Acta agriculturae Slovenica, 121/3, 1–9, Ljubljana 2025
doi:10.14720/aas.2025.121.3.19974 Original research article / izvirni znanstveni članek
Determining the influence of rearing method on lamb  
weaning behaviour
Miroslav SIMEONOV 1, 2, David L. HARMON 3
Received October 14, 2024; accepted July 29, 2025.
Delo je prispelo 14. oktobra 2024, sprejeto 29. julija 2025.
1 Agricultural Academy, Agricultural Institute, 6000 Stara Zagora, Bulgaria
2 Corresponding author, e-mail: msimeonov78@abv.bg
3 University of Kentucky, Department of Animal & Food Science, Lexington, USA
Determining the influence of rearing method on lamb 
weaning behaviour
Abstract: Weaned lambs experience changes in feeding 
and management practices that may influence growth and 
behaviour. The aim of the present study was to evaluate the 
change in growth, and behaviour in early weaned lambs sub-
jected to two rearing methods (natural and artificial) prior to 
weaning. The experiment was conducted with 24 lambs of the 
Assaf breed, divided into two groups (12 animals per group). 
The control group was reared naturally with their mothers 
until weaning (NR), while the lambs in the other group were 
reared artificially (AR) with milk replacer. After weaning, the 
AR lambs grew faster, allowing them to approximate the body 
weight of the NR lambs. On the first day after weaning, the 
NR lambs spent less than 1% of their time consuming con-
centrate and less than 2.5% of their time consuming alfalfa 
hay, resulting in 34.4% fewer feeding attempts than the AR 
lambs (p < 0.01). During the trial period, the NR lambs spent 
more time standing and moving (p < 0.05), and less time ly-
ing down, playing (p < 0.05) and feeding, compared to the AR 
lambs. This shows that the method of rearing before wean-
ing has a significant influence on the behaviour. This warrants 
further research into factors influencing behaviour and its 
control in early weaned lambs.
Key words: small ruminants, sheep, lambs, animal nutri-
tion, weaning, animal behaviour, animal welfare
Ugotavljanje vpliva tehnologije reje na obnašanje jagnjet ob 
odstavitvi
Izvleček: Jagnjeta so ob odstavitvi izpostavljena spre-
membam v prehrani in načinu reje, kar lahko vpliva na nji-
hovo rast in obnašanje. Namen raziskave je bil oceniti spre-
membe v rasti in obnašanju zgodaj odstavljenih jagnjet, ki so 
bila pred odstavitvijo rejena po dveh različnih tehnologijah 
(sesanje pri materi ali vzreja z mlečnim nadomestkom). Po-
skus je bil izveden s 24 jagnjeti pasme assaf, razdeljenimi v 
dve skupini (12 živali na skupino). Kontrolna skupina je do 
odstavitve sesala pri materah (NR), poskusna skupina pa je 
bila napajana z mlečnim nadomestkom (AR). Po odstavitvi 
so jagnjeta AR hitreje pridobivala telesno maso kot jagnjeta 
iz kontrolne skupine (NR), kar je povzročilo, da sta se telesni 
masi med skupinama po odstavitvi skoraj izenačili. Prvi dan 
po odstavitvi so jagnjeta NR porabila manj kot 1 % časa za 
zauživanje koncentrata in manj kot 2,5 % časa za zauživanje 
lucerninega sena, kar je pomenilo 34,4 % manj poskusov hra-
njenja kot pri jagnjetih AR (p < 0,01). V času poskusa so ja-
gnjeta NR, v primerjavi z jagnjeti AR, preživela več časa stoje 
in v gibanju (p < 0,05) ter manj časa leže, pri igri (p < 0,05) in 
zauživanju krme. To kaže, da ima tehnologija reje pred odsta-
vitvijo pomemben vpliv na obnašanje jagnjet po odstavitvi 
in upravičuje nadaljnje raziskave dejavnikov, ki vplivajo na 
oblike obnašanja zgodaj odstavljenih jagnjet.
