Endocrine manipulation of the pregnant animal and growth of her
offspring: a review
G.S.G. Spencer
Growth Physiology, AgResearch, Ruakura Agricultural Centre,
Hamilton, New Zealand
Proceedings of the New Zealand Society of Animal Production. 1995,
55: 97-100
With the increasing sensitivity towards the use of growth promoters in
animal husbandry, the search is on for ěclean, green methodsî of enhancing
animal performance. A novel method of manipulating growth, that is
essentially free from residue problems, has been developed at Ruakura:
maternal treatments to influence development of her fetuses. Various
approaches using this method have been found to be successful. Decreasing
maternal oestrogen levels in rats during pregnancy has produced 25%
increases in postnatal weight gain and masculinization of carcass
characteristics. This method is not applicable to farm animal species, but a
more practical approach (alteration of thryoxine levels) has been patented
and is being applied to sheep. Other manipulations show potential to
enhance lean tissue growth, while yet others appear to stimulate production
of hormones throughout an animalís life. These maternal manipulations
have many advantages: as the placenta acts as a barrier, most treatments do
not reach the fetus, while for those that cross, the time between treatment and
slaughter is very long so there are no residues; early (fetal) treatments
provide maximum time for advantages to accumulate; particularly in pigs,
treatment of a mother can influence growth of a number of animals;
treatment may be as a food additive. The results available to date suggest
that this is an exciting, powerful, versatile and probably acceptable, method
of improving animal performance.
Keywords: NZSAPAB;
growth promotants; residues; pregnancy; maternal manipulation; fetal
growth; neonatal survival
Download abstract in text format
Last Updated 25-01-1997
