Document Detail


Changes in casein composition of goats' milk during the course of lactation: physiological inferences and technological implications.
MedLine Citation:
PMID:  7593829     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Five British Saanen goats were milk sampled during the first 39 weeks of lactation to determine changes in casein composition. Caseins were separated by anion- and cation-exchange FPLC to determine the relative amounts of the individual caseins. Acid, alkaline and SDS-PAGE were used to determine possible genetic polymorphisms and observe any lactational changes. Total casein nitrogen was determined using a micro-Kjeldahl method and this allowed the concentrations of individual caseins to be calculated. The milk of one animal, which had the deduced genotype alpha s1-CnAB, showed higher concentrations of both total and alpha s1-casein. The remainder of the group were either heterozygous alpha s1-CnBE or, more probably, homozygous alpha s1-CnE and produced milk of a generally lower protein concentration. Both FPLC and PAGE results showed that the relative amounts and concentrations of alpha s2-casein decreased with stage of lactation, consistent with its susceptibility to proteolysis. The relative amounts of the breakdown products of plasmin attack on beta-casein, gamma-caseins, were highly negatively correlated with milk yield (r = -0.942, P < 0.001) in the declining phase of lactation, reflecting the gradual involution of the gland at this time. The relative amount of kappa-casein increased by approximately 50% after peak lactation and its concentration almost doubled near the end of lactation. These compositional changes may alter the processing qualities of goats' milk in relation to cheese production.
Authors:
J R Brown; A J Law; C H Knight
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of dairy research     Volume:  62     ISSN:  0022-0299     ISO Abbreviation:  J. Dairy Res.     Publication Date:  1995 Aug 
Date Detail:
Created Date:  1995-12-07     Completed Date:  1995-12-07     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  2985125R     Medline TA:  J Dairy Res     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  431-9     Citation Subset:  IM    
Affiliation:
Hannah Research Institute, Ayr, UK.
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MeSH Terms
Descriptor/Qualifier:
Animals
Anions
Caseins / metabolism*
Cations
Chromatography, High Pressure Liquid
Electrophoresis, Polyacrylamide Gel
Female
Goats / physiology*
Hydrogen-Ion Concentration
Lactation / physiology*
Milk / metabolism*
Nitrogen / analysis
Time Factors
Chemical
Reg. No./Substance:
0/Anions; 0/Caseins; 0/Cations; 7727-37-9/Nitrogen

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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