Ključne besede: drobnica, ovce, jagnjeta, prehrana živa-
li, odstavitev, obnašanje živali, dobrobit živali
Acta agriculturae Slovenica, 121/3 – 20252
M. SIMEONOV and D. L. HARMON
1 INTRODUCTION
The artificial rearing of lambs is a subject in which 
the quality of animals’ life is discussed and is focused on 
the physical and emotional health of the animals so that 
they can display their normal behaviour in the environ-
ment in which they are housed. The desire of humans 
to achieve higher productivity from animals has led to 
the development of intensive livestock farming. Inten-
sive livestock farming can result in consumers concerns 
for the welfare of farm animals. These concerns may 
also be related to the early weaning of lambs, which 
is described as physical separation of the lambs from 
their mothers. This is a common practise to increase the 
economic efficiency of the farm, described , as forcibly 
terminating sucking of maternal milk by the offspring, 
which may affect animal welfare (González-Martínez 
et al., 2023). Napolitano et al. (2008) pointed out that 
weaning is a critical time for lambs due to the involve-
ment of social, nutritional and environmental changes.
The use of milk replacer (MR) in lamb feeding is a 
common practice in dairy sheep farming with the aim 
of increasing physical milk yield (Caroprese et al., 2005; 
David et al., 2014). At the same time, MR is also used in 
artificial breeding of lambs, in the presence of insuffi-
cient milk secretion of ewes, mastitis, and other factors 
that prevent lambs from suckling (McCoard et al., 2020, 
Mialon et al., 2021). Depriving lambs of their mothers 
and feeding them MR has a negative psychological ef-
fect (Gaudin et al., 2018). This is a challenge for young 
lambs because they receive MR that is different from 
their mother’s milk, which affects growth and microbial 
colonization (Belanche et al., 2019). According to Toral 
et al. (2015) MR is not easily influenced by the external 
environment, unlike mother’s milk, and improves lamb 
growth (Ocak and Cankaya, 2013; Zhang et al., 2019), 
immunity and reduces stress due to dietary changes 
(Amdi et al., 2021). 
Different lamb rearing methods are implemented 
worldwide, but the goal is the same, namely to reduce 
farming costs without compromising lamb welfare and 
growth (Heaney et al., 1982). According to Simitzis et 
al. (2012) early weaning is associated with stress, which 
can reduce feed consumption and affect average daily 
gains (Demir, 1995). Wang et al. (2019) point out 
that stress can be minimized if lambs are sepa-
rated from their mothers at an early age, and ac-
climatised to eat dry food, which will encourage 
the development of the forestomach. Already 
in the last century, Selye (1936) defined stress 
as a state of the organism where homeostasis is 
threatened by the stressor. Etim et al. (2013) de-
scribed stress as a reflex reaction resulting from 
the animal’s inability to adapt to the new environment. 
In this case, early weaning of lambs leads to changes in 
the physical and social environment of the animals (de 
Melo et al., 2022). 
The development of a suitable system for rearing 
and weaning lambs to reduce stress and improve wel-
fare serves as the basis for this study. The aim of the 
present study was to evaluate the change in growth, and 
behaviour of early weaned lambs subjected to two rear-
ing methods (natural and artificial) prior to weaning.
2 MATERIAL AND METHODS 
The experiment was conducted in January 2023 
with 24 lambs of the Assaf breed, raised on a private 
livestock farm, Kostelevo Village, Vratsa Municipality, 
Bulgaria (43.21659°N, 23.61234°E).
2.1 EXPERIMENTAL DESIGN 
The animals were divided into two groups (until 
the 24th hour after birth), each of which was equalized 
in terms of body weight, age, sex, and birth type (sin-
gles and twins). The animals were abruptly weaned at 
23 days of age. Until weaning, the lambs in the control 
group were naturally reared with their mothers (NR, 
n = 12) in an indoor facility without air currents. In the 
treatment group, the lambs were artificially reared in a 
separate room where the temperature was maintained 
at 16 to 18 °C and without air current (AR, n = 12). The 
AR lambs were separated from their mothers within 24 
hours after birth. Up to three days of age, each lamb re-
ceived colostrum, after which (from 4 days of age) they 
received MR (Capragno 62, SERVAL, France, contain-
ing 62% skimmed milk powder) ad libitum via an auto-
matic feeder (height-adjustable on four teat), according 
to the following scheme (Table 1).
