PSLBI-5 Ruminal papillae morphology of beef on dairy heifers with abscessed or non-abscessed livers

Abstract The ruminal papillae morphology characteristics of feedlot beef on dairy non-spayed heifers with liver abscess to those with non-abscessed liver were evaluated. Heifers were sourced from 27 lots which were harvested on six dates between November 2022 and February 2023. Upon harvest, a total of 94 rumen tissue samples from animals presenting liver abscesses and 110 rumen tissue samples from animals with non-abscessed livers were collected in pairs, as abscesses were identified within the harvesting facility viscera inspection line, following a randomized complete block design (block = lot within harvest date). Individual fragments (6 cm2) from the cranial sac epithelium of the rumen were collected, rinsed with deionized water, immersed in 70% alcohol, and preserved under refrigeration (4 oC) until analysis. Ruminal tissues were trimmed (1 cm2), in which the number of papillae was counted by three trained personnel, followed by the removal of 12 representative papillae specimens for further area electronic scanning (The University of Texas Health Science Center of San Antonio, Image Tool) to determine average papillae area, number per cm2 (AVP), average papillae area in cm2 (APA), absorptive surface area in cm2/fragment cm2 (ASA), and papillae absorptive surface area, % (ASA). Data were analyzed using the GLIMMIX procedures of SAS, with individual animal ruminal tissue used as the experimental unit, the fixed effect of ruminal condition, and the random effect of lot within the harvesting date. Average papillae number (P = 0.27), average papillae area (P = 0.74), absorptive surface area (P = 0.48), and papillae absorptive surface area (P = 0.43) were not affected by the presence of liver abscess. Severity of liver abscess distinguished as A -, A, or A+ scores compared with non-abscessed liver showed no difference on papillae number (P = 0.34), papillae area (P = 0.89), and absorptive area (P = 0.62). The presence of small or large liver abscesses did not affect the papillae area, size, or absorptive area (P ≥ 0.41). The liver lobe location of abscesses (cranial, caudal, both) did not affect (P ≥ 0.17) any of the ruminal morphological variables measured. The presence of liver abscesses, whether diffuse or localized, in beef on dairy heifers, did not affect (P ≥ 0.58) the development of ruminal papillae. The presence, severity, or location of liver abscess was not connected with ruminal papillae number, area, or absorptive surface area of beef on dairy heifers measured upon harvest time. The absence of ruminal papillae morphological changes in animals committed with liver abscesses may be further investigated with the characterization of potential cellular physical changes of the ruminal tissue and the integrity of the primary barrier in the digestive tract.