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Swine Breeding, Genetics and Reproduction Dr. Randy Harp.

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1 Swine Breeding, Genetics and Reproduction Dr. Randy Harp

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

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

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

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

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

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

8 PSS u either homoz. or heteroz. will cause problems either in transit or at the packing plant u Lauren Christian of Iowa State says to mate the carrier sows to totally free boars u 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 u Nebraska SPF claims that they were the first to have stress free herds u American Yorkshire Club first to take a stand against the stress gene u any York boar used for AI or natural had to be test by DNA test and be free in order to be registered u Duroc & Chester White Associations were second and third to pass similar rules

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

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

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

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

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

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

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

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

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

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

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

21 Types of Breeding cont. u Inbreeding: production of offspring from parents more closely related than the average of a population. u 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 u Breeding Program- a designed system of management to make genetic improvement u Basic steps u establish goals u determine economic traits u utilize records u evaluate performance u stick to your program

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

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

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

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

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

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

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

30 Expected Progeny Differences - EPD’s u 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. u do not cross compare u handout from Duroc Swine Registry

31 Swine Reproductive Anatomy & Physiology

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

33 Reproductive Function & Hormones in the female are influenced in response to: Lactation Length Parity Housing Management

34 Reproduction Depends Upon Hormonal Interaction and Responses:

35 Reproduction in Female Pigs is Cyclic Estrus

36 Estrous Cycle

37 The Hypothalamus Secretes GnRH ( G o n adotropin R eleasing H ormone) in response to:

38 The Pituitary t Secretes gonadotropins in response to GnRH t FSH F ollicle S timulating H ormone t LH L uteinizing H ormone t Source of OXYTOCIN t (PG600 like)

39 Reproduction Depends Upon Hormones:

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

41 Bladder Oviduct Vulva Vagina Cervix Uterus Ovary

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



50 Embryonic Position in the Uterine Horns

51 Reproductive Function & Hormones in the boar are influenced in response to: Housing Management

52 Hypothalamus Gland

53 Pituitary Gland The Pituitary responds to GnRH production

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

55 Reproduction Depends Upon Hormonal Interaction and Responses:



58 Male Hormone Production

59 The Hypothalamus Secretes GnRH ( G o n adotropin R eleasing H ormone) in response to:

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

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

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

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

64 SEMEN u Criteria u motility u percentage of abnormal sperm u volume

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

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

67 FEMALE ANATOMY u SECONDARY SEX ORGANS u receives the semen and transports the sperm to the egg u infundibulum u oviduct (fallopian tube) u uterine horns u uterus u cervix u vagina

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

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

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

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

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

73 HORMONAL CONTROL u FEMALE u PROGESTERONE u hormone of pregnancy u suppresses production of follicles and estrogen u prepares the uterus to receive the fertilized egg

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

75 BREEDING AND REPRODUCTION u Reproduction efficiency is most important economic important trait

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

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

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

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

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

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

82 Repro Facts u gilts in confinement are slower to reach puberty and show estrus u keep gilts grouped together without overcrowding u provide exposure to boars for teasing u 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 u station an old boar (because of stronger boar smell) near the gilt pen u Have a sprinkler system in the summertime u Use lighting in confinement situations to simulate outdoors u Provide 16 hours of artificial lighting at 1/2 watt per sq. ft., esp. in the fall for breeding

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

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

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

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

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

89 Synching more u 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 u Oxytocin - induces uterine contractions (smooth muscle contractions) u 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 u Lutalyse for sows only if accurate records are kept u 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) u Use the herd average as a base u Ex. if the herd ave. is 115 days then give it on day 113

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

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

94 Repro Facts-Vit E u They will pass on Vit E to the baby pigs if they have it in their diet, espec. in the colostrum u In a study at Ohio State, Sows need at least 15,000 IU/ton for proper efficiency u 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 u MMA and pig mortality decreased with increased Vit E > 15K IU/ton u 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 u Available in both feed and injection

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

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

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

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

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

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

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

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