Evaluation of Performance and Carcass Quality of Finishing Beef with Natural Feeding Practices in North Dakota



Vern Anderson and Jon Schoonmaker

NDSU Carrington Research Extension Center



Based on consumer preferences and a growing concern over the use of antibiotics and other growth promoters in the animal feed industry, natural beef programs have expanded in recent years. “Natural” is a widely used label that does not carry legal connotations or infer specific production practices. To some people, natural means cattle are fed only on grass; to others, natural may mean non-genetically modified grains are fed; to most, natural means no antibiotics, ionophores, or implants used. To profitably raise beef without these products, producers need alternatives to keep their animals healthy. Several different additives have been developed that meet the “natural” criteria including yeasts, enzymes, probiotics and fermentation products. Some of the potential benefits associated with yeast include improved rumen fermentation and increased feed digestion. Bovi-Sacc (provided courtesy of Alltech, Nicholasville, KY) is a yeast product that also contains mannan oligosaccharides. The exact mechanism of mannan oligosaccharide is unknown, but it is possible that it binds to cell walls of bacteria preventing the bacteria from attaching to the intestinal cell wall and infecting the animal, or it may enhance the immune system by evoking a direct antibody response.


Because North Dakota has abundant supplies of non-GMO grains including barley, field peas, and sunflower meal, as well as a number of non-GMO forages, producers in the state have an excellent opportunity to profit from the expanding natural beef market. The objective of this study was to compare performance, carcass quality, and economics of cattle fed non-GMO-based diets containing yeast to cattle fed a non-GMO-based diet containing ionophores.



One hundred twenty eight mixed breed steers (initial BW 560.2 ± 40.9 lbs.) were allotted by weight and source to one of four non-GMO-based diets (Table 1): conventional (85% concentrate, rumensin in the diet), natural 85 (85% concentrate, Bovi-Sacc in the diet), natural 70 (70% concentrate, Bovi-Sacc in the diet), and natural 55 (55% concentrate, Bovi-Sacc in the diet). This is a progress report on available data from conventional 85 and natural 85 treatments. Cattle were fed at the Carrington Research Extension Center (CREC) in 16 open drylot pens (8 steers per pen; 4 pens per treatment). Each pen was equipped with automatic waterers and fenceline bunks, which allowed for two feet of bunk space per head. Feed was delivered as a totally mixed ration once daily to appetite.



Prior to feedlot entry, cattle were vaccinated for protection against IBR, BVD, BRSV, PI3 (Bovishield-4; Pfizer, Exton, PA), and clostridia (7-way + somnus; Pfizer, Exton, PA). Health status of the cattle was monitored daily. Rectal temperatures were measured in animals that were visibly anorexic, or had severe nasal mucous drainage and rapid or labored breathing. Any animal with a rectal temperature  greater than 103.0oF was treated with one of two antibiotics according to label instructions (Micotil, Elanco, Indianapolis, IN; Baytril, Bayer, Shawnee Mission, KS). Micotil was used on first and second pulls, followed by Baytril (single day therapy), if cattle were unresponsive. Antibiotic treatment continued until rectal temperature was below 103.0oF. Research protocols regarding animal care followed guidelines recommended in the Guide for the Care and Use of Agricultural Animals in Agricultural Research and Teaching (FASS, 1998).


Cattle in the two treatments reported here were slaughtered on May 7, 2004, after 146 days on feed. Hot carcass weight, fat thickness, percentage kidney, pelvic and heart fat, longissimus muscle area, and USDA quality and yield grades were determined by qualified North Dakota State University personnel 48 hours after slaughter.


Results and Discussion

Information reported here has not been statistically analyzed, and is only offered as observation. Remaining treatments will be compared in future reports. Except for period three (February 19 to March 25), conventional-fed cattle gained slightly faster compared to natural-fed cattle (Table 2). From December until slaughter (May 7) conventional-fed cattle gained 3.07 lbs. /d and consumed 21.7 lbs. of dry matter per day while natural fed cattle gained 2.93 lbs./d and consumed 21.4 lbs. of dry matter per day. Conventional-fed cattle were somewhat more efficient than natural-fed cattle for every period of the trial as well as overall. From December until slaughter (May 7) conventional-fed cattle consumed 7.0 lbs. of dry matter for every pound of gain, while natural-fed cattle consumed 7.3 lbs. of dry matter for every pound of gain. At slaughter conventional and natural calves produced carcasses with similar characteristics. Natural-fed cattle had a higher average marbling score (choice- 82 vs. choice- 54), but slightly fewer carcasses graded choice or better (70.0 vs. 75.0%) compared to conventional-fed cattle. Fat thickness, rib-eye area, and yield grade tended to favor natural fed cattle.


Steers on the Natural Feeding trial.



To profitably raise beef without antibiotics, producers need alternatives to keep their animals healthy. Results of this study indicate that yeast is nearly as effective as rumensin at enhancing cattle performance. The slight decreases in performance seen with yeast may be offset by premiums gained by being able to market calves as “natural”.