Effects of Rumen Protected-Histidine Supplementation Dose on Finishing Beef Cattle.

This study examined the effect of dietary rumen-protected histidine (HIS) supplementation in cattle on growth and carcass traits/product quality. Three levels of daily HIS (Balchem corp.) were tested (control: D_O, low dose: D_L, and high dose: D_H) over a 55-d finishing period in 48 cross-bred steers implanted with Revalor®-XS. Cattle were randomly allocated into eight pens of six head each and fed twice daily using Calan gates. Morning feed was top-dressed with the HIS as follows; control (no HIS), D_L (50g/hd/d), or D_H (100g/hd/d). Individual intakes were recorded, and feed and orts were analyzed every 5 d during the feeding period. Steers were harvested, carcass data was recorded, and carcasses fabricated at a USDA inspected facility. One longissimus lumborum (LL) and one gluteus medius (GM) was acquired from each animal, aged under vacuum (21-d and 14-d respectively) and cut into 2.54 cm steaks. One steak was used for retail display for which subjective (to evaluate visual color components) and objective (l*, a*, and b*) color scores were recorded. Lipid oxidation on d 0 and 9 of retail display were assessed using TBARs. Another steak was used to evaluate cooking loss and tenderness using WBSF. Sensory taste panels were conducted (one panel for each muscle) to determine consumer perception of the product. Muscles were analyzed using HPLC for histidine metabolite (anserine, carnosine) and histidine content.

HIS supplementation increased ADG during d 1-21 (D_H P= 0.07), 42-60 (D_L & D_H P= 0.07), and the final 50 d (D_H P= 0.07) of feeding. Supplementation with HIS also increased the lightness (D_L GM: P= 0.05), degree of yellow hue (D_L & D_H LL: P= 0.01), oxygenated lean color (D_L GM: P= 0.004), uniformity (D_H GM: P= 0.03; D_H LL: P= 0.06) and overall color stability of the product from days 3-9 of retail display. The % surface discoloration (D_L & D_H GM: P=0.04; D_L & D_H LL: P<0.0001), degree of browning (D_L & D_H GM: P=0.002; D_L & D_H LL: P<0.0001), and discoloration (D_L & D_H GM: P= 0.01; D_H LL: P= 0.05) of the product was decreased. The D_L GM steaks were juicier (P= 0.07), more acceptable (P= 0.05), and more satisfying (P= 0.01) than control. Seventy-seven percent of panelists would purchase the D_L GM product (control: 61%, D_H: 60%). In conclusion, 55 d of RP-histidine treatment positively impacts consumer perception and may optimize product quality and marketability in beef cattle.