The concentration (<I>c</I>) of free fatty acids (FFAs) in milk is an indicator of dairy cow nutrition, milk straining, its bacterial contamination and storage quality. High FFA concentrations (<I>cs</I>) caused by lipolysis can damage the quality properties of milk products. Therefore the FFA content is introduced thanks to an increase in the efficiency of modern analytical methods as a milk quality indicator and as an indicator for its price as well. The goal of this paper was to analyse the FFA relations to the other milk quality indicators. The data set (<I>n</I> = 11 586) was evaluated by regression methods. In November and December the respective FFA means were 0.614 ± 0.458 and 0.835 ± 0.491 mmol/100 g with a relatively high variability of 74.6 and 58.8%. The frequency of unsatisfactory FFA values (> 1.3) was 7.51 and 13.93%. Casein content (<I>r</I> = –0.17; <I>P</I> < 0.01) and crude protein content (<I>r</I> = –0.12; <I>P</I> < 0.01) were related more closely with FFA <I>c</I>. The FFAs can increase by 0.066 mmol/100 g with casein decrease by 0.10%. The FFAs in milk fat can slightly increase by the supply of energy to dairy cows (protein and casein decrease) and rise with the deteriorating health state of mammary gland (lactose, <I>r</I> = –0.14; <I>P</I> < 0.01) as well. The somatic cell count correlated with FFAs more weakly (<I>r</I> = 0.07; <I>P</I> < 0.05), similarly like the total mesophilic bacteria count (<I>r</I> = 0.11; <I>P</I> < 0.01), relatively more closely the psychrotrophic bacteria count (<I>r</I> = 0.27; <I>P</I> < 0.05). The deterioration of almost all hygienic indicators signified an FFA c increase. The urea content correlated with FFAs weakly (<I>r</I> = –0.08; <I>P</I> < 0.05) and the fat content imperceptibly as a component of similar substance like FFAs. The mechanical milk stress led to FFA liberation from fat esters proportionally to the intervention intensity (<I>P</I> < 0.001). Even a relatively small mechanical stress caused by mixing comparable to the current milking technology, milk transport and storage increased the FFA c of milk fat from 1.11 ± 0.19 to 1.80 ± 0.40 mmol/100 g (<I>P</I> < 0.05). The highest experimental stress up to 6.88 ± 0.55 mmol/100 g (<I>P</I> < 0.001).
The milk yield (MY) is an important economic and health factor closely connected with the health status of dairy cows, their reproduction performance, longevity and milk composition and properties (MIs). The differences within MIs between high yielding herd (Group 1; 10 282 kg per lactation) and three herds with average MY (Group 2; 7 926 kg) were tested. The files with 96 and 290 milk samples were collected in summer and winter feeding seasons and well balanced in lactation factors. Group 1 had higher genetical value, better nutrition and was milked three times per day and its MY was higher by 30% (P < 0.001). among 23 milk indicators (MIs) under study only a few MIs (30.4%) were influenced (P < 0.05): somatic cell count (SCC); urea (U); acetone (aC); pH acidity; alcohol stability; curd firmness; the ratio of urea nitrogen in non-protein nitrogen (URn). Except for U, these changes were less important. Protein spectrum was not affected (P > 0.05). The U was probably higher due to higher loading of the nitrogen nutrition (4.27 > 3.57 mmol·l Dairy cow, Holstein cattle, milk yield, milk composition, milk properties, health status indicatorsIn dairy cattle, genetic improvement and well balanced nutrition are the main factors improving the milk yield (MY). Furthermore, feeding technology may help to fully exploit the genetic potential as evidenced in current Holstein (H) population. In general, a better use of these factors in dairy herds may enhance the lactation physiology and also the composition and milk properties of high yielding cows. The resistance degree to health disorders (e. g. mastitis) or stress may increase as well. These facts are interesting for milk producers, veterinarians and dairy