. 2019 Oct 18;9(10):824. doi: 10.3390/ani9100824

Table 1.

Effects of environmental enrichment on tail damage ordered by type of enrichment (most successful types at the top of the table).

Enrichment	Other Enrichments Present	Fold Change						Description If ‘Other’	Means (Enr. vs. Ctrl)		Doc-Ked?	Stage	Ref
Enrichment	Other Enrichments Present	Severe Dam.		Mild Dam.		Other		Description If ‘Other’	Sev. Dam.	Mild Dam.	Doc-Ked?	Stage	Ref
Roughage
Suspended haylage ball (650 g/pen/day) at 1st wound	Suspended wooden sticks, straw	-		-		0.12	*	% pens >3 wounded pigs	-	-	No	W	[45]
Hay (60 g/pen twice daily)	Plastic & wooden objects (+ extras if damage occurred)	-		-		0.92	*	% pigs with partial tail loss	-	-	No	All	[33]
Corn silage (50 g/pen twice daily)	Plastic & wooden objects (+ extras if damage occurred)	-		-		0.84	*	% pigs with partial tail loss	-	-	No	All	[33]
Fabric
Wall-mounted hessian sacks pre- & post-weaning	Chain, plastic toy	0.19	*	-		-		-	3 vs. 16%	-	Yes	≤13 weeks	[34]
Separation of space
Mezzanine (adding 0.25 m² extra space)	Chain	∞	*	0.67	*	-		-	0 vs. 2%	2 vs. 3%	Yes	G-F	[37]
Hiding wall	Chain	∞	*	∞	*	-		-	0 vs. 2%	0 vs. 4%	No	G-F	[39]
Earth-like
Compost in overhead rack	No	0.09	*	-		-		-	1 vs. 10%		^?	G-F	[35]
Multiple
Suspended rope + paper prior to weaning only	Pre-wean: shavings + ball Post-wean: rope + plastic toy	0.31	*	1.31	*	-		-	10 vs. 32%	59 vs. 45%	No	W	[38]
Weekly changing objects ²	Wall-mounted chain	0.30	*	0.58	*	-		-	1 vs. 2%	2 vs. 4%	Yes	W +G-F	[36]
Plastic pipe + branched chain + fresh wood	Straw, wood shavings, chain	0.79	^NS	0.58	*	-		-	22 vs. 28%	22 vs. 38%	No	G-F	[32]
Suspended rope with sweet block, end on floor, at 1st wound	Suspended wooden sticks, straw	-		-		0.38	^#	% pens >3 wounded pigs	-	-	No	W	[45]
Wood
Horizontally suspended fresh wood	Straw, wood shavings, chain	1.07	^NS	0.39	*	-		-	30 vs. 28%	15 vs. 38%	No	G-F	[32]
Horizontal, frame mounted post	Chain (control group only)	1.31	^NS	0.47	^NS	-		-	17 vs. 13%	14 vs. 30%	No	W	[40]
Horizontal cylinder of compressed wood shavings	Chain (control group only)	∞	^NS	1.00	^NS	-		-	0 vs. 5%	18 vs. 18%	No	W	[40]
Alternative feeding
Pressed feed block, fixed to frame but rotatable	Chain (control group only)	∞	^NS	0.72	^NS	-		-	0 vs. 5%	13 vs. 18%	No	W	[40]
Pellets scattered on the floor	Chain, plastic ball	-		-		^?	^NS	Tail damage score	-	-	Yes	G-F	[41]
Suspended metal
Cross of chains	Straw, wood shavings, chain	0.57	^NS	1.05	^NS	-		-	16 vs. 28%	40 vs. 38%	No	G-F	[40]
Overhead rack		2.18	¹	-		-		-	22 vs. 10%		^?		[35]
Suspended plastic/rubber
Cross of polythene pipes	Straw, wood shavings, chain	0.61	^NS	1.05	^NS	-		-	17 vs. 28%	40 vs. 38%	No	G-F	[32]
Cross of rubber hose pipes	Chain (control group only)	-		-		0.93	^NS	% pens ≥1 wounded pig	-	-			[42]
Variable ³
Chains or objects	Variable	0.88	^NS	-		-		-	-	-	Both	G-F	[23]
Chains, plastic objects, wood, or rooting material	No	-		-		1.61	^NS	% farms ≥1 wounded pig	-	-	Yes	W	[25]
Chains, plastic objects, wood, or rooting material	No	-		-		0.86	^NS	% farms ≥1 wounded pig	-	-	Yes	G-F	[25]

Severe dam.: severe tail damage (partial or complete tail loss, crust formation, infection, fresh blood, or clearly visible wounds); Mild dam.: mild tail damage (small bite marks, superficial bites or scratches, tail-end hair missing, or blood on the tail); ∞: Infinite (i.e., damage reduced to 0); * Significant difference between enriched and control group within a study (p < 0.05); ^# Tendency towards a significant difference between enriched and control group within a study (p < 0.10); ^NS No significant difference between enriched and control group within a study (p > 0.05); W: Weaners, G-F: Growers/fatteners; ¹ Pairwise significance not clearly identified; ² Rubber bar, rubber ball, yellow ribbon, rope, yellow rubber hose, purple ribbon, grey garden hose, attached to the wall mounted chain; ³ Indicates that a different material was applied in different groups, but these were analysed as one category; ^? Not reported.