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Effect of short-term versus long-term grassland management and seasonal variation in organic and conventional dairy farming on the composition of bulk tank milk

Adler, Steffen A.; Jensen, S.K.; Govasmark, Espen and Steinshamn, Håvard (2013) Effect of short-term versus long-term grassland management and seasonal variation in organic and conventional dairy farming on the composition of bulk tank milk. Journal of Dairy Science, 96 (9), pp. 5793-5810.

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Summary

Bulk tank milk from 28 dairy farms was sampled every second month for 2 yr to assess the effects of grassland management, production system and season on milk fatty acid (FA) composition, concentrations of fat-soluble vitamins, Se, and milk sensory quality. Grassland management varied in terms of time since establishment. Short-term grassland management (SG) was defined as establishment or reseeding every fourth year or more often, and long-term grassland management (LG) was defined as less frequent establishment or reseeding. Fourteen organic (ORG) dairy farms with either short-term or long-term grassland management were paired with 14 conventional (CON) farms with respect to grassland management. Within ORG farms, SG farms differed from LG farms in herbage botanical composition, but not in concentrate FA concentrations, dry matter intake, or milk yield. Within CON farms, herbage composition, concentrate FA concentrations, dry matter intake, and milk yield showed no or insignificant variations. The ORG farms differed from CON farms in herbage botanical composition, concentrate FA concentrations, concentrate intake, and milk yield. Compared with ORG-LG farms, ORG-SG farms produced milk fat with higher proportions of C10:0 and C12:0 associated with higher herbage proportions of legumes (Fabaceae) and lower proportions of other dicotyledon families. Compared with milk from CON farms, milk fat from ORG farms had higher proportions of most saturated FA and all n-3 FA, but lower proportions of C18:0 and C18:1 cis-9 associated with higher forage proportion and differences in concentrations of FA in concentrates. Compared with the outdoor-feeding periods, the indoor feeding periods yielded milk fat with higher proportions of most short-chain and medium-chain FA and lower proportions of most C18-FA associated with grazing and higher forage proportions. Milk concentrations of α-tocopherol and β-carotene were lower during the grazing periods. Inclusion of fishmeal in organic concentrates may explain higher Se concentrations in organically produced milk. Milk sensory quality was not affected in this study. In conclusion, grassland management had minor effects on milk composition, and differences between ORG farms and CON farms may be explained by differences in concentrate intake and concentrate FA concentrations. Milk produced on ORG farms versus CON farms and milk produced during the outdoor versus indoor feeding periods had potential health benefits due to FA composition. In contrast, the higher milk-fat proportions of saturated FA in milk from ORG farms may be perceived as negative for human health.


EPrint Type:Journal paper
Keywords:dairy farm,grassland management, production system, milk composition
Agrovoc keywords:
LanguageValueURI
EnglishUNSPECIFIEDUNSPECIFIED
Subjects: Animal husbandry > Production systems > Dairy cattle
Crop husbandry > Production systems > Pasture and forage crops
Food systems > Food security, food quality and human health
Research affiliation: Denmark > AU - Aarhus University > AU, DJF - Faculty of Agricultural Sciences
Norway > NMBU - Norwegian University of Life Sciences
Norway > Bioforsk - Norwegian Institute for Agriculture and Environmental Research > Bioforsk Organic Food and Farming Division
ISSN:1525-3198
DOI:http://dx.doi:10.3168/jds.2012-5765
Deposited By: Steinshamn, Dr Håvard
ID Code:23130
Deposited On:18 Sep 2013 08:55
Last Modified:18 Sep 2013 08:55
Document Language:English
Status:Published
Refereed:Peer-reviewed and accepted

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