Jeffrey Folmer

Effect of Lactobacillus acidophilus Strain NP51 on Escherichia coli O157:H7 Fecal Shedding and Finishing Performance in Beef Feedlot Cattle†

A 2-year study was conducted during the summer months (May to September) to test the effectiveness of feeding Lactobacillus acidophilus strain NP51 on the proportion of cattle shedding Escherichia coli O157:H7 in the feces and evaluate the effect of the treatment on finishing performance. Steers (n = 448) were assigned randomly to pens, and pens of cattle were assigned randomly to NP51 supplementation or no supplementation (control). NP51 products were mixed with water and applied as the feed was mixed daily in treatment-designated trucks at the rate of 10(9) CFU per steer. Fecal samples were collected (n = 3,360) from the rectum from each animal every 3 weeks, and E. coli O157:H7 was isolated by standard procedures, using selective enrichment, immunomagnetic separation, and PCR confirmation. The outcome variable was the recovery of E. coli O157:H7 from feces, and was modeled using logistic regression accounting for year, repeated measures of pens of cattle, and block. No significant differences were detected for gain, intakes, or feed efficiency of control or NP51-fed steers. The probability for cattle to shed E. coli O157:H7 varied significantly between 2002 and 2003 (P = 0.004). In 2002 and 2003, the probability for NP51-treated steers to shed E. coli O157:H7 over the test periods was 13 and 21%, respectively, compared with 21 and 28% among controls. Over the 2 years, NP51-treated steers were 35% less likely to shed E. coli O157: H7 than were steers in untreated pens (odds ratio = 0.58, P = 0.008). This study is consistent with previous reports that feeding NP51 is effective in reducing E. coli O157:H7 fecal shedding in feedlot cattle.

Sorting Strategies for Long Yearling Cattle Grown in an Extensive Forage Utilization Beef Production System1

One hundred sixty English-cross steers (244 kg, SD=23 kg) were used in each yr of a 2-yr study to determine effects of sorting on performance, carcass characteristics, variability, and profitability in a long yearling system utilizing ranch-source calves. Steers were backgrounded during winter then grazed smooth bromegrass pastures followed by warm season native range prior to entering the feedlot in the fall. Steers were stratified by BW and allotted to 1 of 4 treatments: 1) 40 head sorted by pre-grazing BW where heavy steers entered the feedlot in July

Evaluation of Revalor-IH and Revalor-IS as Initial Implants Compared with Traditional Initial Implants for Finishing Heifers and Steers

Two commercial feedlot experiments were conducted to compare performance and carcass characteristics of feedlot heifers and steers using 2 implant strategies. In Exp. 1, heifers (n = 1,124;

Effect of Intensive Winter Management, Partial Season Grazing, and Sorting on Performance and Economics of a Long Yearling Steer Production System1

A 2-yr study (200 steers/yr) was conducted to evaluate effects of grazing management and sorting by BW at feedlot entry on performance and economics of yearling steers. At receiving, steers (247 ± 21 kg) were randomly allotted to 1 of 2 treatments: low (0.75 kg/d, NORM) or high (0.90 kg/d, INT) gains during backgrounding. After wintering, NORM and INT grazed native range for 128 and 78 d, respectively. At feedlot entry, steers were randomly allotted to 1 of 2 treatments: sorted by BW (25% heavy, 50% medium, or 25% light; SORT) or unsorted (UNSORT). Heavy, medium, light, and UNSORT steers were fed for 78, 100, 115, and 92 d, respectively. At feedlot entry, NORM was 10 kg heavier than INT (P < 0.01); however, final BW was not different (P = 0.52). Compared with INT, NORM had increased (P < 0.01) marbling scores; however, NORM had smaller LM area (P < 0.01). At the end of the winter period (P < 0.01) and at harvest (P < 0.01), NORM was more profitable. However, INT was more profitable at the end of summer grazing (P < 0.01). Sorting increased final BW (P = 0.02) due to increased days fed (P < 0.01). Sorting reduced overweight carcasses by 8.1 percentage units (P < 0.01). Sorting produced no significant difference in profitability (P = 0.13). In this study, management of steers before feedlot entry affected subsequent performance and profitability. Additionally, SORT increased final BW and reduced overweight carcasses but did not change profitability.