b Dominance vs. Recessiveness B Homozygous, Heterozygous Punnett - PDF document

1/ 26/ 2017 Know how. Know now. Know how. Know now. Breeding/Genetics – Objectives Livestock Management CDE Beef: Breeding, Genetic, & Reproductive Mgmt  Students should understand ... B. A. Reiling  Dominance vs. Recessiveness January 19, 2017  Phenotype = Genotype + Environment  Relative heritability of traits  Use of Performance Data & Genetic Evaluations • Actual Data & Ratios • EPDs • Selection Indexes  Benefits of Crossbreeding Programs University of Nebraska–Lincoln Know how. Know now. Know how. Know now. Breeding/Genetics – What to Expect Punnet Square: b  Dominance vs. Recessiveness B  Homozygous, Heterozygous  Punnett Square: Black vs. Red, Polled vs. Horns BB Bb B 2 phenotypes 3 genotypes bB bb b  BB * bb = Bb * bb =  Bb * Bb = University of Nebraska–Lincoln University of Nebraska–Lincoln Know how. Know now. Know how. Know now. Codominance Phenotype = Genotype + Environment  So how do we get a “ROAN” Shorthorn?  Selection is based upon phenotype  Example – Shorthorn Cattle  Phenotype is not only the “looks”  But also, what we measure.  R = Red; W = White • Birth Weights  RW = Roan • Weaning Weights • Yearling Weights • Average Daily Gain • Pregnancy Rate • Etc. University of Nebraska–Lincoln University of Nebraska–Lincoln 1

1/ 26/ 2017 Know how. Know now. Know how. Know now. Relative Heritability of Traits Phenotype = Genotype + Environment  Environmental Effects General Traits Avg Heritability  1) Random  2) Known  Adjusted Performance Records Reproduction LOW (<20%) • 205-day Adjusted Weaning Weight - 1) ADG = (current weight – birth weight) / Days of Age. - 2) (ADG * 205 days) + birth weight Growth Performance Moderate (20-40%) - 3) Adjust for sex of calf & age of dam Mature Size 2 3 4 5-10 11+ HIGH (>40%) Carcass Traits Male +60 +40 +20 --- +20 Female +54 +36 +18 --- +18 University of Nebraska–Lincoln University of Nebraska–Lincoln Know how. Know now. Know how. Know now. Use of Data & Genetic Evaluations Use of Data & Genetic Evaluations  Actual Data  EPDs  Phenotype = Genotype + Environment  B est tool for genetic improvement  For growth traits, heritability = 30%  Comparative Value  Minimal value for estimation of genetic merit  Expressed as + or – Values  Trait Ratios • Theoretical average = 0  Expressed in units of measure  = (Ind Perf / Avg Group Perf) * 100 • For the trait  Provides relative ranking among contemporaries University of Nebraska–Lincoln University of Nebraska–Lincoln Know how. Know now. Know how. Know now. Use of Data & Genetic Evaluations Use of Data & Genetic Evaluations  Comparing EPDs  EPDs are NOT additive  Sire A = +90 Yearling Wt EPD  If the current average carcass weight = 800 lbs • Year 1: Sire CW EPD = +20  Sire B = +65 Yearling Wt EPD 75 pounds! • Year 2: Sire CW EPD = +30  Difference = 35 lbs • Year 3: Sire CW EPD = +10 875 lb CW! • Year 4: Sire CW EPD = +15  Calves of Sire A should weigh 35 lbs heavier (on  After 4 years, how much more carcass weight? average) at one year of age than those of Sire • Compare the differences = 15 lbs added CW B, when bred to the same cows and raised under the same environmental conditions. University of Nebraska–Lincoln University of Nebraska–Lincoln 2

1/ 26/ 2017 Know how. Know now. Know how. Know now. Benefits of Crossbreeding Use of Data & Genetic Evaluations  True / False –  Breed Complementation  Matching the strengths & weaknesses of different breeds  A bull with a negative marbling score EPD is • Angus * Hereford = Black Baldy guaranteed to decrease the % of choice cattle • Angus * Charolais in your herd.  Heterosis (hybrid vigor)  Selection Indexes   in productivity of crossbred progeny  Profitability Indexes that is greater than expected based upon parent’s average performance  Facilitate Multiple Trait Selection University of Nebraska–Lincoln University of Nebraska–Lincoln Know how. Know now. Know how. Know now. The Heterosis Advantage Use of Data & Genetic Evaluations  Weaning weights  What might your students have to do?  Dam (Breed A) = 460 lbs  Answer some basic “test” questions  Sire (Breed B) = 540 lbs  Keep/Cull with data & questions  Average = 500 lbs expected  Sire Summary Quiz  Resources  Crossbred AB = 530 lbs  NebGuide: EPD Basics & Definitions  Heterosis advantage 30 lbs  NebGuide: Economic Indexes for Beef Sire Selection  Beef EPD Definitions (Reiling)  CRITICAL for REPRODUCTIVE Traits  Sample Sire Summary Quizzes with Keys (Reiling) University of Nebraska–Lincoln University of Nebraska–Lincoln Know how. Know now. Know how. Know now. Bovine Female Reproductive Anatomy Objectives – Reproduction  Students should ... Ovary  Identify basic reproductive organs/structures Uterine Horns • of the cow (female reproductive tract) (calf will develop  Describe the importance of scrotal circumference in one of the horns)  Discuss/outline/demonstrate reproductive mgmt practices Uterine Body • Estrous Synchronization & Artificial Insemination • Breeding Soundness Examinations • Process of Calving & Providing Calving Assistance Cervix  Identify & describe purpose of basic reproductive equipment  Know Beef reproductive numbers University of Nebraska–Lincoln University of Nebraska–Lincoln 3

