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See detailAdding value to test-day data by using modified best prediction method
Gillon, Alain ULiege; Abras, Sven; Mayeres, Patrick et al

in ICAR Technical Series (2010, November), 14

Computation of lactation yields from test-day data has lost much of its importance for genetic evaluations as the use of test-day models is currently quite widespread. In the other hand its interest for ... [more ▼]

Computation of lactation yields from test-day data has lost much of its importance for genetic evaluations as the use of test-day models is currently quite widespread. In the other hand its interest for intra-farm management is increasing as a base for advanced management tools. The first and principal aim of this study was to develop a method which takes into account advantages and disadvantages of existing methods, and to test its potential to provide useful management tools to dairy farmers. A test-day model with modifications to able daily run and management tools was developed. Because of its similarities with best prediction, the method developed here was called modified best prediction. The second objective was to compare the accuracy of this new method with best prediction and test interval methods. Modified best prediction showed good results for predicting daily yields and was slightly better than best prediction for lactation yields prediction. Management tools obtained with modified best prediction are explained. [less ▲]

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See detailPotential estimation of titratable acidity in cow milk using mid-infrared spectrometry
Colinet, Frédéric ULiege; Soyeurt, Hélène ULiege; Anceau, Christine ULiege et al

in ICAR Technical Series (2010), 14

Milk coagulation has a direct effect on cheese yield. Several factors influence the milk coagulation kinetics. In addition to calcium and milk protein concentrations, titratable acidity influences all the ... [more ▼]

Milk coagulation has a direct effect on cheese yield. Several factors influence the milk coagulation kinetics. In addition to calcium and milk protein concentrations, titratable acidity influences all the phases of milk coagulation. The objective of this research was to study the feasibility of prediction of titratable acidity directly in bovine milk using mid-infrared spectrometry. In order to maximize the variability in the measurements of titratable acidity, milk samples were collected on basis of several criteria (e.g. breeds). The titratable acidity was recorded as Dornic degree. All samples were also analyzed by MIR spectrometry. Using partial least squares regressions and first derivative pretreatment of spectral data, a calibration equation was built to predict the Dornic degree in cow milk. First results were promising and showed the potentiality to this calibration. The calibration and cross-validation coefficients of determination were 92.25 and 89.88 %, respectively. Moreover, the ratio of standard error of prediction to standard deviation was 3.13 and permits us to consider the calibration equation as usable in most application such as scientific researches and the screening of the Walloon dairy herd particularly in order to improve the milk coagulation properties. [less ▲]

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See detailPotential Estimation of Minerals Content in Cow Milk Using Mid-Infrared Spectrometry
Soyeurt, Hélène ULiege; Bruwier, Damien; Gengler, Nicolas ULiege et al

in ICAR Technical Series (2008, June 16), 13

Mineral contents in milk influence the humanand animal health. The variation of sodium (Na) could also be a good indicator of mastitis and are related to the milk fever. A low intake of calcium (Ca ... [more ▼]

Mineral contents in milk influence the humanand animal health. The variation of sodium (Na) could also be a good indicator of mastitis and are related to the milk fever. A low intake of calcium (Ca) promotes the osteoporosis in human. Consequently, knowingregularly the mineral contents in milk could be interesting. Unfortunately, the commonchemical analyses used to measure theconcentrations of mineral inmilk areexpensive.Theaimof this study was todevelopsome calibration equations to predict the contents of mineral directly in bovine milk using mid-infrared (MIR) spectrometry. Using a principal components approach, 70 samples were chosen based on their spectral variability from the 1609 collected milk samples. A total of 14 samples were considered as outliers. So, 57 samples were analyzed by inductively coupled plasma atomic emission spectrometry (ICP-AES) to estimate the reference concentrations of minerals. Based onthese values and the corresponding spectra, 3 calibration equations were built permitting to predict the contents of Ca, Na and phosphorus (P). To assess the accuracy of the developed equations, a full cross-validation was applied. In the same way, the RPD ratio corresponding to the ratio of the standard deviation to the standard error of cross-validation was estimated. The best accuracy was observed for the calibration equations estimating the contents of Ca (R2cv 0.82, RPD 2.35) and P (R2cv 0.77, RPD 2.06). In conclusion, the MIR spectrometry seemed to be a good alternative method to predict the contents of Ca and Pin bovine milk. [less ▲]

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