hormone) in response to: Nutrition Genetics Season Age & Weight

60 Boar Exposure – Maturity Required
Boars should be Reasonably aggressive Vocal Active secondary sex glands sub maxillary salivary glands pheromones

61 MALE ANATOMY Testicles- primary sex organ
produces sperm cells (spermatogenesis) Scrotum- regulates temperature of the testicles (tunical dartos muscle) Paniform plexus- network of arteries and veins to provide blood supply of the testicles located above the testicle within the spermatic cord

62 MALE ANATOMY Cryptorchidism- one or both testicle that do not descend into the scrotum during embryonic development Epididymis- four functions for sperm cells transport storage maturation concentration

63 MALE ANATOMY Seminiferous tubules- within the testicle
place where sperm cells are formed Vas deferens - function is to transport spermatozoa to the urethra Penis and urethra- transport spermatozoa to the female for natural insemination

64 SEMEN Criteria motility percentage of abnormal sperm volume

65 FEMALE ANATOMY Ovaries- primary sex organ
produces the female reproductive cell “the egg” process of oogenesis unlike the male, it is not continuous controlled by the estrus cycle produces a primary follicle Graafian follicle: mature follicle

66 FEMALE ANATOMY Ovulation: when the tissue ruptures and releases the egg Corpus luteum- cells that grow rapidly replacing the blood clot from the rupture plays an integral role in pregnancy detection by the body

receives the semen and transports the sperm to the egg infundibulum oviduct (fallopian tube) uterine horns uterus cervix vagina

68 FEMALE ANATOMY Infundibulum- catches the released egg
Fallopian tube- place where fertilization occurs important that sperm is at the upper end when ovulation takes place Uterine Horns- where the embryo develops in cattle, sheep, and swine before attachment

69 FEMALE ANATOMY Uterus- major body of storage for the fetus
fetus develops within the uterus within a layer of membranes called the placenta Cervix- overlapping and interlocking folds that form the so-called neck of the uterus passageway for sperm protection from infection during pregnancy Vagina- receptacle for male for service

70 HORMONAL CONTROL MALE TESTOSTERONE- secreted by the testicle
responsible for development and maintenance of the male reproductive tract sex drive increases muscular and skeletal growth essential for sperm formation development of secondary sex characteristics

71 HORMONAL CONTROL MALE Influenced by the anterior lobe of the pituitary gland Gonadotrophic hormones that affect the male FSH (follicle stimulating hormone) development of seminiferous tubules and sperm cells LH (luteinizing hormone) influences interstitual cells to secrete testosterone

72 HORMONAL CONTROL FEMALE Estradiol: produced by the Graafian follicle
Estrogen: a collective term for a number of hormones similar to estradiol Functions: development of secondary sex organs onset of estrus (heat cycle) affects rate and type of growth as well as deposition of fat

suppresses production of follicles and estrogen prepares the uterus to receive the fertilized egg

FSH- stimulates growth of the follicle LH- causes rupture of the follicle LTH (lactogenic hormone)- milk secretion LH (luteotropic hormone)- formation and maintenance of the corpus luteum (CL)

Reproduction efficiency is most important economic important trait

76 REPRODUCTION Puberty 4-7 months Gestation 114 days (3x3x3)
Breed to farrow > than 1 year of age or breed at least 225 lbs. Natural vs A. I. adv: extension of semen, decrease disease spreading

77 Heat Period Standing Heat (2-3 days) Ovulations usually occurs 2nd day of heat swine should be bred at ovulation 1st mating of gilts should be on the 1st day 1st mating of sows should be on the 2nd day each should be re-bred 12 to 24 hours later cycle = 18 to 24 days ave. 21

78 Swine Fertility average - releases 18-25 eggs
fertilizes 14-18 birth 8-14 wean > 8 Breed, nutrition and disease dependent

79 Flushing the Sow increase grain or concentrate in the diet two weeks prior to breeding increase eggs ovulated however, if over-conditioned, lightly exercise gilts for 2-4 weeks before breeding

80 Breeding after farrowing
standing heat occurs 3-10 days after weaning usually breed sows 2nd day after heat detection commercial vs purebred breed 1st vs 2nd heat cycle

81 Reproduction Facts The effect of increased dietary protein and energy can increase gilt mammary tissue slightly, coupled with lipid content in the mammary glands Many cases of mature sows or just weaned sows may deplete their Vit E reserves as they age and while they are nursing High producing sows have higher nutrient requirements

82 Repro Facts gilts in confinement are slower to reach puberty and show estrus keep gilts grouped together without overcrowding provide exposure to boars for teasing replacement gilts are usually kept separate at the end of the finishing floor and then moved to the gestation barn at around 6.5 months of age

83 Repro Facts station an old boar (because of stronger boar smell) near the gilt pen Have a sprinkler system in the summertime Use lighting in confinement situations to simulate outdoors Provide 16 hours of artificial lighting at 1/2 watt per sq. ft., esp. in the fall for breeding

