Effect of a direct-fed microbial (10-G Armor) on feedlot performance, carcass characteristics, and prevalence of Salmonella in fed-beef heifers

Abstract

Crossbred beef heifers [N = 1,394; initial shrunk body weight (BW) 291 ± 9.9 kg] were used to investigate the efficacy of 10-G Armor (Life Products, Inc., Norfolk, NE; 10-G) upon feedlot performance, carcass characteristics, and fecal and subiliac lymph nodes Salmonella prevalence. Heifers were blocked by day of arrival and allocated to 1 of 20 pens (N = 70 heifers/pen) and assigned one of two treatments (10 pens/treatment) : no direct fed microbial (CON) or 2g/heifer/d of L. acidophilus, E. faecium, P. pentosaceus, L. brevis and L. plantarum respectively (Life Products, Inc., Norfolk, NE; 10-G). Twenty four animals were randomly selected from each pen for Salmonella sampling. Recto-anal mucosal swab samples (RAMS) were obtained at initial processing and harvest; subiliac lymph nodes were collected at harvest. In addition, pen surface fecal pats were collected and composited by pen (10 pats per composite, 5 composites per pen) on day 0, 52, 120 and 192. Data were analyzed as a generalized complete block design and pen served as the experimental unit. No differences were observed in live growth performance metrics (P ≥ 0.55). Yield grade distributions did not differ between treatments (P ≥ 0.62), however cattle fed 10-G tended (P = 0.06; 14.6 vs 18.9%) to have fewer USDA Select carcasses and more (P = 0.09; 73.6 vs 78.0%) USDA Choice carcasses. Cattle fed 10-G tended (P = 0.10; 9.2% vs 12.3%) to have fewer liver abscesses and had fewer (P = 0.04; 5.3 vs 8.5%) severe liver abscesses. Salmonella prevalence of RAMS did not differ between treatments at initial processing (P = 0.97; CON = 11.6%, 10-G = 11.5%) or at harvest (P = 0.91; CON = 99.0%, 10-G = 98.6%), however RAMS differed (P < 0.01) in Salmonella prevalence between the two collection times. Cattle fed 10-G had a lower frequency of Salmonella positive lymph nodes (P = 0.01; CON = 15.8%, 10-G = 7.4%) than CON. However, Salmonella log (mpn/g) of lymph nodes did not differ between treatments at harvest (P = 0.34; CON = 0.73, 10-G = 0.34). These data indicate that cattle fed 10-G have decreased rates of severe liver abscesses without altering live animal performance or carcass characteristics. Supplementation of 10-G significantly reduced prevalence rate of Salmonella recovered from the subiliac lymph nodes. The factors responsible for the observed difference in the effects of 10-G on Salmonella warrants further investigation

The effect of a direct-fed microbial (10-G) on live animal performance, carcass characteristics, and Salmonella prevalence of fed beef heifers

“…Initial BW ( Table 2 ) did not differ ( P = 0.89) between treatment groups (CON = 331.9 kg vs. 10-G = 331.6 kg) nor did final BW ( P = 0.64; CON = 570.4 kg, 10-G = 572.1 kg). Previous trials have also observed no difference in final BW ( Elam et al, 2003 ; Stephens et al, 2010 ; Neuhold et al, 2012 ; Luebbe et al, 2013 ; Cull et al, 2015 ; Wilson et al, 2016 ; Smock et al, 2020 ; Mayer et al, 2022 ; Ryan et al, 2023 ) when cattle were supplemented with bacterial ( Bacillus subtilis , E. faecium , L. acidophilus , L. brevis , L. plantarum , P. acidilacticii , and Propionibacterium freudenreichii ) or yeast ( Saccharomyces cerevisiae ) DFM during the finishing period. In contrast, Krehbiel et al (2003) in a review reported final BW was 4 to 7 kg heavier for cattle supplemented with varying concentrations of L. acidophilus (10 4 or 10 6 or 10 8 ) and Pr.…”

“…No difference was observed between treatments for average daily gain ( ADG ; P = 0.51; CON = 1.51 kg/d; 10-G = 1.53 kg/d), dry matter intake ( DMI ; P = 0.78; CON = 9.56 kg/d, 10-G = 9.58 kg/d), or gain-to-feed ratio ( G:F ; P = 0.71; CON = 0.159, 10-G = 0.159). Previous research has demonstrated that supplementing cattle with bacterial or yeast DFM did not alter DMI ( Elam et al, 2003 ; Stephens et al, 2010 ; Neuhold et al, 2012 ; Luebbe et al, 2013 ; Cull et al, 2015 ; Kenney et al, 2015 ; Wilson et al, 2016 ; Smock et al, 2020 ; Mayer et al, 2022 ; Ryan et al, 2023 ) even though it is perceived that feeding a DFM alters the gut microflora toward more efficient bacteria ( Krehbiel et al, 2003 ). Some studies have reported that DFM supplementation with L. acidophilus and Pr.…”

“…Some studies have reported that DFM supplementation with L. acidophilus and Pr. freudenreichii has improved ADG (+0.04 to 0.05 kg/d; Krehbiel et al, 2003 ) or G:F (+0.04 kg:1 kg; Cull et al 2015 ); however, most have reported no difference ( Elam et al, 2003 ; Stephens et al, 2010 ; Neuhold et al, 2012 ; Luebbe et al, 2013 ; Kenney et al, 2015 ; Wilson et al, 2016 ; Smock et al, 2020 ; Mayer et al, 2022 ; Ryan et al, 2023 ) in ADG or G:F following supplementation with bacterial ( B. subtilis , E. faecium , L. acidophilus , L. brevis , L. plantarum , P. acidilacticii , and Pr. freudenreichii ) or yeast ( Sac.…”

“…DFMs also have been reported to provide subtle growth performance benefits ( Krehbiel et al, 2003 ; Cull et al, 2015 ) making them potentially advantageous for feedyards. However, other trials have reported no growth performance advantage ( Elam et al, 2003 ; Stephens et al, 2010 ; Neuhold et al, 2012 ; Luebbe et al, 2013 ; Kenney et al, 2015 ; Wilson et al, 2016 ; Mayer et al, 2022 ), indicating inconsistent results from the feeding of DFMs. Thus, the objective of this study was to evaluate the effect of dietary inclusion of Lactobacillus acidophilus , Enterococcus faecium , P. pentosaceus , L. brevis , and L. plantarum upon feedlot growth performance, carcass outcomes, and Salmonella carriage of finished heifers.…”

“…With rising pressure to declare Salmonella as an adulterant ( USDA, 2023 ), preharvest interventions have been tested to reduce Salmonella prevalence and concentration. Direct-fed microbials ( DFMs ) are one such preharvest intervention that have been reported to reduce the prevalence of Salmonella by up to 13 percentage points in feces and up to 24 percentage points in lymph nodes when included in the fed cattle diet ( Stephens et al, 2007 ; Vipham et al, 2015 ; Mayer et al, 2022 ). DFMs also have been reported to provide subtle growth performance benefits ( Krehbiel et al, 2003 ; Cull et al, 2015 ) making them potentially advantageous for feedyards.…”