Abstract
Grassland management could offer means to produce milk with naturally higher concentrations of unsaturated fatty acids (FA) such as conjugated linoleic acid (CLA). Regrowth stage and N fertilization affect the concentration of FA in grasses, which could affect milk FA. Four paddocks were split and received either 73 or 37 kg N ha -1 ; herbage was subsequently cut daily from 25 to 43 days of regrowth. Two groups of 18 cows were stall-fed during these 19 days with either high or low N fertilized grass. FA concentrations in the herbage and the CLA concentration in the milk were monitored. The high N fertilized plots had a higher herbage mass, but there was no difference in herbage N or FA concentration. There was a negative effect of days of regrowth on the FA concentration in grass, which was associated with a lower CLA concentration in the milk. In general there was no effect of N treatment on milk CLA concentration. Only during the last two days of the experiment, when there was a very large difference in herbage mass between the N treatments (2000 vs. 4000 kg DM ha -1 ), the CLA concentration was significantly (P < 0.05) higher in milk of cows fed grass from the low N treatment. This could be a result of the lower herbage yield and NDF content. The lack of effect of N fertilizer treatment on milk FA composition may be due to the fact that treatments surprisingly did not differ in grass N content. During the final days, effects were confounded with changes in other chemical composition variables. The negative effect of grass regrowth stage on herbage FA and milk CLA concentration confirmed our hypotheses.
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Claims 6
Claim · model-written summary
High N fertilized perennial ryegrass plots had a higher herbage mass.
- Taxon
- perennial ryegrass
Lolium perennet0 - Treatment
- high N fertilizede0
- Outcome
- herbage masse0
- Direction
- highere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The high N fertilized plots had a higher herbage mass”
t0“perennial ryegrass”
Claim · model-written summary
There was no difference in herbage N or fatty acid concentration between high N fertilized and low N plots.
- Taxon
- perennial ryegrassLolium perennet0
- Treatment
- high N fertilizede1
- Outcome
- herbage N or FA concentratione1
- Direction
- no differencee1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“The high N fertilized plots had a higher herbage mass, but there was no difference in herbage N or FA concentration”
t0“perennial ryegrass”
Claim · model-written summary
Increasing days of regrowth had a negative effect on fatty acid concentration in the grass.
- Taxon
- perennial ryegrassLolium perennet0
- Treatment
- days of regrowthe2
- Outcome
- FA concentration in grasse2
- Direction
- negative effecte2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“There was a negative effect of days of regrowth on the FA concentration in grass”
t0“perennial ryegrass”
Claim · model-written summary
The lower grass FA concentration with days of regrowth was associated with a lower CLA concentration in the milk.
- Taxon
- perennial ryegrassLolium perennet0
- Treatment
- days of regrowthe3
- Outcome
- CLA concentration in the milke3
- Direction
- lowere3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e3“There was a negative effect of days of regrowth on the FA concentration in grass, which was associated with a lower CLA concentration in the milk”
t0“perennial ryegrass”
Claim · model-written summary
In general there was no effect of N treatment on milk CLA concentration.
- Taxon
- perennial ryegrassLolium perennet0
- Treatment
- N treatmente4
- Outcome
- milk CLA concentratione4
- Direction
- no effecte4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e4“In general there was no effect of N treatment on milk CLA concentration”
t0“perennial ryegrass”
Claim · model-written summary
During the last two days, milk CLA concentration was significantly higher in cows fed grass from the low N treatment.
- Taxon
- perennial ryegrassLolium perennet0
- Treatment
- low N treatmente5
- Outcome
- CLA concentratione5
- Direction
- highere5
- Qualifier
- P < 0.05e5
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e5“the CLA concentration was significantly (P < 0.05) higher in milk of cows fed grass from the low N treatment”
t0“perennial ryegrass”
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