Effects of Dietary Salt Concentration on Performance of 7 to 10 Kg Nursery Pigs

Two experiments evaluated the effects of added salt and Na on growth performance of 7 to 10 kg pigs. In both experiments, pigs were weaned at 21 d of age and allotted to pens by BW and gender in a randomize block design. After a 7-d common period, experimental diets were fed for 14 d. In Exp. 1, 325 barrows (DNA 200×400; initially 6.6 kg BW) were assigned to 1 of 5 dietary treatments with 13 replications/treatment and 5 pigs/pen. Dietary treatments included 10% dried whey, corn-soybean meal-based diets with 0, 0.2, 0.4, 0.6, or 0.8% added salt. Increasing salt increased (linear, P=0.015) ADG (194, 216, 234, 254, and 253 g/d, respectively) and ADFI (309, 305, 319, 326, and 334 g/d, respectively) while G:F (0.626, 0.705, 0.732, 0.779, and 0.758, respectively) improved (quadratic, P=0.019) up to 0.6% added salt (0.37% Na and 0.75% Cl). In Exp. 2, 360 pigs (DNA 241×600; initially 6.9 kg BW) were assigned to 1 of 4 dietary treatments with 15 replications/treatment and 6 pigs/pen. Four experimental diets included a 10% dried whey diet with 0.6% added salt (0.37% Na and 0.75% Cl); or 3 diets with 7.2% crystalline lactose containing either: 0.35% added salt (0.18% Na and 0.47% Cl); 0.78% added salt (0.35% Na and 0.72% Cl); or 1.15% potassium chloride and 0.4% sodium bicarbonate (0.35% Na and 0.45% Cl). Pigs fed the dried whey diet with 0.6% added salt or crystalline lactose diet with 0.78% added salt had increased (P=0.05) ADG compared to pigs fed crystalline lactose with 0.35% added salt. Pigs fed the dried whey diet with 0.6% added salt had greater (P=0.05) ADFI than those fed the crystalline lactose diet with 0.35% added salt, with other treatments intermediate. There was no evidence that feed efficiency was affected by dietary treatment. In conclusion, ADG and ADFI of 7 to 10 kg pigs were enhanced with a dietary Na concentration of at least 0.35%.

Exp. 2 (d 0-14):
Lactose source:	Whey	Lactose	Lactose	Lactose	SEM	P<
Na source:	0.6% salt	0.35% salt	0.78% salt	KCl and NaHCO3
ADG, g	281a	251b	287a	270ab	9.5	0.038
ADFI, g	445a	390c	427ab	408bc	11.2	0.004
G:F, g/kg	631	643	671	661	13	0.075
abc Means with different superscripts differ P<0.05.