The influence of the number of lambs present on the suckling behaviour of triplet-rearing ewes at pasture

Figures & data

Table 1. Ethogram of ewe suckling behaviour and type of measure observed from video footage.

Variable	Measure type	Definition
Suckling event	Duration (s)	Start of event when lamb approaches within 0.5 m of the ewe and shows active searching behaviour anywhere on the ewe or begins sucking. Events were terminated when no lamb was searching or sucking for more than 10 sec.
Number of lambs	1, 2 or 3	Number of lambs within 0.5 m of the ewe at the termination of an event regardless of the lamb's behaviour.
Ewe behaviour during suckling event
Standing	Duration (s)	Ewe stands stationary to allow lamb(s) to suck
Walking	Duration (s)	Ewe takes two or more steps
Grazing	Duration (s)	Ewe has head down and is harvesting grass, may take the occasional step and lift head to chew and swallow
Ruminating	Duration (s)	Ewe regurgitates rumen content and chews while either standing or sitting, no grass harvesting is observed
Suckling event termination behaviour
Ewe sit	Event (n)	Ewe transitions from a standing to sitting position which prevents the lamb(s) from sucking
Ewe kick	Event (n)	Ewe uses hind foot to prevent lamb(s) from suckling or to displace lamb from teat
Ewe walk	Event (n)	Ewe walks away from lamb(s) when they attempt to initiate or continue sucking
Ewe butt	Event (n)	Ewe uses her head to forcefully push or knock a lamb down or away. Includes her own or foreign lambs
Lamb ends	Event (n)	The suckling event terminated by all lambs in the suckling event either ceasing to search for the teat for 10 s or the lamb moving more than 0.5 m from the ewe

Figure 1. Summary of weather data showing daily minimum temperature (°C, dashed black line), maximum temperature (°C, solid black line) and mean relative humidity (%, solid grey line) and total rainfall (mm, black bars) recorded during the study period.

Table 2. The number of suckling events, events with rain recorded and events with a chill index of greater than 1000 KJ/m² for each wind direction (north, east, south and west). Median and interquartile range in parentheses of wind speed (m/s), temperature (°C), rain rate (mm/h), relative humidity (%), solar radiation (MJ/m²) and chill index (MJ/m²) when wind was from each direction.

	Wind direction
	North	East	South	West
Suckling event (n)	128	229	236	621
Rain (mm/h)	1.2 (1.2–2.4)^a	6.6 (1.2–16.8)^b	2.4 (2.4–2.4)^ab	2.4 (1.2–4.2)^b
Rain > 0 mm (n, %)	39 (30.5)	28 (12.2)	3 (1.2)	64 (10.3)
Wind speed (m/s)	2.5 (1.6–3.4)^b	4.2 (1.6–4.8)^c	1.5 (1.1–2.4)^a	5.5 (3.6–7.1)^d
Temperature (°C)	15.6 (14.6–15.9)^d	15.8 (11.8–16.3)^c	11.6 (11.5–16.0)^a	12.8 (12.6–14.8)^b
Relative humidity (%)	81 (79–84)^b	68 (63–86)^a	76 (67–78)^a	80 (69–88)^b
Solar radiation (MJ/m^2)	0.05 (0.03–0.05)^a	0.17 (0.10–0.23)^c	0.07 (0.06–0.12)^b	0.10 (0.06–0.16)^b
Chill index (MJ/m^2)	883 (862–929)^a	919 (855–987)^c	905 (872–918)^b	967 (934–1023)^d
Chill index >1000 (n, %)	0 (0)	8 (3.5)	0 (0)	225 (36.2)

Figure 2. Histogram of suckling event duration on day 1 when one (white bars), two (grey bars) or three (black bars) lambs were present at the termination of the event.

Table 3. The frequency of suckling events (with the percentage in parentheses) and their duration (s, back-transformed mean with 95% confidence interval in parentheses) on Day 1 by number of lambs present at the end of the event (one, two or three) and on Days 1, 2 and 3 by lambs present at the end of the event or by day of observation.

	Suckling events
	n (%)	Duration (s)
Day 1 only (n = 26 ewes)
Number of lambs present
One	232 (39.7)^b	25.9 (22.2–30.1)^a
Two	178 (30.5)^a	47.5 (39.9–56.4)^b
Three	174 (29.4)^a	62.0 (52.0–73.8)^c
P-value	0.004	<0.0001
Days 1, 2 and 3 (n = 11 ewes)
Number of lambs present
One	305 (39.3)^b	21.6 (18.6–25.1)^a
Two	249 (32.1)^ab	38.3 (32.5–45.1)^b
Three	222 (28.6)^a	61.4 (51.6–73.2)^c
P-value	0.004	<0.0001
Day of observation
Day 1	234 (30.4)	39.5 (33.3–46.8)
Day 2	280 (36.1)	39.9 (34.0–46.8)
Day 3	262 (33.8)	32.2 (27.5–37.8)
P-value	ns	0.11

ns = p-values greater than P = 0.1, ^a,b,cwithin columns mean with different superscripts are significantly different P < 0.05.

