Estimation of genetic parameters and variance components for growth traits in Romosinuano cattle in the Colombian humid tropics

(Co)variance components and genetic parameters were estimated for body weights of a Romosinuano herd located in Sinú Valley, Cordoba, Colombia. Restricted maximum likelihood methods were used with a univariate animal model for birth weight, weaning weight (270 days), 16-month weight (480 days), weaning daily gain, and post-weaning daily gain. Models included random animal direct and maternal genetic effects, maternal permanent environmental effect (c2), and sex-year-month of birth and age of dam, as fixed effects. Estimates of direct effect for birth weight, weaning weight, 480-day weight, weaning daily gain, and post-weaning daily gain were: 0.25 +/- 0.0001, 0.34 +/- 0.063, 0.33 +/- 0.066, 0.32 +/- 0.062, and 0.17 +/- 0.052, respectively. Estimates of direct maternal genetic effects were low and ranged from 0.06 +/- 0.003 for birth weight to 0.20 +/- 0.054 for weaning daily gain. The genetic correlations between direct and maternal genetic effects were negative and low for 480-day weight (-0.05 +/- 0.219) and showed values of -0.37 +/- 0.007, -0.34 +/- 0.133, -0.33 +/- 0.135, and -0.38 +/- 0.232 for birth, weaning weight, weaning, and post-weaning daily gain, respectively. Permanent environmental maternal effects were not significant; the highest values were found for weaning weight, and weaning daily gain (0.086 +/- 0.031 and 0.078 +/- 0.031, respectively). We conclude that direct and maternal effects should be included in a selection program for all of these traits, and also that selection of weaning weights would be the most productive way to improve performance in Romosinuano cattle.

Kinetics of alpha-dicarbonyls reduction by L-glycol dehydrogenase (NAD+) from Enterobacter aerogenes

L-glycol dehydrogenase from Enterobacter aerogenes shows a high affinity by NADH (Ks = 2-4 microM; Km = 4.3-9.7 microM), which indicates that it must operate in vivo saturated with this coenzyme. Michaelis and dissociation constants for the reduction of the carbonyl substrates assayed (diacetyl, 2,3-pentanedione, methylglyoxal and ethyl pyruvate) are similar to those reported for other diacetyl reducing enzymes. The kinetic mechanism followed by these reactions has also been studied. Our results prove that the reduction of diacetyl and ethyl pyruvate takes place via an Ordered Bi-Bi system with the coenzyme as the leading substrate. Methylglyoxal and 2,3-pentanedione are reduced by the same mechanism or by a Theorell-Chance one.

Further purification and characterization of diacetyl reducing enzymes from beef liver

Two diacetyl reducing enzymes have been isolated from beef liver. One of them, a monomer of mol. wt 28-30,000 dalton and pI 6.2, corresponds to the low molecular weight diacetyl reductase formerly accounted for using preparations of this organ; it has been now identified as an L-glycol dehydrogenase. The other one, an oligomer of 78,000 dalton and pI 7.0, which matches the high molecular weight diacetyl reductase, is, in the authors' opinion, a new enzyme for which the systematic name L(+)-alpha-hydroxycarbonyl: NAD(P) oxidoreductase (EC 1.1.1...) and common name alpha-dicarbonyl reductase are proposed.