84 More Repro Facts Yugoslavian research indicates that sows are safely pregnant after 42 days Therefore, it may help to continue to provide boar exposure for 45 days post-breeding Any unusual change in the environment will create estrus Poor ventilation - >20 ppm of ammonia will decrease estrus

85 Don’t let them stop cycling
seasonal feed intake- not enough protein or energy during lactation decreases estrus at weaning first litter sows are later than older sows feeding in gestation- too much can cause more anestrous at weaning litter size ???? combined with nutrient req. and feed intake

86 Detecting heat sows ave. 5 days after weaning
split weaning helps -wean half the litter 2 days before resulting sows in standing heat sooner signs- swollen and reddening of the vulva, mounting, etc. handout

87 Synchronizing Estrus PMS/HCG (PG 600) ~ 75% effective for gilts
PMSG (Pregnant Mare Serum Gonadotropin)- used to stimulate the ovaries to develop eggs - follicular growth and development (heat) HCG (Human chorionic gonadotropin) - cause follicles to rupture ovulation usually occurs within hours

88 In Synch show heat 3-5 days after injection 90% come into heat
PG 600 is used to stimulate follicular growth, heat and ovulation in gilts with inactive ovaries not recommended always, but used for gilts

89 Synching more Prostaglandins- causes the regression of the CL (corpus luteum) for controlling farrowing, but not synchronizing (only causes regression of CL that have been present in pregnant or non-pregnant animals for at least days)

90 Synching further Oxytocin - induces uterine contractions (smooth muscle contractions) Altrenogest (Regumate)- not commercially approved as of early to mid 1990’s. Used to stop follicular development. Can be mixed in with the feed.

91 More Drugs Lutalyse for sows only if accurate records are kept
inject not more than 2 days prior to farrowing date and should see farrowing within 36 hours after injection (92% from one study of 38 sows) Use the herd average as a base Ex. if the herd ave. is 115 days then give it on day 113

92 More on Drugs add oxytocin to Lutalyse ~24 hours after lutalyse injection lower numbers for number born alive yet with Lut. and Oxyt. + attendance numbers came back to the control or Lutalyse Another study observed 129 sows using .5 mg Lutalyse, Bovilene (another prostaglandin), or nothing

93 Much More on Drugs Only 26% farrowed for the control group within 36 hours Bovilene affected 98% and Lutalyse caused 76% to farrow within 36 hours Ave. interval from injection was 25 hrs. for Bovilene and 26 hours for Lutalyse and 58 hours for the control group Lutalyse sows were more restless than the other two groups

94 Repro Facts-Vit E They will pass on Vit E to the baby pigs if they have it in their diet, espec. in the colostrum In a study at Ohio State, Sows need at least 15,000 IU/ton for proper efficiency When compared to 0, 30K, & 60K IU/ton, sows performed at pigs more/ litter at birth and at 7 days after farrowing

95 Repro Facts-Vit E MMA and pig mortality decreased with increased Vit E > 15K IU/ton Also, secondary problems such as sudden death syndrome, diarrhea, spraddle-legs, increased stillborns, gut edema, and poor performance were decreased with an increase of Vit E Available in both feed and injection

96 Natural vs AI More sows bred per boar with AI
Usually extend semen to 5-8 sows instead of 1 sow with Natural mating A combination in commercial operations has shown to increase performance and reduce labor Recommended to breed naturally the first day and AI on the second day of breeding

97 Mating Frequency for gilts
Mating frequency does not affect pregnancy for one-day estrus groups However, those longer than 3 days are problems Those exhibiting 2 day estrus showed greater litter sizes for double breeding (a AM and PM breeding for that day)

98 Mating Frequency cont. Litter size improved for those bred two to four times, but did not improve pregnancy rates In general, as mating freq. increases, reprod performance increases onset, timing, and duration of ovulation varies considerably with gilts

99 Feeding and litter size
flushing increases litter sizes for gilts, yet not necessarily for sows usually at least one pig per litter when flushed However, it is recommended not to flush gilts if they are currently in standing heat Wait till they complete estrus, then start flushing

100 Feeding and litter size
when feeding high fiber within the gestation ration sow weight gains and pig birthweights are not negatively affected, except for extremely high fiber diets when fed 96% fiber, sow did not gain much and had .5 lbs per pig less at birth when fed 20-40% fiber, no real affect was seen as compared to a corn-soybean diet

101 Feeding and Repro gestation and lactation rations (14% CP)
Fungus on milo or Mold on Corn can reduce fertility increase Ca:P and energy for lactation don’t overfeed (embryonic death)

102 Heat Stress an added 2-3 degrees F can cut sperm production in herd boars > 95 F for two days will reduce sperm counts for as long as 60 days for growing-finishing pigs, turn sprinklers on >80 F shade vs. sprinkler vs. air-conditioning

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