Table 4. The frequency of suckling events (with the percentage in parentheses) and their duration (s, back-transformed mean with 95% confidence interval in parentheses) on day 1 only and on days 1, 2 and 3 by wind direction.

Wind	Suckling event
direction	n (%)	Duration (s)
	Day 1 only (n = 26)
North	68 (11.6)^a	51.2 (33.3–78.7)
East	88 (15.1)^a	56.4 (34.3–92.8)
South	120 (20.6)^b	30.3 (20.7–44.5)
West	308 (52.7)^c	43.8 (34.2–55.9)
P-value	0.04	ns
	Days 1, 2 and 3 (n = 11)
North	71 (9.2)^a	69.9 (51.3–95.3)^c
East	184 (23.7)^c	38.9 (32.1–47.2)^b
South	117 (15.1)^b	24.2 (19.0–30.8)^a
West	404 (52.1)^d	36.6 (32.1–41.7)^b
P-value	<0.0001	0.0004

Table 5. The frequency and percentage (in parentheses) of suckling events that were terminated by the ewe (kick, sit, butt and walk) or lambs (walk) on Day 1 by number of lambs present (one, two or three) and Days 1, 2 and 3 by lambs present or by day of observation (Day 1, Day 2 or Day 3).

	Suckling events (n)	Suckling event termination behaviour
		Ewe kick^#	Ewe sit^#	Ewe butt	Ewe walk	Lamb end
Day 1 (n = 26 ewes)
Number of lambs present
One	232	0 (0)	0 (0)	8 (3.4)	121 (52.2)	103 (44.4)
Two	178	1 (0.6)	4 (2.2)	2 (1.1)	94 (52.8)	77 (43.3)
Three	173	2 (1.1)	5 (2.9)	5 (2.9)	92 (52.9)	69 (39.7)
P-value		-	-	ns	ns	ns
Total days of observation
One	240	1 (0.4)	4 1(.7)	2 (0.5)^a	140 (58.3)^b	93 (38.8)
Three	234	1 (0.4)	5 (2.1)	12 (5.0)^b	115 (49.2)^a	102 (43.6)
P-value		-	ns	0.004	0.04	ns
Days 1, 2 and 3 (n = 11 ewes)
Number of lambs
One	306	1 (0.3)	2 (0.7)	11 (3.6)^b	175 (57.4)^ab	117 (38.4)^ab
Two	250	1 (0.4)	5 (2.0)	6 (2.4)^ab	136 (54.6)^a	102 (41.0)^b
Three	223	2 (0.9)	7 (3.2)	3 (1.4)^a	144 (64.9)^b	67 (30.2)^a
P-value		-	ns	0.003	0.08	0.001
Day of observation
Day 1	235	1 (0.4)	5 (2.1)	12 (5.1)^b	115 (49.1)^a	102 (43.6)^b
Day 2	281	1 (0.4)	7 (2.5)	3 (1.1)^a	175 (62.5)^b	95 (33.9)^a
Day 3	263	2 (0.8)	2 (0.8)	5 (1.9)^a	165 (63.0)^b	89 (34.0)^a
P-value		-	ns	0.01	0.03	0.002

ns = P-values greater than P = 0.1. ^a,b,cwithin columns mean with different superscripts are significantly different P < 0.05, ^#insufficient observations were made to allow a Chi² analyses to be conducted.

Table 6. The odds (with 95% confidence interval in parentheses) of suckling events being terminated by the ewe walking away or by the lamb on Day 1 by number of lambs present (one, two or three) and on Days 1, 2 and 3 by the number of lambs present or by day of observation.

	Event termination behaviour
Comparison	Ewe walk		Lamb end
Day 1 (n = 26 ewes)
Lambs 1 vs. 2	0.97 (0.66–1.44)		1.07 (0.72–1.58)
Lambs 1 vs. 3	0.95 (0.64–1.41)		1.24 (0.83–1.84)
Lambs 2 vs. 3	0.98 (0.64–1.48)		1.16 (0.76–1.77)
P-value	ns		ns
Days 1, 2 and 3 (n = 11 ewes)
Lambs 1 vs. 2	1.15 (0.81–1.64)		0.86 (0.60–1.24)
Lambs 1 vs. 3	0.74 (0.50–1.10)		1.52 (1.02–2.28)
Lambs 2 vs. 3	0.65 (0.44–0.96)		1.76 (1.18–2.65)
P-value	0.09		0.02
Day 2 vs. 1	1.83 (1.26–2.66)		0.60 (0.41–0.87)
Day 3 vs. 1	1.78 (1.23–2.59)		0.67 (0.46–0.97)
Day 2 vs. 3	1.03 (0.71–1.48)		0.90 (0.62–1.31)
P-value	0.002		0.02

ns = p-values greater than P = 0.1.

