. 2023 Aug 17;13(16):2650. doi: 10.3390/ani13162650

Table 2.

Effects of immunocastration and dietary protein level on plasma free amino acid (AA) concentrations (µmol/L) of male and female Iberian pigs.

	Sex Group ¹			Dietary Protein ²				p-Value ³
	IC Males	SC Males	IC Females	LP	MP	HP	SEM	Sex	Dietary Protein
Essential AA
Arginine	102	99	107	106	106	96	6	0.634	0.441
Histidine	37 ^a	28 ^b	33 ^ab	34	33	31	2	<0.01	0.498
Isoleucine	228 ^a	217 ^a	192 ^b	210	210	217	7	<0.01	0.657
Leucine	249	259	245	254	251	248	8	0.406	0.887
Lysine	161	172	163	172	176	147	9	0.618	0.051
Methionine	25	26	22	26	26	21	2	0.335	0.105
Phenylalanine	50	49	51	51	50	49	2	0.699	0.427
Threonine	80	84	81	84	82	80	6	0.846	0.838
Tryptophan	11	11	12	13	11	11	1	0.954	0.453
Valine	564 ^a	501 ^b	460 ^b	508	507	510	18	<0.001	0.992
Branched-chain AA	1041 ^a	977 ^ab	897 ^b	971	968	976	30	<0.01	0.984
Σ essential AA	1507	1447	1364	1457	1452	1408	47	0.096	0.705
Non-essential AA
Alanine	335 ^b	345 ^b	412 ^a	357	390	344	22	<0.05	0.300
Anserine	112	103	113	108	118	102	6	0.446	0.191
Aspartic acid	14	15	14	16	14	14	1	0.713	0.348
Glutamine	205	204	221	214	221	195	10	0.402	0.155
Glutamic acid	441	495	502	518	470	450	28	0.225	0.207
Glycine	446	463	527	470 ^b	539 ^a	426 ^b	27	0.093	<0.05
Hydroxiproline	23	27	25	24	26	25	2	0.386	0.827
Ornithine	38	42	42	42	43	36	3	0.410	0.131
Proline	210 ^b	296 ^a	307 ^a	270	294	249	25	<0.05	0.463
Phosphoserine	11 ^c	16 ^b	25 ^a	18	17	17	2	<0.001	0.939
Serine	107	104	119	107	115	108	5	0.099	0.521
Taurine	131 ^b	174 ^a	168 ^a	152	164	157	7	<0.001	0.446
Tyrosine	67	72	72	75	71	65	3	0.409	0.055
Σ non-essential AA	2141 ^b	2355 ^ab	2547 ^a	2372	2482	2189	91	<0.01	0.072
Proteinogenic AA	3232	3340	3431	3379	3460	3163	106	0.398	0.122
Non-proteinogenic AA	417 ^b	461 ^ab	480 ^a	449	474	434	18	<0.05	0.281
Σ total AA	3648	3801	3911	3829	3934	3597	121	0.287	0.126

¹ IC males = immunocastrated males, SC males = surgically castrated males, IC females = immunocastrated females; n = 54 pigs (9 treatments × 6 pigs per treatment). ² LP = low CP diet (119 g CP/kg DM); MP = medium-CP diet (137 g CP/kg DM); HP = high-CP diet (153 g CP/kg DM). ³ Interaction sex group × dietary crude protein (CP) was never significant. a–c Values within a row with different superscripts differ significantly at p < 0.05.