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REPRODUCTION Reproduction is most important trait Bull - represents > 50% of the herd No. of cows per bull ??? percent calf crop & conception rate Ave.

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Presentation on theme: "REPRODUCTION Reproduction is most important trait Bull - represents > 50% of the herd No. of cows per bull ??? percent calf crop & conception rate Ave."— Presentation transcript:

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2 REPRODUCTION Reproduction is most important trait Bull - represents > 50% of the herd No. of cows per bull ??? percent calf crop & conception rate Ave. age of herd- Generation Interval A. I. vs E. T. vs natural Body Condition Scores (1-9)

3 Reproduction of Cattle functions of the cow – produce eggs – develop calf fetus – give birth – produce milk functions of the bull – produce sperm, semen, and testosterone

4 Breeding and selection Breeding habits months of age (Puberty) Age vs. size to breed mos. or at least 65 % of mature weight (breed dependent) Estrus / hours Estrous Cycle / day intervals Occurrence / 6-8 weeks after parturition

5 Breeding and selection signs of estrus – nervousness, attempts to mount others, swelling of vulva, frequent urination, mucous discharge breed the last 10 hours of standing heat or the first 10 hours after standing heat Twelve hours after observed in standing heat or hours after initial heat

6 MALE ANATOMY Testicles- primary sex organ – produces sperm cells (spermatogenesis) – Seminiferous tubules- within the testicle place where sperm cells are formed – Interstitial or Leydig cells Place where testosterone is produced Scrotum- regulates temperature of the testicles (tunical dartos muscle)

7 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

8 MALE ANATOMY Ampullae – storage of sperm before ejaculation Vas deferens - function is to transport spermatozoa to the urethra Secondary sex glands that produce seminal fluid – cowpers, seminal vesicles, and prostate

9 MALE ANATOMY Pampiniform plexus- network of arteries and veins to provide blood supply of the testicles – located above the testicle within the spermatic cord Penis and urethra- transport spermatozoa to the female for natural insemination

10 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

11 SEMEN Criteria – motility – minimum 70% – percentage of normal versus abnormal sperm cells – Volume – concentration

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13 stimulates the development of secondary sex organs and sexual receptivity Produce eggs Produce female hormones  estrogen  progesterone maintains uterine lining during pregnancy keeps estrus from occurring causes mammary system to develop maintains uterine lining during pregnancy keeps estrus from occurring causes mammary system to develop

14 Follicle  blister-like mass on the surface of an ovary containing a developing ovum (egg) follicle ovum

15 Follicle  functions hold the growing ovum produce and store estrogen  at ovulation, the follicle ruptures, expels the ovum, enters the infundibulum and awaits fertilization in the oviduct secreted from follicle to signal the remainder of the reproductive tract to prepare for ovulation

16 Corpus Luteum (CL)  forms after ovum is released from the follicle  function produce progesterone

17 Transport eggs from ovary to uterus Are site of fertilization Pick eggs at ovulation and direct them into the body of the oviducts process of discharging an ovum from the mature follicle of an ovary

18 Consists of horns and a body −uterine horns −uterine body Is site of embryonic growth Is site of placental and fetal development Varies in shape among species A sow has a very long uterus and a mare has a very short uterus

19 Is receptacle for the penis during copulation Serves as birth canal at parturition Is separated from uterus by the cervix Is passageway for expelling liquid wastes major barrier and protection of the uterus and developing fetus

20 Is external portion of the female reproductive tract Serves to:  protect internal system from infection  initially receive the penis at copulation  act as passageway for urine Sensory erectile organ

21 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

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

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

24 Estrous Cycle University of Nebraska-Lincoln Learning Module – – – state.edu/studentorgs/bovine/pdf/Estrous_Cycle_physiolo gy1.pdf state.edu/studentorgs/bovine/pdf/Estrous_Cycle_physiolo gy1.pdf – 5361/the_bovine_estrous_cycle.htm

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26 Estrus Synchronization Cow vs Heifer protocols / Bovine Elite – Website/Handout MGA-PG Select synch, Co-synch, Ovsynch Two shot PG (lutalyse) CIDR- progesterone implant Five day CIDR vs seven day CIDR vs ????

27 Estrus Synchronization eb/Get/Document-1988/ANSI-3166web.pdf eb/Get/Document-1988/ANSI-3166web.pdf state.edu/studentorgs/bovine/pdf/Estrous_Cy cle_physiology1.pdf state.edu/studentorgs/bovine/pdf/Estrous_Cy cle_physiology1.pdf Handouts/Internet – Bovine Elite

28 ARTIFICIAL INSEMINATION or Embryo Transfer DEFINITION: deposition of spermatozoa or egg in the female genitalia by artificial rather than natural methods ADVANTAGES: – Increases the use of outstanding sires – alleviates the danger of keeping several bulls – decreases sire cost – decreases disease transmission

29 ARTIFICIAL INSEMINATION or Embryo Transfer DISADVANTAGES – Requires a skilled technician – Requires more money to start – Honesty

30 Embryo Transfer Expensive, yet yield rate of improved genetics much faster Donor vs recipient Protocols- Handout ???? Time and labor and facilities Expertise and certification

31 Pregnancy Determination Ultrasound Heat detection observed Blood Test Palpation – stages of pregnancy, Fetal sizes, systematic approach, outline of factors to consider

32 Reproductive Ability - cow Milking ability-weaning weight correlation replacement heifer selection/handout quality of udders- udder score – EPD’s Dystocia

33 Calving/Dystocia Calving difficulty Normal parturition = three stages – 1) cervical dilation, 2) expulsion of the fetus, and 3) involves expulsion of the fetal membranes Stage 1 labor begins with initial contraction of the uterus and ends when the cervix is dilated and fetal parts (normally front feet and nose) enter the birth canal (usually lasts 2-6 hours)

34 Calving/Dystocia cont. Stage 2 labor (30 minutes to 4 hours)- begins when the fetal parts enter the birth canal and stimulate the abdominal press. First water bag (chorioallantoic sac) ruptures early stage 2 The second water bag (amniotic sac) is forced through the vulva. Delivery should be completed within 2 hours after the appearance of the amniotic sac at the vulva.

