Rapport d'activités final du premier mandat (du 1er février 2011 au 31 janvier 2013) : ProFARMilk, variabilité et amélioration des aptitudes à la transformation fermière du lait

Report (2013)

Mid-infrared predictions of fatty acids in bovine milk : final results of the RobustMilk project

Poster (2012, August 28)

The development of mid-infrared equations to predict the milk fatty acid (FA) content of milk allows prompt analysis of large numbers of samples and was one of the aims of the RobustMilk project. Data on ... [more ▼]

The development of mid-infrared equations to predict the milk fatty acid (FA) content of milk allows prompt analysis of large numbers of samples and was one of the aims of the RobustMilk project. Data on MIR spectra and FA from multiple countries, production systems, and breeds were used to develop equations to predict milk FA. The calibration set contained 1,776 spectrally different English, Irish, and Belgian milk samples collected for over 6 years. FA were quantified by gas chromatography (GC). Equations were built using partial least squares regression after a first derivative pretreatment applied to the spectral data. The robustness of the developed equations was assessed by cross-validation (CV) using 50 groups from the calibration set. The coefficient of determination (R²) obtained after CV ranged between 0.7101 for the total content of C18:2 and 0.9993 for the saturated FA group. The standard error of CV ranged between 0.0028 and 0.0998 g/dl of milk. Generally, the group or individual FA having the highest content in milk had the highest R²cv. The results obtained in this study confirmed the usefulness of MIR spectra to robustly quantify the FA content of milk permitting the use of these equations by milk laboratories in UK, Belgium or Ireland. Therefore, these equations could be used to develop selection or management tools for dairy farmers in order to improve the nutritional and environmental quality of milk based on the knowledge of the FA composition of their milk. [less ▲]

Mid-infrared prediction of milk titratable acidity and its genetic variability in first-parity cows

Conference (2012, August 27)

Coagulation of milkhas a direct effect on cheese yield. Among several parameters, titratable acidity of milk (TA) influences all the phases of milk coagulation. In order to study the genetic variability ... [more ▼]

Coagulation of milkhas a direct effect on cheese yield. Among several parameters, titratable acidity of milk (TA) influences all the phases of milk coagulation. In order to study the genetic variability of this trait on a large scale, mid-infrared (MIR) chemometric methods were used to predict TA. A total of 507 milk samples collected in the Walloon Region of Belgium from individual cows were analyzed using a MIR spectrometer. TA was recorded as Dornic degree. An equation to predict TA from milk MIR spectrum was developed using partial least squared regression after a first derivative pre-treatment applied to the spectra to correct the baseline drift. During the calibration process, 45 outliers were detected and removed from the calibration set. The TA mean of the final calibration set was 16.62 (standard deviation (SD) = 1.80). The coefficient of determination (R²) was 0.82 for the calibration with a standard error (SE) of 0.76. A cross-validation (cv) was performed (R²cv = 0.81 with SEcv = 0.80). This equation was then applied on the spectral database generated during the Walloon routine milk recording. The variances components were estimated by REML using single-trait random regression animal test-day model. The dataset used included 33,717 records from 9,191 Holstein first-parity cows; the TA mean was 17.05 (SD = 1.35) and TA ranged from 12.83 to 20.87. Estimated daily heritabilities ranged from 0.43 at 5th day in milk to 0.59 at 215th day in milk indicating potential of selection. Further research will study phenotypic and genetic correlations between TA and milk production traits. [less ▲]

Genetics of the mineral contents in bovine milk predicted by mid-infrared spectrometry

in Book of Abstracts of the 63rd Annual Meeting of the European Federation of Animal Science (2012, August)

Knowing the contents of minerals in milk like Ca or Na could be interesting to improve the nutritional quality of milk and to assess the animal health status. This study had two aims: 1) development of ... [more ▼]

