Estimates of correction factors for lactation length and genetic parameters for milk yield in buffaloes

Tonhati, Humberto; Muñoz, M.F.C.; Duarte, J. M. C.; Reichert, Roberto Hauck; Oliveira, J. A.; Lima, André Luís Ferreira

doi:10.1590/s0102-09352004000200016

Cited by 15 publications

(12 citation statements)

References 6 publications

(9 reference statements)

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“…The general structure of the data is shown in Table 1. To obtain the cumulated 270-d milk yield, the lactations were adjusted using the method proposed by Tonhati et al (2004), and lactations with a length above 270-d were truncated at this point. Lactations shorter than 90 d were deleted.…”

Section: Methodsmentioning

confidence: 99%

Genetic parameters of total milk yield and factors describing the shape of lactation curve in dairy buffaloes

Aspilcueta-Borquis

Baldi

Neto

et al. 2011

Journal of Dairy Research

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The objective of this study was to apply factor analysis to describe lactation curves in dairy buffaloes in order to estimate the phenotypic and genetic association between common latent factors and cumulative milk yield. A total of 31 257 monthly test-day milk yield records from buffaloes belonging to herds located in the state of São Paulo were used to estimate two common latent factors, which were then analysed in a multi-trait animal model for estimating genetic parameters. Estimates of (co)variance components for the two common latent factors and cumulated 270-d milk yield were obtained by Bayesian inference using a multiple trait animal model. Contemporary group, number of milkings per day (two levels) and age of buffalo cow at calving (linear and quadratic) as covariate were included in the model as fixed effects. The additive genetic, permanent environmental and residual effects were included as random effects. The first common latent factor (F1) was associated with persistency of lactation and the second common latent factor (F2) with the level of production in early lactation. Heritability estimates for F1 and F2 were 0·12 and 0·07, respectively. Genetic correlation estimates between F1 and F2 with cumulative milk yield were positive and moderate (0·63 and 0·52). Multivariate statistics employing factor analysis allowed the extraction of two variables (latent factors) that described the shape of the lactation curve. It is expected that the response to selection to increase lactation persistency is higher than the response obtained from selecting animals to increase lactation peak. Selection for higher total milk yield would result in a favourable correlated response to increase the level of production in early lactation and the lactation persistency.

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Section: Methodsmentioning

confidence: 99%

Genetic parameters of total milk yield and factors describing the shape of lactation curve in dairy buffaloes

Aspilcueta-Borquis

Baldi

Neto

et al. 2011

Journal of Dairy Research

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“…Milk, fat and protein yields are constantly monitored traits in herds integrated in milk test programs. The test-day milk yield (TDMY), defined as the total yield of a cow over a period of 24 h, replaces the milk yield in 305 days of lactation, as calculated by using formulas and extension factors (Tonhati et al 2004). Buffalo milk is characterised by a high percentage of fat and protein, which could be used to increase milk's added value, following the current tendency of the worldwide milk markets.…”

Section: Introductionmentioning

confidence: 99%

Random regression models to estimate genetic parameters for test-day milk yield and composition in Iranian buffaloes

et al. 2013

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Abstract. The objective of this study was to estimate genetic parameters for milk yield and milk percentages of fat and protein in Iranian buffaloes. A total of 9,278 test-day production records obtained from 1,501 first lactation buffaloes on 414 herds in Iran between 1993 and 2009 were used for the analysis. Genetic parameters for productive traits were estimated using random regression test-day models. Regression curves were modeled using Legendre polynomials (LPs). Heritability estimates were low to moderate for milk production traits and ranged from 0.09 to 0.33 for milk yield, 0.01 to 0.27 for milk protein percentage and 0.03 to 0.24 for milk fat percentage, respectively. Genetic correlations ranged from −0.24 to 1 for milk yield between different days in milk over the lactation. Genetic correlations of milk yield at different days in milk were often higher than permanent environmental correlations. Genetic correlations for milk protein percentage ranged from −0.89 to 1 between different days in milk. Also, genetic correlations for milk percentage of fat ranged from −0.60 to 1 between different days in milk. The highest estimates of genetic and permanent environmental correlations for milk traits were observed at adjacent test-days. Ignoring heritability estimates for milk yield and milk protein percentage in the first and final days of lactation, these estimates were higher in the 120 days of lactation. Test-day milk yield heritability estimates were moderate in the course of the lactation, suggesting that this trait could be applied as selection criteria in Iranian milking buffaloes.

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“…For the calculation of these yields, milk production is generally monitored at average intervals of 30 days and the production of one cow on each test day is called test-day (TD) milk yield. Cumulative yields for different lactation periods are calculated using estimated extension or adjustment factors, with accuracy of cumulative yield depending on the quality and quantity of the available test-day records (Tonhati et al, 2004;ICAR, 2008).…”

Section: Introductionmentioning

confidence: 99%

Test-day milk yield as a selection criterion for dairy buffaloes (Bubalus bubalis Artiodactyla, Bovidae)

et al. 2008

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Due to the great demand for buffalo milk by-products the interest in technical-scientific information about this species is increasing. Our objective was to propose selection criteria for milk yield in buffaloes based on total milk yield, 305-day milk yield (M305), and test-day milk yield. A total of 3,888 lactations from 1,630 Murrah (Bubalus bubalis) cows recorded between 1987 and 2001, from 10 herds in the State of São Paulo, Brazil, were analyzed. Covariance components were obtained using the restricted maximum likelihood method applied to a bivariate animal model. Additive genetic and permanent environmental effects were considered as random, and contemporary group and lactation order as fixed effects. The heritability estimates were 0.22 for total milk yield and 0.19 for M305. For test-day yields, the heritability estimates ranged from 0.12 to 0.30, with the highest values being observed up to the third test month, followed by a decline until the end of lactation. The present results show that test-day milk yield, mainly during the first six months of lactation, could be adopted as a selection criterion to increase total milk yield.

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Estimates of correction factors for lactation length and genetic parameters for milk yield in buffaloes

Cited by 15 publications

References 6 publications

Genetic parameters of total milk yield and factors describing the shape of lactation curve in dairy buffaloes

Genetic parameters of total milk yield and factors describing the shape of lactation curve in dairy buffaloes

Random regression models to estimate genetic parameters for test-day milk yield and composition in Iranian buffaloes

Test-day milk yield as a selection criterion for dairy buffaloes (Bubalus bubalis Artiodactyla, Bovidae)

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