35 Calving/Dystocia cont. Stage 3 labor is the expulsion of the fetal membranes, usually within 8-12 hours following delivery of the fetus. Assistance should be provided if the cow or heifer has been in stage 1 for > 6 hours, or more than 4 hours for stage 2 labor. Usually use chains, nylon straps, or cotton ropes for pulling calves when needed.

36 Causes of Dystocia Improper selection and development of heifers Too rapid growth (<1.75 #/day) Don’t feed excess energy - excess fat Genetic influence (birth EPD’s) Improper calf posture as a fetus Cows with small pelvis Problems - retained placenta & expelled vagina Management Considerations

37 Cattle Normal Presentation Abnormal Presentations

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39 Normal Presentation

40 Calving

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43 Dystocia

44 Calving

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46 Pelvic size in first calf heifers – Calving difficulty scoreYearlingB. W. Score(cm)(lb) – 1 - no assistance15172 – 2 - minor assistance14577 – 3 – major assistance14182 – 4 – caesarean13194

47 Late Gestation, Dry Period Increase in nutrient requirements – establishing greater fat reserve – energy reserve during lactation Problems with underfeeding – calf growth – calf survival lower milk yield, lower weaning wt. – postpartum reproductive problem dystocia, retained placenta, re-breeding

48 Calving Interval Calving Conception (breeding (breeding) Open Gestation/Pregnant (~9.5 mo.) Calving Calving interval components

49 Uterine involution Early postpartum stress 1 st behavioral estrus 1 st AI service 0 45 d Dystocia Retained placenta Uterine infection Metabolic disorders Ovarian cysts Mastitis Peak lactation d Postpartum group Breeding group Suckling -induced gonadotropin inhibition

50 LACTATION 4 Months Energy (TDN lb/d) Protein (CP lb/d) Dry Early postpartum Gestation (late lactation) calving

51 The Effects of Energy During Late Gestation on Calf Growth and Survival Energy Intake High 14.4 Mcal ME Low 9.3 Mcal ME ItemBirthWeaningBirthWeaning Survival (%) Beal, 1996

52 Effect of Body Condition at Calving on Rebreeding Success Body condition at calving Probability of breeding early Probability of Preg. (60-d breeding season) 3<50%88% 450%90% 560%94% 671%97% 779%98% Pruitt & Momont, 1990

53 Effect of Energy Level on Postpartum Interval and Conception Rate Feeding level (pre- & post-calving) % in estrus by 60 d post-calving 1 st service CR High – High8067 High – Low8142 Low – High4565 Low - Low1733

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55 Breeding heifers Breed heifers to calve as two year old (breed one month earlier) disadv: conception rate, %calf crop, dystocia adv: increase one calf per cow lifetime, cow cost/cwt of weaned calf will decrease Replacement hfrs- buy vs raise??????

56 RULES TO FOLLOW with heifers use small headed bulls (lower epd’s) breed only well developed heifers well balanced ration extra care at calving increase feed at lactation wean early if feasible

57 General age and service of the bull 15 mos matings per year 2 yrs. of age 25 matings per year > 3 yrs.40 matings per year Reduces after 7 years of age

58 BREEDING SOUNDNESS IN BULLS days prior to breeding Physical exam- overall appearance including BCS, sound feet and legs, eyes, teeth, hooves, healthiness Repro tract exam-rectal exam of parts – scrotal circumference Semen Evaluation- volume, concentration, motility and viability as well as normality Libido and ability to mate

59 Bull Soundness Exam scoring Sperm motility- 70% Sperm normality – 70% Must have no abnormalities with seminal vesicles, ampullae, prostate, penis, testicles, scrotum (shape and content), etc.

60 Scrotal circumference guide (minimums, except Brahmans) Age (months)Circumference (cm) < > 2534

61 Fall vs Spring Calving Spring Calves most natural season utilize summer pasture (good grass) less labor if sold as yearlings, one winter is saved

62 Reproduction of Cattle Producing fall calves cows are better condition at calving calves escape more parasites, flies, etc. cows give more milk for a longer period calves make better utilization during their 1st spring and summer

63 Rules to follow for higher percentage calf crop Select older heavier heifers for replacement Proper post weaning care – don’t overfeed Select from cows with high reprod. Perf. Breed heifers 30 days earlier Check the cow herd 3-4 X daily during calving Develop adequate working facilities Pregnancy check Maintain herd health program

64 Rules to follow for higher % calf crop cont. Develop and easy ID and record keeping system Breed heifers to bulls with small birth wts. Separate heifers calving as two year old from mature cow herd Provide adequate nutrition Observe the cow herd frequently during breeding Develop a definite breeding and calving season


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