Evaluation of Dietary Electrolyte Balance on Nursery Pig Performance

A recent study observed nursery pigs fed increasing dietary electrolyte balance (dEB) (exceeding 150 mEq/kg) had decreased growth performance. To confirm this response, pigs (n=2,888; PIC 327×L42; initial BW 5.2 kg) were used in a 35d study to evaluate the effects of dEB on growth performance. There were 30 pigs/pen (60 pigs/double-sided feeder) and 12 replications (feeder)/treatment. Pens of pigs were allotted by BW and sex on arrival, and randomly assigned to 1 of 4 dietary treatments. Diets were corn-soybean meal-based with dried whey and other specialty protein sources used in Phase 1 with decreased amounts in Phase 2. Dietary electrolyte balance was determined using the equation: dEB, mEq/kg = (Na*434.98)+(K*255.74)–(Cl*282.06). Phase 1 and 2 diets had dEBs of 84, 137, 190, and 243; and 29, 86, 143, and 199 mEq/kg, respectively. Limestone was used as the main Ca source in the high dEB diet and was replaced by increasing CaCl₂ in other experimental diets. The highest dEB diets required additions of 0.55 and 0.80% limestone for Phase 1 and 2, respectively. The lowest dEB diets were achieved by adding 1.17% and 1.25% CaCl₂ in Phase 1 and Phase 2, respectively. Dietary Ca concentrations were maintained in the three highest dEB diets, but increased in the low dEB diet with the increasing level of CaCl₂. From d 21 to 35, a common Phase 3 diet (257 mEq/kg) was fed to all pigs. Overall (d 0 to 35), increasing dEB from d 0 to 21 increased (linear, P<0.001) ADG and final BW, which was the result of increased (quadratic, P<0.001) G:F and a tendency for greater (linear, P=0.077) ADFI. In contrast to the previous research, this study suggests feeding increasing dietary dEB in nursery diets increased growth performance of weanling pigs.

	mEq/kg					Probability, P <
Phase 1:	84	137	190	243
Phase 2:	29	86	142	199	SEM	Linear	Quadratic
d 0	5.19	5.19	5.20	5.17	0.053	0.704	0.502
d 21	9.40	9.78	10.01	10.21	0.084	<0.001	0.179
d 35	15.56	15.74	15.94	16.02	0.120	<0.001	0.543
d 0-21
ADG, g	193	211	219	235	3.3	<0.001	0.807
ADFI, g	252	256	253	268	3.9	0.003	0.103
G:F	0.77	0.83	0.87	0.87	0.008	<0.001	<0.001
d 0-35
ADG, g	290	295	299	306	3.4	<0.001	0.736
ADFI, g	388	390	391	397	4.8	0.077	0.594
G:F	0.76	0.78	0.80	0.80	0.005	<0.001	0.030