New Zealand Journal of Agricultural Research abstracts
Partial replacement of corn grain with calcium salts of fatty acid
in the concentrate fed to grazing primiparous and multiparous dairy
cows
G. F. Schroeder
Consejo Nacional de Investigaciones
Científicas y Técnicas (CONICET)
Argentina
G. A. Gagliostro*
Instituto Nacional de Tecnología Agropecuaria
Estación Experimental Balcarce, CC 276, (7620)
Balcarce, Argentina
ggagliostro@balcarce.inta.gov.ar
*Author for correspondence.
Abstract The effects of the partial
replacement of corn grain
with calcium salts of unsaturated fatty acids (CSFA) on milk yield and
composition, milkfatty acid profile and parameters linked to body lipid
mobilisation were examined in 32 multiparous (MC) and 18 primiparous
(PC) grazing cows in early lactation. Cows grazed a lucerne pasture and
received a concentrate composed (DM basis) of 4.5 kg day–1
of ground corn grain and 0.4 kg day–1 of fish meal
(Control)
or similar to Control but replacing 1.8 kg of corn grain with 0.8 kg of
CSFA (Fat). Pasture (14.3 kg cow–1 day–1), total
dry matter intake (18.5 kg cow–1 day–1) and
total
energy intake (32.6 Mcal NEL (net energy of lactation) cow–1
day–1) were not affected by dietary treatments or
parity.
Total energy consumed from the concentrates averaged 10.4 Mcal NEL
cow–1 day–1. Milk yield was increased in Fat on
PC (20.4 versus 22.2 kg day–1) but no effects were detected
on MC. Milkfat concentration was reduced (–2.4 g kg–1)
by Fat (P < 0.02). Fat-corrected milk (24.5 versus 21.2 kg day–1)
and milkfat yields (0.93 versus 0.76 kg day–1) were
decreased by feeding CSFA on MC, with no effects on PC. Milk
protein content was increased (31.9 versus 33.0 g kg–1) in
MC but decreased (32 versus 30.9 g kg–1) in PC by
CSFA. The lower fat-corrected milk and milkfat yields in MC fed
Fat lead to a higher (P < 0.05) estimated energy balance
(6.27 Mcal NEL day–1) compared to Control (1.11
Mcal NEL day–1) cows, but changes in body weight
gain (0.03–0.11 kg cow–1 day–1) were not
detected. In PC, body weight was reduced (–0.185 kg cow–1 day–1)
and this affect was not reduced by feeding unsaturated CSFA. Plasma
concentration of non-esterified fatty acids was higher in PC than MC
and not affected by CSFA either before (basal) or after the injection
of a lipolytic agent (isoproterenol). Plasma concentration of glucose,
urea and triglycerides were not affected by treatment or parity. Plasma
cholesterol concentration was similar between PC and MC cows and higher
in CSFA treatments. Concentration of de novo synthesised fatty
acids (C4:0 to C14:1) were decreased and that of
unsaturated long chain FA (C18:1, C18:2 and C18:3)
was increased by supplemental CSFA. Milkfat content of conjugated
linoleic acid (cis-9, trans-11, CLA) was increased
(+0.23 g 100 g–1) by CSFA only in MC. The partial
replacement of corn grain by unsaturated CSFA depressed fat-corrected
milk yield and improved the estimated energy balance in MC without
changes in parameters linked to body lipid mobilisation. The health
value of the milk for the consumer was improved through a reduction in
the hypercholesterolemic fraction of milkfat and the increase in milk
CLA content. PC responded to unsaturated fat feeding through an
increase in milk production without changes in fat-corrected milk.
Supplemental fat did not reduce parameters linked to body lipid
mobilisation. More studies are needed involving grazing PC to better
understand the potential benefits of unsaturated fat feeding in early
lactation.
Keywords fat supplementation; grazing dairy
cows; milkfat
composition
A06073; Online publication date 15 October 2007, Received 23
December 2006; accepted 31 May 2007
New Zealand Journal of Agricultural Research, 2007, Vol. 50:
437–449
0028–8233/07/5004–437 © The Royal Society of New Zealand 2007
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