• Asian-Australasian Journal of Animal Sciences
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• v.17 no.2
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• pp.159-163
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• 2004

Data pertaining to first lactation records of 316 Murrah buffaloes, progeny of 47 sires, maintained at NDRI Farm for a period of 18 years were analysed to construct selection indices and to examine their robustness by changing the relative economic values of different economic traits. A total of 120 selection indices were constructed for three sets of relative economic values ( 40 for each set) considering different combinations of seven first lactation traits viz. age at first calving (AFC), first lactation 305 day or less milk yield (FLMY), first lactation length (FLL), first calving interval (FCI), milk yield per day of first lactation length (MY/FLL), milk yield per day of first calving interval (MY/FCI) and milk yield per day age at second calving (MY/ASC). The three sets of relative economic values were based on economic values of different traits, 1% standard deviation of different traits and regression of different traits on FLMY. The 'optimum' indices for the first two sets had five traits each namely AFC, FLMY, FLL, FCI and MY/ASC giving improvement in aggregate genotype of Rupees 269.11 and Rs. 174.88, respectively. The accuracy of selection from both indices was 70.79 and 69.39%, respectively. The 'best' selection index from the third set of data again had five traits (AFC, FLMY, FLL, FCI and MY/FLL) giving genetic gain of Rs. 124.16 and accuracy of selection of 71.81%. The critcal levels or break-even points for FLMY for varying levels of AFC and FCI estimated from the "optimum index" suggested the need of enhancement of present production level of the herd or reduction of AFC or FCI. It was concluded that economic values of various first lactation traits were the most appropriate to construct selection indices as compared to other criteria of assigning relative economic weights in Murrah buffaloes.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.1
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• pp.56-60
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• 1999

Production and reproduction data of 47 Nili-Ravi buffaloes (162 records) were analyzed with regression techniques. Average lactation milk yield was $2,020.04{\pm}44.59$ liters, lactation length $277.42{\pm}5.70$ d and calving interval $467.10{\pm}11.58$ d. The ranges for these parameters respectively were : 609-3591 lit, 122-614 d and 228-982 d. Year of calving and lactation length had significant effect on total milk yield (p < 0.01), whereas other factors such as month of calving, lactation number and calving interval had no effect on total lactation milk yield. Year of calving had influenced significantly other traits (p < .01) such as calving interval and lactations completed. This indicated considerable environment role in buffalo productivity. Effect of month of calving on total lactation milk yield and other traits was however, found to be non-significant. Nili-Ravi buffaloes produced maximum milk during their first three lactations as compared to subsequent lactations. Regression model explained 40 percent variation in total lactation milk yield due to factors analyzed : animal (dam), year and month of calving lactation length and calving interval.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.2
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• pp.166-171
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• 2007

The objective of this study was to assess the association of polymorphisms in ${\kappa}$-cn, ${\beta}$-lg, ${\beta}$-lg 5′ flanking region, CSN1S2, and IGFBP-3 genes with milk production traits and mastitis-related traits in Chinese Holstein. Traits analyzed were 305 day standard milk yield, protein percentage, fat percentage, the ratio of fat percentage and protein percentage, pre-somatic cell count, somatic cell count, and somatic cell score, respectively. CSN1S2 locus was uninformative because only one genotype BB was found in Chinese Holstein. Allele frequencies of A and B in IGFBP-3 gene were 0.5738 and 0.4262 in Chinese Holstein population, which was different from reported Qinchuan cattle population. The genotypes of animals at IGFBP-3 locus significantly affected 305 day standard milk yield, protein percentage, and somatic cell score. The ${\beta}$-lg genotypes had a significant effect on protein percentage and the ratio of fat percentage and protein percentage. Polymorphism in ${\beta}$-lg 5′ flanking region was associated with 305 day standard milk yield, protein percentage, fat percentage, pre-somatic cell count, and somatic cell count. No significant associations of the polymorphism in ${\kappa}$-cn gene were observed for any trait.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.5
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• pp.695-698
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• 2002

Performance data (from 1985 to 2000) of Jersey cattle imported from USA and maintained at Islamabad, Pakistan were evaluated. The purpose of this study was to assess the genetic merit of Jersey breed under Pakistani environment for further propagation. Cows with at least two calvings were considered for this study; records on 50 daughter-dam pairs were available on production and reproduction performance traits for genetic evaluation. The average age at first calving in parents was $25.2{\pm}2.4$ m as compared to $23.9{\pm}6.6$ m in progeny. Calving interval in parents and progeny was $416{\pm}74$ and $446{\pm}105$ d; lactation length $301{\pm}51$ and $325{\pm}73$ d; lactation milk yield $2,908{\pm}669$ and $2,707{\pm}903$ lit respectively. All these differences were found to be statistically significant except lactation length. The correlations between age at first calving and total lactation milk was -0.25, between calving interval and total lactation milk yield was 0.14, and between lactation length and total lactation milk yield was 0.79. The $h^2$ of these traits were low indicating important role of environment in expressing the genetic potential of animals. The S.E of $h^2$ of all the traits was high due to large variation in data.

