Location: Livestock Issues ResearchTitle: Immune and metabolic responses of beef heifers supplemented with Saccharomyces cerevisiae to a combined viral-bacterial respiratory disease challenge Author
|Word, Alyssa - Texas Tech University|
|Roberts, Shelby - West Texas A & M University|
|Richeson, John - West Texas A & M University|
|Liang, Yu - Texas Tech University|
|Holland, Ben - Cactus Feeders, Inc|
|Cravey, Matt - Phileo Lesaffre Animal Care|
|Corley, Jimmie - Phileo Lesaffre Animal Care|
|Ballou, Michael - Texas Tech University|
|Carroll, Jeffery - Jeff Carroll|
Submitted to: Translational Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/17/2018
Publication Date: 1/1/2019
Citation: Word, A.B., Broadway, P.R., Sanchez, N.C., Roberts, S.L., Richeson, J.T., Liang, Y.L., Holland, B.P., Cravey, M.D., Corley, J.R., Ballou, M.A., Carroll, J.A. 2019. Immune and metabolic responses of beef heifers supplemented with Saccharomyces cerevisiae to a combined viral-bacterial respiratory disease challenge. Translational Animal Science. 3:135-148.
Interpretive Summary: Utilization of feed additives to enhance growth performance and animal health are attracting interest from beef producers, especially with the current push to reduce antibiotic use in beef production. These products have been previously demonstrated to mitigate some of the negative impacts of an immune challenge. Bovine respiratory disease is the most prevalent immune challenge that occurs in feedlots in the U.S. today. Therefore, the objective of this study was to determine if supplementing the diet of feedlot heifers could reduce the severity of a bovine respiratory disease challenge. In this study 32 heifers were fed a typical feedlot diet; however, 16 heifers were supplemented with 2.5 g of a live yeast and 2.5 g of yeast cell wall daily for 31 days. Heifers were then challenged with a virus and bacteria known to cause respiratory disease. Following the challenge, blood samples were collected for 72 hours to measure physiological metabolites of interest to determine the effects of the yeast treatment on the challenge. Temperature was also measured every 5 minutes for the duration of the study via indwelling temperature recording devices. There was no difference in body temperature between treatments after the challenge or in white blood cells. Heifers in the yeast group had increased circulating glucose, but had decreased circulating components of protein breakdown. These data suggest that more energy was available in the yeast supplemented group that could be utilized for growth that is not being sucked up by the demands of the immune system. The yeast product also decreased fat breakdown in circulation further affirming the increased energy availability to the heifers who are supplemented. Nasal lesions caused by the viral infection tended to be less severe in yeast supplemented heifers. Finally, circulating neutrophils (a type of white blood cell) were increased in the yeast supplemented heifers which suggests not as many cells were needed outside of circulation to fight the infection. Overall, supplementing heifers with a combination live yeast and yeast cell wall may help mitigate some of the negative effects of respiratory disease in cattle. This research is vital to stakeholders in the arenas of beef production, animal health, as well as, feed additive companies. Supplementing cattle with low cost products with the capability to enhance growth performance while simultaneously improving animal health and well-being may be a viable way to replace some of the prophylactic pharmaceutical tools implemented in current production systems.
Technical Abstract: Two treatments were evaluated in finishing heifers to determine the effects of a yeast supplement on immune and metabolic responses to a combined viral-bacterial respiratory disease challenge. Thirty-two beef heifers (325 ± 44.4 kg BW) were selected out of a larger population previously assigned to one of two treatments: Control (CON), receiving no yeast supplement in the ration,or yeast (YEAST), CON diet plus a combination live yeast (2.5 g'hd-1'd-1) and yeast cell wall(2.5 g'hd-1'd-1) supplement (Lesaffre Feed Additives, Milwaukee, WI). Cattle were maintained on treatments for 31 d prior to the challenge. On d -3 all cattle were challenged intra-nasally with 1x108 plaque-forming units BHV-1, fitted with an indwelling vaginal temperature recording device, and allowed to rest in outdoor pens for 3 d. On d 0, all cattle were challenged intratracheally with an average dose of 3.0x107 CFU of Mannheimia haemolytica in 100 mL media, were fitted with an indwelling jugular catheter, and were moved into individual stanchions in an enclosed barn. Whole blood samples were collected at the time of BHV-1 challenge (-72 h) and 0, 2, 4, 6, 8, 12, 24, 36, 48, 60, and 72 h (complete blood cell counts) and at 0, 1, 2, 3, 4, 5, 6, 7,8, 12, 24, 36, 48, 60, and 72 h (serum isolation) relative to M. haemolytica challenge (0 h). Data were analyzed using the Mixed procedure of SAS specific for repeated measures with fixed effects of treatment, time, and their interaction. Vaginal temperature and cortisol concentration were similar between treatments (P = 0.39). Although total leukocyte count following BHV-1 challenge was similar between treatments (P = 0.21), there was a tendency (P = 0.07) for heifers in the CON group to have greater neutrophil counts than YEAST heifers. Serum haptoglobin concentration was not different between treatments (P = 0.13), but was numerically decreased in the YEAST treatment compared to CON. Heifers in the YEAST treatment had greater serum glucose concentration (P = 0.01) and decreased serum concentrations of urea nitrogen compared to CON (P = 0.03). Dietary treatment did not affect serum concentrations of NEFA (P = 0.37). Nasal lesion score severity tended (P = 0.07) to be decreased in YEAST compared to CON (3.19 vs. 2.5 ± 0.26). Feeding a combination live yeast and yeast cell wall product decreased some aspects of the acute phase response and improved metabolic outcomes in receiving heifers during a respiratory disease challenge.