Corn Grain Alternatives and Coated Versus Non-Coated Trenbolone Acetate and Estradiol Impants for Feedlot Finishing Animals: Influence on Growth Performance, Carcass Characteristics, Efficiency of Dietary Net Energy Utilization, Beef Production per Hectare and Digestiblilty

Corn grain alternatives are often not used in finishing rations due to reduced caloric densities and reluctance to deviate from traditional methods. Along with optimum nutrition, cattle need to have proper implant strategies to reap maximum returns on investment. Two studies were conducted to evaluate the effects of corn grain alternatives and implant type on feedlot finishing cattle. The objective of the first study was to determine the influence of corn silage (15% or 30% dry matter inclusion), and terminal implant type (coated or non-coated) containing equal hormonal doses on animal growth performance, apparent total tract digestibility, beef production per hectare of cropland, and carcass characteristics in finishing steers harvested at a common rib fat endpoint. The objective of the second study was to determine the effects that complete replacement of dry-rolled corn with unprocessed rye have on dry matter intake (DMI), growth performance, and feed efficiency in finishing beef heifers. In experiment one, 156 Maine- Anjou x Angus cross-bred steers were used with an initial body weight (BW) of 366 ± 37.2 kg. Steers were blocked by weight (n = 5 BW blocks) and randomly assigned to implant and dietary treatment. Dietary treatments consisted of 1) 15% (CS15) or 2) 30% corn silage (CS30) where corn silage displaced corn grain in the diet. Steers received one of two implants containing equal does of trenbolone acetate (TBA) and estradiol benzoate (EB): 1) Synovex PLUS (non-coated implant; 200 mg TBA and 28 mg EB; Zoetis, Parsippany, NJ; PLUS) or 2) Synovex ONE Feedlot (coated implant; 200 mg TBA and 28 mg EB; Zoetis; ONE-F). There was no interaction between implant and dietary treatment for any variables measured (P ≥ 0.08). Carcass-adjusted basis final BW, average daily gain (ADG), and gain to feed efficiency (G:F) were increased (P ≤ 0.02) by 2.2%, 6.5% and 7.2% respectively for CS15. Observed dietary net energy (NE) and the ratio of observed-to-expected NE for maintenance and gain and beef production per hectare were not influenced (P ≥ 0.15) by silage inclusion treatment. Fecal output was increased, and digestibility coefficients for dry matter, organic matter, and crude protein were decreased in CS30 (P ≤ 0.03). Dressing percent (DP) and hot carcass weight (HCW) were greater (P ≤ 0.02) in CS15. Beef production per hectare was not influenced by dietary treatment (P ≥ 0.70). Implant type did not influence any parameters measured (P ≥ 0.14) except for marbling being decreased for PLUS (433 vs. 466 ± 17.5; P = 0.02) compared to ONE-F steers. Study two used fifty-six heifers (433 ± 34.0 kg) which were blocked by weight grouping and allotted to treatment pens (n = 7 heifers/pen and 4 pens/treatment). Treatments included a finishing diet that contained: 1) Dry-rolled corn as the grain component of the diet (DRC) or 2) contained unprocessed rye as the grain component (RYE). Grain was included at 60% DM inclusion. On d 14 all heifers were consuming the final diet and heifers were implanted with 200 mg trenbolone acetate and 28 mg estradiol benzoate (Synovex-Plus). Heifer from DRC had greater (P ≤ 0.01) final body weight, ADG, and G:F; however, tended (P = 0.08) to have lesser DMI compared to RYE. Heifers from DRC had greater (P ≤ 0.01) observed dietary NE for maintenance and gain; heifers from DRC also had a greater (P ≤ 0.01) observed-to-expected dietary NE for maintenance and gain compared to RYE. Dressing percentage, 12th rib fat thickness, ribeye area, and the distribution of USDA Yield and Quality grade were not altered (P ≥ 0.12) by dietary treatment. Hot carcass weight, calculated yield grade, estimated empty body fatness (EBF), and body weight at 28% EBF were increased (P ≤ 0.02) in DRC compared to RYE; and retail yield was decreased (P = 0.01) in DRC compared to RYE heifers. This data indicates that un-processed rye is a palatable feed ingredient for inclusion in finishing diets for beef cattle and rye inclusion only minimally influences carcass quality grade. These two studies show that alternatives to corn grain can be fed successfully to finishing beef animals if marketed correctly and with the correct implant regimen. In times of high corn grain prices these feeding methods can be utilized to ensure cattle producers have alternative method to feeding cattle to a desirable market endpoint