An experiment was conducted in the semi-arid temperate highlands
of central Mexico (1994–95) with
12 adult, female non-pregnant, non-lactating, crossbred Nubian goats to
determine the effects of 36
weeks of feed restriction on body weight, carcass composition and blood
concentrations of glucose
and hormones (insulin, triiodothyronine [T3] and tetraiodothyronine
[T4]). After a 9-week feed intake,
liveweight and body condition stabilization period, the animals were divided
into three groups and
individually offered either 100, 80 or 60% of their observed average daily
consumption. Feed intake
was measured daily, liveweight weekly, and blood-serum glucose and hormone
concentrations every
4 weeks. At the end of the feeding experiment, the animals were slaughtered,
and the carcasses and
viscerae weighed. Liver and muscle samples were obtained and chemically
analysed. Insulin and T4
did not differ between treatments (P>0·05). Final liveweight;
blood-serum glucose and T3; carcass
yield; muscle tissue dry matter, fat, RNA and RNA:protein ratios;
hepatic tissue protein,
RNA:DNA and protein:DNA ratios decreased, while liver and muscle
DNA increased with
restriction (P<0·05). These results suggest that capacity
of goats to adapt to long term undernutrition
and the importance of hepatic and muscle tissues as sources of metabolic
energy.