The University of Arizona

Effects of humic/fulvic acid (Bovigro) in beef cattle finishing diets on animal performance, ruminal ammonia and serum urea nitrogen concentration

C. P. McMurphy*, G. C. Duff, M. A. Harris, S. R. Sanders, N. K. Chirase, C. R. Bailey;
Department of Animal Sciences, The University of Arizona


The use of humates (humic acid/ fulvic acid) as a feed supplement is an increasing interest among scientists and the agricultural industry. Humates are naturally occurring substances that include various biologically active and inactive compounds. The humate supplement referred to is being produced by Mesa Verde Resources and marketed under the title of “Bovigro”. They have already used the supplement in other industries such as the pork, equine, and dairy industries. The humates have been more commonly utilized on monogastrics and in a few instances, ruminants. There is statistical significance showing that when including these humates in poultry diets there has been an increase in feed efficiency and a decrease in illness. The cattle industry is testing humates as a continuous search for a way to decrease input while increasing output. Texas A&M has already performed an experiment that utilized humates as a supplement in the diets of beef cattle. It was concluded that, as the percentage of humate administered was increased the amount of feed intake was decreased, while still increasing weight gain. The cattle industry is a brutally competitive industry that struggles with uncontrollable markets and environmental changes. Therefore, the objective is to decrease costs, and to accomplish this we must find a supplement that will improve conversion and find the optimum level at which to incorporate it. The “Bovigro”, in theory, should allow for the accomplishment of this objective while aiding in other marketing niches such as, the natural fed beef market. This all-natural supplement will enable feeders to increase efficiency while still being able to market their product as a naturally fed product. The humates are also thought to be ammonia binding, which would increase ammonia retention in the rumen. This binding process should increase the use of ammonia and better utilize ATP for microbial production.


This study was designed to investigate the effects of a humate supplement on rumen ammonia N, serum urea N and live performance in beef cattle finishing diets. Twenty-four English cross steers (beginning BW 432 kg ± 5) were stratified by weight, randomly assigned to individual pens and fed one of four diets, containing 0 (control), 0.5, 1.0 or 1.5% Bovigro (Advantage +), for 56 d. Control diets contained 33.3 mg/kg monensin. Steers were weighed at d 0, 28 and 56. Blood (jugular veni-puncture) samples and rumen (esophageal tube) samples were taken prior to feeding on d 0, and samples were collected prior to and 4 h after feeding on d 28 and 56. Rumen fluid pH was determined immediately, acidified with HCL and stored (-20° C) for subsequent rumen ammonia N (RAN) analysis. Venous blood was allowed to clot at room temperature and serum was harvested and stored (-20° C) for analysis of serum urea N (SUN). All performance, RAN and SUN concentration data were analyzed using mixed procedures of SAS. Results indicated that during the 56 d period there was no difference in DMI (P > 0.58), ADG (P > 0.24) or G:F (P > 0.28) between treatments. There were no two or three way interactions for SUN (P > 0.95), RAN (P > 0.87) or rumen pH (P > 0.15). There was a cubic response (P < 0.10) for RAN and SUN however, no biological significance could be determined. These results suggest that Bovigro does not affect DMI, ADG or G:F in finishing steers when compared to those fed monensin. The data also shows that serum and rumen nitrogen levels did not change 4 h after feeding, nor did the pH level change.

Current Research

In conjuction with this study, we are in the process of examining rumen fermentation in cattle administered humic acid. This experiment will determine the ammonia levels in the rumen, serum urea nitrogen levels and the volatile fatty acid (VFA) production differences between cattle fed rumensin or no ionophores and cattle fed humates (Bovigro). Six Holstein steers (average BW 700 lbs) purchased from Kennedy Farms are being used in this humic acid study. All steers were brought into the University of Arizona Feedlot, halter broke and fed a common ration until date of cannulation. The steers are housed in individual pens at the University of Arizona feedlot and fed accordingly. The procedure is a 5 X 5 + 1 Latin Square design where there are three treatments, a control and a negative control. Treatment one consists of 0.5 lb/head/day advantage+ Bovigro, treatment two consists of 1.0 lb/head/day advantage+ Bovigro, treatment three consists of 1.5 lb/head/day advantage+ Bovigro, the control consists of 30g/ton rumensin and the negative control contains no ionophores. These dosages are a baseline dose that has been determined by previous research and by scientists at Mesa Verde Resources. Composite feed samples, collected throughout the trial will also be analyzed for ash, Nitrogen, and acid detergent fiber. In addition, ingredient samples are obtained every 2 weeks for dry matter determination. The calves are being fed a treatment for 21 days and then rumen and serum samples are taken on the 22nd day starting at 0700 hours. Rumen and serum samples are taken at intervals for 24 hours; these intervals are hour 0,1,2,4,8,12,16,20 and 24. The rumen samples are brought back to the lab for ammonia concentration and VFA analysis, while the serum samples are analyzed for serum urea nitrogen. Also, on each collection day the bunks are swept clean and unconsumed feed is weighed and removed and its dry matter is calculated. This process is repeated until each of the six calves have been administered each treatment.

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