Journal Articles

Permanent URI for this collectionhttps://mro.massey.ac.nz/handle/10179/7915

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Author: search.filters.author.Marshall ACSubject: search.filters.subject.Milk coagulation

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    Animal factors affecting the cheese-making properties and the heat coagulation time of milk from dairy sheep in a New Zealand flock
    (Taylor and Francis Group on behalf of the Royal Society of New Zealand, 2024-03-27) Marshall AC; Lopez-Villalobos N; Loveday SM; Weeks M; McNabb W
    The objective of this study was to evaluate the effect of animal factors on the cheese-making properties and on the heat coagulation time of milk from individual dairy sheep in a New Zealand flock. A total of 521 individual records were obtained from a seasonal pasture-based flock of 169 ewes milked once-a-day, from 50 to 182 days in milk. A statistical model was used to quantify the effects of animal factors (coat colour variety, age, litter size and stage of lactation) on the studied traits. Stage of lactation, confounded with seasonality, strongly influenced all properties of milk investigated. With the advancement of lactation, the milk took longer to coagulate after rennet addition, and the curd was softer. Higher relative cheese yield was achieved towards the end of lactation. The milk was also less stable to high-temperature treatment in late lactation. Coefficient of variation for processability traits was high and ranged from 20.2% to 58%, which can be largely attributed to stage of lactation but could also indicate room for genetic improvement of traits. Further genetic studies are underway to define animal genetic variance, heritability, and the phenotypic and genetic correlations between these processability and milk composition traits.
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    Effect of protein polymorphisms on milk composition, coagulation properties, and protein profile in dairy sheep
    (Elsevier Ltd, 2025-01-01) Marshall AC; Vigolo V; De Marchi M; Lopez-Villalobos N; Loveday SM; Weeks M; McNabb W
    The objective of this study was to quantify the effect of protein polymorphisms on milk composition, coagulation properties, and protein profile in dairy sheep from a New Zealand flock. A total of 470 test-day records, from 147 lactating ewes, were used in the statistical analyses. Protein polymorphisms observed in the RP-HPLC were self-named for purposes of the present study. Data were analyzed using a mixed linear model, including the fixed effects of ewe age, litter size, coat-colour, and stage of lactation, and, as a covariate, deviation from the median lambing date of the flock. The effects of protein polymorphisms were added to the model, one at a time. Protein polymorphisms were significantly (p < 0.05) associated with milk composition and protein profile. Polymorphisms of β-lactoglobulin were significantly associated with milk heat stability, being AB type more heat stable than AA. The other processability traits were not significantly affected by protein polymorphisms. Further studies are required to confirm the protein variants and the properties of individual protein polymorphisms.