Animal Breeding: Mating Systems and Pedigrees, Study notes of Animal Biology

Download Animal Breeding: Mating Systems and Pedigrees and more Study notes Animal Biology in PDF only on Docsity! 10/15/2012 1 Breeding and Mating Systems 10-19-09 ‘Here's a good thing to do if you go to a party and you don't know anybody: First, take out the garbage. Then go around and collect any extra garbage that people might have, like a crumpled- up napkin, and take that out too. Pretty soon people will want to meet the busy garbage guy.’ – Jack Handy Objectives • Develop a mating system for a livestock  t ien erpr se. 10/15/2012 2 Breeding • Breeders make 3 choices – 1. – 2. determine rate of reproduction from each individual (esp. sires) – 3. choose mating system to yield most results • Genetic improvement is optimized via selection and mating systems Breeding • Animal Breeders – Seedstock producers – ___________ breeder – Commercial producers – ____________ breeder • Genetic relationship of animals – __________ – defines relationship – Mating systems  • Inbreeding • Outcrossing (outbreeding) 10/15/2012 5 Types of Pedigrees Father (sire) & Daughter = Inbreeding (Father) (Father) (Father) 25% more Homozygosity (RR or rr) (Daughter) (Daughter) Inbreeding • Mating of closely related animals • Benefits: – ______________– if recessive gene present,  recessive gene will appear as defect – Compiles good (valuable) genes – _____________ – due to more homozygous genes • Disadvantages: – Inbreeding depression – may reduce dominant  genes – Brings out (genetic) defects 10/15/2012 6 Intensive Inbreeding • Several generations of inbreeding of multiple  i di id ln v ua s • ________________ traits decline • Used by corn breeders to make hybrids Arrow Pedigree – Three Generations of Sire- Daughter Matings 10/15/2012 7 Line breeding • Mild inbreeding to keep a high genetic  l ti hi t t li f tre a ons p  o an ances or or  ne o  ances ors • Identify superior animals – Maintain relationships to this individual Heterosis • ____________ in superiority of b d d t thcross re progeny compare o e average performance of the parental breeds. • Result of: – heterozygosity____________ – Higher non-additive genetic value due to the masking of recessive genes 10/15/2012 10 Species Crossing Mule Outbreeding • Horse to donkey – Mare and Jack – Mule – Stallion and Jennet ‐ Hinny • Cattle to Bison http://www.ruralmissouri.org/0 4pages/04SeptKahoka.html – Cattalo – Beefalo Beefalo http://michigan-beefalo.com/Jackson.html Crossbreeding • Breeding of different breeds – (eg Angus X Hereford) Outbreeding     • Very common, especially swine, beef and sheep • 2 primary reasons: – – • Increase in a trait in the crossbred progeny above the  average of the lines or breeds crossed • Reproductive traits – Low heritability Crossbreeding Two-Breed Rotation Replacement females Breed A Breed B sires sires » Replacement females Three-breed Rotational Cross Breed B vz sires a Replacement Replacement females females [ \ Breed A Breed C sires sires \ Replacement J females 10/15/2012 11 10/15/2012 12 Terminal-Cross Breeding System Outcrossing Outbreeding • Bred within a breed of unrelated animals • Most widely used • Used to develop maternal lines, growth lines,  carcass lines, etc