Benefits of tactile stimulation and environmental enrichment for the welfare of crossbred dairy calves

Figures & data

Figure 1. Layout of the area where the experiment was carried out. (A) Area with environmental enrichment; (B) non-enriched area; (C) feeding area with hay, concentrate and water, and (D) automatic feeder. Total experimental area 700 m².

Table 1. Description of the structure of the dependent indicator variables of animal welfare and of the models and procedures used for the analyses.

Measured variable	Observation period	No. of observation days	Sampling method	Model
				Fixed effects	Procedure	(Co)variance structure
Duration of tactile stimulation	Days 1–31	24	Time the animal allowed to be brushed	(treatment EE and NE), day of observation, interaction (treatment x day)	MIXED	ar(1)= autoregressive
Behaviour	Days 24, 25, 26	3	1 and 2 h after brushing	(treatment EE and NE), day of observation, interaction (treatment x day)	GLIMMIX
Feeder	Days 1–30	30	Suckling speed, visits with and without food, and total number of visits	(treatment EE and NE), day of observation, interaction (treatment x day)	MIXED	cs = compound symmetry
Cortisol, lactate, and oxytocin	Days 1 and 31	2	Before and after tactile stimulation	(treatment EE and NE), day of observation, interaction (treatment x day)	MIXED	un(1) = unstructured

EE: presence of environmental enrichment; NE: absence of environmental enrichment.

Figure 2. Observed frequencies of the duration of tactile stimulation (A), mean duration of tactile stimulation (brushing) (B) allowed by heifer calves over 24 days of the experiment according to the presence (EE) or absence (NE) of environmental enrichment.

Table 2. Estimated mean time (min) spent in each activity after tactile stimulation over 2 hours of continuous uninterrupted observation (first and second hour) in the presence (EE) or absence (NE) of environmental enrichment.

Time spent in the activity (min)	EE	NE	p-value
First hour after tactile stimulation
Lying down	34.71ª ± 1.13	24.66^b ± 1.01	<0.0001
Walking	4.49^b ± 0.41	8.86ª ± 0.61	<0.0001
Eating	8.62^b ± 0.56	10.91ª ± 0.67	0.0108
Play behaviour	6.07ª ± 0.48	2.49^b ± 0.32	<0.0001
Idling	1.10^b ± 0.20	7.17ª ± 0.58	<0.0001
Cross-sucking	3.97 ± 0.38	4.10 ± 0.41	0.8450
Second hour after tactile stimulation
Lying down	41.68^b± 1.24	49.98ª ± 1.44	<0.0001
Walking	0.60 ± 0.10	0.32 ± 0.10	0.0640
Eating	0.01 ± 1.02	0.003 ± 0.30	0.1310
Play behaviour	0.56 ± 0.10	0.45 ± 0.10	0.4708
Idling	2.96^b ± 0.33	4.32ª ± 0.43	0.0107
Cross-sucking	0	0

Means of each treatment followed by superscript letters in the same row differ significantly from each other by the Tukey test (5% probability).

Figure 3. Suckling speed (A), number of visits to the automatic feeder when food was not available (B), and total number of visits to the feeder (C) according to treatment (presence [EE] and absence [NE] of environmental enrichment). Means with lowercase letters differ significantly between each other on the same day (P < 0.05).

Table 3. Least square means and respective standard errors of biochemical variables before and after tactile stimulation in the groups receiving (EE) or not (NE) environmental enrichment.

Variable	Treatment		p-value
	EE	NE
Lactate before (mg/dL)	20.41 ± 2.09	24.79 ± 2.22	0.162
Lactate after (mg/dL)	15.66^b ± 1.90	25.67ª ± 2.01	0.009
Cortisol before (ng/mL)	13.49 ± 2.02	8.85 ± 2.14	0.125
Cortisol after (ng/mL)	19.53 ± 1.47	16.92 ± 1.55	0.231
Oxytocin before (uIU/mL)	3.29ª ± 0.08	2.97^b ± 0.09	0.013
Oxytocin after (uIU/mL)	4.60ª ± 0.11	3.24^b± 0.11	<0.0001

Means of each treatment followed by superscript letters in the same row differ significantly from each other by the Tukey test (5% probability).

Table 4. Paired analysis of the difference in least square means and respective standard errors of the biochemical variables before and after tactile stimulation in the presence (EE) or absence (NE) of environmental enrichment.

Treatment
Variable*	EE	p-value (EE)	NE	p-value (NE)
Lactate (mg/dL)	−4.75 ± 2.09	0.04	−1.42 ± 2.19	0.527
Cortisol (ng/mL)	6.04 ± 1.36	0.0004	8.07 ± 1.35	<0.0001
Oxytocin (uIU/mL)	1.31 ± 0.20	<0.0001	0.27 ± 0.16	0.104

*Values obtained tactile stimulation – values obtained before tactile stimulation within treatment. Means of each treatment significantly by the Tukey` test (5% probability).