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The effect of breed and stage of lactation on the microbiological status of raw milk
37-45Views:340The microbiological quality of the milk is important not only for food safety, but it can also influence the quality of dairy products. The microbiological status of raw cow milk can be influenced by many factors. Our aim was to determine whether there was a difference between the microbiological quality of milk of two different cow breeds (Holstein Friesian and Jersey) kept and milked in the same conditions, and how the microbiological quality of the raw cow milk changed during lactation (beginning, mid, and end). Samples were taken and analysed in July, August and September in 2018 from two dairy farms in Hajdú-Bihar county. During the conducted studies, the total plate count (TPC), the coliform count, the Staphylococcus aureus count and the coagulase-negative Staphylococcus (CNS) count of raw milk samples were determined.
There was no significant difference (P>0.05) between the milk of the Holstein Friesian and Jersey breeds in the case of TPC. However, the mean coliform count of milk samples taken from Holstein Friesian cows was significantly lower (P<0.05) than the mean coliform count of milk samples taken from Jersey cows. S. aureus was detected in one of the twelve milk samples taken from Holstein Friesian cows, and in two of the eleven milk samples taken from Jersey cows. CNS was found in larger amount in milk samples taken from Holstein Friesian cows, and the difference was significant (P<0.05). Both TPC and CNS count were significantly higher (P<0.05) in individual milk samples taken at the end stage of lactation, than in samples taken in the earlier stages of lactation from Farm “A”. However, in the case of Farm “B”, there was no significant difference (P>0.05) in colony counts at different stages of lactation. S. aureus was only present in milk samples that collected from cows, which were at the beginning and middle stages of lactation. Testimg the hemolysin production ability of S. aureus strains isolated from the raw milk samples, only weak hemolysis was observed on blood agar. In case of antibiotic resistance testing, it was found that all strains were susceptible to cefoxitin, chloramphenicol, clindamycin, erythromycin, gentamicin, penicillin G, tetracycline and trimethoprim/sulphamethoxazole.
Based on the results of our studies, staphylococci were detected in a higher amount in the milk of Holstein Friesian cows, and coliform bacteria were detected in a higher number in the milk of Jersey cows. Summing up the results of the milk samples taken from the different stages of lactation in one of the farms, it can be concluded that higher TPC and CNS count could be detected at the end stage of lactation than in the samples taken from the earlier stages of lactation. The fact that at the end of lactation the microorganisms could be detected in a higher colony count may be related to the fact that teats could be damaged during lactation by the milking machine, which increased the chance of imvading the microorganisms into the udder.
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The variation of breast milk composition during the lactation stage for mothers from the Csík region
93-98Views:124The aim of our research was the examination of breast-milk composition from mothers living in the Csík region and to follow their milk composition variations during lactation. In this article we present the results obtained from three mothers, paying particular attention to essential components. The breast milk samples were collected from healthy mothers with similar habits and age. The milk samples were collected with a hand pump at the
same time after the feeding. The sampling period was from day 5 to the 14th weeks of lactation. The nutrition of mothers was recorded on a questionnaire, completed by the mothers themselves. Comparing our experimental results with data in the literature it was concluded that the milk protein content was very similar to the milk of mothers from other European countries, and is decreased during lactation.
The total saturated fatty acid content was lower, but the palmitic acid content was slightly higher. Regarding the essential fatty acid composition the linoleic- and the arachidonic acid contents were appropriate from a nutritional point of view. The linolenic acid was present in lower amounts, but the docosahexanoic acid was almost undetectable.
The iron and manganese contents were in good agreemen with published results, but the zinc content of the breast milk was lower and its copper content was higher. These differences in milk composition can be explained by the different nutritional habits of our subjects. -
Macro element contents of different genotype cows’ milk
27-31Views:179The level of mineral elements is important factor regarding the quality of milk. The aim of our research study was to determine the content of mineral elements in milk of Holstein, Jersey, Brown Swiss, Ayrshire, Norwegian-red, Swedish-red cows in the first stage of lactation. All cows were fed with the same type (composition) of feed and they were kept under the same condition. The concentration of macroelements (K, Na, Ca, P, Mg, S) in digested milk samples was determined by inductively coupled plasma optical emission spectrometry (ICP-OES).