Changes in Body composition and Maintenance efficiency during periods of restricted and maintenance feeding in immature and mature sheep

Abstract

Improvements in production and quality can occur, without the need for increased inputs, through the use of 'Compensatory growth' or by reducing the maintenance requirements during growth and at maturity. A series of studies were used to examine the changes in body composition that occurred during weight loss and realimentation in immature and mature sheep. The effect of variations in body composition, induced through manipulation of nutrition, on estimates for equilibrium maintenance efficiency of mature sheep was examined. Statistical methods developed, tested for seasonal cycles in body composition in an attempt to determine the impact that any endogenous pattern in tissue deposition has on estimates of efficiencies for growth and maintenance. ..... Seasonality After adjusting for differences in body composition attributable to growth using an allometric function, seasonal oscillations for total body fat and carcass muscle were apparent in growing sheep. The magnitude and phase of the sine oscillations for fat and carcass muscle suggested that seasonal cues affect the priorities for tissue deposition. Seasonal oscillations where present for mature sheep that had been fed at a constant feed level. However a more precise method of describing the patterns of change in body tissues using random effects models and cubic splines did not reveal the presence of any time based deviation in total fat, carcass muscle or visceral lean. Nevertheless, the possibility of oscillations in body composition must be considered when estimating the efficiency of growth and maintenance or when evaluating the effects of nutritional manipulation on tissue development in immature and mature sheep.