Effects of delayed implant protocols on performance, carcass characteristics and meat tenderness in Holstein steers J. L. Beckett, and J. Algeo Cal Poly State University Algeo Consulting

Strategies u Approximately 20 implants approved for use in cattle u Tremendous number of combinations possible u Producers need to establish strategies that best utilize the advantages of the different implants u Long-fed cattle are particularly subjected to repetitive implant regimens

Effects u Increase frame size –Increases growth curve u Decrease quality grade –Lower % Choice –Due to change in physiological endpoint u Increases muscling u Effect on tenderness?

Implant Protocol No Implant Ralgro Revalor-S Synovex-CSyn-S Rev-IS Revalor-G Treatment Groups A B C D E RalgroSyn-S Revalor-S Synovex-C

Average Daily Gain

Final Weight

Gain to Feed

Percentages of Holstein steer carcasses grading USDA Choice or better

USDA Yield Grade

Discussion u Implants: –Increased average daily gains, –Improved feed efficiency –Increased daily dry matter intake –Heavier hot carcass weights –Larger longissimus muscle area u Early implants dramatically influence growth curves u Aggressive estrogens suppressed marbling resulting in lower quality grades

Project Summary u Goal: Identify the time that implants can be initiated to: –Capture maximal growth and performance –Minimize detrimental effects on product u 186 steers on feed for 280 d –Initial weight 156 kg u Weighed every 30 days §At the end of the feeding phase, animals were harvested and carcass data collected

Diet

Average Finishing Ration Analysis u Dry matter 84% u Crude Protein 12.79% u NE g 1.23 Mcal/kg u NE m 1.95 Mcal/kg

Experimental Protocol

Final Weight

Average Daily Gain

Daily Dry Matter Intake

Feed to Gain

Longissimus Muscle Area

Percentages of Holstein steer carcasses grading USDA Choice or better abc c bc ab a

USDA Yield Grade

Meat u Ribs aged for 14 days u 2 steaks from each rib were removed, individually vacuum packed u Steaks sent to Colorado State University u CSU measured tenderness (shear force) and conducted trained taste panel

Warner-Bratzler Shear Force

WB Shear Force over 5

Trained Taste Panel ab bc c a

Summary u Early implants dramatically influence marbling at a given weight u Delaying implants tend to improve marbling without significant effects on growth & efficiency u Aggressive nature of implant strategy should complement the market u Variations in tenderness can not be explained by the use of implants

Percent Empty Body Fat

a ab b b

Adjusted Final Body Weight a a a a b

AFBW from nonimplanted Controls