The milk freezing point (MFP) is used for the control of milk food chain quality especially for possible adulteration with water. A crucial issue is the acceptance of the legislative discrimination limit (RLDL) of MFP for standard quality. The aim was to explain the relations between MFP and spectrum of milk indicators (MI) and possible impacts of MFP on technological milk properties. 76 bulk milk samples (BMS) from Holstein (1, <I>n</I> = 36) and Czech Fleckvieh (2, <I>n</I> = 40) cattle were analyzed for 48 MIs. The dairy cows were relatively healthy as for the occurrence of production disorders. BMSs were taken from February to June. Extraneous water was excluded. 44 MIs were correlated with the MFP. The relations were not regularly consistent between breeds. Milk yield was connected with MFP (<I>r</I> = 0.40; <I>P</I> < 0.05). It shows the necessity of modification of RLDL of MFP in dependence on dairy cow breeding. Further relations (<I>P</I> ≤ 0.05) were among MFP and: total milk solids (<I>r</I> = –0.50); solids-non-fat (–0.33); crude protein (–0.32); true protein (–0.43); whey protein (–0.47); milk fat (–0.46); electrical conductivity (–0.35); lactose (–0.35); somatic cell count (–0.36); fat/protein ratio (–0.36); milk citric acid (0.47); Na (–0.34). The poor relations (<I>P</I> > 0.05) were among MFP and casein, milk urea and acetone. The cheese-making indicators were not affected by MFP. The MFP was related to milk fermentation indicators (<I>r</I> = from –0.34 to –0.39, <I>P</I> < 0.05). It is important for the control of milk food chain quality by MFP and for the estimation of its RLDL.

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

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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...

The possible genetic impact of sire on cattle populations, herd milk yield and milk traits (fat and protein) have been described in the literature along with its impact on some milk indicators (MIs) as somatic cell count, urea and ketones. There is a dearth of information on the impact on a series of other MIs (physical, chemical, health, technological). The goal of this study was to assess the possible effect of sire on a wide range of MIs including technological properties in Czech Fleckvieh to suggest future possible breeding trends. A series of MIs (n=37) was investigated in individual milk samples (MSs). 191 effective daughters (MSs) were included. The sire groups (n=13) were well balanced in terms of herd, lactation stage and sampling season. Only sires with >5 daughters were ranked. A linear model of analysis variance with the fixed effects, sire and combined factor (herd × year × season) was used. 19 MIs as log count of streptococci in fermentation ability of milk (log FAM-CS), FAM-CS, log total fine microflora count in FAM (log FAM-TCM), FAM-TCM, solids non fat (SNF), iodine content, citric acid (CA), titration acidity in FAM, lactose (L), crude protein (CP), true protein (TP), casein (CAS), dry matter, Mg and P content, milk alcohol stability, electrical conductivity (EC), titration acidity, casein numbers (for CP and TP), log count of lactobacilli in FAM (log FAM-CL), FAM-CL and pH in FAM were influenced by sire (P<0.05). However SNF, CA, L, CAS and perhaps EC could be newly reflected as information for genetic improvement of dairy cattle with connection to dairy milk recovery and cow health. CA (10.08±1.92 mmol×l −1 ) deserves special attention. The model variablity explanation moved from 6.97 (SCC) over 29.51 (CA) to 48.32 % (pH) for MIs. This is one of few studies to assess the impact of sire over a wide range of MIs and the results warrant careful evaluation and further study.