Table 3. Effects of different inorganic : organic zinc ratios or combination of low crude protein diet and mixed feed additives on nutrient digestibility and zinc utilization in weaned piglets

Treatment	NC	PC	T1	T2	T3	T4	SE	p-value
Nutrient digestibility
One week ATTD (%)
Dry matter¹⁾²⁾	86.7^c	88.2^b	88.9^ab	89.8^a	89.1^ab	89.2^ab	0.5	0.001
Nitrogen¹⁾	77.1^c	81.8^b	81.8^b	84.4^a	83.0^ab	81.6^b	0.8	0.001
Gross energy¹⁾²⁾	82.8^c	85.1^b	86.7^ab	87.4^a	85.5^b	86.3^ab	0.6	0.001
Two week ATTD (%)
Dry matter¹⁾	87.6^b	89.8^a	89.7^a	89.9^a	90.5^a	90.3^a	0.4	0.001
Nitrogen¹⁾	77.8^b	81.0^a	80.4^a	81.3^a	82.2^a	81.7^a	0.8	0.017
Gross energy¹⁾	83.3^b	86.4^a	86.4^a	86.9^a	87.7^a	87.3^a	0.6	0.001
Zinc utilization
One week
Feed intake (g)	340.0	340.0	340.0	340.0	340.0	340.0	0.0	1.000
Zinc intake (mg)¹⁾²⁾³⁾	34.0^c	382.5^a	374.0^a	340.0^b	340.0^b	34.0^c	3.1	0.001
Zinc excretion (mg)¹⁾²⁾³⁾	32.3^d	344.8^a	299.2^b	264.5^c	253.7^c	29.2^d	7.5	0.001
ATTD of zinc¹⁾²⁾³⁾	5.1^d	9.6^c	19.9^ab	22.3^ab	25.3^a	14.2^bc	2.7	0.001
Two week
Feed intake (g)¹⁾²⁾³⁾	350.0^c	380.0^a	380.0^a	370.0^b	380.0^a	350.0^c	0.0	0.001
Zinc intake (g)¹⁾²⁾³⁾	35.0^c	427.5^a	418.0^a	370.0^b	380.0^b	35.0^c	2.4	0.001
Zinc excretion (mg)¹⁾²⁾³⁾	31.4^c	381.1^a	349.3^a	298.6^b	291.8^b	29.5^c	10.6	0.001
ATTD of zinc¹⁾²⁾	10.4^b	10.9^b	16.4^ab	19.3^ab	23.2^a	15.8^ab	3.2	0.045
AID of zinc (%)¹⁾²⁾	8.9^c	9.3^c	14.1^b	18.1^ab	21.1^a	14.1^b	1.5	0.001

NC, no additional added zinc oxide in diet (negative control); PC, NC+1,000 mg/kg zinc oxide (positive control); T1, NC + inorganic : organic zinc 850 : 150 mg/kg; T2, NC + inorganic : organic zinc 700 : 300 mg/kg; T3, NC + inorganic : organic zinc 500 : 500 mg/kg; T4, 10% reduced crude protein diet + 0.1% essential oil + 0.08% protease + 0.02% xylanase.
Contrast: NC vs other treatments ( p < 0.05).
Contrast: PC vs T1, T2, and T3 ( p < 0.05).
Contrast: T4 vs T1, T2, and T3 ( p < 0.05).
Means in the same row with different superscripts differ ( p < 0.05).
ATTD, apparent total tract digestibility; AID, apparent ileal digestibility.