Influence of Energy-yielding Nutrients in Summer and Winter Feed Rations on the Levels of Non-esterified Fatty Acids in the Blood Plasma of Cows in Various Lactation Phases

Abstract

Lebeda M., Pfikrylova J.: Influence of Energy-yielding Nutrients in Summer and Winter Feed Rations on the Levels of Non-esterified Fatty Acids in the Blood Plasma of Cows in Various Lactation Phases. Acta vet. Bmo, 50, 1981: 179 -189. The NEFA concentration in the blood plasma of 552 cows held at large-scale production units was determined and the degree of requirement coverage of digestible nitrogen substances (DNS) and of energy (starch equivalent SE) and their ratio according to the Czechoslovak Standard CSN 46 7070 was found. Ten feed rations and 178 cows were included into the period of green food, 21 feed rations and 374 cows in the winter feeding period. The sets of 18 cows were divided into groups containing six animals each and were examined: 1. in the 1st-2nd month of lactation, 2. in the 4th-6th month of lactation and 3. in the 8th-9.5 month of pregnancy, in the dry period.The NEFA concentrations in the whole cow popUlation were found to be significantly (P < 0.01) higher if summer feed rations were used (0.165 mmol .1-1 ± ± 0.138) with a marked average surplus of DNS and SE when compared with winter feed rations (0.131 mmol .1-1 ± 0.153) with a mild average deficiency of DNS and small surplus of SE. The difference of summer and winter NEFA levels in the whole cow population is caused first of all by significantly (P < 0.001) higher NEFA values in cows in the first lactation phase (0.23 mmol . 1-1 ± 0.19 in summer; 0.145 mmol .1-1 ± 0.161 in winter) which have in average a slight DNS deficiency and higher SE deficiency in summer and higher deficit of DNS and SE within the level of the standard in winter. The NEFA concentrations of cows in the first lactation phase and of late-pregnant cows (0.168 mmol .1-1 ± 0.142 in summer; 0.145 mmol.I-1 ± 0.1428 in winter) were found to be both in summer and winter significantly (P < 0.001) higher than of those in the second lactation phase (0.086 mmol .1-1 ± 0.0767 in summer; 0.078 mmol .1-1 ± 0.0635 in winter).The NEFA concentration of cows in the first lactation phase and late-pregnant cows was found to differ significantly neither in summer nor in winter although there is a substantial difference in the coverage of energy nutrient requirement. The reasons of different NEFA concentrations in individual phases of a reproduction cycle from the point of view of found saturation of energy nutrient requirements and of the influence of other factors, the applicability of plasma NEFA determination as an indicator of adequacy of cow nutrition have been discussed.Cows, digestible nitrogen substances, starch equivalent, calorie-protein ratio, plasma NEFA, first and second lactation phases, late pregnancy.Non-esterified fatty acids (NEFA) present in blood plasma are loosely bound to albumin. They are released from this bond during oxidation or during the reserve deposition, the source of NEF A being the hydrolysis of triglycerides from food. This takes partly place in the intestine and to a greater extent in liver. Another source of NEFA is seen in the hydrolys...