Casein SNP in Norwegian goats: additive and dominance effects on milk composition and quality

<p>Abstract</p> <p>Background</p> <p>The four casein proteins in goat milk are encoded by four closely linked casein loci (<it>CSN1S1</it>, <it>CSN2</it>, <it>CSN1S2 </it>and <it>CSN3</it>) within 250 kb on caprine chromosome 6. A deletion in exon 12 of <it>CSN1S1</it>, so far reported only in Norwegian goats, has been found at high frequency (0.73). Such a high frequency is difficult to explain because the national breeding goal selects against the variant's effect.</p> <p>Methods</p> <p>In this study, 575 goats were genotyped for 38 Single Nucleotide Polymorphisms (SNP) located within the four casein genes. Milk production records of these goats were obtained from the Norwegian Dairy Goat Control. Test-day mixed models with additive and dominance fixed effects of single SNP were fitted in a model including polygenic effects.</p> <p>Results</p> <p>Significant additive effects of single SNP within <it>CSN1S1 </it>and <it>CSN3 </it>were found for fat % and protein %, milk yield and milk taste. The allele with the deletion showed additive and dominance effects on protein % and fat %, and overdominance effects on milk quantity (kg) and lactose %. At its current frequency, the observed dominance (overdominance) effects of the deletion allele reduced its substitution effect (and additive genetic variance available for selection) in the population substantially.</p> <p>Conclusions</p> <p>The selection pressure of conventional breeding on the allele with the deletion is limited due to the observed dominance (overdominance) effects. Inclusion of molecular information in the national breeding scheme will reduce the frequency of this deletion in the population.</p

Structural rheological properties of model nutritional beverage emulsions stabilized by bovine lactoferrin: Influence of pH and oil type

The objective of this study was to demonstrate the microstructure and rheological properties of model beverage emulsions containing 1% (w/w) canola oil (CO) or rice bran oil (RBO) stabilized by bovine lactoferrin (bLF) 1% (w/w) subjected to highly acidic and neutral pH conditions. The o/w emulsions were characterized using phase contrast microscopy, confocal scanning laser microscopy and image analysis and rheology. Both CO and RBO emulsions exhibited pseudo-plastic behaviour with the flow behaviour index values being less than 1. Irrespective of pH, a difference between CO and RBO emulsions with respect to median droplet size was observed (p<0.05), which might be attributed to the differences in density and viscosity of the respective dispersed phases. The differences in surface hydrophobicity and electrostatic charge of bLF between pH 2 and 7 influenced the emulsion properties. The results might have implications in formulating highly acidic/neutral nutritional beverages containing n-3 and n-6 fatty acids and lactoferrin