Understanding Genetics For Use In Goat Production Dr. Dennis Onks Director Middle TN Research Center University of Tennessee PHENOTYPE AN ANIMAL’S VISUAL EXPRESSION OR PERFORMANCE IN ANY TRAIT The Phenotype is the outcome of Genetic Transfer as developed in a production Environment PHENOTYPE Defined as the sum of the genetic and environmental variation The Genetic variation accounts for 25% of The Phenotype while the Environment Accounts for 75%! Sound Breeding Program Maximum Genetic Improvement occurs In a Herd Environment that allows the Improved Genetics to be Expressed Sources of Environmental Variation 1. Weather 2. Land Topography 3. Structural Resources 4. Forages and Feeding 5. Health and Sanitation Genetic Variation is the study of How Traits are Inherited •All body cells contain “Blueprints” with instructions as to how an animal will look or act etc. •DNA or Deoxyribonucleic Acid contains the genes of traits in the double helix ribbons located in every cell GENE The combination of genes are attached to chromosomes which guide the animal to express A trait or response http://library.thinkquest.org Species differ in chromosomes Humans 23 pairs of chromosomes Cattle 30 pairs of chromosomes Sheep 27 pairs of chromosomes Swine 19 pairs of chromosomes Chicken 39 pairs of chromosomes Goat 30 pairs of chromosomes Horse 16 pairs of chromosomes How Traits are Inherited The science of ½’s since each living animal receives a Sample ½ of its genetics from its father and a sample ½ of its genetics from its mother. The process of halving is done by Meiosis Gene Dominance One Gene overshadows The expression of its other pair (allele) We’re heterozygous (different) WW and Ww = White Recessive Genes We’re Homozygous (the same) •The gene that is overshadowed by a dominant gene. Recessive genes can only be expressed when they both are present RED COAT COLOR = ww QUALITATIVE TRAITS TRAITS THAT ARE AFFECTED BY A SINGLE OR A FEW PAIR OF GENES COAT COLOR TEETH HORNS QUANTITATIVE TRAITS TRAITS AFFECTED BY NUMEROUS PAIRS OF GENES The thousands of genes present make countless combinations possible in an animal. Since genes are too small to identify individually, they express their presence by such outward effects as differences in growth, carcass or reproduction traits Quantitative Traits (cont’d) Growth traits Birth weight Weaning weight Yearling weight Growth rate (ADG) Frame size Carcass traits Rib eye area Fat thickness Marbling Reproduction traits fertility/adaptability Which buck has the best genetics for growth? Is the buck on the left bigger because he had better genetics for growth or because he was provided a better environment? IMPROVEMENT OF ANY TRAIT DEPENDS: MEASURING DIFFERENCES IN A TRAIT ACCURATELY IDENTIFYING SUPERIOR INDIVIDUALS IN THE TRAIT USING SUPERIOR INDIVIDUALS AS PARENTS HOW HERITABLE THE TRAIT IS (heritability) What is Selection? • Choosing animals to be parents for the next generation to produce certain characteristics • Low Birth weight • Heavier Weaning Weight • Gaining Fast • Horned or Polled • Temperament • Better Eating Quality Heritability(h2) Percentage of the differences (measured or observed) in a trait between animals that are transmitted to the offspring. Reproduction Low fertility,etc. Production Moderate growth Product High carcass (Heritability is a measure of how a trait will respond to selection) Low Heritable Traits • • • • • Birth Interval Number Born Rear Legs Udder Support Reproduction 5-10% 15% 15% 20% 15% Moderately Heritable Traits • • • • • • • Birth Weight Weaning Weight Yearling Weight Feed Conversion Quality Grade Ribeye Area Muscling 30-40% 20-30% 40% 40% 40% 40-45% 40-45% Highly Heritable Traits • • • • • Mature Weight Milk Fat Stature, Frame Carcass Weight Scrotal Circumference 65% 55% 45-50% 45-50% 50% Selection for traits is Impacted by the Correlation(r2) Between Traits • Genetic Correlation measures the genetic association between traits • Phenotypic Correlation measures the local or environmental association between traits • Correlation ranges in value of +1.0 to –1.0 (indicates the direction of association) Phenotypic Correlations Body WT Length Heart Girth Backfat Loin Area Kidding -.50 Difficulty Length +.92 Heart Girth +.97 +.87 +.60 +.45 +.51 Loin Area +.90 Scrotal +.86 Circumference +.74 +.89 +.79 +.87 +.77 +.51 Backfat +.67 Use of Heritability and Correlations • Selection for Weight makes moderate progress (h2=40-65%) • Positive Correlation (r2=+.50) between birth, weaning and carcass traits means Selection will result in increases in all three traits. Use of Heritability and Correlations • Selection for Weight makes moderate progress (h2=40-65%) • Negative Correlation (r2=-.50) between Weight and Kidding Difficulty means Selection will result with increased Kidding Difficulty and birth, weaning and carcass weight. Selection for the Industry • • • • • Consumer Packer Feeder Commercial producer Purebred Breeder • Each section may have differing trait criteria CONSUMER • • • • • Price/ Value Consistency Holidays Taste/ Flavor Safety/ Health PACKER • Dressing Percent • Quality Grade • Yield Grade FEEDER • Health • Gain • Feed Efficiency Commercial or Purebred Producer • Reproduction • Maintenance Cost • Growth – Weaning – Yearling ECONOMIC IMPORTANCE TRAIT RELATIVE IMPORTANCE REPRODUCTION 2 PRODUCTION 1 PRODUCT 1 Heritability (Heritability is a measure of how a trait will respond to selection) Reproduction Production Product Low Moderate High “or how well the offspring resemble their parents phenotype” MEASURABLE TRAIT (Phenotype) • GENETIC EFFECTS – ½ GENETICS FROM BUCK – ½ GENETICS FROM DOE • ENVIRONMENTAL EFFECTS – WEATHER – NUTRITION – HEALTH – Etc. Measures of Phenotype P = G + E Birth weights Weaning weights Yearling weights Carcass Traits Reproductive traits Adaptability Measures of Phenotype P = G + E Requires: 1. Identification of animals 2. Equipment to record trait measure 3. Record Keeping System 4. Computer with Spreadsheet is economical and recommended Genetic Evaluations Phenotypes and Pedigrees Objective: convert data into genetic information for the purpose of selection Separate genetic portion of phenotype from environment. 41 lbs • • • • 90 DAYS OLD ON FARM “A” BUCK 2 YR DOE 38 lbs • • • • 105 DAYS OLD ON FARM “A” BUCK 4 YR DOE WHAT ARE THE KNOWN ENVIRONMENTAL EFFECTS? Known Environmental Effects 650 680 AGE - 15 DAYS + 15 DAYS AGE OF DOE 2 YR OLD 4 YEAR OLD FARM SAME SAME Adjusted 90 day wt. formula (Actual Wt - Birth wt) X 90 + doe age adj. + birth wt Age in days Breed associations are calculating adjustments as they accumulate data from the breeders Adjusted 90 day wt. (41 –8) 90 days X 90 + 5 + 8 = 45.999 Lbs. (42 – 7) X 90 + 0 + 7 105 days = 36.999 Lbs. Contemporary Group Ratios adj. 90 day wt 39 Buck A adj. 90 day wt 37 Buck B Herd Avg. = 36 Herd Avg.= 36 Ratio = 39/36 Ratio = 37/36 108 102.8 Useful for within herd selections but not between herds We must expect differences between animals across different environments Future Genetic Evaluations Source of data Ancestors Collateral relatives Descendents Own performance Correlated traits (EPD)-Expected Progeny Difference • A prediction of the genetics a goat will pass on to his kids, when compared to other goats within the breed • Takes into account the actual measurements, all ancestral measurements and environment • Not a perfect science, so use as a risk management tool College Football BCS Purpose is to identify best college football teams Source of Data : AP ranking USA Ranking Record Strength of schedule etc. Ranking changes as more games are played National Goat Evaluation Breed Specific Breed summaries report EPDs. Expected Progeny Difference And Breeding Values The American Boer Goat Association, American Dairy Goat Association, National DHI Program Interpreting EPDs Provide a prediction of future progeny performance of one individual compared to future progeny of another individual within a breed for a specific trait. Allow one to compare or rank the genetic superiority of individual animals within a breed for a specific Trait. EPDs are reported in the actual unit that the trait is Measured (Lbs. for growth traits). They can be positive or negative numbers Effective EPDs: Examples • Scrotal Circumference (SC) High SC bucks sire does with earlier Puberty • Birth Weight (BW) Low BW bucks have more live kids • Average Daily Gain (ADG) Allows choice for replacements or sale of weanlings • Carcass Merit (CM) Allows