Knowing the contents of minerals in milk like Ca or Na could be interesting to improve the nutritional quality of milk and to assess the animal health status. This study had two aims: 1) development of mid-infrared equations for mineral contents in milk by using an approach combining multiple countries, breeds, and production systems and 2) study of the genetic variability of these traits in the Walloon Holstein dairy cattle. Samples included in the calibration set were collected in Belgium, Luxembourg and France over 5 years. The calibration set included at least 400 samples analyzed by coupled plasma atomic emission spectrometry to quantify the contents of Na, Ca, Mg, P and K. The calibration coefficient of determination ranged between 0.69 for K and 0.93 for Na. The standard error of cross-validation was 63.35, 49.24, 64.33, 7.04, and 93.22 mg/kg of milk for Na, Ca, P, Mg and K. From these results, the quantification of milk minerals by mid-infrared is feasible. These equations were applied to more than 140,000 spectral records collected from 43,797 first parity Holstein cows in 1,233 herds. The variance components were estimated using Gibbs Sampling using single trait random regression models derived from the one used for the Walloon genetic evaluation of milk production traits. First results gave a daily heritability of 0.26 for Na, 0.45 for Ca, 0.48 for P, 0.46 for Mg, and 0.41 for K. Moderate negative genetic correlations were found between Na and the other studied traits. The highest correlation (0.69) was observed between P and Mg. These results confirmed the genetic variability of these traits. Further studies will be conducted to study the relationship between these traits and other traits (e.g., production, health). [less ▲]

Genetic parameters for methane indicator traits based on milk fatty acids in cows

Conference (2012, July 18)

Relationships between methane emissions of dairy cattle and farm management.

Poster (2012, February 10)

Livestock is considered as an important contributor to global methane emissions, predominately due to methanogenesis from ruminants. Moreover, these emissions also represent major losses of energy for ... [more ▼]

Livestock is considered as an important contributor to global methane emissions, predominately due to methanogenesis from ruminants. Moreover, these emissions also represent major losses of energy for dairy cows and therefore are linked to production efficiency. The on-going development of predictive equations (e.g., from milk composition) would allow to relate methane emissions to farm management (e.g., nutrition, environment) on a large scale in the Walloon Region of Belgium. Finally, by acquiring improved knowledge of these relationships, contributions to mitigate methane emissions could be based on an improved management of dairy herds. [less ▲]

Mid-Infrared Prediction of Lactoferrin Content in Bovine Milk: Potential Indicator of Mastitis

in Animal (2012), 6

When MIR spectrometry helps to promote a local and vulnerable breed

Poster (2011, August 31)

The dual purpose Belgian Blue breed (DP-BB) is a vulnerable breed rooted in the tradition of the Walloon Region of Belgium. DP-BB has interesting features (e.g. robustness, good longevity and ease of ... [more ▼]

The dual purpose Belgian Blue breed (DP-BB) is a vulnerable breed rooted in the tradition of the Walloon Region of Belgium. DP-BB has interesting features (e.g. robustness, good longevity and ease of calving). Due to its dual purpose type, income generated by both milk and meat is more stable and more flexible in responding to market fluctuations. Registered DP-BB cows are milk recorded (one of the conditions for them to be registered as DP-BB and therefore to get AEM subsidies). Since near 4 years, during routine milk recording, nearly all mid-infrared (MIR) spectra generated at the milk labs and the information of test-day records were collected in a database. Calibration equations using the MIR spectrometry were developed permitting the prediction of several bovine milk components (e.g., fatty acids (FA)). Their application on the MIR spectral database would allow comparing milk composition from 920 DP-BB and 52,497 Holstein cows (selected cows had a proportion of Holstein or DP-BB in their breed composition of at least 90%). On average, each cows had 6 test-day records with MIR spectra in the database. MIR predictions were analyzed using GLM procedure with 5 fixed effects (breed, herd, lactation number, month of test-day recording and lactation stage); values presented are lsmeans (± s.e.) of the breed. Although milk and fat yields were lower for DP-BB, their FA proportions in fat were different from Holstein. Indeed, there are 66.0% (0.2) and 67.6% (0.0) of saturated FA in fat of milk for DP-BB and Holstein, respectively. Furthermore, the DP-BB milk fat was richer in omega-9 (20.7% (0.2) vs. 19.6% (0.0) for DP-BB and Holstein, respectively). Use of MIR predictions may help stakeholders to promote milk and future dairy products from DP-BB. [less ▲]