From the age of 4 days until weaning, the lambs in 
both groups had free access to dry feed (protein con-
centrate with 33% crude protein, maize and alfalfa hay, 
Table 2), lukewarm water to drink and a rock salt to lick. 
For the control group (NR lambs), the aforementioned 
Age of lambs, day Nutrition 
until the 2nd day afer birth Colostrum
from the 3rd to the 14th day millk replacer (190 g/L of water)
from the 15th to the 18th day millk replacer (120 g/L of water)
from the 19th to the 22nd day millk replacer (80 g/L of water)
Table 1: Scheme of feeding the lambs with milk replacer
Acta agriculturae Slovenica, 121/3 – 2025 3
Determining the influence of rearing method on lamb weaning behaviour
feeds were provided in a “creep” (with a total area of 15 
m2) to which the lambs had free access (Alcock, 2006). 
During the experiment lambs were weighed at birth, on 
day 14 after birth, and daily from day 21 to 29 using an 
electronic scale to determine body weight (BW). 
2.2 ANIMAL BEHAVIOR
The behaviour of the lambs was recorded for six 
lambs from each group (NR lambs, n = 6; AR lambs, 
n = 6) for 9 days (2 days before weaning and 7 days 
after weaning). The following behaviour was recorded, 
considering definitions by Broekman (2015): stand-
ing (the time when the lamb is on all fours and not 
moving); movement (the time the lamb is on all fours 
and moving, forwards or backwards); lying (when the 
lamb’s belly is in direct contact with the ground); play-
ing (building social interactions between lambs in the 
form of running, jumping, stroking, hanging). Intake 
of concentrate feed and alfalfa hay was assessed in NR 
lambs (n = 6) and AR lambs (n = 6). Each of the behav-
ioural parameters was recorded if its duration was not 
less than 5 s.
The remaining number of animals 
(NR lambs, n = 6 and AR lambs, n = 6) 
were divided into six subgroups (3 from 
NR and 3 from AR) with 2 lambs in each 
subgroup, which were housed in pens with 
dimensions of 3 m × 1.5 m, where they 
had free access to dry feed (Table 2), luke-
warm drinking water and rock salt. This 
made it posible to determine the feeding 
behaviour and feed consumption of the 
lambs for 7 days after weaning. During 
this period, the following indicators were 
determined: number of meals (per 24 h), 
feeding duration (min/24 h), time to con-
sume 1 kg dry matter (DM)/min (this is 
the recorded time for the animal to con-
sume an average of 1 kg of dry matter 
(DM) in 24 hours, calculated by dividing 
the time spent feeding by the amount of 
feed DM consumed), intake rate (g DM/
min) and duration of meal (min).
To achieve the above objectives, ani-
mal behaviour was recorded with XMART 
WI-FI cameras with built-in BC202 bat-
teries (Langshixing Electronic Shenzhen 
Co. Ltd., China) installed at 4 m above the 
floor. The lambs were marked with a red 
spray (OVI-line, Ukal Eschbach, France) 
to make it easier to identify individual 
behaviors. During the experiment, protein concen-
trate and maize were placed together in the feeder at a 
60/40 ratio, separated from the alfalfa hay. The chemical 
content of feeds (Table 2) was determined by standard 
methods AOAC (2007), as described by Todorov et al. 
(2010).
A total of 54 recordings were made during the ex-
periment, 42 of which were used for determining the 
feeding behaviour of the lambs. Each recording covered 
a period of 24 hours, which allowed the following ac-
tions to be recorded: standing (min); movement (min); 
lying (min); playing (min); feeding attempts (number) 
and feeding duration (min).
