Livestock selection Flashcards
what are female reproductive traits favoured in cattle
conception rates
calving intervals
fetal survival
survival to weaning
calving ease
what are male reproductive traits
sperm count
sperm morphology
scrotal circumference
: sperm count, age of puberty and fertility of daughtser
what are adjsted weights
age, sex, dams age, and twins
is feedlot gain
feed to gain, feed efficiency and feed conversion
what is carcass quality
slaughter grade
rib eye area
tenderness
marbling = quality grade
what is branded beef
cattle will be marketed by certain criteria that imply good beef quality - breed programs, brand named products and characteristics
why is longevity important
heifers have more problems calving old cows may abort more
lowering overall production cost
what are the main products of purebreds
bulls, semen and some embryos
what are the selection objections of dairy cows
selection objectives are based partly on tradition
veal and or meat production under no selection in north america
in britian the lower half of dairy herd is bred to a beef bull, so selection is pre breeding
in Israel twinning is under selection to increase meat avaliability
production traits, fertility traits, longevity and health
what is in the selection criteria
reproduction - fertility - non additive gene action, do not typically cross breed
milk and butter fat - genetic correlations
production life span - purchases, home bred for mean milking years
upper type and comformation includes:
large udders
proper teat placement
sound feet and legs
- udder conformation is positively correlated with milking ability
what are the main dairy breeds
holstein, Ayrshire, jersey, brown swiss and guernsey
how do chickens breed
expliots hybrid vigor, especially in laying hens becasue of low hieretability
easier franchise distribution
protects ownership of pure lines
what are selection objectives of poultry
unique crossbred
minimal variation
flock = unit not individual
how do you sex a chicken
K locus primary feathers
K slow feathering (dominant)
k fast feathering (recessive)
male ZKZk - slow
female ZkW - fast
S locus
ZSZs - white or silver = male
ZsW - gold - female
