scholarly journals Estimation of Genetic and Phenotypic Parameters for Production Traits and Somatic Cell Count for Jersey Dairy Cattle in Zimbabwe

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Edward Missanjo ◽  
Venancio Imbayarwo-Chikosi ◽  
Tinyiko Halimani
Keyword(s):  
Dairy Cattle ◽  
Somatic Cell ◽  
Cell Count ◽  
Somatic Cell Count ◽  
Production Traits ◽  
Fat Percentage ◽  
Milk Traits ◽  
Phenotypic Correlations ◽  
Genetic And Phenotypic Correlations ◽  
Improvement Programme

Genetic and phenotypic parameters for production traits and somatic cell count (SCC) for Jersey dairy cattle in Zimbabwe were estimated. A total of 10986 lactation records were obtained from Zimbabwe Livestock Identification Trust, with cows calving in the period from 1996 to 2008. An ASReml program fitting an animal model was used for the analyses. Heritability estimates for milk yield, fat yield, protein yield, fat percentage, protein percentage, and Log10SCC were 0.30, 0.32, 0.33, 0.42, 0.44, and 0.08, respectively. The corresponding repeatability estimates were 0.39, 0.38, 0.39, 0.49, 0.51, and 0.16, respectively. The genetic and phenotypic correlations between different production traits ranged from −0.86 to 0.95 and from −0.88 to 0.98, respectively. The genetic and phenotypic correlations between production traits and Log10SCC were weak almost nonsignificantly differentl from zero. The results imply that milk traits for Jersey dairy cattle in Zimbabwe are more heritable. Therefore, these traits may be preferred by breeders as selection criteria for development of effective genetic improvement programme.

scholarly journals Genetic and environmental factors influencing milk, protein and fat yields of pasture-based dairy cows in Tasmania

2010 ◽  
Vol 50 (4) ◽  
pp. 265 ◽  
Author(s):  
S. A. Adediran ◽  
P. Nish ◽  
D. J. Donaghy ◽  
D. A. Ratkowsky ◽  
A. E. O. Malau-Aduli
Keyword(s):  
Dairy Cows ◽  
Somatic Cell ◽  
Cell Count ◽  
Milk Fat ◽  
Somatic Cell Count ◽  
Milk Protein ◽  
Herd Size ◽  
Production Traits ◽  
Phenotypic Correlations ◽  
Genetic And Phenotypic Correlations

The objective of this study was to provide an update on milk production performance, heritability, genetic and phenotypic correlations among production traits that are valuable for management, breeding and selection decisions in pasture-based dairy systems. The study utilised a total of 106 990 lactation records of Holstein–Friesian (FF), Jersey (JJ) and their crossbreds (HF) from 428 Tasmanian dairy herds collected between 2000 and 2005. The data were analysed using the least-squares approach with a general linear model and restricted maximum likelihood approach with a linear animal model. Results indicated highly significant (P < 0.01) effects of breed, herd size, cow’s parity, season and year of calving on milk, protein and fat yields. Average milk and protein yields per cow per lactation were highest in the FF breed (5212 L and 171 kg, respectively) and lowest in the JJ breed (3713 L and 143 kg, respectively). FF cows also produced 13.5 kg more milk fat than JJ and HF cows. Furthermore, milk, fat and protein yields were highest for cows calving during spring and lowest for autumn-calving cows. It was also evident that cows in very large herds (>1110 cows/herd) out-produced those in smaller herds. Heritability was highest for milk yield and lowest for somatic cell count ranging from 0.28 to 0.41. Genetic and phenotypic correlations between milk, fat and protein yields ranged from 0.41 to 0.85, and 0.66 to 0.92, respectively. However, genetic and phenotypic correlations between the log of somatic cell count and the production traits ranged from 0.03 to 0.09 and –0.03 to –0.05. We conclude that breed, herd size, parity, season and year of calving were among the main factors correlated with the productivity of dairy cows in Tasmania and adjustments for these factors would be mandatory for any unbiased comparison of lactation performance within and between pasture-based dairy production systems. The practical application of this information would be valuable to dairy farmers for decisions related to breeding, selection and management of their herds.

scholarly journals Associations between Bovine β-Defensin 4 Genotypes and Production Traits of Polish Holstein-Friesian Dairy Cattle

Animals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 723
Author(s):  
Brodowska ◽  
Zwierzchowski ◽  
Marczak ◽  
Jarmuż ◽  
Bagnicka
Keyword(s):  
Somatic Cell ◽  
Cell Count ◽  
Milk Fat ◽  
Somatic Cell Count ◽  
High Rate ◽  
Breeding Value ◽  
Production Traits ◽  
Milk Traits ◽  
Breeding Values ◽  
Holstein Friesian

