Hops Βeta-Acid Extract Yields Feedlot Performance Similar to Rumensin

Hops (Humulus lupulus) have played an integral role in beer manufacturing and are widely known for their antimicrobial and preservative properties. α-acids of hops are extracted and utilized to enhance beer flavor, leaving residues largely composed of β-acids. Beta-acid extracts of hops are structurally similar to ionophores and may express ionophore-like traits. Ionophores, including Rumensin (Elanco Animal Health, Greenfield, IN), are used to improve feed efficiency and to decrease the incidence of digestive disturbances in feedlot cattle. A large portion of in vitro studies show benefits from feeding hops or hop acids with results similar to ionophores; however, live animal experiments are needed to confirm these observations. The objectives of this study were to assess the effects of β-acid extracts of hops on feedlot performance in cattle fed high-concentrate diets and determine a response to varied doses of β-acid extracts of hops.


Introduction
Hops (Humulus lupulus) have played an integral role in beer manufacturing and are widely known for their antimicrobial and preservative properties.Alpha-acids of hops are extracted and utilized to enhance beer flavor, leaving residues largely composed of β-acids.Beta-acid extracts of hops are structurally similar to ionophores and may express ionophore-like traits.Ionophores, including Rumensin (Elanco Animal Health, Greenfield, IN), are used to improve feed efficiency and to decrease the incidence of digestive disturbances in feedlot cattle.A large portion of in vitro studies show benefits from feeding hops or hop acids with results similar to ionophores; however, live animal experiments are needed to confirm these observations.The objectives of this study were to assess the effects of β-acid extracts of hops on feedlot performance in cattle fed highconcentrate diets and determine a response to varied doses of β-acid extracts of hops.

Experimental Procedures
Yearling crossbred heifers (n = 80; initial body weight 855 lb) were randomly allotted to five treatments consisting of a control (no additive); Rumensin fed at 33 ppm of diet dry matter; and β-acid extracts of hops fed at 10, 25, or 50 ppm of diet dry matter.Heifers were housed individually in partially covered concrete pens equipped with individual feed bunks and fed a basal diet presented in Table 1.Feed additives (Rumensin or β-acid beadlet) were preblended into a carrier consisting of finely ground corn and mixed daily prior to feeding.The negative control premix consisted of ground corn only.Heifers were weighed after 23 days on feed, and subsequent weights were captured in 21-day intervals.Average daily gain, dry matter intake, and feed efficiency were determined for each period.Ruminal digesta samples (4 to 8 ml) were collected via rumenocentesis on days 44 and 86 to analyze ruminal concentrations of volatile fatty acids and ammonia.

Results and Discussion
One heifer was removed from the study due to lameness.Live performance parameters such as average daily gain (Figure 1), dry matter intake (Figure 2), and feed efficiency (Figure 3) did not differ among treatments (P = 0.31; P = 0.85; P = 0.26, respectively).When comparing two separate sampling days, no significant differences were observed between treatments for any ruminal volatile fatty acid acetate:propionate or ammonia concentrations (P = 0.67; P = 0.30; P = 0.91, respectively; Figures 4 and 5).This study consisted of a small population size, which may warrant further investigation of in vivo studies with larger population sizes to further elucidate response and mode of action of β-acid extracts of hops in ruminant diets.

Implications
Hops β-acid extract showed feedlot performance similar to Rumensin and could be fed as an alternative to this ionophore.The control diet contained no additive, Rumensin provided 33 ppm Rumensin in the final diet (dry matter), Beta10 provided 10 ppm β-acid in the final diet (dry matter), Beta25 provided 25 ppm β-acid in the final diet (dry matter), and Beta50 provided 50 ppm β-acid in the final diet (dry matter).The control diet contained no additive, Rumensin provided 33 ppm Rumensin in the final diet (dry matter), Beta10 provided 10 ppm β-acid in the final diet (dry matter), Beta25 provided 25 ppm β-acid in the final diet (dry matter), and Beta50 provided 50 ppm β-acid in the final diet (dry matter).

Table 1
1 Diets including feed additives(Rumensin, Elanco Animal Health, Greenfield, IN)or (β-acid beadlet, DSM Nutrition Products, Village-Neuf, France) were blended into ground corn and are included in the percentage.The final diet (dry matter) provided either no additive, 33 ppm Rumensin, or 10, 20, or 50 ppm β-acid.The negative control consisted of ground corn only.Optaflexx (Elanco Animal Health, Greenfield, IN) was combined with a ground corn carrier and fed at a rate of 40 ppm throughout days 118-147. 2 Formulated to provide at least 14% crude protein, 1000 IU/lb vitamin A,