• Animal Bioscience
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• v.35 no.10
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• pp.1499-1511
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• 2022

Objective: This study was aimed to estimate the genetic parameters, including genetic and phenotypic correlations, of milk yield, lactation curve traits and milk composition of Thai dairy cattle from three government research farms. Methods: The data of 25,789 test-day milk yield and milk composition records of 1,468 cattle from lactation 1 to 3 of Holstein Friesian (HF) and crossbred HF dairy cattle calved between 1990 and 2015 from three government research farms in Thailand were analysed. 305-day milk yield was estimated by the Wood model and a test interval method. The Wood model was used for estimating cumulative 305-day milk yield, peak milk yield, days to peak milk yield and persistency. Genetic parameters were estimated using linear mixed models with herd, breed group, year and season of calving as fixed effects, and animals linked to a pedigree as random effects, together with a residual error. Univariate models were used to estimate variance components, heritability, estimated breeding values (EBVs) and repeatability of each trait, while pairwise bivariate models were used to estimate covariance components and correlations between traits in the same lactation and in the same trait across lactations. Results: The heritability of 305-day milk yield, peak milk yield and protein percentage have moderate to high estimates ranging from 0.19 to 0.45 while days to peak milk yield, persistency and fat percentage have low heritability ranging from 0.08 to 0.14 in lactation 1 cows. Further, heritability of most traits considered was higher in lactation 1 compared with lactations 2 and 3. For cows in lactation 1, high genetic correlations were found between 305-day milk yield and peak milk yield (0.86±0.07) and days to peak milk yield and persistency (0.99±0.02) while estimates of genetic correlations between the remaining traits were imprecise due to the high standard errors. The genetic correlations within the traits across lactation were high. There was no consistent trend of EBVs for most traits in the first lactation over the study period. Conclusion: Both the Wood model and test interval method can be used for milk yield estimates in these herds. However, the Wood model has advantages over the test interval method as it can be fitted using fewer test-day records and the estimated model parameters can be used to derive estimates of other lactation curve parameters. Milk yield, peak milk yield and protein percentage can be improved by a selection and mating program while days to peak milk yield, persistency and fat percentage can be improved by including into a selection index.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.9
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• pp.1242-1246
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• 2003

Data pertained to 335 crossbred cows comprising of 1/2 Friesian (F) + 1/2 Hariana (H), 1/2 F + 1/4 Jersey (J) + 1/4 H, 1/2 F + 1/4 Brown Swiss (BS) + 1/4 H, 1/2 F + 1/4 Red Dane (R) + 1/4 H, FR (I) and FRH (I) genetic groups extending over a period of 21 years (1970-1990) maintained at Animal Farm of CCS HAU, Hisar. The averages for first lactation milk yield was $2,486.24{\pm}80.26kg$ and peak yield of first three lactation were $11.35{\pm}0.72kg$, $13.97{\pm}0.60kg$ and $16.02{\pm}0.42kg$, respectively. The lifetime milk production was observed as $11,305.16{\pm}1,004.52kg$ in crossbred cattle. The average first lactation fat yield was observed as $102.06{\pm}0.01kg$ and peak fat yield of first three lactation were $0.458{\pm}0.01$, $0.490{\pm}0.01$ and $0.500{\pm}0.02kg$, respectively. The lifetime fat production was estimated as $502.31{\pm}45.90kg$. LTMP and LTFP had reasonably good additive genetic variance which could be exploited either through mass selection/combined with family or pedigree selection. FLMY, peak yields and LTMP had significant positive phenotypic correlation with FLFY and LTFP and the correlation at the genetic level were also higher and positive for these traits. Finally, peak week milk yield of first lactation (PMY1) was the earliest available trait having desirable and significant correlation at phenotypic and positive at genetic level with FLFY, PFY1 and PFY2, PFY3 and LTFP and selection for this trait will help in early evaluation of sires and dams and will increase genetic advancement per unit of time.