2.3 STATISTICAL ANALYSIS 
All statistical analyses were performed using Sta-
tistica for Windows, version 6.0 (StatSoft Inc., 2006). 
The General Linear Model (GLM) was used in the cal-
culation of least squares analysis of variance. Animal 
behaviour was considered as a quantitative variable and 
the calculation measured the mean time (minutes per 
24hours) spent by the lambs standing, moving, lying 
Ingredient, % PPC 1 Maize Alfalfa hay
Sunflower meal 37.4
Soybean meal 30.2
Peas (grain) 19.4
Molasses 5
Calcium carbonate 2.5
Vitamins and minerals 2.5
Sodium chloride 1.5
Sodium bicarbonate 1.5
Nutrient Analyses, g kg −1
Dry matter 918 897 893
Feed units for growth 2 1.04 1.49 0.62
Crude protein 311.4 87.6 198.4
Digestible protein in the intestine 140.4 91.2 74.2
Balance of the protein in the rumen 123.5 −33 51.4
Crude fats 14.6 36.4 27.2
Calcium 17.1 0.27 16.6
Phosphorus 8.7 3.1 2.5
Vitamin A, IU/kg 43
Vitamin D, IU/kg 8529
Vitamin E, mg/kg 261
Table 2: Component and chemical composition of feed used
1 PPC – pelleted protein concentrate; 2 Feed units for growth is = 6 MJ N
Acta agriculturae Slovenica, 121/3 – 20254
M. SIMEONOV and D. L. HARMON
ration for AR lambs (p < 0.05). The study found no sig-
nificant differences in the time and speed of intake of 
1 kg of DM.
The behaviour of the lambs during the study pe-
riod (Figure 3) shows, significant differences in the 
behaviour of the animals (standing, moving, lying and 
playing), even before weaning (p < 0.05). On the first 
day after weaning, NR lambs increased standing and 
moving time to 32% and 35%, but decreased lying and 
playing time to 29% and 0.4% (Figure 3). Such large 
behavioural change were not observed in AR lambs 
(Figure 3).
The effects of weaning on the behaviour of the 
lambs is described in Table 1. During the study period, 
NR lambs spent 60% more time standing and 32.8% 
more time moving compared to AR animals (p < 0.01). 
The time spent lying, playing and eating was higher 
(p < 0.01) in the AR lambs, 11.6%, 42.2% and 47.4%, re-
spectively (Table 4).
4 DISCUSSION
In the present study, the NR lambs had higher 
BW and ADG compared to AR lambs before wean-
ing (p < 0.05). After weaning at 23 days of age, the NR 
lambs showed a sharp drop in BW in the first two days 
after weaning, indicating acute stress. A decrease in 
body weight and negative growth during the first day 
after weaning was also reported in the study by Mo-
down, playing and feeding. The level of statistical sig-
nificance was set at p < 0.05 and p < 0.01.
3 RESULTS
From birth to weaning, NR lambs maintained sig-
nificantly higher BW (p < 0.05) and average daily gain 
(ADG, p < 0.01) compared to AR lambs (Figure 1a). 
In the first two days after weaning, growth was posi-
tive in the AR lambs , while it ws negative in the NR 
lambs(Figure 1). The reported low ADG in NR lambs 
after weaning (p < 0.01, Figure 1b) allowed the animals 
artificially reared at 23 days of age to reach the body 
weight of animals from the control group (Figure 1a).
On the first day after weaning, consumption time 
decreased in both groups of lambs, being most notice-
able in the NR lambs (Figure 2). Lambs that were NR 
before weaning spent less than 1% of their time con-
suming concentrate (Figure 2a) and less than 2.5% of 
their time consuming alfalfa hay, compared to the AR 
animals (Figure 2b). After this day, the time spent on 
feed intake increased in both groups of animals (Fig-
ure  2ab).
The feeding behaviour of the lambs in the first 
week after weaning in Table 3 shows that after weaning, 
NR lambs made 34.4% fewer feeding attempts and used 
27% less time feeding compared to AR lambs (p < 0.01). 
