Here is the summary from the study, its pretty interesting.
SUMMARY
The Hereford and Aberdeen _Angus breeds were used in this project
to raise eight calf crops. Each year, one-half of the cows of each breed
raised purebred calves, while the remainder of each breed raised crossbred calves sired by bulls of the other breed. The following year, the
breeding program was reversed, so that each cow raised a purebred
and a crossbred calf each two-year period. There were four two-year
periods and a different pair of bulls for each period. A total of 397
gestations resulting in 201 purebred and 196 crossbred calves, was
obtained. Complete records were kept to provide data on length of
gestation, birth weights, calf losses, gains to weaning, performance on
pasture and in the feed lot, dressing percentages and carcass grades.
These data were treated statistically.
The gestation period required to produce purebred Hereford calves
was ten days longer than that required to produce purebred Angus
calves. In the case of crossbred calves, crossed both ways, the gestation
period was intermediate, indicating that the sire as well as the dam
had influence in determining length of gestation.
Calves of the Angus breed were lighter at birth than calves of the
Herefords. The crossbred calves, both crosses, were intermediate. When
the difference in length of gestation was considered, the birth weights
of all groups of calves were similar.
There were fewer losses of the crossbred calves at birth or as young
calves than of the purebred calves.
Calves from the Angus cows, both purebred and crossbred, were
heavier at weaning than calves, purebred and crossbred, from the Hereford cows. However, crossbred calves from both the Hereford and the
Angus cows outgained the corresponding groups of purebred calves
from birth to weaning.
Calves from the Hereford cows gained more on pasture than the
calves from the Angus cows. A calculation of the gains on pasture on
the basis of weaning weights shows that a greater than average weaning weight resulted in less than average gain on pasture. The heifers,
both purebred and crossbred, from the Angus cows gained the least
on pasture. This difference cannot be explained by differences in weaning weights.
The first two calf crops were fed protein supplement more liberally
than the last six calf crops. The Angus and Hereford bulls that sired
the first four calf crops were larger than the bulls of the respective
breeds used during the last four years. The purebred Herefords and
both crossbred groups gained more rapidly in the feed lot than the
purebred Ang11s steers and heifers.
The purebred Herefords made the most efficient gains in the feedlot.
They were followed, respectively, by the crossbred calves, both steer
and heifer, from the Hereford and from the Angus cows. The difference in feed efficiency between calves crossed either way was not
statistically significant. The purebred Angus calves made the least
efficient gains in the feed lot in this test.
All groups of calves from the Angus cows had a higher dressing percentage than corresponding groups of calves from the Hereford cows.
The crossbreds from the Hereford cows had a slightly higher dressing
percentage than the purebred calves from the Angus cows.
The crossbred calves, steers and heifers, from the Angus cows yielded
the highest grading carcasses of all the groups, followed by the purebred Angus calves. The crossbred steers from the Hereford cows
yielded higher grading carcasses than the purebred Hereford steers.
The purebred Hereford heifers yielded higher grading carcasses than
the crossbred heifers from the Hereford cows.
On the basis of this experiment the advantages from crossbreeding
Angus bulls on Hereford cows are as follows: shorter gestation period ;
lighter weight calves, less possibility for calving trouble; heavier
weaning weights; more rapid daily gain in feed lot; higher dressing
percentage; higher proportion of choice carcasses from the steers.
The disadvantages of crossing the Angus bulls on Hereford cows
are as follows: less efficient gains in feed lot; fewer choice carcasses in
the crossbred heifers than in the purebred Hereford heifers.
The advantages of crossing the Hereford bulls on Angus cows are
as follows: heavier weaning weights for crossbred heifers over purebred Angus heifers; greater daily gain, birth to weaning, for the crossbred heifers; slightly greater daily gains on pasture and in the feed
lot for the heifers; more efficient use of feed in feed lot; increased dressing percentage; and increased proportion of choice carcasses.
The disadvantages of crossing the Hereford bulls on the Angus cows
are as follows: longer gestation period; heavier calves at birth; and
lighter weight crossbred steers than purebred Angus steers.
Although size was not considered in the experimental design, some
of the results obtained in this test raise the question as to whether
there is more opportunity for making progress in beef cattle production by paying attention to size and milk production within a breed
rather than by crossing beef breeds of the same size.
###