• Asian-Australasian Journal of Animal Sciences
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• v.29 no.11
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• pp.1530-1540
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• 2016

This study was conducted to estimate the genetic parameters of ${\beta}$-hydroxybutyrate (BHBA) and acetone concentration in milk by Fourier transform infrared spectroscopy along with test-day milk production traits including fat %, protein % and milk yield based on monthly samples of milk obtained as part of a routine milk recording program in Korea. Additionally, the feasibility of using such data in the official dairy cattle breeding system for selection of cows with low susceptibility of ketosis was evaluated. A total of 57,190 monthly test-day records for parities 1, 2, and 3 of 7,895 cows with pedigree information were collected from April 2012 to August 2014 from herds enrolled in the Korea Animal Improvement Association. Multi-trait random regression models were separately applied to estimate genetic parameters of test-day records for each parity. The model included fixed herd test-day effects, calving age and season effects, and random regressions for additive genetic and permanent environmental effects. Abundance of variation of acetone may provide a more sensitive indication of ketosis than many zero observations in concentration of milk BHBA. Heritabilities of milk BHBA levels ranged from 0.04 to 0.17 with a mean of 0.09 for the interval between 4 and 305 days in milk during three lactations. The average heritabilities for milk acetone concentration were 0.29, 0.29, and 0.22 for parities 1, 2, and 3, respectively. There was no clear genetic association of the concentration of two ketone bodies with three test-day milk production traits, even if some correlations among breeding values of the test-day records in this study were observed. These results suggest that genetic selection for low susceptibility of ketosis in early lactation is possible. Further, it is desirable for the breeding scheme of dairy cattle to include the records of milk acetone rather than the records of milk BHBA.

• Asian-Australasian Journal of Animal Sciences
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• v.18 no.9
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• pp.1231-1236
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• 2005

Genetic parameters for first lactation milk production based on test day (TD) records of 56319 Iranian Holstein cows from 655 herds that first calved between 1991 and 2001 were estimated with restricted maximum likelihood method under an Animal model. Traits analyzed were milk yield and milk fat percentage. Heritability for TD records were highest in second half of the lactation, ranging from 0.11 to 0.19 for milk yield and 0.038 to 0.094 for milk fat percentage respectively. Estimates for lactation records for these traits were 0.24 and 0.26 respectively. Genetic correlations between individual TD records were high for consecutive TD records (>0.9) and decreased as the interval between tests increased. Estimates of genetic correlations of TD yield with corresponding lactation yield were highest (0.78 to 0.86) for mid-lactation (TD3 to TD8). Phenotypic correlations were lower than corresponding genetic correlations, but both followed the same pattern. For milk fat percentage no clear pattern was found. Results of this study suggested that TD yields especially in mid-lactation may be used for genetic evaluation instead of 305-day yield.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.3
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• pp.328-333
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• 2015

A genome wide association study was conducted using estimated breeding value (EBV) for milk production traits from 1st to 4th lactation. Significant single nucleotide polymorphism (SNP) markers were selected for each trait and the differences were compared by lactation. DNA samples were taken from 456 animals with EBV which are Holstein proven bulls whose semen is being sold or the daughters of old proven bulls whose semen is no longer being sold in Korea. High density genome wide SNP genotype was investigated and the significance of markers associated with traits was tested using the breeding value estimated by a multiple lactation model as a dependent variant. As the result of significance comparisons by lactations, several differences were found between the first lactation and subsequent lactations (from second to 4th lactation). A similar trend was noted in mean deviation and correlation of the estimated effects by lactation. Since there was a difference in the genes associated with EBV for each trait between first and subsequent lactations, a multi-lactation model in which lactation is considered as a different trait is genetically useful. Also, significant markers in all lactations and common markers for different traits were detected, which can be used as markers for quantitative trait loci exploration and marker assisted selection in milk production traits.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.11
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• pp.1479-1483
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• 2004

Milk protein polymorphisms were genotyped by polyacrylamide gel electrophoresis (PAGE) from 109 Maiwa and 100 Jiulong yaks. The relationships between milk protein polymorphisms and 3 milking traits were studied. The results showed that $\beta$-CN, $\kappa$-CN and $\alpha$-La were monomorphic, and ${\alpha}_{s1}$-CN and $\beta$-Lg were polymorphic, with ${\alpha}_{s1}$-CN D and $\beta$-Lg E as dominant genes, respectively. The frequencies of ${\alpha}_{s1}$-CN D were 0.8073 and 0.6000 in two populations and $\beta$-Lg E were 0.9770 and 0.9700. The mean heterozygosities were 0.1021 and 0.1867 in the two populations. No significant effects on milking traits and milk protein compositions were observed except for ${\alpha}_{s1}$-CN locus on fat percentage in Jiulong yak.