choice for direct or wholesale Marketing Avg. Array of genetic value of an individual (EPD), adjusted trait performance Difference in Array for two Bucks Full Brothers have a sample 1/2 genetics of buck & of the doe but Not necessarily the exact same genetics HOW ABOUT a BREAK? How do you use genetic tools in a selection program ? Start by using available information Evaluate Goat Breed Characteristics that Appear to fit your marketing plan Average Breeding Values of Six Dairy Goat Breeds Breed Milk Fat Protein Alpine 0 0.0 0.0 LaMancha -114 -0.7 -1.3 Nubian -531 4.4 -1.9 Oberhasli -476 -15.7 -14.3 Saanen 60 0.8 1.9 -6.4 -.35 Toggenburg -18 Alpine LaMancha Nubian You would expect 114 and 531 pounds less milk From LaMancha and Nubian as compared to Alpine Oberhasli Saanen Toggenburg When compared to Alpine, you would expect 60 lbs more Milk for Saanen, 476 lbs less milk from Oberhasli and 18 lbs less milk from Toggenburg Infant Meat Goat Industry • Breed Associations are growing • Members are sending data through membership • Information is increasing • Most selections must come from individual and herd data Infant Meat Goat Industry • Majority of information reports data on Spanish (brush), Boer, Kiko, San Clemente, Myotonic (fainting) and crossbreds • This data provides ranges for comparison • Emerging breed associations will help supply needed breeding values KIKO Spanish Common Meat Goat Breeds BOER San Clemente Boer Buck Performance Test (Langston Univ. & Okla. State Univ., 2004) Total Gain (lbs) 53.1 27.5-68.2 Average Daily Gain (lbs per day) 0.63 0.33-0.81 Feed Efficiency (lbs of feed per lb of gain) 6.8 5.1-9.3 Loin eye area (square inches) 1.95 1.29-2.54 Growth Performance (Langston Univ., 2003) DM intake (lb/day) Avg Daily Gain (lb) Feed Efficiency (adg/dm feed) Alpine 1.56 0.13 0.339 Angora 1.05 0.13 0.61 Boer 1.53 0.19 0.559 Spanish 1.13 0.08 0.32 Carcass Performance (Texas A&M Univ, 1999) Feedlot Range Feedlot Range Live Wt 83.97 45.12 73.74 40.52 Carcass Wt Back Fat 47.78 22.0 42.33 19.25 .047 .012 .028 .012 Type 11.42 3.25 8.33 1.83 Marbling 3.35 1.70 3.06 1.80 Angora Cashmere Common Fibre Goat Breeds Mohair Production & Value Year Value of Production (1000 $) 2003 Goats Production Price Clipped per Unit (1000 hd) (1000 lbs) (US $) 283 2,174 1.58 2002 283 2,174 1.58 3,432 2001 402 2,628 4.00 10,609 2000 444 2,896 3.00 10,016 1999 700 5,045 2.00 12,562 1998 931 6,814 2.00 15,341 3,435 Putting it Together at this Point • • • • • • Develop Marketing Plan Use Breed Characteristics Evaluate Breeding Values Gather herd performance data Compare Animal Performance Develop Record System Genetic Selection or Breeding Plans Interpreting Adjusted Performance Traits These tools predict the average value of genetic ability offered by an animal. Available Breeding Tools • First: Pedigree Evaluations • Second: Use of Heterosis • Third: Trait Calculation & Indexes FIRST 87 ½ % of genetics of kid crop is a result of last 3 bucks used!! Buck 1 (50%) Kid 87 ½ % Buck 2 (25%) Doe 1 by buck 2 Buck 3 (12.5%) Doe 2 by buck 3 FIRST Calculating Pedigree Estimate EPDs Buck (1/2 Trait Value ) KID MG Buck (1/4 Trait Value) Doe Pedigree Est. = ½ Buck Value + ¼ MGB Value FIRST Calculating Pedigree Estimate EPDs Toots (birth value=6.4) KID Caesar (birth value=8.8) Doe Pedigree Est. Birth value= ½ (6.4)+ ¼ (8.8)= 5.4 SECOND Benefits of Crossbreeding Optimizing breed complementarity Capitalizing Heterosis (Hybrid Vigor) HETEROSIS (HYBRID VIGOR) Measure of superior performance of a trait of the ‘Crossbred individual’ over and above the average performance of that trait of the two parental breeds. breeds % HETEROSIS Crossbred Avg. – Parental Breeds Avg. X 100 Parental Breeds Avg. Heterosis Cross Bred Boer-Spanish Reproduction Breed A F1 Cross Breed B Growth Carcass Example of % heterosis: Breed A avg. weaning weight = 45 Lbs. Breed B avg. weaning weight = 51 Lbs. AB crossbred avg. weaning weight = 50 % Heterosis = 50– 48 X 100 48 = 4% Response to Heterosis Inversely related to the heritability of the trait The More diverse differences of breeds used The greater the response Types of Heterosis Individual expressed in the XB kid Maternal expressed in the doe Paternal expressed in the buck Expected % Heterosis Trait Individual Maternal Kidding % 3.4 6.6 Adaptability 1.7 2.0 Birth wt. 2.7 1.6 Lbs. kid/doe 8.5 14.8 Wean Wt. 4.7 4.2 % of Maximum Heterosis realized in different crossbred percentages Crossbred % 50: 50 50 : 25 : 25 9/16 : 7/16 3/8 : 5/8 5/16 : 11/16 75 : 25 3/16 : 13/16 7/8 : 1/8 % Max. Heterosis 100 100 87.5 75 62.5 50 37.5 25 SECOND Crossbreeding Systems To improve: 1. 