Effects of Several Factors on Quantification of Fat, Protein, and Somatic Cells in Milk

Coleman, David; Moss, B.R.

doi:10.3168/jds.s0022-0302(89)79491-1

Cited by 9 publications

(6 citation statements)

References 19 publications

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“…Due to practical aspects of the above-mentioned occurrence of differences in the results of milk analyses between laboratories, which is often criticized by users of the results, many authors have analysed and explained the existing variability of the results and differences in the values in comprehensive studies (Sherbon, 1975;Biggs, 1978;Vines et al, 1986;Coleman and Moss, 1989;Barbano et al, 1991;Golc-Teger et al, 1996;Golc-Teger, 1996, 1997. For this reason the plan of so called "netting of laboratories" was performed, where the check of variability of the results using reference milk and other standards (defined samples) and methods of proficiency testing (ring or star tests) is possible.…”

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confidence: 99%

Relationships between the results of various methods of urea analysis in native and enriched milk

Hering¹,

Hanuš²,

Frelich³

et al. 2008

Czech J. Anim. Sci.

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Milk urea concentration (MUC) is a suitable indicator of the health and nutrition state of dairy cows. MUC is in relation to their reproduction performance, longevity and technological milk indicators. The interpretation correctness of results depends on their reliability. There are a lot of principles of MUC analyses. Their results can be affected by a number of interferential factors. Disproportions were noticed in practice. Therefore the sources of variation in results are studied. The goal of this study was to investigate relationships between different methods of MUC determination with the use of standard samples of native milk with an artificial urea addition. After evaluation I (n = 7) the results of methods BI-1 and BI-2 (photometrical ones with diacetylmonoxime) were disqualified because of poor recovery (R), poor correlation (C) with other methods, higher random error (RER) and highest systematic error (SE). Evaluation II is more effective with stricter discrimination limits. Cs of all methods mutually (0.977 up to 0.998; P < 0.001) confirmed the methods as effective with the exception of BI-2 with poor Cs (0.713 up to 0.774), poor R (16.0 up to 69.0%) and high RER ±5.292 mg/100 ml. R of better methods was 44.0 up to 96.7%. The BI-1 method had good Cs (0.986 up to 0.994; P < 0.001), higher SE -7.546 mg/100 ml and poorer R (48.5 up to 75.3%). BI-1 method was a case of mistaken performance. BI method could be improved by the use of more samples in calibration. FT-MIR method (infra-analysis) has good addition R 69.5 up to 95.0% and Cs 0.981 up to 0.994 (P < 0.001). EH method (photometrical one with Ehrlich's agent) has good R 59.0 up to 96.7%, higher SE 4.755 (I) and 2.556 (II) mg/100 ml and close Cs 0.977 up to 0.994 (P < 0.001). UR method (ureolytical difference-conductometric) showed the best combination of results about R, C, SE and RER. MUC measurement was almost independent of fat in milk (r = 0.16 for UR and 0.01 for FT-MIR; P > 0.05) and MUC of both the methods did not increase significantly with lactose increase (r = 0.16 and 0.27; P > 0.05), which increased logically (r = -0.88; P < 0.001) during the fat concentration increase. The relationship of MUC results between UR and FT-MIR was significant (validation r = 0.96; P < 0.001) at average difference -0.93 ± 1.663 mg/100 ml. It is possible to see the result reliability as good after calibration performance of FT-MIR according to results of UR. It is not necessary to see the effects of fat, protein and lactose on MUC methods as substantial. FT-MIR method for MUC has good result reliability at the use of native milk samples, incidentally with urea additions. It is suitable to calibrate the FT-MIR method according to specific determination of MUC (UR). However, the most important for elimination of disproportions is the calibration method with concrete audited R, though nonspecific.

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confidence: 99%

Relationships between the results of various methods of urea analysis in native and enriched milk

Hering¹,

Hanuš²,

Frelich³

et al. 2008

Czech J. Anim. Sci.

