FEED QUALITY RESTRICTION AND COMPENSATORY GROWTH IN GROWING SHEEP - DEVELOPMENT OF BODY ORGANS

The effects of feed quality restriction and the consequent compensator y growth on body organ development was measured in 56 crossbred Swifte r (Texel male x Flemish female) male lambs born in March 1993 and wean ed at approximate to 2 months of age. The ration was gradually changed to an experimental diet of grass straw (51 g crude protein (CP) per k g dry matter (DM)) ad libitum and 35 g kg(-0.75) d(-1) of mixed concen trate (173 g CP per kg DM). At 3 months of age, animals were randomly assigned to a restricted (R) or a control (C) group. Group R was subje cted to feed quality restriction by withholding concentrates from 3-6 months of age. A serial slaughtering procedure was used to determine c hanges in body organ weights. At the beginning of the experiment eight lambs, thereafter every 3 weeks four lambs (two per group), and final ly eight lambs (four per group) were slaughtered. Growth was modelled using a linear function. Estimated parameters clearly indicated reduce d growth during feed quality restriction and compensation during reali mentation. The carcass showed an earlier effect of restriction and rea limentation compared to body weight (BW). Non-carcass components showe d a delay in growth after restriction but had a similar trend to BW af ter realimentation. At the end of the experiment, the weight of the sm all intestine was higher in R group (P < 0.05). No differences (P > 0. 05) were observed for other organs between groups. In general, early m aturing parts (head, feet and visceral organs) have high priority for use of the available nutrients in the blood stream and are affected le ss than the late maturing parts by feed quality restriction. After rea limentation, the responses are mainly related to their reactions durin g restriction, i.e., the organs which are most affected and have the g reatest reduction, respond quicker than those which are less affected. (C) 1998 Elsevier Science B.V. All rights reserved.