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VikingNews UK 01 2016
18 / 24
only 6% difference in
fertility
between
sexed
and conventional doses when a farmer wants to decide the gender of the calf, he chooses
sexed
semen, semen cells carrying either male or female genes. when making a
sexed
dose, they are separated to provide the farmer with a calf of desired sex. it is a revolutionary technique used by many farmers world-wide. but as every method, it is not free of drawbacks and the two main issues are; sex rate and
fertility
. sex rate the most important question is how can we ensure that farmer will get the wanted sex of the born calf? unfortunately, there is no guaranty for that. before release, each
sexed
dose is quality-controlled and we measure so called ?purity?. that means that we measure what the percentage of semen cells carrying wanted sex withing dose is. only doses with ?purity? 90% or more are released, meaning that if you order an x-vik- dose, in nine out of ten births, you should get a heifer.
fertility
fertility
is another concern and none of the farmers are willing to risk
fertility
to drop in their herds. a
sexed
dose contains only 2 million semen cells, compared to 15 million semen cells in a conventional dose. this is the explanation why a
sexed
dose has lower
fertility
than conventional doses. it has been a focus point for several years for scientists and manufacturers, to try to improve sorting method and
fertility
. in february 2014, viking genetics started to use a new sorting method called ?ultra? and
fertility
of
sexed
semen has been increasing since then. the latest
fertility
results from the field show an average increase of 3.4%. that means that farmers should be less worried about the
fertility
of their cows as difference in
fertility
between
sexed
and convention- al semen has been reduced from 10% to 6.6%. this is a clear progress and more work will be done to make
sexed
semen as fertile as conventional. o f course, there is not only one optimal
mating
solution for each female. farmers with high knowledge about the individual cow can also successfully correct the proposed
mating
sire if he or she has additional in- formation not available for the computer program making the
mating
plan. best choice for a slow milking cow? for example, we have a slow milking cow with positive pedigree index for milking speed. milking speed is calcu- lated with an animal model ? and for that reason, the cow?s own registration is included in the index. however, if it is a young cow ? her own performance is often still not included in her index at the time of her first insemination in first lactation. "in this case, i recom- mend the farmer to use his or her own observation and choose among the rec- ommended bulls, the bull with highest index for milking speed", lars says. more accurate index if the female is genomically tested if the female is genomically tested, the reliability of the milking speed index will be between 60% and 70%, which is quite high. "in this case, i would look more to the breeding value", lars ex- plains. also remember that milking speed of the offspring will not necessar- ily be average of the parents? as we still have the mendelian variation. in general, we can say that the quali- ty of
mating
decisions in
mating
plans depends on the information available ? genomic tests, classification etc. use also your own observations if a cow has any specific weaknesses not available for the
mating
program. always choose bulls with high ntm "as long as you choose the
mating
sire from bulls on daily plan level with high ntm, it is only positive to take as many parameters as possible into considera- tion. but if you start compromising too much on ntm level to find the ?right bull? for a certain trait, it is more likely that you will get a weaker result", lars concludes. slow milking cow which bull is the right
mating
sire? a large majority of our dairy farmers are using
mating
plans when selecting bulls for insemination, and that is a very good choice. when using a
mating
plan, you have several options for optimizing the bull selec- tion to fit the needs in your herd while maximizing genetic progress and keeping inbreeding on an acceptable level. lars nielsen kasia kupisiewicz by kasia kupisiewicz, r&d, vikinggenetics by lars nielsen, breeding manager, vikinggenetics 18 vikingnews | february 2016
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