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“…AfiLab analyses every 200 mL of harvested milk and presents 1 average value after the cow's milking. The milk sampled by DHIA may be different from the analyzed milk (often analyzed the day after collection) due to inconsistencies in milk col- lection, storage, or transportation (Coleman and Moss, 1989). For example, violent shaking of the DHIA milk sample increases the amount of free fatty acids in the milk, which causes a decreased fat test at the laboratory.…”

Section: Discussionmentioning

confidence: 99%

Agreement between milk fat, protein, and lactose observations collected from the Dairy Herd Improvement Association (DHIA) and a real-time milk analyzer

Kaniyamattam

Vries

2014

Journal of Dairy Science

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The objective of this study was to quantify the agreement between AfiLab real-time milk analyzer (Afimilk, Kibbutz Afikim, Israel) measures for fat, protein, and lactose based on near-infrared spectrum light scattering, and those collected on Dairy Herd Improvement Association (DHIA) test days and measured with the Bentley 2000 analyzer (Bentley Instruments Inc., Chaska, MN), which uses mid-infrared spectrum light. The AfiLab data were collected twice daily for each milking cow in the herd at 12-h intervals from the double-12 parlor at the University of Florida Dairy Unit (Hague, FL) from January 2010 to December 2011. Bentley data for the 23 DHIA test days in 2010 and 2011 were also obtained. Approximately 450 cows were tested each month. Tested milk was collected during 1 milking each month, alternating monthly between morning and evening milkings. AfiLab data were matched with Bentley fat and protein (n=10,273; 23 test days) and lactose (n=6,741; 16 test days). Overall means ± standard deviations (SD) of monthly mean Bentley fat, protein, and lactose were 3.74 ± 0.80%, 3.06 ± 0.37%, and 4.76 ± 0.30%, respectively. Overall means ± SD of monthly mean AfiLab minus Bentley observations were -0.08 ± 0.12 percentage points (PP) for fat (n=23), 0.02 ± 0.11 PP for protein (n=23), and -0.02 ± 0.08 PP for lactose (n=16). Overall means ± SD of monthly within-test-day SD of AfiLab minus Bentley observations were 0.66 ± 0.11 PP for fat, 0.27 ± 0.03 PP for protein, and 0.26 ± 0.03 PP for lactose. Overall means ± SD of the corresponding monthly correlations were 0.59 ± 0.09 for fat, 0.67 ± 0.04 for protein, and 0.46 ± 0.08 for lactose. Averaging the AfiLab observations from up to 6 milkings before and after the test-day milking improved the agreement for protein and lactose but not for fat. Averaging the 13 protein observations improved the mean difference to 0.01 ± 0.10 PP and the SD of the difference to 0.23 ± 0.03 PP. The correlation increased to 0.78 ± 0.04. Averaging the 13 lactose observations improved the SD of the difference to 0.23 ± 0.02 PP, but the mean of the difference decreased to -0.03 ± 0.09 PP. The correlation for lactose increased to 0.55 ± 0.05. Generally, AfiLab slightly overestimated low Bentley components and underestimated high Bentley components. We found some evidence for a systematic cow effect on lack of agreement for lactose, but not for fat and protein. The agreement between AfiLab and Bentley observations was better for protein and lactose than that for fat. Combinations of AfiLab observations from various milkings improved the agreement for protein and lactose. AfiLab real-time milk analyzers may be helpful to estimate DHIA observations.

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“…Currently, the protein content of milk is analysed through automated flow analysers (Silveira et al, 2004) which are based on the mid-infrared (MIR) spectroscopy (Biggs, 1978;Coleman and Moss, 1989;Botaro et al, 2011). These analysers use optical filter technology (MIR) or whole infra-red spectrum scan in mid-range (MIR-FT, Fourier transform).…”

Section: Routine Methodsmentioning

confidence: 99%

Milk Protein Analysis: an Overview of the Methods - Development and Application

Kala

Samková

Hanuš³

et al. 2019

Acta Univ. Agric. Silvic. Mendelianae Brun.

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Milk protein content is an important component of milk, especially from a nutritional point of view and also for payment purposes. The aim of work was to draw up an overview on reference and routine methods for protein determination. Reference methods perform accurate analyses comply according to the International Standard ISO whereas routine methods perform analyses using routine instrumental techniques for faster and cheaper results with acceptable accuracy and a large number of processed samples. In most of cases, using of routine indirect methods for milk protein analysis requires their specific calibrations according to biological kind of measured milk (cow’s, goat’s or sheep’s milk) or specific conditions of milk technology treatment. Also, the quality control measures have a significant role for result determination reliability.

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Effects of Several Factors on Quantification of Fat, Protein, and Somatic Cells in Milk

Cited by 9 publications

References 19 publications

Relationships between the results of various methods of urea analysis in native and enriched milk

Relationships between the results of various methods of urea analysis in native and enriched milk

Agreement between milk fat, protein, and lactose observations collected from the Dairy Herd Improvement Association (DHIA) and a real-time milk analyzer

Milk Protein Analysis: an Overview of the Methods - Development and Application

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