Contrasting effect of high-starch and high-sugar diets on cattle

Francesio, Andrea (2020) Contrasting effect of high-starch and high-sugar diets on cattle. MVM(R) thesis, University of Glasgow.

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Subacute Ruminal Acidosis (SARA) is a metabolic pathology of high yielding dairy cows traditionally linked with daily bouts of low ruminal pH. Due to its mild clinical appearance, on field diagnosis of SARA is difficult and often the result of a “by exclusion” process. Several attempts have tried in the past to developed diagnostic sensor systems capable of correctly identifying the disease. Our trial investigated the systemic effect of two different sources of carbohydrates hypothesising that sugars and starches would have reflected differently on rumen milieu and, hence, on animal health. Secondly, we compared and discussed different statistical models and their effectiveness to detect acidotic disturbances. The last objective of the study was to explore the capability of a sensor developed to continually monitor reticuloruminal contraction, to diagnose SARA under experimental conditions. The study, designed as a 3 × 3 Latin square, lasted nine weeks and involved six adult cows. During the first two weeks of each experimental period cows were fed with a maintenance diet and in the last week of each experimental period animals were allocated to a control (CON), a high starch (HSt) and a high sugar diet (HSu). Reticular pH and motility were recorded throughout the study, blood and ruminal samples were taken the 1st, the 2nd and the last day of each challenge week. Cows’ health was monitored daily for diarrhoea, inappetence, depression and ruminal tympany. Blood parameters were analysed with linear mixed effects models (LME). pH data were analysed using three different models. In the first one, numbers of minutes for which pH < 5.6 and pH < 5.8, were obtained for each cow for each day and, in the second one, randomly chosen samples subsets were compared against the same thresholds. In the last approach, data points were used to generate a list of predicted values for each animal according to a generalised additive model. For each data point, the absolute value of the residual was used for the subsequent analysis. Motility readings were described according to their amplitude and period. Both challenge diets decreased the inter-contraction period and HSt diet only increased contraction amplitude. HSu diet was more likely to be not eaten and both the challenge diets were more likely to cause diarrhoea compared with CON diet. HSt diet increased plasma concentration of Serum Amyloid A (SAA) and neutrophils, affected several inflammatory markers and VFA concentration while CON and HSu diets resulted in less significant changes. All the models tested, indicated HSu diets reflected more severely on rumen pH and no model resulted in a better prediction of inflammatory response. In conclusion this study indicated that similar values in ruminal pH can reflect differently on clinical and subclinical health parameters, suggesting that ruminal pH is a suboptimal marker for rumen health.

Item Type: Thesis (MVM(R))
Qualification Level: Masters
Keywords: Haematology, inflammation, reticuloruminal acidosis, SARA.
Subjects: R Medicine > RB Pathology
R Medicine > RC Internal medicine
Colleges/Schools: College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine > Pathology Public Health & Disease Investigation
Supervisor's Name: Jonsson, Professor Nicholas and Viora, Doctor Lorenzo
Date of Award: 2020
Depositing User: Mr Andrea Francesio
Unique ID: glathesis:2020-81318
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 19 May 2020 08:37
Last Modified: 07 Sep 2022 13:09

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