An experiment was conducted to test the hypothesis that the supplementation of crude protein (CP) results in rumen acidosis and increased histamine concentrations in dairy cows. Six ruminally fistulated, non-pregnant dry cows were fed three experimental rations in a replicated 3 × 3 Latin square design. The CP contents in the low-CP, the high rumen undegradable protein (high-RUP) and the high rumen degradable protein (high-RDP) rations were 112, 259 and 266 g/kg dry matter (DM) respectively. The cows were fed 7.7 kg DM of the concentrates and 2.7 kg DM of rice straw. High levels of RDP in the ration significantly increased the ammonia, total volatile fatty acid (VFA) and histamine concentrations in the rumen fluid. However, supplemental CP, whether degradable or undegradable, did not significantly affect the pH of rumen fluid. Plasma urea nitrogen concentration was higher in both high-RDP and high-RUP in relation to cows fed the low-CP ration. The rise in ruminal histamine concentrations was physiologically non-relevant, most likely because rumen pH was not affected by supplemental CP at the installed level of DM intake. Therefore, it can be concluded that the issue of supplemental CP, rumen pH and ruminal histamine concentrations has not yet been settled. Further research is warranted to understand these relationships.

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The objective of this study was to investigate the milk protein profiles of normal milk and those of milk during the course of subclinical mastitis, caused by natural Streptococcus agalactiae infection. Two-dimensional gel electrophoresis and liquid chromatography mass spectrometry were used to assess protein profiles and to identify the proteins. The results showed that S. agalactiae subclinical mastitis altered the protein profiles of milk. Following Mascot database matching, 11 and 12 protein types were identified in the milk collected from healthy and S. agalactiae subclinical mastitic udders, respectively. The distinct presence of the antibacterial protein cathelicidin-1 was detected in infected milk samples, which in turn was highly correlated to the severity of subclinical mastitis as represented by the milk somatic cell count (r = 0.616), but not the bacterial count. The protein profile of milk reveals changes in the host response to S. agalactiae intramammary infection; cathelicidin-1 could therefore serve as a biomarker for the detection of subclinical mastitis in dairy cows.

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The investigation aimed to study the effect of vegetable oil sources on feed intake, nutrient digestibility and biohydrogenation bacterial population in Thai Friesian dairy cows. Three fistula Thai Friesian cows with mean body weight (BW) of 600±100 kg were assigned to receive three vegetable oil sources i.e. palm oil (PO), soybean oil (SBO) and sunflower oil (SFO) included at 4 %DM in commercial concentrate. All cows were fed on different diets that contained concentrate of 1 %BW and rice straw of 1 %BW according to a 3×3 latin square design (LSD). The results revealed that dry matter digestibility (DMD) and organic matter digestibility (OMD) tended to be higher in cows fed on SBO and SFO (P=0.06). Moreover, the DNA copy numbers (copies/ml) of biohydrogenation bacteria (Ruminococcus albus) and cellulolytic bacteria (Ruminococcus flavefaciens and Prevotella ruminicola) were higher in cows fed on SBO (P less than 0.05). In summary, supplementation of SBO in diet resulted in a higher nutrient digestibility and rumen biohydrogenation bacteria population.

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This study was conducted to investigate the effect of vegetable oil and yeast fermented cassava pulp (YFCP) supplementation on feed intake, nutrient digestibility and rumen fermentation in Thai Friesian dairy cows (Thai native x Holstein Friesian). Eight Thai Friesian dairy cows (447±44 kg.BW) were assigned to 4×4 double latin square design (DLSD) with two sources of oil i.e. palm oil (PO) or soybean oil (SBO) and four levels of YFCP (0, 5, 10 and 20%DM) in the dietary treatments. All cows received total mixed ration (TMR) comprised of rice straw to concentrate at a ratio of 40:60. The results showed that supplementation of SBO had lowered feed intake, nutrients digestibility, metabolize energy intake (MEI), total digestible nutrient (TDN) and methane emission than PO treatment. However, cows received SBO had greater total volatile fatty acid (TVFA), propionic acid (C3), butyric acid (C4) than cows received on PO (P less than 0.05). In addition, supplementation of YFCP at 10%DM in the diet as an optimum level in dairy cow diets (P greater than 0.05). Finally, the interaction between the addition of SBO and YFCP at 10%DM (SBO+YFCP) had a positive effect on enhancing ether extract intake (EEI) in dairy cows.

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