Table 7. The frequency (with the percentage in parentheses) of suckling events during which ewes were observed to walk, stand, ruminate or graze on Day 1 by number of lambs present (one, two or three) and on Days 1, 2 and 3 by lambs present (one, two or three), day of observation or total days of observation (one or three).

	Suckling events (n)	Ewe behaviour during event
		Walk	Stand	Ruminate	Graze
Day 1 (n = 26 ewes)
Number of lambs present
One	232	15 (6.5)	78 (33.6)^a	62 (26.7)^a	155 (66.8)^b
Two	178	19 (1.7)	85 (47.8)^b	81 (45.5)^b	97 (54.5)^a
Three	173	20 (11.5)	93 (53.4)^b	74 (42.5)^b	111 (63.8)^ab
P-value		ns	0.0002	0.0001	0.04
Days 1, 2 and 3 (n = 11 ewes)
Number of lambs present
One	306	15 (4.9)^a	65 (21.3)^a	51 (16.7)^a	255 (83.6)^b
Two	250	35 (14.1)^b	87 (34.9)^b	108 (43.4)^b	170 (68.3)^a
Three	223	36 (16.2)^b	98 (44.1)^c	92 (41.4)^b	153 (68.9)^a
P-value		<0.0001	<0.0001	<0.0001	<0.0001
Day of observation
Day 1	235	24 (10.3)	96 (41.0)^b	89 (38)^b	154 (65.8)^a
Day 2	281	25 (8.9)	78 (27.9)^a	82 (29.3)^a	219 (78.2)^b
Day 3	263	37 (14.1)	76 (29.0)^a	80 (30.5)^ab	205 (78.2)^b
P-value		ns	0.003	0.08	0.001
Total days of observation
One	240	21 (8.8)	125 (52.1)	82 (34.2)	147 (61.3)
Three	234	24 (10.3)	96 (41.0)	89 (38.0)	154 (65.8)
P-value		ns	0.016	ns	ns

ns = p-values greater than P = 0.1. ^a,b,cwithin columns mean with different superscripts are significantly different P < 0.05.

Table 8. The frequency (with the percentage in parentheses) of suckling events during which ewes were observed to walk, stand, ruminate or graze on Day 1 and Days 1, 2 and 3 by wind direction during the event.

Wind direction	Suckling events (n)	Ewe behaviour during event
		Walk	Stand	Ruminate	Graze
Day 1 (n = 26 ewes)
North	68	5 (7.4)	19 (28.0)^a	54 (38.6)^b	48 (54.6)^a
East	88	7 (8)	46 (52.3)^b	53 (22.1)^a	52 (76.5)^b
South	120	8 (6.7)	52 (43.3)^ab	73 (39.2)^b	67 (55.8)^ab
West	308	34 (11)	139 (45.1)^b	187 (39.3)^b	195 (63.3)^b
P-value		ns	0.02	0.06	0.02
Days 1, 2 and 3 (n = 11 ewes)
North	71	43 (10.6)	62 (33.7)	130 (70.7)	32 (45.1)^c
East	184	10 (14.1)	23 (32.4)	50 (70.4)	54 (29.4)^ab
South	117	20 (10.9)	34 (29.1)	96 (82.1)	23 (19.7)^a
West	404	13 (11.1)	131 (32.4)	302 (74.8)	142 (35.2)^bc
P-value		ns	ns	ns	0.001

ns = P-values greater than P = 0.1. ^a,b,cwithin columns mean with different superscripts are significantly different P < 0.05.

Table 9. The median percentage (with interquartile range in parentheses) of the total suckling event duration that ewes were observed to walk, stand, ruminate or graze by the number lambs present at the end of the event or day of observation.

