Fit of different functions to the individual deviations in random regression test day models for milk yield in dairy cattle

Objective: Considering the importance of dairy farming and the negative effects of heat stress, more tolerant genotypes need to be identified. The objective of this study was to investigate the effect of heat stress via temperature-humidity index (THI) and diurnal temperature variation (DTV) in the genetic evaluations for daily milk yield of Holstein dairy cattle, using random regression models.Methods: The data comprised 94,549 test-day records of 11,294 first parity Holstein cows from Brazil, collected from 1997 to 2013, and bioclimatic data (THI and DTV) from 18 weather stations. Least square linear regression models were used to determine the THI and DTV thresholds for milk yield losses caused by heat stress. In addition to the standard model (SM, without bioclimatic variables), THI and DTV were combined in various ways and tested for different days, totaling 41 models.Results: The THI and DTV thresholds for milk yield losses was THI = 74 (–0.106 kg/d/THI) and DTV = 13 (–0.045 kg/d/DTV). The model that included THI and DTV as fixed effects, considering the two-day average, presented better fit (–2logL, Akaike information criterion, and Bayesian information criterion). The estimated breeding values (EBVs) and the reliabilities of the EBVs improved when using this model.Conclusion: Sires are re-ranking when heat stress indicators are included in the model. Genetic evaluation using the mean of two days of THI and DTV as fixed effect, improved EBVs and EBVs reliability.

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Random regression test day model for estimation of genetic parameter for milk yield and protein percentage of primparous Frisian cows in Egypt

Egyptian Journal of Animal Production ◽

10.21608/ejap.2004.107027 ◽

2004 ◽

Vol 41 (1) ◽

pp. 1-10

Keyword(s):

Milk Yield ◽

Genetic Parameter ◽

Random Regression ◽

Protein Percentage ◽

Regression Test

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Genetic parameters of somatic cell scores using random regression test-day models with Legendre polynomials in Tunisian dairy cattle

Livestock Science ◽

10.1016/j.livsci.2020.104178 ◽

2020 ◽

Vol 241 ◽

pp. 104178

Author(s):

Nabil Soumri ◽

Maria Jesus Carabaño ◽

Oscar González-Recio ◽

Sonia Bedhiaf-Romdhani

Keyword(s):

Dairy Cattle ◽

Somatic Cell ◽

Legendre Polynomials ◽

Genetic Parameters ◽

Random Regression ◽

Regression Test

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Genetic Analysis of Milk Yield in First-Lactation Holstein Friesian in Ethiopia: A Lactation Average vs Random Regression Test-Day Model Analysis

Asian-Australasian Journal of Animal Sciences ◽

10.5713/ajas.15.0173 ◽

2015 ◽

Vol 28 (9) ◽

pp. 1226-1234 ◽

Cited By ~ 1

Author(s):

S. Meseret ◽

B. Tamir ◽

G. Gebreyohannes ◽

M. Lidauer ◽

E. Negussie

Keyword(s):

Genetic Analysis ◽

Milk Yield ◽

Model Analysis ◽

Random Regression ◽

Holstein Friesian ◽

Regression Test

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Estimation the Genetic Parameters for Milk Yield in Romanian Spotted, Simmental Type Cattle Breed

Archiva Zootechnica ◽

10.2478/azibna-2021-0017 ◽

2021 ◽

Vol 24 (2) ◽

pp. 105-121

Author(s):

Rodica Stefania Pelmuș ◽

Mircea Cătălin Rotar ◽

Cristina Lazăr ◽

Răzvan Alexandru Uță

Keyword(s):

Animal Model ◽

Milk Yield ◽

Genetic Parameters ◽

Genetic Correlations ◽

Cattle Breed ◽

Random Regression ◽

Breeding Value ◽

Regression Test ◽

Fat Yield ◽

Heritability Estimates

Abstract The aim of this study was to estimate the genetic parameters for test-day traits milk yield and the breeding value in Romanian Spotted, Simmental type cattle. Random regression test-day animal model was used to estimate the genetic parameters. The number of records were 2062 test-day from 302 cows. The data were obtained from Romanian Breeding Association Romanian Spotted, Simmental type. The heritability estimates values for milk yield ranged between 0.377 and 0.417. The heritability for fat test-day yield in our study was low the values ranged between 0.117 and 0.236 and for protein test-day yield was medium, the values ranged between 0.308 and 0.372. The breeding value for the best ten cows for milk yield ranged from 1946.57 to 3250.38 kg, for fat yield were between 64.92 and 98.86 kg and for protein ranged from 67.26 to 102.21 kg. The correlations between test-day milk yields ranging from 0.28 to 1. Genetic correlations between test day fat and protein yields were high.

