I have been eating Jersey beef for over 30 years. My jersey nurse cows I would breed jersey for replacement heifers long before they did much with sexed semen... so you got a percentage of bulls obviously. I have bred them angus and limi also. The angus x jerseys were the smallest calves, and most were not very robust.. taking more after the jersey in size and fineness of bones. The limi x jersey cross were often larger calves, and grew a little better. I used to buy all the jersey/beef crossed calves from one farmer, getting about 10-20 a year. I get most all the jersey bull calves off one farm close by, that still has 6-10 in their milking herd of 100 cows. They are not as "skinny" as you think if they are getting enough milk in the first 3 months... no, they are not as round as a beef calf, but they do not have hips and ribs sticking out either.
I prefer the jersey beef for the "sweeter taste" and the tenderness... having killed a couple heifers at 4 years old, mostly on pasture with 2-3 lbs grain a day the last 2-3 months... and they were tender, not tough. Both bred too young, aborted them so they did not calve at 14-15 months, , and then did not breed back...
Have a couple neighbors here that bemoan the fact that they cannot find jersey bull/steer calves to raise for beef hardly anywhere like they used to...
They don't take that much longer to finish, and mine are 90% pasture and only fed a minimal amount of grain while running on pasture right up to kill day... maybe get 5-10# grain a day at most the last 30 days? But they get fed with other cattle I am teaching to come in for grain, so not like they can just stand and eat, they are competing for their grain. I kill at 24-28 months, so can get the backbones and all under the rules of the mad cow disease of nothing with spinal cord etc after 30 months old.
I have a jersey/hol/angus bull calf out of my last nurse cow that suddenly dropped dead on me with her calf only 3 weeks old...I put that calf and the other holstein bull calf I had grafted on her, on bottles and it is definitely smaller, finer boned... he will be beef in 2 years; they are about 8-9 weeks old now... and the holstein will get sold down the road.
I have a 1/2 longhorn, 1/2 angus steer that is roly poly, that will be beef next year... just turning yearling...and will get killed late this year or next year... as soon as I find out the kill dates we have. The 1/2 longhorn looks exactly like the longhorn cow in color ... and built like the angus bull... just shorter. The longhorn cow might weigh 900 and the calf is already 3/4 as tall as her and son says he probably weighs 600.... sure not huge at 11 months... but they also are the grazingest 2 animals in that pasture... she keeps the dogs and coyotes at bay so she has a home forever.... and when she doesn't breed back, her horns will go on my wall and her meat will get ground and go in the freezer... if she doesn't outlive me...
I will attest to Jersey beef being some of the best I have ever eaten... and will keep eating it, and jersey crosses, as long as I can find some. The cows also make great nurse cows if you have the patience to work with them... I had 5 at one time with 17 calves between them... looking for another one or 2 now that my new knees are working and the ankle replacement was so successful; and to replace the one I just unexpectedly lost. She had some age, she had raised me alot of calves... just found her dead in the barn with the 2 calves one morning... SH!T happens...