engleski

Effects of dietary clinoptilolite supplementation on udder health and chemical composition of milk in dairy cows over two consecutive years

Objectives. The aim of the present study was to investigate whether the supplementation of clinoptilolite (Vibrosorb®, Croatia) in the concentrate feed of dairy cows has an effect on udder health and chemical composition of milk in dairy cows over two consecutive years. Materials and methods. Forty-six clinically healthy Holstein-Frisian cows, aged between 3-5 years, were randomly assigned to one of two groups: control (n=23) and CPL-fed group (n=23). The CPL group received 50 g zeolite in the ratio for dairy cows, twice a day. Initial milk sampling was performed prior to adding CPL to feed. Additional sampling sessions were carried out on a monthly basis up to the 7th month of pregnancy, and next lactation starting from the first month of lactation and over the next 6 months. Milk samples were analysed for chemical composition (milk fat, proteins, lactose, solids non-fat dry and urea), somatic cell counts (SCC) and by bacteriological examination. The data were analysed using the program Stata 13.1 (Stata Corp., USA). The average values of milk components were compared by the Student t-test between two groups for each sampling point. In repeated samplings within the same group of cows, the values for a milk component were compared using the repeated ANOVA. Post hoc analysis of values was performed by the paired t-test. Results. The results showed that clinoptilolite supplementation had no adverse effects on the tested chemical composition of milk at any of sampling points. However, the chemical composition of milk was found to be more stable in CPL-fed cows, especially at next lactation. A statistically significant difference between single samplings in CPL-fed cows was found for milk fat and urea. The SCC in milk did not differ significantly between groups but was higher in the control group (412, 260 vs. 339, 980, respectively). Average milk fat, proteins, lactose, solids non-fat dry and urea were slightly higher in the control than in CLP-fed cows (4.38±0.77 vs. 4.02±0.56, 3.85±0.37 vs. 3.64±0.32, 4.38±0.16 v.s.4.37±0.14, 9.21±0.36 vs. 8.94±0.29, 21.66±7.00 vs. 20.90±5.11, respectively). The values recorded in the frequency of isolation of the mastitis causative agent differed significantly between groups (P=0.01). Cows from the control group had a four-fold higher and at next lactation had a seven-fold higher incidence of intramammary infections than CPL-fed cows. Conclusions. The observed differences in the content of a particular milk component and SCC between the groups of cows did not differ significantly at any of sampling points. The beneficial outcome of the study may be attributed to the antibacterial, immunostimulating, detoxifying and antioxidative effects of CPL on udder health.

ietary clinoptilolite ; udder health ; chemical composition of milk ; dairy cows

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