operations because of impacts on farmer milk price, processing efficiency and product quality. Relevant changes are observed due to routine performance of milk recording in dairy herds. However, it is only possible for a limited number of milk indicators such as MY, fat, protein, lactose and urea contents and somatic cell counts. These are usually included in milk recording and dairy herd improvement programmes. Of course, interesting changes could be found in other milk components and properties as well. The genetic and nutritional improvements are in accordance with the basic equation phenotype = genotype + environment the main factors of cow MY increase. However, high MY is often a reason for breeder fears from its possible negative consequences. It could cause production health disorders as a result of impaired immunity decrease of cows including a shorter production age of dairy cows. Poor reproduction
Hanuš O., J. Frelich, L. Janů, A. Macek, I. Zajíčková, V. Genčurová, R. Jedelská: Impact of Different Milk Yields of Cows on Milk Quality in Bohemian Spotted Cattle. Acta Vet. Brno 2007, 76: 563-571.The milk yield (MY) is a significant economic and health factor. MY influences the health state of dairy cows, their reproduction performance, longevity and milk indicators (MIs). Differences within MIs between 2 higher (1; 8 348 kg per lactation; 240 individual milk samples) and 2 lower yielding herds (2; 7 344; 239) of Bohemian Spotted dairy cows (B) were tested. Sampling was carried out during summer and winter feeding seasons. Lactation factors were well balanced. Group 1 was on a higher genetical level, had better nutrition and higher MY by 13.7% (P < 0.001). All herds were milked twice a day. Twenty-three MIs were examined and 39.1% (9 of 23; 30.4% it was formerly in Holstein (H) with higher MY by 30%) were influenced (P < 0.05) by relatively smaller difference in MY: fat; log somatic cell count; urea (U); acetone (AC); alcohol stability; time for enzymatic coagulation; whey volume; ratio of urea nitrogen in nonprotein nitrogen (URN); fat/protein content ratio. It shows a higher susceptibility of B cows to the impact of higher MY on lactation physiology than H. Most changes were in more important MIs, usually with higher differences compared with H. The whole milk protein spectrum was not influenced (P > 0.05). The U was higher (5.707 > 4.365 mmol·l Dairy cow, Bohemian Spotted cattle, milk yield, milk composition, milk properties, health status indicatorsDecisions on many aspects of cattle keeping (breeding, feeding and milking technologies) are necessary for a good farmer strategy. Additional information about processing capacities or situation on the milk market are essential for competent decisions. These facts are of paramount importance for the milk yield (MY) and consequently its economic efficiency both under extensive and intensive production systems. High MY is preferred because of higher milk income. However, high MY is also under criticism because of the suspected negative impact on animal health, poor reproduction performance and propensity of cows to production disorders and reduced longevity. A poor reproduction performance and longevity were found under a long protein over-loading of dairy cows metabolism by nutrition to ensure high MY. This was connected with high urea concentrations in their body fluids (Piatkowski et al. 1981;Butler et al. 1996;Ropstad and Refsdal 1987; Říha and Hanuš 1999ab;Hanuš et al. 2001). Despite this fact, most breeding programmes focus on the genetical improvement (GI) of MY beside the desirable increase of milk components, particularly protein content. The average MY has increased by more than 40% in the Czech Republic during the last fifteen years. The MY efficiency depends on numerous external and internal factors. The question is, what MY level is still efficient? There is no general answer to this question. The MY is increased by GI in most dairy herds a...