This study analyzed the associations between two single-nucleotide polymorphisms (C2239T and A1674C), used together as a genotype located in BNBD4, and milk traits and breeding values of productivity traits of Polish Holstein-Friesian dairy cows. The research was carried out on 322 cows, with 7070 milk parameter and somatic cell count records in daily milking, as well as 897 records covering data on whole lactations, and 2209 breeding value records for productivity traits. The DMU statistical package with a one-trait repeatability test-day animal model was used to estimate the associations. The differences between the genotype effects were analyzed using Duncan’s post-hoc tests. The CC/AA and CT/AC genotypes had the highest frequencies (0.62 and 0.23, respectively). For use in marker-assisted selection, the CC/AC genotype is the most promising as an indicator of high-yielding cows potentially resistant to mastitis, because it was associated with the lowest somatic cell count (SCC), highest milk, fat, and protein yields in daily milking, as well as with milk yield in the whole lactation. The studied genotypes were also related to the breeding values of all the investigated production traits. However, some simulation studies have indicated a high rate of false-positives in GWAS based on classically calculated EBVs.

Comparative analyses of enteric methane emissions, dry matter intake and milk somatic cell count in different residual feed intake categories of dairy cows

2020 ◽  
Author(s):  
Dagnachew Hailemariam ◽  
Ghader Manafiazar ◽  
John A. Basarab ◽  
Paul Stothard ◽  
Filippo Miglior ◽  
...  
Keyword(s):  
Dairy Cows ◽  
Somatic Cell ◽  
Cell Count ◽  
Milk Yield ◽  
Feed Intake ◽  
Somatic Cell Count ◽  
Dry Matter ◽  
Residual Feed Intake ◽  
Dry Matter Intake ◽  
Milk Traits

This study compared the different residual feed intake (RFI) categories of lactating Holsteins with respect to methane emission, dry matter intake (kg), milk somatic cell count (SCC, 103/mL) and β-hydroxybutyrate (BHB, mmol/L). RFI was calculated in 131 lactating Holstein cows that were then categorized into –RFI (RFI<0) vs. +RFI (RFI>0) and low (RFI<-0.5 SD) vs. high RFI (RFI>0.5 SD) groups. Milk traits were recorded in 131 cows while CH4 and CO2 were measured in 83. Comparisons of –RFI vs. +RFI and low vs. high RFI showed 7.8% (22.3±0.40 vs. 24.2±0.39) and 12.9% (21.1±0.40 vs. 24.2±0.45) decrease (P<0.05) in DMI of –RFI and low RFI groups, respectively. Similarly, –RFI and low RFI cows had lower (P<0.05) CH4 (g/d) by 9.7% (343.5±11.1 vs. 380.4±10.9) and 15.5% (332.5±12.9 vs. 393.5±12.6) respectively. Milk yield was not different (P>0.05) in –RFI vs. +RFI and low vs. high comparisons. The –RFI and low RFI cows had lower (P<0.05) SCC in –RFI vs. +RFI and low RFI vs. high RFI comparisons. BHB was lower (P<0.05) in low RFI compared to the high RFI group. Low RFI dairy cows consumed less feed, emitted less methane (g/d), and had lower milk SCC and BHB without differing in milk yield.

A COMPARISON OF MASTITIS DETECTION METHODS IN DAIRY CATTLE

1984 ◽  
Vol 64 (2) ◽  
pp. 305-312 ◽  
Author(s):  
T. R. BATRA ◽  
A. J. McALLISTER
Keyword(s):  
Dairy Cattle ◽  
Somatic Cell ◽  
Cell Count ◽  
Somatic Cell Count ◽  
Good Accuracy ◽  
Subclinical Mastitis ◽  
Detection Methods ◽  
Considerable Proportion ◽  
Milk Samples ◽  
California Mastitis Test

The potential value of electrical conductivity, somatic cell count, and California Mastitis Test (CMT) Score in composite milk samples as a screening test for subclinical mastitis was evaluated. The effect of genetic group was significant (P < 0.05) for conductivity and somatic cell count while the effects of parity and month of lactation were significant (P < 0.01) for all the three traits studied. Somatic cell count and CMT score increased from first to fourth parity while there was general trend for increasing conductivity from second to fourth parity. All the three methods identified healthy cows with a good accuracy but failed to recognize a considerable proportion of infected cows. The error rate for misclassification was lowest for CMT score (9.1%), followed by somatic cell count (13.9%) and conductivity (29.4%). Composite strict foremilk samples from cows infected with primary pathogens had significantly (P < 0.01) higher conductivity than those from uninfected cows. Staphylococcus aureus were isolated in 60% of the milk samples and appeared to be in the major organism causing mastitis in this herd. Key words: Dairy cattle, mastitis detection methods

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