Genetics of the mid-infrared prediction of lactoferrin content in milk for Holstein first-parity cows

in International Journal of Dairy Science (2012), 95, Suppl. 2

Genetic correlations of days open with production traits and contents in milk of major fatty acids predicted by mid-infrared spectrometry.

in Journal of Dairy Science (2012), 95(10), 6113-21

The objective of this study was to estimate the genetic relationships between days open (DO) and both milk production traits and fatty acid (FA) content in milk predicted by mid-infrared spectrometry. The ... [more ▼]

The objective of this study was to estimate the genetic relationships between days open (DO) and both milk production traits and fatty acid (FA) content in milk predicted by mid-infrared spectrometry. The edited data set included 143,332 FA and production test-day records and 29,792 DO records from 29,792 cows in 1,170 herds. (Co)variances were estimated using a series of 2-trait models that included a random regression for milk production and FA traits. In contrast to the genetic correlations with fat content, those between DO and FA content in milk changed considerably over the lactation. The genetic correlations with DO for unsaturated FA, monounsaturated FA, long-chain FA, C18:0, and C18:1 cis-9 were positive in early lactation but negative after 100 d in milk. For the other FA, genetic correlations with DO were negative across the whole lactation. At 5 d in milk, the genetic correlation between DO and C18:1 cis-9 was 0.39, whereas the genetic correlations between DO and C6:0 to C16:0 FA ranged from -0.37 to -0.23. These results substantiated the known relationship between fertility and energy balance status, explained by the release of long-chain FA in early lactation, from the mobilization of body fat reserves, and the consequent inhibition of de novo FA synthesis in the mammary gland. At 200 d in milk, the genetic correlations between DO and FA content ranged from -0.38 for C18:1 cis-9 to -0.03 for C6:0. This research indicates an opportunity to use FA content in milk as an indicator trait to supplement the prediction of genetic merit for fertility. [less ▲]

Assessing heat stress effects on production traits of Holsteins in a temperate region

Conference (2012)

Heat stress impaired productive, reproductive and animal behaviour. Examination of milk production loss due to heat stress was mainly evaluated in USA and few tropical countries using the temperature ... [more ▼]

Heat stress impaired productive, reproductive and animal behaviour. Examination of milk production loss due to heat stress was mainly evaluated in USA and few tropical countries using the temperature humidity index (THI1) developed in the 1950’s. The main objective of this study was to evaluate the effects of six new environmental stress indices on production traits in a temperate region. These indices include solar radiation and wind speed in addition to the temperature and humidity only defining THI1. For that purpose, 530820 milk, fat, protein, and somatic cell count first-lactation test-day records (TD) collected between 2000 and 2011 in Luxembourg were used. TD records were merged with meteorological data from 14 public weather stations. Each TD was assigned to the average daily thermal index of the 3 days before. Firstly, broken-line regression models were applied to identify the threshold of heat stress (THR) for each of the thermal indices. The decline of daily production of the different traits above THR point was assessed by mixed linear models including regression on unit of each of the thermal index. Estimates of THR were specific to each thermal index and trait. Significant decrease of milk, fat and protein yields above THR was observed for all studied thermal predictors. Whereas, an increase of the somatic cell score was observed above the specific THR point. THR estimates for THI1 and THI6 were of 68 and 80 and 62 and 78 for milk and protein yields respectively. Respective rate of decline per unit were of 0.243 and 0.188 kg and 0.0045 and 0.0051 kg respectively. Results from this phenotypic analysis show that evaluating heat tolerance based on bio-meteorological indicators is promising and phenotypic and genetic implications should be investigated. [less ▲]

Genetic variance in environmental sensitivity for milk and milk quality in Walloon Holstein cattle

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

Estimation of genetic parameters for longitudinal measurements of feed intake in Piétrain sire lines

in Book of Abstracts of the 63rd Annual Meeting of the European Association of Animal Science (2012)

Estimation of genetic parameters for birth weight, pre-weaning mortality and hot carcass weight in a crossbred population of pigs

in Journal of Animal Science (2012), 90(E-Suppl.3), 721

Genetic relationships between milk fatty acids and fertility of dairy cows

in Interbull Bulletin (2012), 44

Is It Possible to Define a European Total Merit Index?

