Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis (Jan 2005)
The effects of over sea height of locality on some chemical, health, microbiological, physical and technological parameters of cow milk and sensorical properties of cheeses
Abstract
In general, the over sea height is cumulative factor, which can influence significantly the farm conditions. This effect consists of temperature (mean year temperature), rain (sum of rainfulls), sunshine (total period of sunshine) and so on, in terms of climate, which can influence the dairy cow keeping directly and indirectly. Direct effects can influence the welfare of dairy cows in terms of hot stress for example, which could decrease a mastitis resistance of cows or their milk yield in simply way. Indirect effects can influence the dairy cows and their milk production (milk yield and milk composition and quality) by typical kinds of forages and preserved rough fodders, by their botany composition and nutritional quality. In general it is possible to say, that increasing over sea height decreases economical efficiency of dairying. On the other hand the higher over sea height is sometimes linked with pastoral system of dairy cow rearing and nourishment and more often with possibility to ecological and biodynamical agriculture application. In the fact, the mountain and submountain localities are named as less favourable areas (LFAs) in terms of agriculture efficiency and sustainability under the Czech Republic conditions. Despite of above mentioned facts, the pastoral system of dairying plays very important role for tourism development in different countries such as Alpine or Scandinavien countries, Ireland, The Netherlands or in particular in New Zealand.It could be very good to know the incidentaly possible impacts of over sea height of dairy cow rearing localities on milk quality, composition and its technological properties because of discussions about incidental dairy subsidies. Of course, in some countries including the Czech Republic, the governmental production subsidies or governmental environmental subsidies are partly linked with over sea height of localities of dairy farms, according to different calculation formulas as well.The individual milk samples, feedstuff samples (total mixed ration (TMR) on feeding trough) and mean excrement samples were collected at seven dairy cow herds and two main milked breeds of cattle (in the CR) for three years. Bulk milk samples were collected as well. It was done two times per year in winter (February, Marz) and summer (August, September) seasons. The herds were localised in lowland (N; ≤ 350 m of o.s.h.) and highland (P; > 350 m of o.s.h.) areas. The breed effect (H = Holstein and C = local Bohemian spotted cattle based on Simmental breed) was good balanced between N and P areas. The milk yields of herds varied from 5500 to 10000 kg of milk per lactation. The different but typical varieties of nourishment and feeding systems of dairy cows were applied in the herds: N = alfalfa silage with maize silage; P = clover-grass silage, grass silage with maize silage and grass pasture as well. The concentrates were feeded according to milk yield and nutrition demand standards.Investigated chemical-compositional, physical, health and technological parameters in individual milk samples were as follows: daily milk yield (ML; kg of milk per day); fat content (Tuk; g/100ml); lactose content (Lak; g/100g of monohydrate); solids non fat (STP; g/100g); somatic cell count (PSB; tis./ml); urea content (Mo; mg/100ml); acetone concentration (Ac; mg/l); acidity, concentration of H ions (pH); electrical conductivity (Vod; mS/cm); alcohol stability (Alk; consumption of 96% ethanol to milk protein coagulation point); titratable acidity (SH; ml NaOH solution 2,5 mmol/l); time for enzymatic coa- gulation (Čas; sec.); rennet curds firmnes (PEV; mm in contrary sense); subjective estimation of rennet curds quality (KV; from 1st = good to 4th = bad); volume of the whey at rennet precipitation (SYR; in ml); crude protein content (HB; Kjeldahl total N×6,38; g/100g); casein content (KAS; Kjeldahl casein N×6,38; g/100g); true protein (ČB; Kjeldahl protein N×6,38; g/100g); whey protein (SB; difference ČB-KAS; g/100g); non protein nitrogen matter (NNL; non protein nitrogen×6,38; HB-ČB; g/100g); ratio of urea nitrogen in non protein nitrogen (MNN; %); fat/crude protein ratio (T/HB); casein numbers as % ratio casein in crude protein and true protein (KAČ-HB and KAČ-ČB).Investigated hygienical and microbiological parameters in bulk milk samples, in preserved rough fodder (total mixed ration (TMR) on the feeding trough) samples and in mean excrement samples were as follows: milk - all parameters are expressed in CFU/ml; TRM = termoresistent microorganisms; SAG = Streptococcus agalactiae; SAU = Staphylococcus aureus; BCE = Bacillus cereus; BLI = Bacillus licheniformis; BAO = other bacilli; BAC = total bacilli (mostly aerobic termoresistent sporulated microorganisms); excrements – similar as milk TRM, BCE, BLI, BAO and BAC, results are expressed in CFU/ml solution, which was prepared by dilution of 1 g of material in 100 ml of distilling water; preserved rough fodders – the same parameters and conditions as at excrements. The hygienical parameters were chosen in consideration of hypothesis about possibility to affect milk hygiene and bacterial contents of excrements by the quality of feedstuff (forages or preserved forages – TMR on the feeding trough) sources and their microbial contamination.The 30 hard natural model cheese productions were processed from milk of four farms (two N and two P). These cheeses were fermented for 120 days and after that were evaluated for sensorical properties (taste and flavour; 1 = good, 5 = bad). The conditions for cheese processing were identical in all cases.The obtained values of some milk parameters (PSB, Ac and all microbiological data) were logarithmically transformed at their statistical evaluation because of their not normal frequency distribution.Differences between N and P areas are shown and tested in tab. I and II in terms of climate. The differences were mostly significant. Differences in milk composition, quality and properties, which were linked with areas are shown in tab. III. More significant effects were observed at milk technological properties such as Alk, Čas and PEV (P < 0,05, P < 0,01 and P < 0,05), where the advantages are at N area for Čas and PEV and at P area for Alk. Significant effects were observed at nitrogen phase of milk (NNL and MNN: P < 0,001 and P < 0,05) as well. These last mentioned are without practical importace.TRM and BAC (BCE) microbiological parameters can be linked beside hygienic practice of milking also with preserved rough fodder quality, which could depend on climate and over sea height conditions. Despite of this hypothesis, all investigated differences between N and P areas within bulk milk, feedstuffs and excrements were statistically no significant (P > 0,05; tab. IV). It is possible to produce the preserved rough fodders at very good level of quality in less favourable areas with today preservation technologies as well, without dependence on over sea height.The cheese sensorical quality (tab. V) was a little better in P area with higher variability (37,8% in comparison to 30,5% in N area). It is probably possible to explain by positive effects of feeding of grass silages with higher dry matter contents and with excellent nutrition digestibility and utilisation of nutrients (including effects of their botany species composition and their aromatic compounds and beta-carrotens), which were produced from young grass regularly under excellent fermentation conditions at one of investigated P farms (tab. V; n. 1). Of course, this above mentioned effect was statistically no significant in terms of N and P areas (P > 0,05), because of smaller difference and higher variability of quality parameter in P area, which were 0,07 and 37,8%. It was probably caused by different bacterial contamination still after milk pasteurization (thermoresistent bacteria). The long period differences within sensorical cheese quality between individual farms were mostly also statistically no significant (P > 0,05). Only in one case the difference was statistically significant (P < 0,02), just within P area. Under specific conditions there could be an advantage at cheesemaking.The mentioned results supported the necessity to keep the primary milk production in highland less favourable areas beside lowland areas, because of good balanced structure of agriculture in the country as well.
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