GRASS FED - too BIG or too LITTLE?

[Brandonm2]

At 550 carcass weight would only be 916 lbs live weight (60% dress weight). I don't think there are a lot of cattle killed at this weight. And would have 1.25 inches of REA per 100 lbs of live weight which is pretty good. The rule of thumb I always used was that they need 1 inch per 100 lbs.

The 800 lb carcass would be 1333 live weight. For this calf to have a 14.4 eye he would only be at 1.08 per 100 lbs which I think is not really a big stretch. I am sure that ratio of REA to live weight does tend to drop at heavier weights.

My point was that if you make them smaller framed you will need to kill at lighter weights to keep from getting them too fat. If the cattle we have in the feedlots now were slaughtered at lower weights I am sure they would have less backfat and a lower numerical YG but probably also a lower % choice.

The feedlots supposedly do a decent job (more or less) at estimating avg fat cover in a pen. What they CLAIM they are running into is that too many of these carcasses aren't hitting the amount of muscle that an animal that size is supposed too have so it is raising the yield grade (particularly in heifers). I don't think they encounter too many really thick yield grade 4s. With ultrasound, you can harvest them at a desired backfat thickness if you will do the work; but there is nothing the feedlots can do about putting muscle into a calf that doesn't have any. I am not making any predictions on whether dropping frame size will affect avg quality grade. There are too many other variables. 7% of the cattle graded today are YG4s and .3% are YG5s. This is up from 3% and .2% in 1975. I don't think it is coincidental at all that avg carcass weight has increased substantially. Were cattle thicker in 1975???? I don't really know; but the research seems too indicate that they graded better (quality) and were less likely to be fat toads than today's herd.

http://www.bifconference.com/bif2006/pdfs/Morgan.pdf