Zinc effect on milk somatic cell count in dairy cows

Abstract

Background: The cow's requirement of zinc must be provided in the diet. The contents vary between different feedstuffs, and can be negatively influenced by factors like soil type, harvest, storage conditions. Also vary due to stage of lactation and health status of cow. Therefore, extra supplementation of zinc is sometimes warranted. Adequate zinc intake is particularly important during the late dry period and the early stages of lactation in order to prevent diseases around parturition. The aim of this study was to measure the concentrations of zinc in blood samples taken from dairy cows in different state of lactation and comparing with somatic cell count in cows milk. Materials, Methods & Results: A total of 45 Holstain cows were divided on days of milking into 3 groups of 15 cows (group A, B and C). All cows were stabling with dry straw for bedding and with ad libitum access to potable water, and feed by total mixed ration. Blood samples were taken after the morning milking from the caudal vein by applying the principles of asepsis and antisepsis. Blood samples were taken in vacutainer tubes with added anticoagulant K3E in quantities of 0.072 mL. Milk samples were taken during morning milking. The whole milk samples were taken with milk meter for somatic cell count. When quarter milk samples were taken the teat ends were disinfected. After analyzing the results, blood mean zinc concentration was found to be lower in group B of cows. Group C had highest level of blood zinc concentration. The mean estimate blood zinc concentration in group A was 16.66 μmol/L, in group B was 8.26 μmol/L and in group C was 17.82 μmol/L. Mean value of milk somatic cell count in group A was 298.67/mL, in group B was 451.33/mL and in group C 492.67/mL. Discussion: Analyzing the results in this examination, it has been noticed that zinc concentration varied through all three groups of cow. Cows in group B have mean value of blood zinc concentration 8.26 μmol/L, and that results are match with several authors. Other authors, found that dairy cows around parturition have decrease in blood concentrations of vitamins A and E, and Zn. Physiological blood level of zinc in dairy cows is 7-13 μmol/L, and cows from group A and C have mean value 16.66 μmol/L and 17.82 μmol/L. The blood zinc level was adequate for dairy cows in these groups of cows in this study. Adequate zinc intake is particularly important during the late dry period and the early stages of lactation in order to prevent diseases around parturition. During involution and again towards the end of the dry period, risk for intramammary infection is at the highest level. Somatic cell count in milk is one of the best indicators of udder health status both in pathogenic and non-pathogenic cases. In this research, mean value of somatic cell count in group A was 298.67x103/mL, in group B was 451.33x103/mL and in group C 492.67x103/mL. It is known that cows in first 30 days of milking have high somatic cell count. According to that, cows in group C and A have adequate somatic cell count, and adequate value of blood zinc concentration. All this can indicate a good immune system and absence of intamammary infection and clinical mastitis. Analyzing statistical correlation test, it has been noticed negative correlation within blood zinc concentration and milk somatic cell count in all three groups of cows. That means increasing levels of zinc cause a decline number of milk somatic cell count.