H. Barash et al., EFFECTS OF LOW-ENERGY DIETS FOLLOWED BY A COMPENSATORY DIET ON BODY-WEIGHT GAIN AND PLASMA-HORMONE CONCENTRATIONS IN BULL CALVES, Journal of dairy science, 81(1), 1998, pp. 250-254
Holstein bull calves at 138.4 d of age were fed one of four diets that
contained 2.28, 2.43, 2.61, or 2.8 Meal of metabolizable energy/kg of
dry matter and 10.8, 11.7, 12.8, or 13.9% crude protein, respectively
, for 77 d followed by a diet that contained 2.80 Meal of metabolizabl
e energy/kg of dry matter and 13.9% CP. During the energy restriction
period, the metabolizable energy of the diets was positively correlate
d with the plasma concentration of insulin-like growth factor-I, which
was positively correlated with daily body weight (BW) gain during thi
s period and the plasma concentration of total thyroxin. During the fi
rst 37 d of the realimentation period, compensatory growth occurred, a
nd the rate of increase in plasma concentrations of insulin-like growt
h factor-I was positively correlated with that of daily BW gain. At d
37 of the compensatory period, the mean plasma concentration of total
thyroxin in calves in three of the four groups did not differ signific
antly; only the concentration of total thyroxin in the plasma of calve
s fed the highest energy restricted diet was significantly higher. The
mean BW of calves in groups fed the high energy diets during the rest
riction period tended to be heavier even after 158 d of the realimenta
tion period.