butterfat inheritance question

[librarian]

This must be well understood from the dairy point of view, but I am having a hard time tracking down where one would look for the root of this trait

Specifically, one (me) wants to evaluate cows for this trait based on pedigree. (don't know the cows from observation) 

Would it be transmitted from the top or bottom of the pedigree?
I am guessing maybe it is heritable in the same way marbling is...
If it is introduced by sire, Should I be looking at sire or maternal grand sire?

This question is badly put, but hopefully someone can phrase it better.

 

[knabe]

challenges.


measuring it in the first place.


analyzing by pedigree if useless if one doesn't have the tools to analyze.


it makes sense that a smaller udder with higher butterfat would be better, i.e. chianina, but then chi's aren't in favor any more.


so i don't know if it makes sense to measure it.


calves won't necessarily measure it either because they could be gaining because they have a better appetite, are more efficient etc.


unless one can isolate it and measure a trait, pedigree is mostly useless


one could also have higher butter fat in a line of cattle that isn't noticeable due to the small increase, but is another pathway or whatever than major contributors, hence to me, the danger of eliminating lines of cattle because they aren't the most popular prefixes.


some popular prefixes has gotten some cattle in trouble before for many traits like milk, stiff pasterns, post legs, hard doing, inefficient, lack of mothering, attitude etc.  unfortunately , most people don't live long enough, have enough cattle to introgress traits of interest and have time for mistakes etc.

 

[librarian]

Oh well. Biggering causes all this mischief. We need a Lorax to speak for the breeds.

 

[knabe]

Oh well. Biggering causes all this mischief. We need a Lorax to speak for the breeds.

lorax liked trees more than butterfat.

i wouldn't trust lorax with anything.

although that was just the movie, don't know about the book.

 

[librarian]

The Lorax was an extremist opposing extremism. One's as bad as the other in real life ...but this is Dr Suess, Don Quixote of the ridiculous extreme.
I cannot put words to how horrible that movie was and it pains me to think of it.
Pictured:
The authentic Lorax...a genuine crank
And
The Hollywood Lorax...a Pillsbury doughboy with a Sam Elliot mustache. An insult to both  Dr Suess and Sam Elliot

 

[knabe]

absolutism for thee, but not for me, the message from any cult leader.

 

[librarian]

Without the luxury of data, I attempt to answer my own question.

Every experiment begins with a hypothesis.
Unless you work backwards from results but that's not cool.

On butterfat.
There is an ecological threshold to growth. When we change the evolutionary rate of growth we change the fitness landscape.
Or we change the landscape when we change the rate of ecological change.

My Hypothesis
Cows standing on a fitness peak with high butterfat milk also have more reproductive success with low birth weight calves.
A low birth weight bull that throws high butterfat producing daughters will optimize his genetic survival in that landscape.

(Baby polar bears are tiny. There's a dark side to this, if the calf, our cub dies, the parent lost less investment.)

But if we change the landscape, (higher protein feed, less exposure to harsh weather) the population will move, genetically, to a different peak. (Higher birth weight, greater juvenile size,  more milk but LESS BUTTERFAT.)
See Caveats and Limitations way neat illustration.
https://en.m.wikipedia.org/wiki/Fitness_landscape

And so, my experiment would measure the butterfat content of the daughters of bulls from low birth weight lineages vs high birth weight lineages.
Because of my landscape, I would select for low birth weight for high butterfat.

Larger question, how long does the change in  energy availability take to change energy storage.

Okay, grad students, go milk those Angus.