Effect of beta-lactoglobulin polymorphism and seasonality on bovine milk composition

Detection of the β-lactoglobulin genotype in zebu cattle (Gangatiri) milk using high-resolution accurate mass spectroscopy

We studied the genetic polymorphism of beta-lactoglobulin (β-Lg) whey protein in Gangatiri zebu cows for this Research Communication. The polymorphic nature of milk protein fractions and their association with milk production traits, composition and quality has attracted several efforts in evaluating the allelic distribution of protein locus as a potential dairy trait marker. Genetic variants of β-Lg have highly significant effects on casein number (B > A) and protein recovery (B > A) and also determine the yield of cheese dry matter (B > A). Molecular techniques of polyacrylamide gel electrophoresis and high-resolution accurate mass-spectroscopy were applied to characterize the β-Lg protein obtained from the Gangatiri breed milk. Sequence analysis of β-Lg showed the presence of variant B having UniProt database accession number P02754, coded on the PAEP gene. Our study can provide reference and guidance for the selection of superior milk (having β-LgB) from this indigenous breed that could potentially give a good yield of β-Lg for industrial applications.

Molecular characterization of Kappa-casein and β-lactoglobulin genes in Anatolian Black cattle and Holstein breeds

ABSTRACT κ-Cn and β-lactoglobulin are important candidate genes associated with milk yield and milk protein content. The present investigation is carried out to determine the polymorphisms status of κ-Cn and β-lactoglobulin genes in Anatolian Black cattle and Holstein breeds. PCR-RFLP technique was used to determine Kappa-Casein and β-lactoglobulin polymorphisms in both cattle breeds. The allele frequency of Anatolian Black cattle in terms of κ-Cn and β-lactoglobulin genes were 0.50 (A) 0.50 (B) and 0.20 (A) 0.80 (B) respectively, whereas in Holstein were 0.29 (A) 0.71 (B) and 0.44 (A) 0.56 (B) respectively. The chi-square test showed that each cattle breed was in Hardy-Weinberg equilibrium (P>0.05).

The Effect of Compositional Changes Due to Seasonal Variation on Milk Density and the Determination of Season-Based Density Conversion Factors for Use in the Dairy Industry

The objective of this study was to determine the effect of seasonal variation on milk composition and establish an algorithm to predict density based on milk composition to enable the calculation of season-based density conversion calculations. A total of 1035 raw whole milk samples were collected from morning and evening milking of 60 spring-calving individual cows of different genetic groups, namely Jersey, Elite HF (Holstein–Friesian) and National Average HF, once every two weeks for a period of 9 months (March–November, 2018). The average mean and standard deviation for milk compositional traits were 4.72 ± 1.30% fat, 3.85 ± 0.61% protein and 4.69 ± 0.30% lactose and density was estimated at 1.0308 ± 0.002 g/cm³. The density of the milk samples was evaluated using three methods: a portable density meter, DMA 35; a standard desktop version, DMA 4500M; and an Association of Official Agricultural Chemists (AOAC) method using 100-mL glass pycnometers. Statistical analysis using a linear mixed model showed a significant difference in density of milk samples (p < 0.05) across seasonal and compositional variations adjusted for the effects of days in milk, parity, the feeding treatment, the genetic group and the measurement technique. The mean density values and standard error of mean estimated for milk samples in each season, i.e., spring, summer and autumn were 1.0304 ± 0.00008 g/cm³, 1.0314 ± 0.00005 g/cm³ and 1.0309 ± 0.00007 g/cm³, respectively.

Relationships between milk protein polymorphisms and production traits in cattle: a systematic review and meta-analysis

Abstract. Many researchers who have studied the relationships between milk protein polymorphisms and some yield traits in dairy cattle have reported incompatible results. In this study, in order to examine the overall relationships between milk protein genes known as major genes (CSN1S1, CSN2, CSN3, and BLG) and some yield traits (daily milk yield, lactation milk yield, fat yield, fat content, protein yield, and protein content), a meta-analysis was performed using some genetic models reported in the results of previous studies on cattle. The results suggest that the relationships of major milk protein genes with other factors should be studied using the codominant genetic model in general. Relationships among some CSN3 genotypes and fat yield, fat content, and protein content, and relationships between some BLG genotypes and daily milk yield, fat content, protein yield, and protein content were significant (P<0.05). No significant (P>0.05) relationships were found between these genotypes and other milk production traits. In addition, no significant (P>0.05) relationships between the CSN1S1 and CSN2 genotypes with the milk production traits examined were observed.