THE EFFECT OF THE STRUCTURE OF THE PASTURE GROWTH ON THE SUBSTITUTION OF FATTY ACIDS IN THE MILK OF GRAZING DAIRY COW

Abstract

The milk fat is unique among animal kinds of fat, because of its high content of fatty acids with short and medium long strings. Milk industry should be able to produce milk and dairy products with raising part of unsaturated FAs, which is useful and desirable for consumer. The milk samples were withdrawal individually once a month from 20 dairy cows of Holstein breading. The milk fat was separated by extraction in petrol-eter and further on it was re- esterifasised and methyl ester fatty acids were analysed by the help of gas chromatography (GLC). In exception of the current fatty acids was monitored also the substitution of families of fatty acids, it means saturated (SAFA), mono-non-saturated (MUFA) and poly-non-saturated (PUFA) greasy acids. From pasture growth is assessed the percentage of nitrogen matters (NL) according to Kjeldahla, crude fibre (CF), acidodetergent fibre (ADF) and neutral- detergent fibre (NDF) on instrument called Ankom Technology. The content of nitrogen matters in the herbal growth decreases during the herdsmen season and at the same time the content of CF increases. The content of coarse fibre during the herdsmen season in herbal growth increases from 18,72 % in May to 28,54 % in July and afterwards again diminishes to 20,51 % in September. It was stated the significant differences in funds ADF between the begin and the end of the pasture period (PMilk performance during the pasture period showed decreasing tendency in daily vessel from 23,4 l/piece/day in July to 22,10 l/piece/day in September. The content of oil in milk (as well as content of CF in pasture growth) during the pasture increases, namely from 3,78 % in May to 3,82 % in September. During the pasture season was the average efficiency of a dairy cow per day 22,44 l and during pasture period 20,27 l milks. The average concentration of fat in milk was higher during the winter period, up to 4,11 %, compared with 3,78 % in month September

Keywords

• pasture dairy cows
• chemical constitution growth
• milk performance
• fatty acids