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Apparent recovery of C18 polyunsaturated fatty acids from feed in cow milk: A meta-analysis of the importance of dietary fatty acids and feeding regimens in diets without fat supplementation

Khiaosa-ard, Ratchaneewan; Kreuzer, Michael and Leiber, Florian (2015) Apparent recovery of C18 polyunsaturated fatty acids from feed in cow milk: A meta-analysis of the importance of dietary fatty acids and feeding regimens in diets without fat supplementation. Journal of Dairy Science, 98, pp. 6399-6414.

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Summary

A meta-analysis was conducted using the results of 82 experiments (78 publications, 266 treatments) to investigate the importance of dietary C18 fatty acids (FA) and feeding regime for milk C18 FA profile and apparent recovery of selected FA relative to intake of these FA or their precursors. Feeding treatments based on lipid-supplemented diets were excluded. Feeding regimes were defined as grazing (including partial and full-time grazing, at dietary concentrate proportions from 0 to 44% dry matter (DM)), forage-based indoor feeding (> 65% forage of total DM intake, DMI) and concentrate-based indoor feeding (forage DMI ≤ 65% of DMI). Linoleic acid (LA), α-linolenic acid (ALA) and total C18 FA proportions in milk fat increased linearly with the respective dietary FA content in all feeding regimes tested. This effect was highest in the forage-based indoor feeding. Slopes were lowest for the grazing regimes, especially regarding ALA and the sum of all C18 FA while the intercepts of the prediction equations of milk ALA and total C18 FA proportions were highest for grazing regimes. This indicates that in grazing cows factors other than dietary FA contents determine the C18 FA composition of the milk fat. At equal dietary LA contents, the type of feeding regime showed no significant effect on LA proportion in milk fat. Milk fat proportions of rumenic acid (RA) and vaccenic acid (VA) were positively related to the sum of dietary ALA and LA contents. Grazing regimes led to the strongest enrichment of RA and VA in milk fat. The apparent recovery of ALA, LA and total C18 FA (secreted, % of intake), an estimate for transfer efficiency, decreased with increasing dietary content. This relationship followed a nonlinear decay function. When the dietary content of these FA exceeded a certain threshold (about 0.2, 0.8 and 2.8% of DM for ALA, LA and total C18 FA, respectively) the recovery in milk remained constant at about 5, 10 and 82% of the ingested ALA, LA and total C18 FA, respectively. At dietary proportions below 0.01% ALA and 1.5% total C18 FA of DM their apparent recovery in milk fat exceeded 100%. In conclusion, a general inverse relationship between dietary C18 FA and the corresponding apparent recovery in milk fat seems to exist. Within this frame, the impact of different types of feeding regimes to alter the eventual milk C18 FA profile varies. Among them, grazing appears to provide the most variable properties.


EPrint Type:Journal paper
Agrovoc keywords:
LanguageValueURI
Englishdiethttp://aims.fao.org/aos/agrovoc/c_2261
EnglishFatty acidshttp://aims.fao.org/aos/agrovoc/c_2818
EnglishPolyunsaturated fatty acidshttp://aims.fao.org/aos/agrovoc/c_29254
EnglishMilk fathttp://aims.fao.org/aos/agrovoc/c_4828
EnglishPasture feedinghttp://aims.fao.org/aos/agrovoc/c_17038
EnglishroughageUNSPECIFIED
EnglishConcentrateshttp://aims.fao.org/aos/agrovoc/c_1800
EnglishLinolenic acidhttp://aims.fao.org/aos/agrovoc/c_15993
Subjects: Animal husbandry > Production systems > Dairy cattle
Animal husbandry > Feeding and growth
Research affiliation: Switzerland > FiBL - Research Institute of Organic Agriculture Switzerland > Animal Husbandry and Breeding
Austria > Univ. VMU Wien
Switzerland > ETHZ - Agrarwissenschaften
ISSN:1525-3198
Deposited By: Leiber, Dr. Florian
ID Code:29262
Deposited On:15 Aug 2015 16:10
Last Modified:15 Aug 2015 16:10
Document Language:English
Status:Published
Refereed:Peer-reviewed and accepted

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