Mongastric Production Swine Section Breeding and Selection of Swine

Eight major breeds of swine in the U.S. today include: Berkshire (England) Chester White (U.S.) Duroc (U.S.) Hampshire (England) Landrace (Denmark) Poland (U.S.) Spotted Breed or Spots (U.S.) Yorkshire (England)

Composite swine breeds developed by breeding Co. PIC (Pig Improvement Co.) Monsanto Choice Genetics Genetipork Babcock ( Danbred

What general factors determine swine performance? GeneticsEnvironment Genetics x Environment (generally referred to as the interaction of genetics and environment)

What methods are used by swine producers to select breeding stock? 1) Visual appraisal 2) Performance data 3) Pedigree

Why visual appraisal? Type (conformation) Soundness: feet and legs; underline & reproduction. HealthBehavior

What kind of performance data is used for selection? Sow productivity index (SPI) which may include number of pigs born and litter weight at weaning. Growth rate (ADG or perhaps days to a given weight) Feed efficiency (F/G or G/F) Backfat (BF)at a given weight Loin eye area (LEA) at a given weight

Where are pigs performance tested? From the late 50s until about the mid 80s boars were often tested in Central Test Stations. Seedstock producers have also tested their own boars (and some gilts) on their own farm. This is known as on-the-farm testing. Today breeding companies collect their own performance data on boars and gilts sold for breeding. Some Individual seedstock producers collect progeny data from prospective sires via commercial swine producers

Performance vs Progeny Testing Performance testing is collecting performance data on the individual you use in the breeding herd as the boar or the sow. Progeny testing is collecting performance data on the offspring of the boar (sometimes gilts) you plan to use in your breeding herd.

Predicting Genetic Progress GP = S.D. x Heritability S.D. refers to selection differential. Selection Differential refers to the average reach or superiority of selected boars and gilts. Reach is the superiority of individuals (boars and gilts) compared to the herd average. Heritability is the percent of the total variation of a trait that is due to heredity.

Example of calculating GP Herd average BF at 250 lbs = 1.25” Select a boar =.70” Select a group of gilts that average = 1.0” Reach of the boar = -.55” Reach of the gilts = -.25” Average reach (S.D.) = -.40”

GP calculation continued Assume heritability for BF = 50% GP = -.40” x.50 = -.20” (S.D.) x (Heritability) (S.D.) x (Heritability) Expected BF of the progeny 1.25” minus.20” = 1.05”

SD vs EBV vs EPD EBV = Estimated Breeding Value EBV = Reach x Heritability EBV of boar = -.55 x.50 = -.275” EBV of gilt = -.25 x.50 = -.125” EBV of boar + gilt = -.40” EPD = Expected Progeny Difference

SD vs EBV vs EPD continued EPD = ½ EBV (Reach x Heritability) EPD of boar = -.275/2 = ” EPD of gilt = -.125/2 = ” EPD of boar + EPD of gilt = -.20” So, G.P. = EPD of boar + EPD of gilt

Comparison of terms GP = S.D. x Heritability EBV = Reach x Heritability EPD = ½ EBV GP = EPD (male) + EPD (female)

Heritability of economically important traits High>40% Med 20-40% Low<20%

Heritabilities of various swine traits Reproductive traits = low NBA (10%) Production traits = medium ADG (30%) F/G (35%) Carcass traits = high BF (50%) LEA (50%)

How are pedigrees used for breeding stock selection? To avoid inbreeding To identify productive families To avoid genetic defects, such as PSS, scrotal hernias, etc.

Crossbreeding Programs for Commercial Swine Producers Nearly all commercial hogs are crossbred. Which commercial hogs are not crossbred? Answer: purebred animals that do not meet the selection criteria to be marketed as breeding animals.

Why raise crossbred hogs? To capitalize on hybrid vigor (heterosis). Lowly heritable traits benefit the most from heterosis. To combine the desirable characteristics of different breeds. From a practical standpoint crossbred sows farrow more pigs, wean more pigs and wean heavier litters.

What is heterosis? H.V. = the average superiority of the crossbred offspring compared to the parent average for a particular trait. H.V. = ((F 1 -P 1 )/P 1 ) x 100) where F stands for “filial” or offspring and P refers to the parents.

Calculating heterosis Duroc boar from a litter of 10 pigs Landrace sow from a litter of 12 pigs NBA of crossbred offspring = 13 Avg litter size of parents = 11 Heterosis = (13 – 11)/11 x 100)) (F 1 – P 1 )/P 1 = 18.2% (F 1 – P 1 )/P 1 = 18.2%

Systems of crossbreeding Rotational cross = generally uses home raised replacements Illustrate a three breed rotational cross through several matings. Terminal cross = all progeny are marketed. Illustrate how a terminal crossbreeding system works.

What breeds should be used to produce commercial hogs? Research and practical experience have shown that all breeds were not created equal. White breeds such as Landrace, Yorkshire and Chester White excel in sow productivity traits. Durocs are recognized for their superiority in ADG and F/G. Hampshires are well known for superior carcass traits. Colored breeds seem to be more hardy and are especially durable in outside systems.

Coat Color Inheritance in Pigs Self Black (unbelted Hampshire) and Black Spotted (Poland and Berkshire) are both dominant to Red (Duroc). Self White (Chester White, Landrace and Yorkshire) is dominant over most black and red breeds. Self Black x Self White = commonly produces a blue roan (white hair with patches of dark pigmented skin). Referred to as Blue Butts.

What breeds are used? Actually most of today’s seedstock are composite breeds that have been developed by the various breeding companies based upon a combination of white and colored breeds. Landrace and Yorkshires are commonly used as maternal lines. Durocs and Hampshires are used as paternal lines.

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