in Interbull Bulletin (2012), 44

Developing a common European bull list is an objective of the PROTEJE (PROduction Traits European Joint Evaluation) workgroup started in 2001 as an initiative of the European Holstein herdbooks. Six Total ... [more ▼]

Developing a common European bull list is an objective of the PROTEJE (PROduction Traits European Joint Evaluation) workgroup started in 2001 as an initiative of the European Holstein herdbooks. Six Total Merit Indexes were compared to define a common breeding goal across Europe. A principal component analysis was used to observe the direction of the largest common variation among the studied Total Merit Indexes. Results showed that the considered indexes had a lot in common. The first principal component explained 86% of the total variation. Based on previous researches establishing combined proofs on a European phantom scale for most traits and trait groups and using a multiple regression for this European Total Merit Index, relative emphases on production and functionality of 37% and on conformation of 26% could be established. [less ▲]

Mid-infrared predictions of cheese yield from bovine milk

Conference (2011, August 31)

Economically, cheese yield (CY) is very important. Todate, empirical or theoretical formulae allow estimating the theoretical CY from milk fat and casein or protein content of milk. It would be ... [more ▼]

Economically, cheese yield (CY) is very important. Todate, empirical or theoretical formulae allow estimating the theoretical CY from milk fat and casein or protein content of milk. It would be interesting to predict CY during milk recording directly without the need to estimate milk components. Through the BlueSel project, 157 milk samples were collected in Wallonia from individual cows and analyzed using a mid-infrared (MIR) MilkoScanFT6000 spectrometer. Individual laboratory cheese yields (ILCY) were determined for each sample and expressed as g of dry coagulum/100 g of milk dry matter. An equation to predict ILCY from MIR was developed using partial least squared regression (Winisi III). A first derivative pre-treatment of spectra was used to correct the baseline drift. To improve the repeatability of the spectral data, a file which contained the spectra of samples analyzed on 5 spectrometers was used during the calibration. During calibration, 23 outliers were detected a nd removed from the calibration set. The ILCY mean of the final calibration set was 63.9% with a SD of 11.2%. The calibration (C) coefficient of determination (R²) was equal to 0.76 with a standard error (SE) of calibration of 5.5%. A full cross-validation (CV) was preformed to assess the robustness. R²cv was 0.72 with a SECV of 6.0%. The similarity between R²c and R²cv as well as between SEC and SECV permits to consider robustness of the developed equation as good. Even if it is planned to improve the equation with additional samples, this first equation will permit to study ILCY in the Walloon dairy cattle. [less ▲]

Integration of foreign breeding values for stallions into the Belgian genetic evaluation for jumping horses

Poster (2011, August 30)

The aim of this study was to test the integration of foreign estimated breeding values (EBV) for stallions into the Belgian genetic evaluation for jumping horses. Belgian breeders import horses from ... [more ▼]

The aim of this study was to test the integration of foreign estimated breeding values (EBV) for stallions into the Belgian genetic evaluation for jumping horses. Belgian breeders import horses from neighbouring countries for which foreign information is needed as prior to estimate a more accurate EBV. The Belgian model is a bivariate repeatability BLUP animal model. For the year 2009, pedigree and data files contained 101 382 horses and 712 212 performances. 98 French and 67 Dutch stallions were selected and their foreign EBVs were converted into Belgian national trait. Associated reliabilities were also estimated. A Bayesian approach (Legarra et al., 2007) was applied to integrate this prior information into the Belgian evaluation. It led to a slight modification of the average EBV and of the standard deviation for the whole population. It also led to a new Belgian ranking of the foreign stallions more similar to foreign rankings. However, the adequacy of the Belgian model was not damaged. With regards to prediction ability, Bayesian evaluations using conversion equation estimated by Weighted Least Squares procedure predicted the best traditional EBVs of the year 2009 for the French stallions. For the Dutch ones, it were the evaluations associated to the conversion equation based on Wilmink et al. (1986). For both countries, Bayesian evaluations using conversion equation based on Goddard (1985) improved the most the stability of EBVs. Finally, integration of French and Dutch information improved reliabilities of the Bayesian EBVs of at least 5% and 2% for French and Dutch stallions, respectively. These results confirm the interest to integrate foreign information into the Belgian evaluation for jumping horses. [less ▲]