2. 3. 3. Lbs. Calf weaned per cow maintained Adaptability Live Births Other Traits of Interest Basic Two Way Cross A B AB + 8.5% Lbs. Kid/Doe Only capture Individual Heterosis in the Kid 11 Rotational Crossbreeding 2 Breed A B 3 Breed A B C Heterosis increases Heterosis increases lbs. kid per doe lbs. kid per doe 15% 10 20% Rotational-Terminal Sire Crossbreeding A B T 11 +23.3 % Lbs. kid/doe Heterosis in different crossbreeding systems % Heterosis in XB Population System Does Two breed 0 2 breed crisscross 67 3 breed rotation 86 3 brd cross terminal 100 Backcross 100 Kids 100 67 86 100 50 lbs kid wn/doe 8.5 15.6 20.0 23.3 19.0 % Heterosis for Lbs. Wean/Doe 25 % Heterosis 20 15 Ind + Mater Mater. Het. Ind. Het. 10 5 0 Ind. Het. Mater. Het. Ind + Mater Maternal & Individual Heterosis is additive 100 Different Breeds of Goats Worldwide 4,950 Combinations • Two Breed Crosses with 100 different Breeds 161,200 Combinations • Three Breed Crosses with 100 Different Breeds Use Genetic Tools and Breeding Values or EPDs When Available Identify bucks that will contribute to Improvement in economically important traits PERFORMANCE BENCHMARKS What is the current level of herd performance? What direction (if any) should the herd move? Single Most Important Trait In The Goat Industry ?? REPRODUCTION THIRD Measure of Production/ Reproduction Lbs kid weaned / doe exposed = % kid crop weaned X avg. wn. Wt. Prorates total lbs. kid weaned across all does maintained Best measure of productivity THIRD Lbs. Kid Weaned / Doe Exposed % kid crop Avg. W.W. Lbs. / doe 120 39 46.8 105 39 40.9 95 39 37.1 85 39 33.2 Where Can I Find Quality Data ? Individual herd Owners Breed Associations National Dairy Program Establish Benchmark of Production Determine which traits need improvement Select for that trait(s) BW= birth weight WW= weaning weight SC= scrotal circumference Adaptability Identify How to Use Different Bucks for Different Purposes Produce Replacement Does Terminal Cross Bucks Kidding Ease Bucks Carcass Merit Bucks Remember Genetic Correlations (Antagonisms) Milk production, Growth rate (size) vs. Fertility vs. Maintenance requirements Quality vs. Red Meat Yield Growth rate and Calving ease Birth weight vs. Yearling weight Use Trait Qualities Heritability Heterosis Reproduction (fertility) LOW HIGH Production (growth) MODERATE MODERATE Product (carcass) HIGH LOW A B C D -1.1 22 18 43 .48 Which is the “BEST Buck”? Pick Your Buck B A B=10, W=35, S=39, M=130 B=12, W=42, S=40, M=155 C 5. 7 47 11 90 .09 D -1.1 22 18 43 .48 B=11, W=38, S=33, M=160 B=15, W=45, S=41, M=170 Brth Ww SC M Breed Avg. 11.5 42 33 150 GOOD BUCK? Don’t Buy a “Billy in a Cart” USE A Source of Quality Information Preliminary Selection on Performance Then FOCUS on: -Structural Soundness -Temperament -Scrotal Circumference -ect STRUCTURAL SOUNDNESS Skeletal design & how well the bones support the animal’s body Related to Longevity And Adaptability FEET LEGS Correct Structures Angle of Pastern is usually the same as Angle of Shoulder Breeding Systems Develop your Marketing Plan Choose your breeds: Breeding Values and Characteristics In a crossbreeding system, balance the characteristics of the breeds used. Choose Bucks with performance data. Use EPDs when available. Crossbreeding Considerations •Systematic crossbreeding has benefits. –Heterosis; Complementarity •Planning is critical. –Use EPDs when available. •Crossbreeding is NOT a substitute for poor management. Action Plan Selection Considerations Use Breeding Values as a selection tool when available. Target kidding difficulty, growth and doe size genetics to match environment. Know your market --- what your herd will “produce” Adopt a “consumer-focused” mindset towards carcass merit (avoid misfits). Characterize strengths and weaknesses. Consumers will shape our future and set the Pace!