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Genetic parameters for milk production and persistency in the Iranian Holstein population by the multitrait random regression model

Archives Animal Breeding ◽

10.7482/0003-9438-57-012 ◽

2014 ◽

Vol 57 (1) ◽

pp. 1-12 ◽

Cited By ~ 2

Author(s):

Khabat Kheirabadi ◽

Sadegh Alijani

Keyword(s):

Milk Yield ◽

Milk Fat ◽

Genetic Correlations ◽

Random Regression ◽

Genetic Dissection ◽

Production Traits ◽

Data Set ◽

Random Regression Model ◽

Regression Test ◽

Fat Yield

Abstract. For genetic dissection of milk, fat, and protein production traits in the Iranian primiparous Holstein dairy cattle, records of these traits were analysed using a multitrait random regression test-day model. Data set included 763 505 test-day records from 88 204 cows calving since 1993. The (co)variance components were estimated by Bayesian method. The obtained results indicated that as in case of genetic correlations within traits, genetic correlations between traits decrease as days in milk (DIM) got further apart. The strength of the correlations decreased with increasing DIM, especially between milk and fat. Heritability estimates for 305-d milk, fat, and protein yields were 0.31, 0.29, and 0.29, respectively. Heritabilities of test-day milk, fat, and protein yields for selected DIM were higher in the end than at the beginning or the middle of lactation. Heritabilities for persistency ranged from 0.02 to 0.24 and were generally highest for protein yield (0.05 to 0.24) and lowest for fat yield (0.02 to 0.17), with milk yield having intermediate values (0.06 to 0.22). Genetic correlations between persistency measures and 305-d production were higher for protein and milk yield than for fat yield. The genetic correlation of the same persistency measures between milk and fat yields averaged 0.76, and between milk and protein yields averaged 0.82.

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Genetic perspective of milk yield persistency in the first three lactations of Iranian buffaloes (Bubalus bubalis)

Journal of Dairy Research ◽

10.1017/s0022029917000498 ◽

2017 ◽

Vol 84 (4) ◽

pp. 434-439 ◽

Cited By ~ 1

Author(s):

Navid Ghavi Hossein-Zadeh ◽

Mohammad Ali Nazari ◽

Abdol Ahad Shadparvar

Keyword(s):

Milk Yield ◽

Genetic Correlations ◽

Reproductive Traits ◽

Bubalus Bubalis ◽

Random Regression ◽

Genetic Trend ◽

Breeding Center ◽

Regression Test ◽

The Difference ◽

Estimated Breeding Values

The objectives of this study were to estimate the genetic parameters and genetic trends for different measures of persistency (PM) for milk yield in Iranian buffaloes using a random regression test day model. Test day records of the first three lactations of buffaloes within 715 herds comprising 43 014, 38 941 and 33 937 records, respectively, were obtained from the Animal Breeding Center of Iran during 1992 to 2012. Legendre polynomial functions were chosen to fit the lactation curves in the framework of a random regression test day model for estimating (co)variance components. Three measures of persistency were modified based on the lactation curve conditions of buffaloes: (1) The average of estimated breeding values (EBVs) for test day milk yields from day 226 to day 270 as a deviation from the average of EBVs from day 44 to day 62 (PM1), (2) A summation of contribution for each day from day 53 to day 247 as a deviation from day 248 (PM2), (3) The difference between EBVs for day 257 and day 80 (PM3). The highest heritability estimates were observed for PM2over the first three lactations (0·29, 0·80 and 0·42, respectively). Estimates of genetic correlations between persistency measures and milk yield varied from −0·48 to 0·29 (first lactation), from −0·12 to 0·48 (second lactation), and from −0·62 to 0·63 (third lactation). Estimate of genetic trend for first lactation PM2was negative (−0·0088 ± 0·0043;P< 0·05). It is essential to include milk yield persistency in the breeding goal of Iranian buffaloes along with other important traits such as milk yield or reproductive traits.

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