breed and animal choices are dictated by what factors
-environmental constraints
-product type considerations
breeding system choices are dictated by what
-ease of management
-replacement animals
-hybrid vigor
Genetic Contributions in
-input costs
-production efficiency
Input costs: breeding animals
Production efficiency: breeding system
genetic factors on probability/efficiency
-breed characteristics
-hybrid vigor
do we care more about hybrid vigor in paternal or maternal in production systems?
Maternal
what is the most important decision in breeding program development
breed characteristics of animals produced
complementarity definition
some terminal crosses have the ability to be more efficient than others to get the same progeny type(Increases efficiency by using specialized sire and dam lines)
what is one of the most important things to consider in a crossbreeding strategy? why?
the impact on birth weight
-heavy birth weights cause dystocia which can permanently damage the dams reproductive ability
what traits are crossbred cows good at
milk production
low maintenance
reproductive performance
crossbreeding major concepts
-blending of breed characteristics
-hybrid vigor for direct and maternal effects
-some crossbreeds can be made more than one way, and some ways make more sense than others
-sustainability
terminal breeds/types definition
animal is goin to market not back into the breeding pool
Maternal hybrid vigor definition
increased performance in dams due to crossbreeding
direct hybrid vigor definition
increased performance of progeny due to crossbreeding
what is the mid parent value
expected mean of group that is 1/2 parent A and 1/2 parent B(halfway between mean of A and B)
what is heterosis
the amount of deviation of the crossbred population from the mid parent value
what generation is maximum heterosis
F1
T/F hybrid vigor tends to be greater for pairs of breeds that are less genetically different
FALSE. more genetically different
why does hybrid vigor in dams effect progeny characteristics until weaning
increased milk production greatly effects preweaning growth as well as progeny survival
key points for bos indicus-bos taurus crosses
-claves with indicus sire and taurus dam will have a heavier birth weight, and bull claves will be heavier than heifer calves(reciprocal cross sees little difference in sex BW, purebred difference is about 5lbs)
-the more Bos indicus the sire the heavier the calves and the greater the BW sex difference
possible reason for fetal overgrowth in crossbreeds
improper/incomplete imprinting
T/F increased birthweights of crossbred calves can be greatly dependent on the good uterine environment of the dam
FALSE.
the cause has occurred by day 7 of pregnancy and is little influenced by the uterine environment
T/F F2 calves from maternal heterosis are likely to outperform the F1. Why/Why Not?
TRUE.
while F1 always has 100% heterosis, maternal heterosis is really beneficial in a breeding line
