Short communication: Effect of preadjusting test-day yields for stage of pregnancy on variance component estimation in Canadian Ayrshires

Loker, S.; Miglior, F.; Bohmanová, J.; Schaeffer, L.R.; Jamrozik, J.; Kistemaker, G.J.

doi:10.3168/jds.2008-1806

Cited by 3 publications

(3 citation statements)

References 18 publications

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“…Similar estimates were obtained with the models with or without the effect of pregnancy, a fact indicating that the lack of inclusion of this effect did not affect the estimates of covariance components. These results agree with Loker et al (2009b), who studied data of milk, fat and protein yield and somatic cell count preadjusted or not for the effect of pregnancy in Canadian Ayrshire cows. The authors found no significant difference in genetic parameters between the two data sets.…”

Section: Resultssupporting

confidence: 82%

Effect of pregnancy on the genetic evaluation of dairy cattle

Pereira¹,

Júnior²,

Bignardi³

et al. 2011

Genet. Mol. Res.

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ABSTRACT.We investigated the effect of stage of pregnancy on estimates of breeding values for milk yield and milk persistency in Gyr and Holstein dairy cattle in Brazil. Test-day milk yield records were analyzed using random regression models with or without the effect of pregnancy. Models were compared using residual variances, heritabilities, rank correlations of estimated breeding values of bulls and cows, and number of nonpregnant cows in the top 200 for milk yield and milk persistency. The estimates of residual variance and heritabilities obtained with the models with or without the effect of pregnancy were similar for the two breeds. Inclusion of the effect of pregnancy in genetic evaluation models for these populations did not affect the ranking of cows and sires based on their predicted breeding values for 305-day cumulative milk yield. In contrast, when we examined persistency of

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Section: Resultssupporting

confidence: 82%

Effect of pregnancy on the genetic evaluation of dairy cattle

Pereira¹,

Júnior²,

Bignardi³

et al. 2011

Genet. Mol. Res.

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“…Jamrozik et al, 1997;Jensen, 2001). TD models are used in many countries (Interbull, 2015), but few studies (Loker et al, 2009) have examined the effects of stage of pregnancy on TD milk yields in variance component estimates. Loker et al (2009) reported that the average heritabilities for daily yields estimated by using a random-regression TD model with TD records that were pre-adjusted for stage of pregnancy were similar to those estimated by using unadjusted records.…”

Section: Introductionmentioning

confidence: 99%

Effects of stage of pregnancy on variance components, daily milk yields and 305-day milk yield in Holstein cows, as estimated by using a test-day model

Yamazaki

Hagiya

Takeda

et al. 2016

Animal

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Pregnancy and calving are elements indispensable for dairy production, but the daily milk yield of cows decline as pregnancy progresses, especially during the late stages. Therefore, the effect of stage of pregnancy on daily milk yield must be clarified to accurately estimate the breeding values and lifetime productivity of cows. To improve the genetic evaluation model for daily milk yield and determine the effect of the timing of pregnancy on productivity, we used a test-day model to assess the effects of stage of pregnancy on variance component estimates, daily milk yields and 305-day milk yield during the first three lactations of Holstein cows. Data were 10 646 333 test-day records for the first lactation; 8 222 661 records for the second; and 5 513 039 records for the third. The data were analyzed within each lactation by using three single-trait random regression animal models: one model that did not account for the stage of pregnancy effect and two models that did. The effect of stage of pregnancy on test-day milk yield was included in the model by applying a regression on days pregnant or fitting a separate lactation curve for each days open (days from calving to pregnancy) class (eight levels). Stage of pregnancy did not affect the heritability estimates of daily milk yield, although the additive genetic and permanent environmental variances in late lactation were decreased by accounting for the stage of pregnancy effect. The effects of days pregnant on daily milk yield during late lactation were larger in the second and third lactations than in the first lactation. The rates of reduction of the 305-day milk yield of cows that conceived fewer than 90 days after the second or third calving were significantly ( P < 0.05) greater than that after the first calving. Therefore, we conclude that differences between the negative effects of early pregnancy in the first, compared with later, lactations should be included when determining the optimal number of days open to maximize lifetime productivity in dairy cows. Keywords: dairy cattle, days open, days pregnant, test-day model ImplicationsDaily milk yields of cows decline as pregnancy progresses. By using a test-day model, we revealed that stage of pregnancy did not affect the estimated heritability of daily milk yield. However, 305-day milk yields were decreased in cows with fewer days open, and the rates of reduction associated with decreased days open (⩽90) in the second and third lactations were larger than that in the first lactation. These differences between the effects of stage of pregnancy in the first compared with later lactations should be included when determining the optimal number of days open for lifetime productivity in dairy cows.

