To address the gaps in current scientific knowledge, the objective of the present study was to investigate the impact of fumonisin exposure on feedlot cattle intake and performance. Fifty steers were received (day 0; 361 ± 6.4 kg), housed individually and fed once daily at 0800 hours. All steers were transitioned to a dry-rolled corn-based finishing diet from days 0 to 21 and then were fed the control finishing diet until day 50. Treatment diets were formulated to achieve ≤5 (CON), 15 (15PPM), 30 (30PPM), 60 (60PPM), or 90 ppm (90PPM) of total dietary fumonisin. Steers were fed the fumonisin treatment diets from day 50 until harvest on day 160; individual animal body weights (BW) were measured on days 0, 50, 100, 150, 159, and 160. Liver, kidney, and skeletal muscle tissue samples were collected at harvest for histopathological analyses, and liver samples were further analyzed for sphinganine (SA) and sphingosine (SO) concentration. Animal performance, carcass data, and liver enzyme concentration were analyzed using a mixed model; categorical data were analyzed via nonparametric models. Contrasts were used to test for linear and quadratic responses. Throughout the study, there was no effect of treatment (P > 0.60), or a linear response (P > 0.16) from increasing fumonisin levels, on BW or dry matter intake (DMI). However, CON tended to have a lower average daily gain (ADG) than the fumonisin treatments during the fumonisin treatment period (P = 0.10), and there was a positive linear response (P = 0.02) of ADG to fumonisin during the treatment period. There were no treatment differences in hot carcass weight, dressing percentage, marbling score, ribeye area, or yield grade. There were no effects of treatment on either liver abscesses (P = 0.95) or telangiectasis (P = 0.13). We observed a treatment difference for SA and SA:SO (P < 0.01), as well as a quadratic response (P < 0.02); both SA and SA:SO increased as dietary fumonisin increased. There were no observed differences between treatments for histopathology scores of kidney (P = 0.16), liver (P = 0.25), or skeletal muscle (P = 0.59) tissue. No adverse effects were observed in steers fed increasing dietary levels of fumonisin for 110 d prior to harvest. While elevated liver amino alcohol concentration did occur, negative effects on growth and carcass characters were not observed.
An alpha-amylase enzyme has the potential to increase starch digestibility, thus improving feedlot cattle performance and efficiency. The objective of this experiment was to evaluate the addition of an alpha-amylase enzyme on two steam-flaked bulk densities and subsequent performance of finishing beef steers. Forty-eight crossbred steers (325 ± 19 kg), were used in a complete randomized block design with a 2 × 2 factorial treatment design. Factors were corn processing and enzyme addition. Dietary treatments were steam-flaked corn-based diets with two bulk-flake density weights of corn (0.32 kg/L vs. 0.39 kg/L). Experimental treatments were 1) 0.32 kg/L with no enzyme (32NE), 2) 0.39 kg/L with no enzyme (39NE), 3) 0.32 kg/L with enzyme (32E), and 4) 0.39 kg/L with enzyme (39E) on a DM basis. The enzyme was applied at 0.50 kg/T of steam-flaked corn (As-fed basis). Data were analyzed using a mixed model with fixed effects of flake weight, enzyme, and flake weight × enzyme interaction. Throughout the feeding period, starch availability for 0.32 kg/L and 0.39 kg/L corn averaged 60.7% and 42.2%, respectively. Steers receiving the alpha-amylase enzyme had no differences in BW (P ≥ 0.62), ADG (P ≥ 0.55), and DMI (P ≥ 0.56) compared to NE steers. Furthermore, carcass characteristics did not differ (P ≥ 0.26) between E and NE steers. Feeding an alpha-amylase enzyme to finishing cattle had no detrimental effects on performance or carcass characteristics. Overall, a more highly processed corn was observed to decrease dry matter intake and increase the potential for digestive upsets. This may limit the use of the alpha-amylase enzyme to a lesser processed corn.
Crossbred beef heifers [n = 96; initial shrunk BW=238 kg (SD 21.5)] were used in a completely randomized design to evaluate climatic effects on feedlot heifer growth and efficiency. The study was conducted from November 8, 1991 to May 11, 1992. Heifers were assembled into groups at the Ruminant Nutrition Center (RNC) in Brookings, SD. One group (TX; n = 48) was shipped to New Deal, Texas and fed on slatted-concrete floors, and the second group (SD; n = 48), was shipped half-way to Texas, returned to the RNC, and fed on solid-concrete floors. Transit distance was 1,530 km. Pen was the experimental unit (6 to 8 head·pen-1); diets, health management, and implant programs were normalized across locations. The finishing diet was fed from d 33 to 185 at both locations and the energetics assessment was for the period from d 60 to 185. There were 18 d below -7.8°C and 102 d below 5°C in SD. Transit shrink, estimated empty body fat % (EBF), BW adjusted to 28% EBF (AFBW), and DMI did not differ (P ≥ 0.10). Heifer ADG was 18% greater (P < 0.05) in TX (1.40 vs. 1.16 ± 0.037 kg). Observed vs. predicted dietary energy differed (P ≤ 0.05), for NEm (0.97 vs. 0.87 ± 0.013) and NEg (0.97 vs. 0.84 ± 0.016) for TX and SD, respectively. Using calculated diet energy values based upon TX heifer performance as a reference, relative adjustments to metabolic rate were calculated. The estimated metabolic rate was elevated (P < 0.05) for SD heifers (0.077 vs. 0.101 ± 0.0031 Mcal/MBS). These results indicate that heifers fed in South Dakota had a 31% increase in metabolic rate when compared to heifers fed in the Texas panhandle. More of these types of assessments are needed to improve projection and tracking models used in precision cattle feeding.
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