Milk urea concentration (MUC) is a suitable indicator of the health and nutrition state of dairy cows. MUC is in relation to their reproduction performance, longevity and technological milk indicators. The interpretation correctness of results depends on their reliability. There are a lot of principles of MUC analyses. Their results can be affected by a number of interferential factors. Disproportions were noticed in practice. Therefore the sources of variation in results are studied. The goal of this study was to investigate relationships between different methods of MUC determination with the use of standard samples of native milk with an artificial urea addition. After evaluation I (n = 7) the results of methods BI-1 and BI-2 (photometrical ones with diacetylmonoxime) were disqualified because of poor recovery (R), poor correlation (C) with other methods, higher random error (RER) and highest systematic error (SE). Evaluation II is more effective with stricter discrimination limits. Cs of all methods mutually (0.977 up to 0.998; P < 0.001) confirmed the methods as effective with the exception of BI-2 with poor Cs (0.713 up to 0.774), poor R (16.0 up to 69.0%) and high RER ±5.292 mg/100 ml. R of better methods was 44.0 up to 96.7%. The BI-1 method had good Cs (0.986 up to 0.994; P < 0.001), higher SE -7.546 mg/100 ml and poorer R (48.5 up to 75.3%). BI-1 method was a case of mistaken performance. BI method could be improved by the use of more samples in calibration. FT-MIR method (infra-analysis) has good addition R 69.5 up to 95.0% and Cs 0.981 up to 0.994 (P < 0.001). EH method (photometrical one with Ehrlich's agent) has good R 59.0 up to 96.7%, higher SE 4.755 (I) and 2.556 (II) mg/100 ml and close Cs 0.977 up to 0.994 (P < 0.001). UR method (ureolytical difference-conductometric) showed the best combination of results about R, C, SE and RER. MUC measurement was almost independent of fat in milk (r = 0.16 for UR and 0.01 for FT-MIR; P > 0.05) and MUC of both the methods did not increase significantly with lactose increase (r = 0.16 and 0.27; P > 0.05), which increased logically (r = -0.88; P < 0.001) during the fat concentration increase. The relationship of MUC results between UR and FT-MIR was significant (validation r = 0.96; P < 0.001) at average difference -0.93 ± 1.663 mg/100 ml. It is possible to see the result reliability as good after calibration performance of FT-MIR according to results of UR. It is not necessary to see the effects of fat, protein and lactose on MUC methods as substantial. FT-MIR method for MUC has good result reliability at the use of native milk samples, incidentally with urea additions. It is suitable to calibrate the FT-MIR method according to specific determination of MUC (UR). However, the most important for elimination of disproportions is the calibration method with concrete audited R, though nonspecific.
HANUŠ, O., JANŮ, L., SCHUSTER, J., KUČERA, J., VYLETĚLOVÁ, M., GENČUROVÁ, V.: Exploratory analysis of dynamics of frequency distribution of raw cow milk quality indicators in the Czech Republic. Acta univ. agric. et silvic. Mendel. Brun., 2011, LIX, No. 1, pp. 83-100 A consistent link of the raw milk quality (RMQ) to the farmer price is essential. The aim was to analyse the properties of milk quality indicators (MQIs) and propose a new synthetic relative MQI (SQSM) from among various individual MQIs. SQSM could serve for consistent inclusion each quality change into the price. The paper was focused on exploratory analysis (normality (N) testing of fi les of MQIs). On the basis of the results, the MQIs were divided into two groups without and with necessity of original data transformation (TRN). Log and Box-Cox TRNs were tested in terms of possibilities of the fi les approach to the normal data frequency distribution (FD). The compositional MQIs deviated less and health and hygienic MQIs more from normal FD in original data (P < 0.05). The TRNs approached the data fi les to N very markedly in health and hygienic MQIs. The synthesis of various values of MQIs into SQSM was proposed. SQSM values were derived from model fi le of real data about MQIs and validated for use at farmer milk price modifi cations by the normality FD test. 33.3% of month SQSM fi les were normal (P > 0.05), the other were very close to the N with negligible deviations. The useability of the SQSM system for the balancing of raw milk purchase price premiums and penalties was tentatively confi rmed. dairy cow, raw milk, bulk sample, milk quality indicator, exploratory analyse, data frequency distributionThe raw milk quality (RMQ) is a crucial factor of the dairy food chain safety (Vyletělová et al
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