Fabrication yields and allometric growth coefficients of carcass components of serially slaughtered implanted or non-implanted beef steers

Objective

Our objective was to quantify differences in carcass fabrication yield and allometric coefficients of carcass components from implanted and non-implanted steers.

Materials and Methods

Steers (n = 80; initial BW 271 ± 45 kg) were paired and randomized to slaughter date (d 0, 42, 84, 126, 168, 210, 252, 294, 336, 378). Individuals were randomized to treatment of negative control (CON) or Revalor-XS on d 0 and 190 (REV). One side of each animal was fabricated after a 48-h chill into primals, denuded subprimals, lean trim, trimmed fat, and bone. Weights (g) of non-carcass and carcass components were log-transformed and consolidated to arithmetic means by treatment and slaughter date. Growth coefficients were calculated using the allometric equation.

Results and Discussion

Cattle administered REV had increased cold side weights (CSW) 7.7%, bone yield 4.9%, and red meat yield 8.5%, with no differences in fat yield. Forequarter primal weights (chuck, brisket, foreshank, rib) increased 8.4%, 6.9%, 7.2%, and 5.2%, respectively, for REV cattle. Hindquarter primals (loin, flank, round) increased by 7.0%, 8.6%, and 6.3%, respectively, for REV steers. Length of feeding period notably did not affect chuck or loin yields proportionate to CSW. Fat as percentage of CSW increased at 0.04% per day, whereas bone and red meat yield decreased at −0.013% and −0.024% per day, respectively. Allometric growth coefficients were greater for REV in 2 carcass components (chuck eye roll, eye of round), whereas CON was greater in 1 component (flank steak). All primals except the round (0.81) and foreshank (0.87) exhibited growth coefficients greater than the empty body.

Implication and Applications

These data indicate that REV steers are more likely to have heavier side weights, greater bone yield, and increased red meat yields than CON steers. Additionally, minimal differences were observed in allometric growth coefficients between CON and REV steers. Steers administered REV greatly improved carcass yield over CON during a 378-d finishing period.