|Abstract or Summary
- This investigation for the first time reports information on the
correlation of various forms and ratios of nicotinamide nucleotide
coenzymes in the liver tissue and endocrine glands weight with
various production traits. Fifty-five inbred and line cross beef bulls
raised under standard management conditions and slaughtered at 1000
lbs. body weight were used in the study.
Fluorometeric determinations of the nicotinamide nucleotide
coenzymes showed that NADH was present in lower concentration per
gram of frozen liver tissue than NAD⁺ while the concentration of
NADP⁺ was lower than NADPH per gram of frozen liver tissue. All
forms of coenzymes showed a positive significant correlation with
age (at 1000 lbs. body weight) and percent fat in the body. The coenzymes
in the meantime also showed a significant negative correlation
with percent lean in the carcass. Thyroid gland weight also showed a negative correlation with age, percent fat in the carcass and all the
coenzymes which were positively associated with age and percent fat
in the carcass. Thyroid gland weight was positively correlated with
the NADP⁺/NADPH ratio since this ratio had a negative association
with percent fat in the carcass.
There was a positive correlation of thyroid weight with the
NADP⁺/NADPH ratio. The latter ratio showed a significant positive
association with feed per unit gain. Feed per unit gain, in the meantime,
was positively associated with NADP⁺ and negatively associated
with NAD⁺, percent lean in the carcass and gain per day.
As age at 1000 lbs. body weight increases, the amount of
thyroid tissue at 1000 lbs. body weight decreases and simultaneously
feed per unit gain and percent fat in the carcass increases while percent
lean and gain per day decreases.
No significant correlation of any kind was observed between
pituitary gland weight and production traits. This was attributed to
the involvement of this gland with various hormones that may have
antagonistic inducing action on these coenzymes. Evidence obtained,
however, indicates both hormones (STH and TSH) increases percent
lean, water content and gain per day and decreases percent fat in the
carcass. Based on this evidence a model for the action of these
hormones was presented.
Inbreeding showed a negative significant correlation with percent
lean in the carcass. In the meantime inbreeding was positively associated with total coenzymes (NAD⁺ + NADP⁺, NADH +
NADPH). These coenzymes all have a significant negative correlation
with percent lean in the carcass. Heterozygosity, therefore,
seems to have a heterotic effect on growth as it increases percent
lean in the carcass whereas it shows a negative heterotic effect on
coenzyme concentration in liver tissue. This seems proper since
the above coenzymes have a significant negative correlation with
percent lean in the carcass. High percent lean and low coenzyme
levels were characteristics associated with the line crosses while
the opposite was true of inbred animals.
Lines and line crosses showed statistically significant differences
in coenzymes and production traits. This trend was also true
for the average of parents compared with their offspring. Although
statistically significant differences were not obtained when all inbreds
of 17 and 21 percent inbreeding were compared with line
crosses, a trend indicating higher gain per day, lower feed per unit
gain and lower coenzyme levels, was noted in the line crosses.
Diallel analysis showed no general combining ability for either the
coenzymes or production traits. Specific combining ability and reciprocal
effects were shown to exist for various coenzymes and production