Effect of feeding different sources of nitrogen on performance of growing pigs fed diets deficient in non-essential amino acid nitrogen

Abstract Text:

When formulating diets with low nitrogen (N) content, the supply of dietary non-essential amino acids (NEAA) is reduced and essential amino acid (EAA) may be catabolized to supply N for endogenous synthesis of NEAA, which can lead to compromised pig performance.  The objective of this study was to evaluate the effect of supplementing different sources of N in diets deficient in NEAA-N on performance of growing pigs.  In total 36 barrows (BW 15.5 ±1.0 kg) were randomly assigned to 9 different diets: a basal cornstarch and casein-based diet, not deficient in EAA but low in CP (N x 6.25; 8.01%); and the basal diet supplemented with 4 different sources of N (urea, ammonium citrate, glutamic acid and a mix of NEAA) at 2 levels each, supplying 1.37 and 2.75% additional CP, respectively.  The mix of NEAA was based on body composition of NEAA of 20 kg pigs, and aimed to minimize endogenous synthesis of NEAA.  Pigs were housed individually and fed at 3.0 x maintenance requirement for ME during 3 consecutive weeks.  BW gain was monitored weekly.  BW gain and gain:feed of pigs fed urea were lower than any other sources of N (P < 0.05), but they were similar across the other treatments (P > 0.10).  As the level of N increased, BW gain and gain:feed increased (P < 0.05).  Feeding ammonium to pigs is as efficient as supplementing glutamate or NEAA mix to support growth performance when diets are deficient in NEAA-N, while utilization of urea-N is lower.

Table 1.    BW gain, feed intake and gain:feed in growing pigs fed a diet deficient in NEAA-N supplemented with different sources of N at different levels of N supplementation.

		BW gain, g/d	Feed intake, g/BW0.6/d	Gain:feed
Source	Urea	367a	169	0.381a
	Ammonia	399b	169	0.415b
	Glutamate	404b	169	0.421b
	NEAA mix	402b	169	0.418b
	SEM	7.5	0.1	0.008
Level	0.0	363a	169	0.378a
	1.37	387b	169	0.403b
	2.75	429c	169	0.445c
	SEM	6.4	0.01	0.007
P-value	Source	0.006	0.219	0.004
	Level	<0.001	0.286	<0.001
	Interaction	0.070	0.247	0.069

^a,b,c Values in the same column followed by different superscripts differ (P < 0.05)

Keywords: growth, nitrogen, pig