Effects of milk yield on biological efficiency and profit of beef production from birth to slaughter

Effect of milk yield (MY) on biological efficiency and gross margin as an i ndicator of profit potential of beef production from birth to slaughter was determined. Data included 9 yr of spring-born single male calves. Biologic al efficiency was calculated as carcass weight/total feed energy intake, in cluding nonlactating and lactating intakes of cow and creep and feedlot; in takes of calf. Slaughter end point was finish constant at 9 mm of fat thick ness. Gross margin was determined as returns minus feed costs. Three breedi ng systems were analyzed: purebred Hereford (HE), large rotational (LR),and small rotational (SR). Analyses were performed separately by breeding syst em when differences in the effect of MY among breeding systems were signifi cant. Increased MY was associated with increased preweaning gain (P < .001) , increased weight at start of feedlot trial (P < .001), and increased hot carcass weight (P < .05). No significant (P > .10) effect; of MY on age at slaughter or on carcass weight per day of age at slaughter was found. Incre ased MY was associated with increased cow lactating energy intake (P < .10) and negatively associated with calf creep intake (P < .01), No effects of MY on intake of the cow during the nonlactating period, calf feedlot intake , or total feed intake were found. Increased MY was associated with a reduc tion in backfat thickness of the cow during the lactating period (P < .01) with no change in body weight. In the subsequent nonlactating period, incre asing MY was associated with increased backfat thickness (P < .10) and body weight (P < .05). No effect of nn on change in backfat or weight of cow fr om calving to the end of the next nonlactating period was found. No effect of MY on biological efficiency to slaughter was detected. Milk yield was po sitively associated with gross margin from birth to slaughter(P < .05); res ults were similar when cow feed prices were reduced by 30%. Increased MY wa s associated with increased biological efficiency to weaning in HE (P < .01 ) and SR(P < .10), with no effect found in LR. When feeding cows to require ments, milk yield has a positive effect on the profit potential of beef pro duction from birth to slaughter.