L9

• Crossbreeding


  Mating two different breeds to produce offspring with characteristics of both parent breeds
• Crossbreeding process


  Establish breeding objective

  2. Determine best method (straight, crossbreeding, composite)

  3. Select breeds to achieve objective
• Why use crossbreeding


  • Introduce new breed

  Take advantage of hybrid vigour

  Combine good qualities of two or more breeds

  Improve market suitability
• Breed choice


  Identify performance characteristics that best suit your farm

  Likely involves compromises

  Can minimise compromises by using sires and dams with different attributes
• Ideal beef breeding cow


  • Minimal maintenance requirements but enough body condition

  Produces plenty of milk

  Gets pregnant on time every time

  Displays good maternal behaviour
• Breeds suitable as breeding cows

  • All British breeds

  Any dairy by beef cross

  Some smaller continental breeds (e.g. Saler, Brown Swiss)

  Novelty breeds (e.g. Lowline, Dexter, Pinzgaur, Speckle Park, Belted Galloway, Highland)
• Finishing steers


  Faster growing steers consume less feed

  Winter feed is most valuable, so grow steers as fast as possible
• Breeds suitable for finishing

  • Continental breeds (fastest growing, most lean beef)

  Jersey (may have yellowish fat)

  British breeds (higher marbling, tender beef)

  Double-muscled breeds (e.g. Belgian Blue, Piedmontese)
• Research has shown the Myostatin allele produces beef that is leaner, more tender, and higher yielding. The Piedmontese breed is homozygous for the Myostatin allele.
• Summary - Breed choice

  Know what you want your cattle to do

  Choose a breeding or finishing system or both

  Select breeds that fit your objectives
• Hybrid vigour


  Trait dependent

  Breed dependent - more genetically distinct, greater the heterosis

  Can decline with inbreeding, depends on breeds and crossbreeding system
• Individual heterosis


  Advantage of the animal itself being a crossbred
• Maternal heterosis


  Effect on a calf of having a crossbred dam (more milk, better mothering)
• Combining best traits of breeds

  Use a high growth rate terminal breed of bull on moderately sized cows with good milk production and high reproductive rate
• Types of breeding systems

  • Self-replacing (breed own replacements, buy sires)

  Terminal (all progeny slaughtered, buy replacements and sires)

  Composite (stabilised crossbred)
• Terminal 3-way cross


  Purchase crossbred heifer replacements

  Mate all cows to terminal sire of third breed

  Maximises maternal and individual heterosis
• Three-breed specific cross


  Requires input of three breeds (e.g. Angus, Hereford, Simmental)

  Mating system to generate crossbred cows and terminal sired progeny
• Rotational crosses


  Two or more breeds used in a rotational system

  Retains 67% (2-breed) or 87% (3-breed) of maximum heterosis
• Composite breeds


  1. 9 breeds interbred to form a new stabilised breed

  Often 50% British and 50% continental breeds
• Stabilizer - a composite breed

  Original composition 25% each of Angus, Simmental, Hereford, Gelbvieh

  Retains 75% of F1 hybrid cross
• Heterosis retention in crossbreeding systems

  • Straightbred: 0%

  Terminal sire by F1 dam: 100%

  1. breed rotational: 67%
  2. breed rotational: 87%
  3. breed composite: 50%
  4. breed composite: 75%
  5. breed composite: 81.25%
• Crossbreeding has disadvantages of extra management, more precise recording, and potential for incorrect mating policies
• Crossbred cow trial found high-milk cows weaned heavier calves but at expense of body condition, with no difference in reproductive rate
• Calves from beef-cross-dairy cows were heavier at weaning and processing compared to purebred Angus