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The aim of the in vitro study was to determine the effect of corn dried distillers grains with solubles (corn DDGS), used as a replacement for the concentrate ingredients of sheep diet, on rumen fermentation. The material for the study was the ruminal fluid of Polish Merino sheep which was incubated during 4-, 8- or 24-hour periods. Five groups of samples were prepared for in vitro fermentation: C – control, incubated with the substrate consisting of the concentrate ingredients; D1, D2 and D3, where DDGS was used as a substrate added in proportions of 10, 20 and 30% of dry matter of the concentrate; and D4, where 100% DDGS was used as a substrate. After fermentation, the gas and short chain fatty acids (SCFAs) analyses were performed using gas chromatography. The ammonia concentration and pH were also determined, and the SCFA utilization index (NGR), the fermentation efficiency (FE) and the index of cell yield of ruminal microorganisms (CY) were calculated. This research showed no effect of DDGS on the methane emission. The positive correlations between the amount of methane and ammonia concentrations in the 8- and 24-hour fermentation periods were found. DDGS addition increased propionate proportion, but decreased production of acetate (p<0.01). Additionally, D1, D2, D3 and D4 substrates lowered isobutyrate (p<0.05) and isovalerate (p<0.01) production. Based on the results obtained, it can be stated that partial substitution of the concentrate ingredients with DDGS did not have deleterious effect on sheep rumen fermentation processes.
The aim of this study was an evaluation of the effects of two species of coagulase negative staphylococci (CNS), Staphylococcus xylosus and Staphylococcus warneri, on the changes in technological parameters of cows’ milk. The study was conducted in a herd of Slovak Pied cattle breed (with share of HF blood). Based on the performance results from three subsequent months, cows in the 2nd and 3rd lactation with SCC up to 200 thousand/ml (8 heads, 32 quarters), and above 800 thousand/ml (8 heads, 32 quarters), after the 4th month of lactation, were selected. The samples were subjected to microbiological analysis, total bacteria count, somatic cell count; basic milk composition and physicochemical properties were also examined. The research has found the impact of bacterial infection on the increasing (p<0.05) of the number of somatic cells and a decrease (p<0.01) in protein levels in milk due to both types of staphylococci. There was a significant (p<0.05) reduction in C8: 0, C10: 0 and the total amount of saturated fatty acids in the milk of the infected cows in comparison to the healthy ones. The research also revealed higher (p<0.01) levels of C14: 0 and C20: 1 in milk from the healthy cows.
An effect of mammary gland infection caused by Streptococcus uberis on the changes in cows’ milk composition and its physicochemical properties was examined. The study was conducted in the herd of Slovak Pied breed cattle (with a share of HF blood), in 2nd and 3rd lactation, after 4th month of milking. Milk samples were collected from a quarter milking. The samples were subjected to microbiological analysis, basic milk composition, total bacteria count, somatic cell count and physicochemical properties were examined. Also analyses of protein fractions share and fatty acids profile were conducted. An effect of bacterial infection of the mammary gland bring an increase (P<0.01) in somatic cell count was observed in this study. Milk samples contaminated with S. uberis were characterized by higher (P<0.05) total bacteria count and total protein compared to milk samples collected from non-infected mammary gland. The level of κ-casein was significantly (P<0.05) decreased in cows with subclinical mastitis caused by S. uberis. Significant (P<0.05) reduction in the share of C13:0 acid, and an increased level of C18:0, C18:1n7t and CLA were observed in milk contaminated with S. uberis compared to healthy cows’ milk. It should be concluded that S. uberis causes the increase in total bacteria count, SCC and the decrease in κ-casein level, which significantly affects deterioration of technological quality of cows’ milk.
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