Blood samples, taken on 6 occasions during 1 year from 172 cows resident in a dairy herd, were analysed for packed cell volume, blood glucose, haemoglobin (Hb), serum albumin, urea N, total protein, Ca, inorganic phosphate, Mg, Na and K. The data were analysed statistically, firstly with respect to date of sampling, stage of pregnancy or lactation and the interaction between stage of pregnancy or lactation and date of sampling, and secondly with milk yield as an additional factor for the data for lactating cows.Concentrations of all constituents except inorganic phosphate and K varied significantly (P < 0-001) with stage of lactation and/or pregnancy. The most significant changes in concentrations were confined to the periods up to 3 months either side of calving. The greatest changes in concentration during these periods occurred for Mg which rose during late pregnancy and for albumin which fell at or near calving. Albumin, urea and glucose were all, on average, lowest in concentration during the first month of lactation; globulin concentrations showed the reverse trend. Haemoglobin concentrations decreased during late pregnancy and early lactation and were lowest in the period 30-120 d post partum. Calcium concentrations decreased during late pregnancy and rose during early lactation. Sodium concentrations rose during late pregnancy. Interactions between dates of sampling and stages of lactation or pregnancy were significant (P < 0-001) for all constituents, and most marked for glucose, urea, albumin, Hb, Ca and Na.Haemoglobin and K concentrations fell and Mg concentrations rose with increasing milk yield, but the proportions of the total variance accounted for by differences in milk yield were small in relation to those accounted for by stage of lactation. These findings are of significance in relation to the selection of animals for sampling in the Compton Metabolic Profile Test.
SummaryThe contribution that the computer has made in the interpretation and analysis of a metabolic profile test, which is designed to monitor the metabolic health of a dairy herd and assess the adequacy of dietary intake for production, is described. The test is based on an assessment of blood chemistry for any number of variates, which constitute the metabolic profile, measured for randomly selected cows from 3 groups of a herd: dry cows, cows giving intermediate quantities of milk and cows giving high daily yields. The computer program is designed to give an objective and comprehensive assessment of the test in an easily interpretable form based on a pictorial form of print-out. The profile is displayed as a ‘histogram’ presented as standard deviations from the normal base-line, and for each variable a scatter diagram is included presenting the individual variates plotted against the particular animal's daily milk yield.
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