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Impact of grain in finishing programs
Drovers news source  |  Thursday, June 10, 2010

Researchers at Auburn University recently conducted a trial comparing cattle performance and carcass traits from grass-only finishing, grass finishing with different levels of grain supplements and drylot finishing on high-concentrate rations.

A group of 72 steers (out of British-cross cows and sired by Angus, Charolais, or Brangus bulls) were weaned and maintained for 90-days on a forage-based ration. At that time, the steers were divided equally by breed cross into the following treatment groups for finishing to an estimated 0.25 inch fat thickness, the amount found to be possible in previous studies at this location before forage growth limited weight gain:

• ryegrass grazing only (control)
• grazing plus 0.5% body weight whole shelled corn fed daily
• grazing plus 1.0% body weight whole shelled corn fed daily
• grazing plus 1.5% body weight whole shelled corn fed daily
• grazing plus 2.0% body weight whole shelled corn fed daily
• drylot on high-concentrate ration.

Results were as follows:

Treatment	Days to slaughter	ADG	Dressing percent	Lb. hot carcass	Marbling	Yield Grade
Grazing only	172	2.28	56.3	616	SI 39	2.11
0.5% corn	169	2.09	57.3	605	SI 18	2.08
1.0% corn	158	2.55	58.6	638	SI 03	1.94
1.5% corn	143	2.79	58.6	660	SI 60	2.40
2.0% corn	155	2.55	60.6	660	SI 39	2.34
Drylot	151	2.64	60.1	653	SI 69	2.54

Treatment effects on the traits tabled above were all significantly different (P<.05), except for marbling (P<.12). Increasing the amount of corn supplementation tended to decrease days on feed and increased ADG, dressing percent, hot carcass weight, and numerical Yield Grade (decreased leanness). The only statistically significant effects on palatability traits were that beef flavor score trended higher as amount of corn increased (P<.001) with the highest value for drylot-fed, which also had the highest tenderness and juiciness ratings. All groups fell into the Select USDA Quality Grade.

The fat end-point in this study of 0.25 inches is roughly half or less of what would usually be obtained with high-concentrate feeding, which would not have been possible with grass finishing. Extending fat thickness to industry norms would have resulted in higher Quality Grade for high-concentrate feeding. Grass-finishing and high-concentrate finishing are difficult to compare. They are different systems designed to produce different end products. At this point, the industry generally makes better use of grass and grain by separating into growing and finishing phases.

 

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