Further elucidating the effects of ruminal and hindgut acidosis on the ruminant animal

Linder, Haley Faith

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https://hdl.handle.net/2142/125502 Copy

Description

Title

Further elucidating the effects of ruminal and hindgut acidosis on the ruminant animal

Author(s)

Linder, Haley Faith

Issue Date

2024-05-23

Director of Research (if dissertation) or Advisor (if thesis)

McCann, Joshua C

Doctoral Committee Chair(s)

McCann, Joshua C

Committee Member(s)

• Shike, Daniel W
• Berger, Larry L
• Dilger, Anna C
• Loman, Brett R

Department of Study

Animal Sciences

Discipline

Animal Sciences

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

Rumen acidosis, hindgut acidosis, beef cattle

Abstract

The objective of the first study was to determine the impact of a bout of ruminal acidosis on rumen fermentation, rumen microbiome, and energy metabolism of cattle unadapted to a concentrate-based diet. Eleven ruminally cannulated steers (body weight = 352 kg ± 27) were blocked into 3 groups based on initial body weight. Prior to the start of the experiment, animals were consuming a forage-based diet. For the experiment, steers were moved into headbox style respiration chambers at the conclusion of a 24-h fast and subsequently received 1 of 2 treatment diets: control (CON), forage-based diet or acidosis (ACD), concentrate-based diet. Steers remained in the headboxes for 48 h. Gas concentrations from each headbox were collected hourly. Ruminal pH, fecal pH, VFA, and lactate were also measured during the treatment period. A treatment × day effect (P = 0.03) was observed for dry matter intake with intake being similar for both CON and ACD steers on d 1 but ACD steers consuming less on d 2. Treatment affected ruminal pH (P < 0.01) as CON steers had a greater ruminal pH than ACD steers. Greater total volatile fatty acid concentrations (P < 0.01) were observed for steers on ACD treatment compared with CON. A treatment × time interaction (P < 0.01) was observed for ruminal lactate concentration with ACD steers having greater concentrations from h 16 to 36. Respiratory quotient was not by affected by treatment, day, or their interaction (P ≥ 0.19). Digestible and metabolizable energy were greater (P = 0.02) on d 1 for ACD steers than CON. Control steers tended (P = 0.06) to have greater heat production than ACD. Heat production as a percentage of gross energy was greater (P = 0.03) for ACD steers than CON on d 2. Results from this study suggest that intake reduction following acidosis contribute to its energetic costs. In study 2, the objective was to determine the effects of induced acidosis in the late-finishing phase on rumen fermentation in feedlot steers. Eleven ruminally cannulated steers (body weight = 795 kg ± 54) were blocked into 2 groups based on initial body weight. For 195 d prior to the start of the study, cattle were consuming a basal finishing diet. Steers were randomly assigned to 1 of 2 treatments: control (CON), or induced acidosis (ACD). Both treatments were fasted for 24 h then fed the basal finishing diet. Steers on the ACD treatment received 0.05% of BW of wheat starch via rumen cannula at 0800 h and 2000 h on d 1 and ad libitum refeeding following the fast. On d 1 and 2, CON steers were provided 25% of allotted feed every 6 hours. Rumen fluid was collected every 4 h during the challenge period (h 0 – 48), and 0, 6, and 12 h after feeding during the recovery period (h 54 – 96). Rumen fluid was analyzed for pH, ammonia, VFA, and lactate. Fecal grab samples were collected every 8 h to determine fecal pH. A treatment × day interaction (P = 0.03) was observed for dry matter intake during the challenge period with steers on the ACD treatments consuming more on d 1 than CON steers. Intake was not different on d 2 (P = 0.88). A treatment × hour effect (P < 0.01) was observed for ruminal pH during the challenge period with the ACD steers having a lesser pH than CON from h 12 to 32. During the challenge period, a treatment × time interaction (P = 0.04) was observed for total VFA concentration with ACD steers having greater total VFA concentration from h 12 to 36. Rumen ammonia and lactate concentrations did not differ (P ≥ 0.25) between treatment or the interaction with time. Challenge and recovery period fecal pH were not affected (P ≥ 0.13) by treatment, time, or their interaction. Recovery period ruminal pH was not different (P = 0.99) between treatments. For the