Potentials to differentiate milk composition by different feeding strategies 2009
 Slots T, Butler G, Leifert C, Kristensen T, Skibsted LH, Nielsen JH
 
Abstract
 To investigate the effect of the dietary intake of the cow on milk  composition, bulk-tank milk was collected on 5 occasions from  conventional (n = 15) and organic (n = 10) farms in Denmark and on 4  occasions from low-input nonorganic farms in the United Kingdom, along  with management and production parameters. Production of milk based on  feeding a high intake of cereals, pasture, and grass silage resulted in  milk with a high concentration of alpha-linolenic acid (9.4 +/- 0.2  mg/kg of fatty acids), polyunsaturated fatty acids (3.66 +/- 0.07 mg/kg  of fatty acids), and natural stereoisomer of alpha-tocopherol  (RRR-alpha-tocopherol, 18.6 +/- 0.5 mg/kg of milk fat). A milk  production system using a high proportion of maize silage, by-products,  and commercial concentrate mix was associated with milk with high  concentrations of linoleic acid (LA; 19.7 +/- 0.4 g/kg of fatty acids),  monounsaturated fatty acids (27.5 +/- 0.3 mg/kg of fatty acids), and a  high ratio between LA and alpha-linolenic acid (4.7 +/- 0.2). Comparing  these 2 production systems with a very extensive nonorganic milk  production system relying on pasture as almost the sole feed (95 +/- 4%  dry matter intake), it was found that the concentrations of conjugated  LA (cis-9, trans-11; 17.5 +/- 0.7 g/kg of fatty acids),  trans-11-vaccenic acid (37 +/- 2 g/kg of fatty acids), and  monounsaturated fatty acids (30.4 +/- 0.6 g/kg of fatty acids) were  higher in the extensively produced milk together with the concentration  of antioxidants; total alpha-tocopherol (32.0 +/- 0.8 mg/kg of milk  fat), RRR-alpha-tocopherol (30.2 +/- 0.8 mg/kg of milk fat), and  beta-carotene (9.3 +/- 0.5 mg/kg of milk fat) compared with the organic  and conventional milk. Moreover, the concentration of LA (9.2 +/- 0.7  g/kg of fatty acids) in milk from the extensive milk production system  was found to approach the recommended unity ratio between n-6 and n-3,  although extensive milk production also resulted in a lower daily milk  yield.
http://dx.doi.org/10.3168/jds.2008-1392
- Journal of Dairy Science
 
- Volume: 92
 
- Number: 5
 
- Pagination: 2057-2066
 
- Publisher: American Dairy Science Association
 
- Place Published: 1111 N DUNLAP AVE, SAVOY, IL 61874 USA
 
- Date: 01-05-2009
 
- Type of work: Research article
 
- ISBN/ISSN: 0022-0302, 1525-3198