Abstract
The objective of the thesis was to investigate the effect of the addition of a natural zeolite, clinoptilolite, in cattle rations, on the prevention of subacute ruminal acidosis. In total 10 Holstein cows were used, which were in the dry period and not pregnant. The animals were examined before the start of the experiment and based on clinical examination and the results of biochemical, haematological and fecal examinations were found healthy. After the creation of a permanent external fistula of the rumen by placing a hose in the dorsal sac, the animals were given a diet that met their maintenance needs and consisted of 3 kg of alfalfa hay, 3 kg of wheat straw and 2,5 kg of a compound feed for 21 days. Following the adaptation period, the cows were divided in two uniform groups based on age and body weight (BW). A day prior to the start of Part I of the experiment, 5 and 17 hours after feeding two blood samples were taken from the jugular vein of each animal, one in a tube without an ...
The objective of the thesis was to investigate the effect of the addition of a natural zeolite, clinoptilolite, in cattle rations, on the prevention of subacute ruminal acidosis. In total 10 Holstein cows were used, which were in the dry period and not pregnant. The animals were examined before the start of the experiment and based on clinical examination and the results of biochemical, haematological and fecal examinations were found healthy. After the creation of a permanent external fistula of the rumen by placing a hose in the dorsal sac, the animals were given a diet that met their maintenance needs and consisted of 3 kg of alfalfa hay, 3 kg of wheat straw and 2,5 kg of a compound feed for 21 days. Following the adaptation period, the cows were divided in two uniform groups based on age and body weight (BW). A day prior to the start of Part I of the experiment, 5 and 17 hours after feeding two blood samples were taken from the jugular vein of each animal, one in a tube without anticoagulant and one with anticoagulant (K3-EDTA). At the same time, using the vacuum pump through the fistula of the rumen, stomach contents were collected and pH was measured using a portable pH-meter.In blood serum, levels of beta-hydroxybutyric acid, acetoacetic acid and glucose were determined, while hematocrit, haemoglobin, white blood cell count and percentage of lymphocytes and neutrophil granulocytes were estimated in whole blood.Total concentration of volatile fatty acids (VFA) and molar percentage of acetic acid, propionic acid, butyric acid, valeric acid and isofatty acids were estimated in the liquid contents of the rumen. Part I of the experiment lasted 5 days and included the implementation of the nutritional protocol by Krause and Oetzel in both groups of animals.The experimental group was given 200g of clinoptilolite per animal daily. The samples of blood and stomach contents were taken twice daily, 5 and 17 hours after feeding. Fifteen days after the end of the experiment the same process was repeated after reversing the groups.Part II of the experiment began 15 days after the completion of Part I and lasted 90 days. On day 0 the cows were weighed and blood samples as well as stomach contents were collected. On day 1 50% of the total quantity of feed was offered, while from the 2nd day until the end of the experiment the animals consumed the ration offered at Part I of the experiment plus 1,7 kg of a pelleted wheat and barley mixture. Animals of the experimental group were also given 200g clinoptilolite per cow daily. The samples of blood and fluid content of the rumen were collected every three days, 5 hours after feeding, while daily clinical examination was conducted and feed intake was ensured in all animals, simultaneously with possible diarrhoea grading. The clinoptiloforic material used contained 92% clinoptilolite and its cation exchange capacity was 220 mEq/100g. As the experiment was carried out it was ascertained that feed intake was unaffected by the addition of clinoptilolite in the mixture of concentrate feed.As shown by the results of experiments, both the dietary protocol by Krause and Oetzel applied in Part I and the protocol followed in Part II, led to clear signs of subacute rumen acidosis in animals not receiving clinoptilolite. Thus, the control group showed a significant decrease of pH of the liquid contents of the rumen, an increase of the total concentration of VFA and significant variations in the percentage of the three major VFA: The percentage of acetic acid decreased significantly and that of butyric acid increased; propionic acid percentage increase was inconsistent. In the experimental group the feeding of clinoptilolite prevented the decrease in the pH of stomach contents, acting as a regulatory agent and the total concentration of VFAs and their percentage ratio did not change significantly. The increased levels of hematocrit and hemoglobin in the control group were a consequence of dehydration, which follows subacute ruminal acidosis. The elevation of beta-HBA and AcAc concentrations was attributed to an increased concentration of butyric acid. The increase in white blood cell count and neutrophil granulocytes was a result of the inflammation of the rumen, due to the elevated concentration of acids. On the contrary, no significant changes in hematological parameters were noted in the experimental group. After the completion of the experiment a significant reduction in the BW of the control group was evident, as opposed to the experimental group. Lesions such as mild to moderate subacute inflammation, mild to moderate thickening of the mucosa and abnormal keratinization of the stratum corneum that are common findings of subacute ruminal acidosis were observed in the control group. The absence of such lesions from the experimental group was attributed to the regulatory effect of clinoptilolite in the pH of stomach content and in the production of VFAs.
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