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“…(Olori et al, 1997;Penasa et al, 2016). In later stages of gestation, the growth and nutrient requirements of conceptus increases compared with earlier stages (Loker et al, 2009). Furthermore, estrogen levels in maternal blood gradually increase from 3 mo with no meaningful differences in levels between 3 to 5 mo and 5 to 7 mo of pregnancy, followed by a sudden increase thereafter (Parkhie et al, 1966), thereby potentially affecting nutrient partitioning (Olori et al, 1997).…”

Section: Comparison Of Models For Diagnosing Pregnancymentioning

confidence: 97%

The use of milk Fourier-transform mid-infrared spectroscopy to diagnose pregnancy and determine spectral regional associations with pregnancy in US dairy cows

Khanal

Tempelman²

2022

Journal of Dairy Science

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Accurate early diagnosis of pregnancy is important for timely reproductive management of dairy farms. Fourier-transform mid-infrared (FT-MIR) milk spectral data are routinely used for determining milk components such as fat and protein, whereas milk composition is known to change with advancing stages of pregnancy. The objectives of this study were to compare partial least squares discriminant analysis (PLS-DA) and a Bayesian variable selection regression model (BayesC) for the diagnosis of pregnancy status (PS) from milk FT-MIR data and to infer any spectral regions that might be highly associated with PS at various stages of pregnancy. Conception dates on confirmed pregnant cows were obtained from Holstein cows within 123 herds in Michigan, Ohio, and Indiana during 2018 and 2019. Milk samples from these pregnant cows at 7 different stages of pregnancy were case-control matched to open contemporary herd mates to be within the same stage (±10 d for days in milk) of lactation for the same milk sample test date. The FT-MIR data were obtained for all of these milk samples. Ten-fold herd-independent cross-validation was used to compare PLS-DA versus BayesC using the area under the receiver operating characteristic curve (AUC). The BayesC model demonstrated higher mean AUC compared with PLS-DA at all stages exceeding 60 d of pregnancy. The mean BayesC AUC at stage 1 (1-30 d) was 0.58 ± 0.02, which was superior to a random guess (AUC = 0.50) yet too low to be of practical use. The mean BayesC AUC at stage 7 (≥180 d) was 0.13 greater compared with that of stage 1 (1-30 d) and 0.07 to 0.10 greater compared with stages 2, 3, 4, 5, and 6 (31-180 d in 30-d increments). The mean AUC of stages 2 to 6 were 0.03 to 0.06 greater compared with stage 1 yet again too low to be of practical use. Because of high multicollinearity between many adjacent wavenumbers, a spatially constrained clustering algorithm was used to adaptively partition wavenumbers into 68 windows before inferring associations of spectral regions with pregnancy. Pregnancy status was highly associated with wavenumber windows 1,063 to 1,134 cm −1 , 1,201 to 1,257 cm −1 , and 1,260 to 1,432 cm −1 based on an estimated BayesC posterior probability of association (PPA) approaching 100% for each of these windows at all pregnancy stages. Other windows ranging from 1,730 to 1,764 cm −1 , 1,775 to 1,992 cm −1 , 1,995 to 2,163 cm −1 , and 2,167 to 2,316 cm −1 had varying medium to high PPA (30% to 100%) across stages. The estimated PPA in wavenumber regions from 1,477 to 1,507 cm −1 , and 1,510 to 1,574 cm −1 was weaker in stages 1 and 2 compared with later stages, whereas for the regions 2,984 to 3,077 cm −1 and 3,081 to 3,133 cm −1 the effect of pregnancy was greater for stage 1 compared with other stages. Despite our conclusion that milk FT-MIR data poorly diagnose PS, our study provides new insights into spectral regions that are strongly associated with PS and warrant greater attention.

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Short communication: Effect of preadjusting test-day yields for stage of pregnancy on variance component estimation in Canadian Ayrshires

Cited by 3 publications

References 18 publications

Effect of pregnancy on the genetic evaluation of dairy cattle

Effect of pregnancy on the genetic evaluation of dairy cattle

Effects of stage of pregnancy on variance components, daily milk yields and 305-day milk yield in Holstein cows, as estimated by using a test-day model

The use of milk Fourier-transform mid-infrared spectroscopy to diagnose pregnancy and determine spectral regional associations with pregnancy in US dairy cows

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