The objective of this investigation was
to compare fatty acid composition of calves from Bos
taurus and Bos indicus cows across different stages of
growth. Hereford (H) and Brahman (B) embryos
were transferred to H or B cows (n = 58) to produce
purebred Brahman (BB), purebred Hereford (HH),
Hereford ´ Brahman (HB), and Brahman ´ Hereford
(BH) offspring. Calves were castrated at 2 to 3 wk of
age. Before weaning (210 d of age), calves were fed
native grasses. After weaning, calves were fed a
concentrate diet in dry-lot pens. Adipose tissue was
obtained by biopsy at two times: at weaning during
forage feeding and 3 mo after weaning when placed on
feed. A third sample was collected from the fed steers
at slaughter (approximately 430 d of age). Samples
obtained by biopsy and after death were collected from
the perianal region. Fatty acid composition for each
sample was determined as the normalized percentage
area means from the duplicate measures. Generally,
BB calves grew slowest and BH steers grew fastest (P
< .05). The BH steers exhibited 15 and 20% heavier
( P < .05) carcasses per day of age than H-sired steers
and BB steers, respectively. Adipose tissue samples
from calves from Brahman sires or dams were less
saturated ( P < .05) than samples from calves from
Hereford sires or dams. Differences in degree of
unsaturation primarily were due to the percentages of
monounsaturated fatty acids (MUFA). As calves
became older, MUFA increased markedly, polyunsaturated
fatty acids increased slightly (due to inverse,
nearly proportional changes in 18:2 and 18:3), and
saturated fatty acids decreased by 10 percentage units
( P < .001). Thus, adipose tissue from Brahman and
Hereford purebred and crossbred calves became markedly
more unsaturated early postweaning; this
change was less dramatic in the purebred Hereford
calves.