Effect of Dietary Alpha-Amylase Enzyme Supplementation on Growth Performance, Eating Pattern and Carcass Quality in Crossbred Dairy Beef Bulls Fed High-Concentrate Diets

Abstract The aim of this study was to evaluate the effect of dietary alpha-amylase supplementation on growth performance and carcass quality in crossbred dairy beef bulls fed high-concentrate diets. Ninety-nine bulls (187 ± 2.6 kg of BW, and 146 ± 1.0 days of age) were grouped in 6 pens of 15 to 17 animals/pen and fed concentrate, straw, and water ad libitum. Pens were assigned to one of 2 treatments: 1) CTR (n = 51), no treatment; 2) RUM (n = 48), RumiStar600 CT concentrate inclusion (630 mg/kg DM, based on 600 kilo novo units (KNU) of alpha-amylase activity). After 168 days, using twelve 14-days periods to record daily concentrate intake per animal, daily water consumption per pen, and fortnightly BW per animal animals were transported to slaughterhouse within one month, the whole study lasted an average of 210 days. Also, on days 0, 42, 84 and 168 concentrate samples were collected for enzyme activity and nutrient content analyses. Carcass quality was recorded at the slaughterhouse. Data were analyzed using a mixed model. The BW was greater (P < 0.01; interaction treatment by time) in RUM than in CTR treatment from period 1 to period 12. Concentrate intake tended (P = 0.10) to be greater in RUM than in CTR treatment in periods 1, 9 and 10. Bulls from RUM treatment had a greater (P < 0.01) ADG and a better feed conversion ratio than CTR bulls in periods 8, 10 and 12. Water consumption was similar between treatments, and no health problems related to treatments were recorded. Treatment did not affect carcass conformation. Preslaughter BW (539 vs. 523 ± 6.4 kg, RUM vs. CTR, respectively; P = 0.01) and hot carcass weight (306 vs. 295 ± 4.1 kg, RUM vs. CTR, respectively; P < 0.01) were greater in RUM than in CTR bulls. Also, fatness grade tended (P = 0.08) to be greater in RUM than in CTR treatment (score 1: 8 vs. 25 %; score 2: 77 vs. 63 %; score 3: 15 vs. 12 %; RUM vs. CTR, respectively). In conclusion, dietary alpha-amylase supplementation (600 KNU of alpha-amylase activity/kg DM of concentrate) for at least 168 days improved growth performance and carcass quality in crossbred dairy beef bulls fed high-concentrate diets.