When MIR spectrometry helps to promote a local and vulnerable breed

in Book of Abstracts of the 62nd Annual Meeting of the European Association for Animal Production (2011, August)

The dual purpose Belgian Blue breed (DP-BB) is a vulnerable breed rooted in the tradition of the Walloon Region of Belgium. DP-BB has interesting features (e.g. robustness, good longevity and ease of ... [more ▼]

The dual purpose Belgian Blue breed (DP-BB) is a vulnerable breed rooted in the tradition of the Walloon Region of Belgium. DP-BB has interesting features (e.g. robustness, good longevity and ease of calving). Due to its dual purpose type, income generated by both milk and meat is more stable and more flexible in responding to market fluctuations. Registered DP-BB cows are milk recorded (one of the conditions for them to be registered as DP-BB and therefore to get AEM subsidies). Since near 4 years, during routine milk recording, nearly all mid-infrared (MIR) spectra generated at the milk labs and the information of test-day records were collected in a database. Calibration equations using the MIR spectrometry were developed permitting the prediction of several bovine milk components (e.g., fatty acids (FA)). Their application on the MIR spectral database would allow comparing milk composition from 920 DP-BB and 52,497 Holstein cows (selected cows had a proportion of Holstein or DP-BB in their breed composition of at least 90%). On average, each cows had 6 test-day records with MIR spectra in the database. MIR predictions were analyzed using GLM procedure with 5 fixed effects (breed, herd, lactation number, month of test-day recording and lactation stage); values presented are lsmeans (± s.e.) of the breed. Although milk and fat yields were lower for DP-BB, their FA proportions in fat were different from Holstein. Indeed, there are 66.0% (0.2) and 67.6% (0.0) of saturated FA in fat of milk for DP-BB and Holstein, respectively. Furthermore, the DP-BB milk fat was richer in omega-9 (20.7% (0.2) vs. 19.6% (0.0) for DP-BB and Holstein, respectively). Use of MIR predictions may help stakeholders to promote milk and future dairy products from DP-BB. [less ▲]

Estimating daily yield of major fatty acids from single milking: first approach.

in Journal of Dairy Science (2011, July), 94(E-Suppl. 1), 29

Reducing the frequency of milk recording and the number of recorded samples per test-day could be a solution in order to reduce costs of milk recording. However, this solution leads to decrease also the ... [more ▼]

Reducing the frequency of milk recording and the number of recorded samples per test-day could be a solution in order to reduce costs of milk recording. However, this solution leads to decrease also the accuracy of predicting daily yield. According to the literature, several authors have already worked on this problematic. Unfortunately, some effects used in previous studies are not often available or reliable in used databases. This study was aimed to enlarge these investigations to milk fatty acids (FA) production: saturated FA, mono-unsaturated FA, unsaturated FA, medium-chain FA, and long chain FA and to propose a simple, robust and practical method for estimating accurate daily major FA yield from single milking. To do this, five dairy cows were followed between January 2007 and December 2010. FA contents were predicted by mid-infrared spectrometry. The final database contained 1,440 records. The first step was to ensure that used effects were available in most used databases. According to the availability of data, height models were tested to estimate daily yields from both morning and evening milking. These models were compared on the basis of the coefficient of determination values between estimated and observed daily yields and the mean square error. The proposed models included progressively several effects such as the milk yield, the fat and protein content, some classes of stage in lactation, of month of test or of month of calving. As expected, R² values were higher when these effects are introduced in the model and were comprised between 0.87 and 0.88 when daily yield were estimated from morning milking, and from 0.75 and 0.86 when daily yield were estimated from evening milking. It was concluded that the introduction of these effects did highly improve the daily predictability of all trait yield and can partially replace the milking interval effect. It was also observed that daily yields estimated from evening milkings are less accurate than those estimated from morning milkings. Finally, the applied model will depend on the availability of the data and to the convenience of the applied model to the studied population. Keywords: Milk recording, Fatty acids, prediction [less ▲]