Effects of starch dilution with corn stalks or wet distillers grains with solubles on growth performance and carcass characteristics of feedlot steers

Objective

This study evaluated the effects of starch dilution with different sources of dietary fiber from terminal implant to slaughter on growth performance, energy utilization, and carcass characteristics of feedlot cattle.

Materials and Methods

Steers (n = 416; initial BW = 372 ± 2.67 kg) were allocated to 48 pens in a randomized complete block design. Pens of cattle (n = 12 per treatment) were assigned to 1 of 4 treatments consisting of diets based on steam-flaked corn, containing (1) 7.50% corn stalks on a DM basis fed for the entire feeding period (CON), (2) 14.75% corn stalks on a DM basis fed from terminal implant to slaughter (CS), (3) 9.50% wet distillers grains with solubles and 7.50% corn stalks on a DM basis fed from terminal implant to slaughter (WD), and (4) 19.00% wet distillers grains with solubles and 0.0% corn stalks on a DM basis fed from terminal implant to slaughter (NR). Six days before administration of the terminal implant, steers were transitioned to their treatment diets using a 2-ration system, whereas CON consumed the same diet throughout the entire feeding period.

Results and Discussion

As expected, performance (BW, DMI, ADG, G:F) was not different from d 0 of the study to dietary transition. Dry matter intake and calculated ME intake from dietary transition to slaughter were greatest for cattle consuming CS, intermediate for WD and CON, and least for NR. Final BW and ADG did not differ among treatments from dietary transition to slaughter; G:F was greatest for NR, intermediate for WD, and least for CS and CON. There was no difference in hot carcass weight, DP, marbling score, QG, YG, or percentage KPH among treatments. Steers consuming CS had greater 12th-rib s.c. fat thickness. The proportion of abscessed livers did not differ among treatments.

Implications and Applications

Increasing the proportion of corn stalks in the diet after terminal implant administration increased DMI and ME intake with no effect on G:F. In contrast, removing corn stalks from the diet and increasing the proportion of wet distillers grains with solubles to provide an equivalent starch concentration reduced DMI and improved G:F.