1825
Milk fatty acid profile of dairy cows grazing a tropical pasture supplemented with sources of rumen protected fat
The objective of this experiment was to investigate the effects of supplementation of early lactation dairy cows grazing a tropical pasture with diets containing calcium salts of palm oil (CSPO) or calcium salts of soybean oil (CSSO) on milk fatty acid profile. Twenty-seven cows (15 ± 3 DIM) were used in a randomized block design and subjected to the following treatments: a) control (no fat); b) 400 g CSSO cow-1 d-1; c) 400 g CSPO cow-1 d-1. Cows grazed paddocks of Pennisetum purpureum and received 8 kg cow-1 d-1 (DM) of concentrate twice daily. Treatment periods were 90 d in length and milk samples were taken at 30, 60 and 90 d of experimental period for milk fatty acid analysis by gas chromatography. Data were analyzed as repeated measures using a mixed model with block as random effect and means were compared by Tukey test. The CSSO increased C18:2 cis-9 trans-12, CLA cis-9 trans-11 and CLA trans-10 cis-12 in the milk fat compared with control and CSPO. Both fat sources increased C18:3 cis-9 cis-12 cis-15 in the milk fat. The de novo synthesis was reduced by both fat sources and the CSPO increased mixed fatty acids (C16 + C16:1), due to greater incorporation of C16 from the diet. The preformed fatty acids were increased by CSSO supplementation. The CSSO decreased total saturated fatty acids, and increased MUFA and PUFA compared to control and CSPO. Overall, both sources of fat changed the milk fatty acid profile, and CSSO increased unsaturated fatty acid whereas CSPO increased saturated fatty acids.
Table 1. Milk fatty acid profile of grazing dairy cows supplemented with fat.
g/100g of fat |
Control |
CSSO |
CSPO |
SEM |
P value |
C18:2 cis-9 trans-12 |
1.66 c |
2.07 a |
1.92 b |
0.09 |
0.002 |
C18:3 cis-9 cis-12 cis-15 |
0.33 b |
0.43 a |
0.39 a |
0.02 |
0.07 |
CLA cis-9 trans-11 |
0.66 b |
0.86 a |
0.69 b |
0.05 |
0.005 |
CLA trans-10 cis-12 |
0.02 b |
0.09 a |
0.019 b |
0.003 |
0.0001 |
De novo |
25.6 a |
20.8 b |
21.4 b |
0.99 |
0.005 |
Mixed |
30.7 b |
30.2 b |
33.9 a |
1.4 |
0.04 |
Preformed |
43.7 b |
49.0 a |
44.7 b |
2.2 |
0.04 |
Total of saturated |
66.9 a |
61.5 b |
64.1 a |
1.76 |
0.01 |
Total of MUFA |
28.9 b |
33.6 a |
31.6 ab |
1.3 |
0.04 |
Total of PUFA |
4.2 b |
4.9 a |
4.3 b |
0.24 |
0.02 |
Keywords: palm oil, soybean oil, tropical pasture