1/ 26/ 2017 Know how. Know now. Know how. Know now. Bovine Female Reproductive Anatomy Bovine Female Reproductive Anatomy Corpus Luteum Ovary Follicle Oviduct (Fallopian Tube) Oviduct (Fallopian Tube) University of Nebraska–Lincoln University of Nebraska–Lincoln Know how. Know now. Know how. Know now. Basic Reproductive Hormones Bovine Female Reproductive Anatomy  Ovarian Structures  Follicle Stimulating Hormone (FSH)  Follicles  Causes the follicles to grow • Grows in response to FSH  Application – superovulation & embryo transfer • Secretes Estrogen  Estrogen  Corpus Luteum  Secreted by the follicles • Secretes progesterone  Estrous behavior • Maintain pregnancy  Luteinizing Hormone (LH)  Causes ovulation of egg from the follicle University of Nebraska–Lincoln University of Nebraska–Lincoln Know how. Know now. Know how. Know now. Basic Reproductive Hormones Male Reproductive Management  Progesterone  Breeding Soundness Examination  Secreted by corpus luteum (CL)  4 components  Maintains the pregnancy • 1) External Body Evaluation • 2) External Reproductive Organ Evaluation • Keeps “heat” from recurring - Scrotal Circumference  Application = Estrous synchronization • 3) Internal Reproductive Tract Evaluation  Prostaglandin • 4) Semen Evaluation  Secreted by uterus, due to atrophy of egg - Motility, Morphology  Regresses CL; restarts the cycle  Application = Estrous synchronization University of Nebraska–Lincoln University of Nebraska–Lincoln 4

1/ 26/ 2017 Know how. Know now. Know how. Know now. Possible Skill Activities (Hands-on) Possible Skill Activities (Hands-on)  Artificial Insemination  Calving Assistance  Demonstrate proper loading of an AI pipette.  Demonstrate proper obstetrical chain application • https://www.youtube.com/watch?v=KKlM0YZ_83A • https://www.youtube.com/watch?v=9aIcnLBXdL0  Demonstrate proper AI technique (on tracts)  Scrotal Circumference  Demonstrate proper measurement of SC • https://www.youtube.com/watch?v=U8PhqLZtrZk University of Nebraska–Lincoln University of Nebraska–Lincoln Know how. Know now. Know how. Know now. Reproductive Equipment (20) Beef Reproduction By the Numbers ...  AI gun/pipette  Heat Detection Patch  AI sheath  Hemacytometer  Age of Puberty: 8-15 months  Artificial Vagina  Obstetrical Chains  Estrous cycle length: 21 days  Bulb Syringe  Pelvimeter, Rice  Duration of Estrus: 18 hours  Cane  Pelvimeter, Krautman  Time of Ovulation: 12-14 hrs AFTER estrus  CIDR  Scrotal Tape  Gestation Length: 285 days  CIDR applicator  Semen Collection Device  1 st estrus post-calving (PPI) : 30-60 days  Cito cutter  Semen Straw  Electroejaculation Probe  Warm Water Thaw  Ultrasound Endocavity Probe  Goblet University of Nebraska–Lincoln University of Nebraska–Lincoln Know how. Know now. Know how. Know now. Reproductive Management Resources Questions  Ext Circular: Synchronizing Estrus in Beef Cattle  NebGuide: Assisting the Beef Cow at Calving Time &  Bull Management & Nutrition  From the Range Beef Cow Symposium, 2009 Discussion University of Nebraska–Lincoln University of Nebraska–Lincoln 5

1/ 26/ 2017 Know how. Know now. Know how. Know now. Extension is a Division of the Institute of Agriculture and Natural Resources at the University of Thank You Nebraska–Lincoln cooperating with the Counties and the United States Department of Agriculture. The Youth Development program abides with the nondiscrimination policies of the University of Nebraska–Lincoln and the United States Department of Agriculture. University of Nebraska–Lincoln University of Nebraska–Lincoln 6