New Zealand Journal of Agricultural Research abstracts
Growth hormone secretion and pituitary gland weight in suckling lambs from
genetically lean and fat sheep
S. M. FRANCIS
B. A. VEENVLIET
S. K. STUART
R. P. LITTLEJOHN
J. M. SUTTIE*
AgResearch
Invermay Agricultural Centre
Private Bag 50034
Mosgiel, New Zealand
Abstract Previous studies have found that weaned lambs from
Coopworth sheep selected for low (lean) backfat depth have higher mean plasma
growth hormone (GH) levels and heavier pituitary glands than those selected for
high (fat) backfat depth. This study examined whether these differences between
genotypes occurred in young suckling lambs. Six ewes from each genotype which
were suckling a male/female set of twins were kept indoors. Four weeks after
birth, ewes and lambs were blood-sampled for 6 hours at 10 minute intervals and
plasma GH levels measured. Lambs were then slaughtered and carcass composition
determined. Subcutaneous fat depth was lower in lean than fat lambs at four of
the five different sites measured (P < 0.05). Lean lambs
and ewes had greater mean and basal plasma GH concentrations and a greater
amplitude of GH pulses than fat sheep (P < 0.05). Plasma
IGF-I levels did not differ (P < 0.05) between genotype for
either ewes or lambs. Pituitary glands were heavier
(P < 0.001) in lean than fat genotype lambs (0.29 versus
0.19, SED = 0.017 g). It is concluded that differences between genotypes in
body composition, plasma GH, and pituitary gland weight occur at an early age.
An investigation of foetal development patterns may be required to elucidate
the relationship between these parameters.
Keywords growth hormone; insulin-like growth factor I;
pituitary gland; fatness; suckling lambs; carcass composition
New Zealand Journal of Agricultural Research, 1998, Vol. 41: 387-393
0028-8233/98/4103-0387 $7.00/0 (c) The Royal Society of New Zealand
1998
PDF file of entire paper: medium quality (567K); (scanned from paper original: notes about this process)
This year's abstracts |
Journal home page |
All abstracts |
Publishing home page