	Suckling events (n)	Ewe behaviour (% of event)*
		Walk	Stand	Ruminate	Graze
Day 1 only (n = 26 ewes)
Number of lambs present
One	232	6.7 (1.6–11.1)	70.2 (33.9–100.0)^b	76.6 (33.1–100.0)	100.0 (88.9–100.0)^b
Two	178	3.8 (2.2–7.0)	66.1 (20.3–99.7)^b	70.7 (33.5–100.0)	94.0 (42.7–100.0)^a
Three	173	3.8 (1.9–10.0)	41.4 (16.2–92.1)^a	78.6 (34.6–98.5)	81.7 (41.4–100.0)^a
P-value		ns	0.01	ns	<0.001
Days 1, 2 and 3 (n = 11 ewes)
Number of lambs present
One	306	7.0 (1.3–19.8)	68.0 (33.9–100.0)^b	46.0 (27.0–77.2)^a	100.0 (98.1–100.0)^b
Two	250	3.4 (1.9–11.7)	48.5 (17.9–87.23)^a	67.4 (34.9–99.5)^ab	100.0 (48.3–100.0)^b
Three	223	3.4 (1.8–6.5)	25.1 (11.0–73.23)^a	81.0 (52.7–98.5)^b	96.8 (44.1–100.0)^a
P-value		ns	<0.001	<0.001	<0.001
Day of observation
Day 1	235	3.8 (2.6–9.3)	49.1 (17.9–100.0)^b	65.8 (33.1–98.1)^ab	99.3 (57.7–100.0)^a
Day 2	281	3.2 (1.8–8.3)	40.0 (15.1–98.2)^a	60.7 (28.7–87.1)^a	100.0 (88.5–100.0)^b
Day 3	263	3.2 (1.8–8.5)	36.5 (11.7–71.8)^a	78.8 (51.5–98.7)^b	100.0 (79.9–100.0)^ab
P-value		ns	0.05	0.05	0.01

ns = p-values greater than P = 0.1. ^a,b,cwithin columns mean with different superscripts are significantly different P < 0.05. * Ewe behaviour duration (% of the event) was calculated from events in which the ewe was observed to show the behaviour.

Table 10. The median percentage (with interquartile range in parentheses) of the sum of the suckling events that ewes were observed to walk, stand, ruminate or graze by the number of lambs present or the day of observation.

	Ewes (n)	Ewe behaviour while suckling (%)
		Walk	Stand	Ruminate	Graze
All ewes	26	0.5 (0.2–0.9)	16.5 (9.2–21.7)	37.0 (30.7–45.1)	37.2 (22.7–54.5)
Number of lambs present
One	24	0.4 (0.0–1.2)	8.1 (3.3–16.8)	18.3 (6.7–42.8)^a	68.8 (38.9–87.3)^b
Two	26	0.4 (0.0–1.1)	12.9 (5.0–25.3)	42.3 (25.9–54.4)^ab	44.7 (20.0–55.7)^a
Three	22	0.6 (0.3–1.2)	17.8 (8.1–26.6)	43.8 (14.0–57.2)^b	32.4 (16.3–49.4)^a
P-value		ns	ns	<0.05	<0.05
Day of observation
Day 1	26	0.3 (0.1–1.0)	19.2 (10.5–27.5)^b	39.0 (25.7–49.8)	40.0 (13.9–54.8)
Day 2	15	0.5 (0.4–0.8)	7.5 (4.8–23.6)^ab	45.8 (25.7–93.1)	40.3 (23.7–63.6)
Day 3	11	1.1 (0.4–1.7)	8.3 (6.1–19.2)^b	38.3 (29.3–60.2)	35.2 (22.9–60.5)
P-value		ns	0.07	ns	ns

ns = p-values greater than P = 0.1. a,b within columns means with different superscripts are significantly different P < 0.05. * Ewe behaviour duration (% of the sum of all events) was calculated only from events in which the ewe was observed to show the behaviour.

Table 11. The odds (with 95% confidence interval in parentheses) of a ewe being observed to walk, stand, ruminate or graze at any time during all periods they were observed to suckle their lambs by number by the number of lambs present or day of observation.

Comparison	Ewe behaviour while suckling
	Walk	Stand	Ruminate	Graze
Lambs 1 vs. 2	1.15 (0.41–3.24)	0.76 (0.29–2.02)	0.04 (0.01–0.13)	3.88 (1.41–10.72)
Lambs 1 vs. 3	0.91 (0.31–2.73)	0.19 (0.06–0.55)	0.04 (0.01–0.14)	10.23 (3.32–31.52)
Lambs 2 vs. 3	0.80 (0.27–2.38)	0.25 (0.09–0.71)	0.97 (0.35–2.67)	2.63 (0.94–7.37)
P-value	ns	0.006	<0.0001	<0.0001
Day 1 vs. 2	0.64 (0.18–2.21)	2.52 (0.71–8.98)	0.32 (0.09–1.14)	1.06 (0.31–3.65)
Day 1 vs. 3	0.12 (0.3–0.53)	4.04 (0.96–17.1)	0.23 (0.6–0.99)	2.70 (0.65–11.14)
Day 2 vs. 3	0.19 (0.04–0.81)	1.61 (0.39–6.57)	0.73 (0.18–2.96)	2.56 (0.62–10.55)
P-value	0.017	ns	0.09	ns