recovery period, total VFA and ammonia concentration were not affected by treatment, time, or their interaction (P ≥ 0.07). Ruminal pH and VFA were affected in the initial 48 h of induced acidosis in the late-finishing phase. The objective of the third study was to determine the effects of induced hindgut acidosis in sheep on cecal pH, ruminal fermentation, and gut permeability. Eleven ruminally and cecally cannulated ewes (49 ± 4 kg) were assigned to one of two treatments: control (CON; n = 5) or induced hindgut acidosis (HGA; n = 6). To induce hindgut acidosis, 3 g wheat starch/kg BW per 24 h was continuously infused via the cecal cannula for 4 d. Control ewes received a constant infusion of deionized water. Chromium EDTA was dosed once daily via the cecal cannula as a marker of gut permeability. Rumen, cecal, and fecal samples were collected to determine pH and VFA. Rumen fluid was collected on d 4 for an ex vivo fermentation to determine pH, VFA, ammonia and in vitro dry matter digestibility (IVDMD). On d 5, sucralose was infused through the cecal cannula and blood was collected from a mesenteric catheter under anesthesia. Transepithelial electrical resistance (TEER) was determined in ileum, cecum, and colon in Ussing chambers. There was a treatment × time effect (P = 0.05) for cecal pH with HGA ewes having lesser cecal pH after d 1. A treatment × time interaction was also observed (P < 0.01) for fecal pH and followed the same trend as cecal pH. Total fecal VFA concentration was greater (P < 0.01) in HGA ewes than CON. Rumen pH was not affected (P = 0.87) by the interaction of treatment × time but was affected (P < 0.01) by treatment as ewes on the HGA treatment had a lesser rumen pH than CON ewes. Control ewes had lesser ruminal VFA and ammonia concentrations than HGA ewes (P < 0.01). Despite this, the ex vivo fermentation did not indicate any differences in pH, VFA, or IVDMD (P ≥ 0.11). Urinary Cr recovery was not affected by the interaction of treatment × time, or treatment (P ≥ 0.13). There were no effects (P ≥ 0.22) of treatment, time, or their interaction on mesenteric plasma sucralose concentration. In cecal tissue, TEER tended (P = 0.09) to be lesser, indicating increase permeability in HGA ewes than CON ewes. In contrast, TEER was not different (P ≥ 0.83) in ileal or colonic tissues between treatments. A cecal infusion of starch induced hindgut acidosis and affected hindgut fermentation. The objective for study 4 was was to determine the effects of induced hindgut acidosis in sheep on rumen, cecal, and fecal microbiome, and mesenteric plasma metabolites. The same animals and treatments are previously described in Study 3 were utilized. On d 0, 2, and 4, immediately before feeding, and 12 h after feeding, rumen fluid, cecal contents, and fecal samples were collected for extraction of microbial DNA. On d 5, mesenteric plasma was collected for untargeted metabolomics. In cecal contents, observed amplicon sequence variants and Shannon index were decreased (P < 0.01) in HGA ewes compared with CON. Furthermore, HGA ewes had greater (P < 0.01) relative abundance of Bifidobacterium, Streptococcus, and Limosilactobacillus in cecal contents than CON ewes. In feces, alpha-diversity metrics were also decreased (P < 0.01) in HGA ewes compared with CON. Specifically, relative abundance of Bifidobacterium and Streptococcus were greater (P < 0.01) in HGA feces than CON. A treatment effect (P < 0.01) for relative abundance of Bacteroides, Akkermansia, and Treponema was observed with CON ewes having greater relative abundance than HGA ewes. In rumen fluid, alpha-diversity was not affected (P ≥ 0.43) by treatment. The relative abundance of 9 genera in the rumen were affected (P ≤ 0.05) by treatment with CON ewes having greater relative abundance than HGA ewes. A principle component analysis plot of mesenteric plasma metabolites did not discriminate CON and HGA ewes. However, 11 metabolites differed (P ≤ 0.05) between CON and HGA ewes. Induced hindgut acidosis drastically altered the microbiome composition of cecal contents and feces with minor effects observed in the rumen. Respective changes in hindgut microbial community composition impacted mesenteric plasma metabolites in ewes experiencing hindgut acidosis.

Graduation Semester

2024-08

Type of Resource

Thesis

Handle URL

https://hdl.handle.net/2142/125502

Copyright and License Information

Copyright 2024 Haley Linder

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