Effect of legume-grass silages and alpha-tocopherol supplementation on fatty acid composition and alpha-tocopherol, beta-carotene and retinol concentrations in organically produced bovine milk

Sammanfattning

Two feeding experiments were performed to study the effects of silage botanical composition, regrowth interval and α-tocopherol supplementation on the fatty acid (FA) composition and α-tocopherol, β-carotene and retinol concentrations of milk. In experiment 1, 24 Swedish Red dairy cows were fed two- or three-cut red clover-grass silages (R2 and R3, respectively), or two-cut birdsfoot trefoil-grass silage (B2). In experiment 2, 16 Norwegian Red dairy cows were fed short-term ley silage with red clover (S3) or long-term ley silage with white clover (L3) in combination with supplementation of RRR-α-tocopheryl acetate (1,600 mg/day). The FA proportions in the milk and the recoveries of C18:2n-6 and C18:3n-3 were higher on the red clover diets R2, R3 and S3 than on B2 and L3 and the n-6/n-3 FA ratio was also higher on the red clover diets. Because the concentrate used in experiment 1 had a higher FA concentration and a higher proportion of c9-C18:1 than that of the concentrate used in experiment 2, milk proportions of C16:0 were lower and those of c9-C18:1 were higher in experiment 1 than experiment 2 regardless of diet. Shorter regrowth interval increased both the concentration of FA in silage and the proportion of unsaturated FA in milk. Intakes of α-tocopherol, β-carotene and lutein were higher on B2 than on R2 due to higher silage intake on B2. However, highest intake was on diet R3 due to a shorter regrowth interval between the cuts. In experiment 2, intakes of α-tocopherol, β-carotene and lutein were higher on L3, mainly because of the botanical composition of the silage. However, not all of these differences affected the milk, since the only significant differences in the two experiments were a higher milk α-tocopherol concentration on L3 than on S3 and a slightly higher β-carotene concentration on R2 and R3 than on B2. Supplementation with α-tocopherol increased milk α-tocopherol concentrations from 0.77 to 1.05 and from 1.07 to 1.24 mg/kg milk for S3 and L3, respectively, but did not affect milk FA composition. The botanical composition of silage and regrowth interval had clear effects on silage FA and antioxidant concentration and composition. However, in the milk these differences were reduced due to relatively low recovery of unsaturated FA and antioxidant from feed to milk. Nevertheless, higher concentrations of antioxidants in the feed might still be beneficial as a larger proportion of the animal’s vitamin requirements would be met by the forage.

Nyckelord

Linoleic acid; Linolenic acid; Carotenoid; Legume; Trifolium ssp.; Fat-soluble vitamin

Publicerad i

Livestock Science
2012, Volym: 148, nummer: 3, sidor: 268-281 Utgivare: ELSEVIER SCIENCE BV

SLU författare

• Martinsson, Kjell

  • Institutionen för norrländsk jordbruksvetenskap, Sveriges lantbruksuniversitet
    

• Gustavsson, Anne-Maj

  • Institutionen för norrländsk jordbruksvetenskap, Sveriges lantbruksuniversitet
    

• Höjer, Annika

  • Institutionen för norrländsk jordbruksvetenskap, Sveriges lantbruksuniversitet
    

UKÄ forskningsämne

Livsmedelsvetenskap
Jordbruksvetenskap


Publikationens identifierare

DOI: https://doi.org/10.1016/j.livsci.2012.06.016

Permanent länk till denna sida (URI)

https://res.slu.se/id/publ/40002