Ridecamp: Re: [RC] FYI--long response

The whole point behind the use of ET is to increase the ability of superior
females to influence the gene pool, and it is most effective when females
with a wide number of desirable traits are used as donors.  Until its
development, female contribution to the gene pool in single-offspring
species was limited by the number of offspring they could produce within
their lifetime, and most of these species are limited to 1 gestation a year.
This means that while the male in a herd might produce 20-30 offspring in a
given year, the individual females each only added their genes to the pool
once.  This is why more rapid improvements in the pork and poultry
industries occurred due to maternal contribution as compared to beef and
dairy industries until ET was developed.    For the same reason, ET is a bad
idea in companion and recreational animals.  I think there are too many dog,
cat, and horse breeders who make decisions based on pleasing judges, and not
with the best long-term interests of either breed or species in mind.
Judging is driven by fads, and breeding decisions based on fads are
dangerous.  I think breeders driven by fads are going to be more prone to
making bad decisions as far as the overall quality of the gene pool is
concerned.  Too many judging fads are surface-based--despite the fact that
we preach conformation as being a key issue in breeding decisions, too many
breedings are still driven by halter class placings.    Racehorse breeders
seem to be driven by a quest for the ultimate purse or the winning a certain
race, rather than lifetime performance.  When people breed for these goals,
they tend to focus on single traits to the exclusion of other important
traits, with a greater chance of perpetuating dangerous genes within
bloodlines.  That's why we have so many horses with HyPP and neonatal
isoerythrolysis and weak legs among other problems.  For cats and dogs
insert your genetic problem of choice.  Until breeders in these species are
willing to accept slow steady progress resulting in healthier animals
overall instead of searching for the next star, ET has no place in those
particular industries.

The ET issue addressed, I feel the need to step up to bat for my industry a
little (I'm a dairy nutritionist, even though I'd rather do horse nutrition!
LOL):

Kathy has mentioned the problems associated with fat levels in the dairy
industry, Holsteins in particular. I'm not sure where she gets a breed
average for Holsteins at 2-2.5% butterfat.  The literature I have suggests
otherwise:  the 1999 breed averages for butterfat (according to Michael
Hutjens, University of Illinois, 2000 Western Dairy Management Conference
proceedings) were Ayrshire=3.86%, Brown Swiss=3.95%, Guernsey=4.42%,
Holstein=3.66%, and Jersey =4.57%).  The Holstein is the most prolific breed
in terms of milk production (thus the lower average butterfat level).
Butterfat and milk protein percentages are functions of nutrition,
production level, and stage of production more than they are genetics in
many respects.  Jersey milk is high in butterfat not only because of
genetics but also because they are not physically capable of producing large
volumes of milk.  In addition, they are different enough genetically from
the larger breeds that certain restrictions in feeding them have to be taken
into consideration.

Then there's animal health to consider.  High butterfat levels aren't
necessarily a good thing.  If a cow is less than 50 days in milk and her
butterfat percentage is greater than 1 percentage point over breed average,
this is an indication that she's losing too much weight-some weight loss is
expected until a fresh cow gets to full feed intake, but the amount of
weight loss necessary to produce that level of butterfat is inappropriate.
During peak (50-150 days in milk) production is when the lowest butterfat
occurs, and in high producing Holsteins 3.0% is considered a minimum
acceptable level.  From 150 days on, the goal is to have them around the
breed average.

Just for kicks, I pulled up an old feed intake analysis file from a Holstein
herd I used to work with for illustration purposes.  For the week in
question (first week in July), there were 3678 cows in the milk string.
They were producing an average of 79.47 lbs/cow, with BF=3.42% and Protein =
3.19%.  Base milk price was $13/cwt.  The adjusted milk price (based on
premiums for milk components) was $12.93.  Why?  Because their milk company
docks them if butterfat drops below 3.5%, and protein below 3.2%.  The milk
company in question is the largest dairy in the valley, and it's a cheese
market.  Obviously, component minimums in Class I fluid milk markets are
different, because the milk goes to a different use.  In Pennsylvania, there
is no minimum for butterfat, but there is for protein.   Breeding for 2-2.5%
butterfat would obviously not be in a dairyman's best interests.

I hear someone asking the inevitable question:  Why is this herd below breed
average?  Simple.  The herd average on any given test date or bulk tank
collection day is determined by the lactation profile of the herd. Average
DIM for this herd tended to run somewhere around 170-175, so that means
butterfat percentage should be on the rise for most of the herd as the
majority of cows were coming off peak lactation.  Also, breed averages are
based on average butterfat production per lactation, and this data was from
only one week out of the lactation.

Are there animals that only manage 2-2.5% on test day?  Sure--during certain
seasons depending on where they are in their lactation and bases on
nutritional issues or testing errors.   Cows that don't manage to maintain a
certain minimum butterfat are usually culled, unless there are a number of
other criteria which make her worth keeping despite her butterfat potential.

Then there is the issue of keeping bulls.  They are management problems,
pure and simple.  For every well-behaved Cuddles out there, there are many
more that would willingly run a human down.  Bulls are simply too
unpredictable.  As a result, getting and keeping farm help that are willing
to work around them is difficult.  A bull is only capable of breeding a
certain number of cows in a month without fertility decreasing
significantly.  That means on these large dairies AI (and ET, sometimes) is
the method of choice.  Calves are required for cows to produce milk, after
all.  Some keep cleanup bulls, some simply rely on keeping good AT techs,
but the only places you see bulls kept as the sole breeder on dairy farms
these days are small herds.  Even then, some of the Amish and Mennonites are
beginning to embrace AI technology.

Just my $.02 worth.

Lisa (Stepping off the tack box now)


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