Table 5.

Least square means for growth performance of nursery pigs fed increasing standardized total tract digestible (STTD) P from 11- to 23-kg body weight (BW), Exp. 2¹

	STTD P2, %3
	0.30	0.33	0.38	0.43	0.48	0.53	0.58		Probability, P
Item4  % of NRC5	90	100	115	130	145	160	175	SEM	Linear	Quadratic
Days 0 to 21
ADG, g	515	523	539	549	547	542	545	8.6	<0.001	0.009
ADFI, g	747	749	753	768	773	770	762	15.4	0.060	0.198
G:F, g/kg	691	700	716	715	708	706	716	5.6	0.002	0.027
STTD P, g/d	2.24	2.47	2.86	3.30	3.71	4.07	4.42	0.072	<0.001	0.321
STTD P, g/kg gain	4.34	4.72	5.31	6.01	6.79	7.51	8.10	0.049	<0.001	0.223
BW, kg
d 0	11.1	11.1	11.1	11.1	11.1	11.1	11.1	0.24	0.978	0.990
d 21	22.0	22.2	22.5	22.7	22.6	22.6	22.6	0.39	0.028	0.125

¹A total of 2,140 pigs (PIC 337 × Camborough, initial pen average BW of 11.1 ± 0.24 kg) were used in a 21-d growth trial with 24 to 27 pigs per pen and 12 pens per treatment. Pigs were weaned at approximately 19 d of age, fed a common phase 1 and phase 2 diets for 25 d postweaning, then fed experimental diets. Low (0.30% STTD P) and high (0.58% STTD P) diets were blended at the farm by a robotic feeding system to create the 0.33%, 0.38%, 0.43%, 0.48%, and 0.53% STTD P dietary treatments.

²STTD P = Standardized total tract digestible phosphorus.

³Phytase (Ronozyme HiPhos, DSM Nutritional Products, Parsippany, NJ) was included at 1000 FYT/kg releasing an assumed 0.15% avP and 0.132% STTD P.

⁴ADG = average daily gain; ADFI = average daily feed intake; G:F = gain-to-feed ratio; BW = body weight.

⁵The NRC requirement estimate for nursery pigs from 11 to 25 kg, expressed as a percentage of the diet, is 0.33% STTD P. Therefore, treatment concentrations represented 90%, 100%, 115%, 130%, 145%, 160%, and 175% of the NRC (2012) requirement.