Effect of growth rate and placement weight of stocker-feeder cattle on subsequent finishing performance and carcass characteristics: a meta-analysis

Abstract Text: Many studies have been conducted evaluating the effect of forage species, stocking rate, supplementation strategies, and length of grazing on subsequent finishing performance and carcass characteristics; however, it is still difficult to ascertain the impact of stocker programs on subsequent finishing performance. The objective of this study was to use meta-analysis methods to determine the effect of two important factors of stocker programs, ADG and placement BW, on subsequent finishing performance and carcass characteristics. Following a literature search, a dataset was compiled of 24 studies comprising 29 research trials where stocker treatments differed significantly in rate of gain by ≥ 0.10 kg/d during the stocker phase.  Regression analyses were conducted using a mixed model (Proc Mixed of SAS) that included ADG or placement BW as fixed effects, and intercept by ADG or placement BW cross product terms, when slopes differed among trials, as random effects and trial as the subject. The squared standard error for the dependent variable was used as a weighting factor to compute regression coefficients. Stocker ADG and placement BW had a negative relationship (P < 0.10) with finishing G:F, but when both ADG and placement BW were included in the model neither were significant (P > 0.10). Stocker ADG and placement BW had positive relationships (P < 0.05) with LM area, but not 12^th-rib fat thickness or yield grade. When both ADG and placement BW were included in the model for rib fat-adjusted marbling score, neither were significant (P > 0.10).  However, addition of HCW to the model indicated that HCW had a positive relationship (P < 0.05) with rib fat-adjusted marbling score even though ADG and placement BW were included. Stocker ADG had a negative relationship (P < 0.05) with rib fat-adjusted HCW, whereas, placement BW had a positive relationship (P < 0.05). These data suggest that slower rates of gain during the stocker phase, but with longer grazing periods to increase placement BW can increase rib fat-adjusted HCW and marbling score.

Keywords: carcass characteristics, finishing performance, stocker-feeder cattle