AHEAD IN ANIMAL HEALTH
Reference intervals for concentrations of trace elements in serum of dry cows S. van der Drift1, R. Grotentraast1, S. Carp – Van Dijken1, J. Muskens1 and G. Counotte1 1 Royal GD, PO Box 9, 7400 AA Deventer, The Netherlands
Aims of the study • Investigate (variation in) serum concentrations of copper, zinc, selenium, and iodine in dry cows • Assess dry cow reference intervals for trace element concentrations in serum. Background 30,0
A
1,8
B
25,0
1,6 1,4
20,0
10,0
Zinc (µmol/L)
15,0
1,2 1,0 0,8 0,6 0,4
5,0
0,2
0,0 -60
-50
-40
-30
-20
-10
0,0
0
-60
Days to calving
Materials and Methods
Iodine (µmol/L)
• Trace elements are required by all animals in minute amounts and play essential roles in the body, usually as part of functional organic molecules such as enzymes. • Serum concentrations of trace elements in cows are used in the field to monitor (short term) uptake of these elements from the ration. • Reference intervals and cut-off values are, however, usually based on serum results from lactating cows and specific dry cow reference values are often lacking.
-50
-40
-30
-20
-10
0
Days to calving
1,6
25
Copper (µmol/L)
Selenium (µmol/L)
• From September 2014 to April 2015, serum samples of 625 C D 1,4 dry cows from 40 Dutch dairy herds were collected during 20 1,2 two farm visits (three-month interval). 1,0 15 • At each farm visit, all dry cows present were sampled. The 0,8 number of cows sampled per farm ranged from 2 to 32. 10 0,6 • Samples were analysed for copper, zinc, selenium 0,4 5 and iodine using inductively coupled plasma mass 0,2 spectrometry (ICP-MS). Only samples of cows with 0,0 0 -60 -50 -40 -30 -20 -10 0 complete data records were analysed. -60 -50 -40 -30 -20 -10 0 Days before calving Days to calving • Descriptive statistics were performed on serum results (n=535) using Statistix. Linear regression was used to Figure 1 Concentrations of zinc (A), iodine (B), copper (C), and selenium (D) in serum (µmol/L) of 535 dry cows from 60 to 0 days to indicate time trends in trace element concentrations parturition from 40 Dutch dairy herds (including linear trend lines). towards parturition. Reference intervals for concentrations of trace elements for dry cows were calculated using the Reference Value Advisor (Geffre et al., 2011). Table 1 Descriptive statistics for concentrations of zinc, copper, selenium and iodine in serum of 535 dry cows from 60 to 0 days to parturition from 40 Dutch dairy herds and corresponding reference intervals for the dry period.
Results
• Descriptive statistics are shown in Table 1. Trace mineral Mean (± SD) Median Min - Max 25th – 75th perc. • Zinc, iodine, copper en selenium concentrations are (µmol/L) plotted against day relative to calving in Figure 1. Zinc 14 (± 2.8) 14 3 – 28 12 – 16 • Serum zinc concentrations were significantly lower in cows Iodine 0.5 (± 0.20) 0.5 0.2 – 1.7 0.4 – 0.7 Copper 11 (± 2.4) 11 3 – 21 10 – 13 with fewer days towards partition (P<0.05); no such trend Selenium 0.7 (± 0.18) 0.7 0.2 – 1.4 0.6 – 0.8 was present for the other elements (P>0.05). • Iodine concentrations were often low in dry cows (22% of Calculated with Reference Value Advisor (Geffre et al., 2011) cows had a serum concentration below the commonly used cut-off value of <0.4 µmol/L). Conclusions • Serum copper concentrations were also low, but this may • Considerable variation exists in serum concentrations of trace elements in dry cows. be due to loss of copper-containing proteins during the clotting process of the sample (Laven and Livesey, 2006), • The iodine status of dry cows may need extra attention to optimize cow health and calf vitality. • Reference intervals for dry cows were calculated. which limits the diagnostic value.
Reference interval1 9 - 20 0.3 – 1.1 8 - 17 0.3 – 1.0
1
References • Geffre, A., Concordet, D., Braun, J.P., Trumel, C. 2011. Reference Value Advisor: a new freeware set of macroinstructions to calculate reference intervals with Microsoft Excel. Vet. Clin. Pathol. 40(1): 107–112. • Laven, R.A., Livesey, C.T. 2006. An evaluation of the effect of clotting and processing on the recovery of copper from bovine blood. Veterinary Journal 171(2), 295–300.
s.v.d.drift@gdanimalhealth.com
Acknowledgements The authors thank all dairy farmers that participated in the study.
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GD1965/06-19