1877
Potassium carbonate as a cation supplement to increase dietary cation anion difference and improve dairy feed efficiency in lactating dairy cows
Supplementation with potassium carbonate (K2CO3) increases dietary cation anion difference (DCAD) which results in increased dairy feed efficiency. Our previous study with early lactating Holstein cows showed that increasing DCAD from approximately 250 to 400 meq/kg (Na-K-Cl Equation, DM basis) resulted in a linear increase in 3.5% FCM/DMI [feed efficiency (FE)]. However, the optimal DCAD for maximal FE could not be determined as the maximal FE response was achieved at a DCAD of 400 meq/kg. The objective of this study was to determine the optimal DCAD required for maximal DMI, milk production and FE using a broader range in dietary DCAD concentrations. Twenty Holstein cows (8 primiparous and 12 multiparous) averaging 95 (± 25) DIM were individually fed a basal diet containing 64% corn silage, 6% alfalfa hay, and 30% concentrate (DM basis). Dietary treatments consisted of 250 (basal), 375, 500, and 625 meq/kg DCAD where K2CO3 was added to the basal diet to obtain the desired DCAD concentrations. The treatments were applied in a 4 x 4 Latin square design with 3-wk experimental periods. Dietary treatments had no effect on milk production or milk protein concentration. Increasing DCAD from 250 to 625 meq/kg linearly increased DMI (P = 0.007) and milk fat percentage (P < 0.001), while 3.5% FCM increased curvilinearly (linear, P = 0.008; quadratic, P = 0.037) with increasing DCAD. There was a quadratic trend (P= 0.085) for dairy FE where maximal FE occurred at DCAD concentrations of 375 and 500 meq/kg. The optimal DCAD for DMI and fat percent could not be determined since maximums occurred at a DCAD of 625 meq/k. FE and 3.5% FCM were optimized at a DCAD concentration of 442 meq/kg. Results of this and other studies in our laboratory show that DCAD can be used to increased feed efficiency to help dairy producers reduce feed costs and improve profitability.
TABLE 1. Effects of DCAD concentration on production parameters.
DCAD, meq/kg |
P < |
|
|||||||
Item |
250 |
375 |
500 |
625 |
SEM |
Linear |
Quadratic |
||
DMI, kg/d |
22.3 |
22.9 |
23.1 |
23.6 |
0.52 |
0.007 |
0.902 |
||
Milk, kg/d |
38.9 |
39.5 |
39.5 |
38.8 |
1.52 |
0.937 |
0.228 |
||
Fat, % |
3.28 |
3.50 |
3.50 |
3.62 |
0.146 |
0.001 |
0.418 |
||
Protein, % |
2.95 |
2.99 |
2.95 |
2.92 |
0.056 |
0.167 |
0.152 |
||
3.5% FCM, kg/d |
37.1 |
39.2 |
39.2 |
39.1 |
0.98 |
0.008 |
0.037 |
||
FE, 3.5%FCM/DMI |
1.67 |
1.71 |
1.71 |
1.66 |
0.038 |
0.759 |
0.085 |
||
Keywords: DCAD, Feed Efficiency, Dairy Cows