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
how do you determine skin colour
WW or Ww = white epidermis
ww - yellow epidermis - recessive colour
how can you determine egg colour
Ble eggs OO or Oo over white
green over brown
oo white and brown
what do you select for in layers
egg number, egg weight, shell texture, egg shape, blood spots
albumen quality
what causes maximum shell production
early sexual maturity (19 weeks)
high intensity of lay (80-100%)
persistence of lay - canada clears barns
number of broody periods (bred out except turkeys)
what is a hen day
number of eggs/number of hens
per henhouse?
number of eggs and number of hens that started
what is in a clutch size
1 egg a day
25 hours to produce 1 egg
1 hour later each day
1 day off
restart
what are broilers selected for
male line selected for growth
weight at 6 weeks
fat deposition
breast fleshing
female line
fertility
hatchability
chick survival
what is in meat selection
body weight
carcass quality
survival/livabiliy
