THE EFFECT OF A DIRECT FED MICROBIAL (10-G) ON LIVE ANIMAL PERFORMANCE, CARCASS CHARACTERISTICS, SALMONELLA PREVALENCE OF FED BEEF HEIFERS

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2022-08-01T07:00:00.000Z

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Abstract

Salmonella is a major cause of food borne illness in the U.S. as this naturally occurring bacteria causing upwards of 1.35 million cases of foodborne illness annually. Cattle may harbor Salmonella in the gastrointestinal tract (GI) as well as in their lymph nodes and other areas of the animal body. This creates a challenge because lymph nodes are impervious to post-harvest pathogen interventions, thus leading to potential contamination in ground beef production. Direct-fed microbials are a possible pre-harvest intervention to reduce the burden of Salmonella. The objective of this study was to determine the efficacy of the direct-fed microbial 10-G upon cattle and carcass performance, as well as prevalence and enumeration of Salmonella in feces and lymph nodes. Fed beef heifers (n = 1,400; 343.3 ± 36.2 kg) were blocked by day of arrival and randomly allocated to one of two treatments (0 or 2g/animal/d; CON and 10-G, respectively) with ten pens per treatment. Pen served as the experimental unit. Cattle fed 10-G were provided 1 billion CFUs per animal per day of Lactobacillus acidophilus, Enterococcus faecium, Pediococcus pentosaceus, Lactobacillus brevis and Lactobacillus plantarum. Recto-anal mucosal swab samples (RAMS) and subiliac lymph nodes (SLN) were collected longitudinally at harvest from twenty-four heifers per pen (n = 476). Quantification of RAMS and SLN’s were completed via BAX® Salmonella PCR assay following the SalQuant™ approach. Data were analyzed using the GLIMMIX procedure of SAS; pen served as the experimental unit and block and harvest date were random effects. Heifers fed 10-G did not differ in dry matter intake (P = 0.78), final body weight (P = 0.52), average daily gain (P = 0.49), gain to feed (P = 0.74), hot carcass weight (P = 0.56), dressed carcass yield (P = 0.83), 12th rib fat depth (P = 0.23), ribeye area (P = 0.62), calculated empty body fat (P = 0.35), or marbling score (P = 0.83). Distributions of liver scores (P > 0.14), yield grade (P > 0.22), and quality grade (P > 0.15) were not different between treatments. We detected a tendency for fewer inflated lungs at harvest of cattle fed 10-G (P = 0.10; 10-G 0.2%, CON 1.0%); other lung outcomes did not differ (P > 0.12). Salmonella prevalence of RAMS samples did not differ (P = 0.76; 10-G 93.7%, CON 93.3%) nor did SLN (P = 0.12; 10-G 22.7%, CON 12.2%). Salmonella log of CFU/g of RAMS and SLN did not differ between treatments at harvest (P = 0.49; 10-G 3.78, CON 3.37; P = 0.12; 10-G 0.35, CON 0.08), respectively. These results do not demonstrate any improvement live animal performance, carcass characteristics or reduction in Salmonella for heifers fed 10-G.

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Animal Science

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