DIFFERENT PERIODS OF FEED RESTRICTION BEFORE COMPENSATORY GROWTH IN BELGIAN BLUE BULLS - I - ANIMAL PERFORMANCE, NITROGEN-BALANCE, MEAT CHARACTERISTICS, AND FAT COMPOSITION

Thirty double-muscled Belgian Blue bulls were maintained at a rate of gain of .5 kg/d during four periods of time, 115 (G2), 239 (G3), or 41 1 (G4) d (low growth period, LGP), before fattening (rapid growth peri od, RGP). Ten control animals (CG) were fed a diet rich in energy and protein. The G2, G3, and G4 were fed a diet low in energy and protein and the same diet as CG during RGP. Live weight was recorded biweekly, feed intake (FI) daily, and nitrogen balance at three times for each group. At the slaughterhouse, the 7, 8, and 9th ribs were removed to d etermine carcass composition, meat quality, and meat and fat compositi on. Compensatory growth reached a maximum 2 mo after refeeding and the n decreased rapidly, leading to a sharp increase in the feed conversio n ratio. Nitrogen balance was higher in compensating groups (P < .05). Compensating animals had higher carcass connective and adipose tissue contents (P < .05) but lower meat fat content (P < .05). Cattle exhib iting compensatory growth had higher redness, yellowness, cooking loss es, and drip losses, but had lower Warner-Bratzler peak shear force va lues. The saturated fatty acid content of the fat decreased with the d uration of the LGP. During the first 2 mo after refeeding, compensator y growth in double-muscled bulls was ascribed to one or more of the fo llowing mechanisms: higher FI, lower maintenance requirements, or bett er efficiency of lean meat production. Compensatory growth at the expe nse of higher FI increased peripheral fat but decreased intramuscular fat deposition.