In vitro investigations on the use of non-nutritive sorbent additives to sequester boar taint compounds

Abstract Text: The objective of this study was to explore the effectiveness of four (4) low-cost feed additives with adsorbing capacities against androstenone and assess for their feasibility as dietary interventions to control boar taint. Boar taint is an unsavory odor and taste detected from pork of some intact male pigs when cooked, caused by high accumulation of the sex steroid androstenone and the indole skatole. Available research exploring dietary approaches to control androstenone is scarce. Candidate additives (bentonite, BNT; diatomaceous earth, DE; spent filter aid, SFA; and sodium-calcium aluminosilicate, JUMP) have all been found to be effective treatments against aflatoxin B1 and zearalenone in the gut of pigs and chickens as dietary supplementation. Each was used to bind radiolabeled androstenone (AND), estrone (E1), and estrone sulfate (E1S) from buffer solutions in a pH 7.4 in vitro system developed in our laboratory (n=4). Michaelis-Menten enzyme kinetics was used to analyze binding effectiveness, expressed as Bmax (maximum binding) and Km (amount of additive required to reach 50% of Bmax). Tukey’s range test was performed for statistical significance with SAS (SAS Institute, Cary, NC). All tested additives demonstrated high Bmax against AND, with BNT being the most effective binder of both AND and E1 (Table 1). Most additives also appear to exhibit selective binding between steroids, with the highest difference seen between binding of AND versus E1S (P<0.05). We conclude that all four additives tested in this experiment effectively bound androstenone under in vitro conditions, and that further research involving animal models is warranted to explore their effectiveness and selectivity in the gastrointestinal tract of pigs to control boar taint.

Table 1.  Michaelis-Menten parameters (value ± SEM) of four adsorbents against steroids AND, E1, and E1S. Letters represent statistical significance between treatments within bound steroid (P<0.05); values with numbers indicate no difference across bound steroids within each treatment (P>0.05).

		Bmax (%)	Km (µg/mL)
AND	BNT	87.1 ± 0.08a	17.1 ± 2.1a,1
	DE	80.6 ± 0.5b	14.5 ± 1.9ab
	SFA	74.5 ± 0.2c	9.1 ± 2.1b,3
	JUMP	82.2 ± 0.2d	22.1 ± 0.2a
E1	BNT	66.9 ± 0.1a	14.1 ± 0.03a,1
	DE	59.0 ± 0.1b	0 ± 0b,2
	SFA	72.6 ± 0.5c	15.1 ± 1.8a,3
	JUMP	59.0 ± 0.4b	0.5 ± 0.1b,4
E1S	BNT	49.4 ± 0.6	0.03 ± 0.03
	DE	48.8 ± 0.6	0.01 ± 0.012
	SFA	49.7 ± 0.5	0.2 ± 0.1
	JUMP	49.7 ± 0.1	0.8 ± 0.14

Keywords: boar taint