1712
Positive effect of fat supplementation in the early postpartum period can continue throughout lactation after fat supplementation ceases
Objective was to determine whether increased milk yield detected during the period of fat supplementation in early lactation would continue throughout lactation after supplemental fat was removed from the diet. Three studies were conducted at the University of Florida dairy farm in which Holstein cows produced more milk in response to fat supplementation in the early postpartum period. Experiments 1 and 2 had the same dietary treatments. Cows consumed a control diet without fatty acid (FA) supplementation, a diet supplemented with mostly saturated free FA (SFA; 1.9% of dietary DM), or a diet supplemented with Ca salts enriched with essential FA (EFA; 2.4% of dietary DM). In the first experiment, cows (n=74) were assigned randomly to treatments 56 d before calving and treatments were maintained until 90 DIM. In the second experiment, cows (n=30) were fed the same 3 dietary treatments from 15 to 106 DIM. In experiment 3, Holstein cows (n=39) were assigned to diets supplemented with a mixture of Ca salts of fish, safflower, and palm oils (1.4% of dietary DM) to create 3 supplemental ratios of 4, 5, or 6 parts of n-6 to 1 part of n-3 FA (R4, R5, and R6). Diets were fed from 15 to 105 DIM. Cows in experiment 2 and 3 had a covariate based on milk produced during the first 6 to 10 DIM. Milk production was recorded through 43 wk of lactation using AFI-MILK system. Orthogonal contrasts were used to test for effects of fat supplements during the fat-feeding period and for the complete lactation. In general, when fat supplementation improved or tended to improve milk production during the fat-feeding period, milk yield also was improved or tended to be improved for the whole lactation. Milk composition was minimally changed. Strategic feeding of FA during early lactation can benefit milk yield after fat is removed from the diet.
|
Treatments |
SEM |
P-value |
|||
Control |
SFA |
EFA |
(SFA+EFA) vs. Control |
EFA vs. SFA |
||
Experiment 1 |
Milk yield, kg/d |
|
||||
Fat supplement |
31.6 |
31.8 |
34.3 |
0.99 |
0.28 |
0.06 |
Full lactation |
29.1 |
28.0 |
30.6 |
1.00 |
0.85 |
0.05 |
Experiment 2 |
|
|
|
|
|
|
Fat supplement |
37.7 |
39.9 |
42.8 |
1.07 |
0.01 |
0.07 |
Full lactation |
31.5 |
34.5 |
34.1 |
1.26 |
0.08 |
0.84 |
|
Treatments |
SEM |
P-value |
|||
R4 |
R5 |
R6 |
Linear |
Quadratic |
||
Experiment 3 |
Milk yield, kg/d |
|
||||
Fat supplement |
46.4 |
44.7 |
43.0 |
0.98 |
0.02 |
0.98 |
Full lactation |
36.7 |
35.2 |
33.5 |
1.33 |
0.10 |
0.97 |
Keywords:
Dairy cow, fatty acids, milk yield