The average duration of a meal for NR lambs was 1.8 
minutes, which was 11.1% longer than the average du-
  
 
 
 
 
 
**
**
** ** ns ns ns ns
ns ns
ns
4
6
8
10
12
14
At
birth
14 21 22 23
(Wea-
ning)
24 25 26 27 28 29
B
od
y 
w
ei
gh
t, 
kg
Age of lambs, day
a
Natural rearing Artificial rearing
* *
*
* *
*
* * *
*
-0,4
-0,3
-0,2
-0,1
0,0
0,1
0,2
0,3
0,4
0,5
14 21 22 23
(Wea-
ning)
24 25 26 27 28 29
G
ai
n,
 k
g/
da
y
Age of lambs, day
b
Natural rearing Artificial rearing
* p < 0.01; ** p < 0.05, ns (non significant)
Figure 1: BW (a) and ADG (b) in the lambs depending on the rearing method before weaning (LSM ± SE)
Acta agriculturae Slovenica, 121/3 – 2025 5
Determining the influence of rearing method on lamb weaning behaviour
hapatra et al. (2021) in lambs weaned at 60 days of 
age. According to Kuhn et al. (1990), the separation of 
neonates from the mother leads to a sharp decrease in 
growth hormone secretion, while the increase in corti-
costerone levels occurs with a considerable delay, and 
only starts several hours after the stressful event or the 
reduced amount of feed intake (Dantzer & Mormede, 
1979). Although AR lambs reduced their growth in 
the first two days after weaning, it remained positive 
and did not reach the negative values observed in NR 
lambs (p < 0.01, Figure 1b). This may be an indication 
of a greater weaning stress in NR lambs. According to 
Mora-Medina et al. (2015), the disruption of the ewe-
lamb relationship, the lack of milk in combination with 
the changes occuring in endocrine and behavioural re-
sponses reduce the growth of the animals. 
After weaning, the NR lambs received the same 
dry feed as they received in the creep and during the 
suckling period. However, they spent less time feeding 
(Figure 2) and made fewer feeding attempts (p < 0.01), 
which affected the duration of a meal (p < 0.01). The 
possible cause is the adaptation of the digestive system 
to the sudden change in diet, which according to de 
Melo et al. (2022) lead to altered behavioral responses 
in NR lambs. This can be explained by the fact that, the 
amount of MR was gradually reduced in the AR lambs 
from 15 days of age (Table 1). Consequently, the lambs 
could not fully meet their nutritional requirements 
through the MR and switched to consuming dry feed 
(concentrate and hay). In contrast, NR lambs primar-
ily relied on their mother‘s milk, which adequately met 
their requirements. When lambs are raised with their 
mothers, there is a strong bond between them that is 
associated with several neurochemicals involved in 
neuronal activity, which act in synergy for affection and 
care. In this context, Lynch et al. (2019), who studied 
  
 
 
 
 
0
1
2
3
4
5
6
7
8
9
10
21 22 23
(Wea-
ning)
24 25 26 27 28 29
Ti
m
e,
 %
Age of lambs, day
a*
Natural rearing Artificial rearing
0
2
4
6
8
10
12
14
16
21 22 23
(Wea-
ning)
24 25 26 27 28 29
Ti
m
e,
 %
Age of lambs, day
b
Natural rearing Artificial rearing
* Combination of protein concentrate + maize (60/40)
Figure 2: Time spent for intake of concentrates (a*) and alfalfa hay (b) in lambs depending on the rearing method before and 
after weaning (average per 24h)
Indicators NR AR SEM p-value
Number of meals per 24 h 39.2 59.8 1.96 *
Time spent feeding, min/24 h 69.38 95.01 2.54 *
Time to intake of 1 kg DM, min# 189.1 181.0 3.60 ns
Rate of intake, g DM/min 5.3 5.5 0.09 ns
Duration of meal, min 1.8 1.6 0.04 **
Table 3: Feeding behaviour of lambs during the first week after weaning
*p <  0.01; **p <  0.05; ns (non significantly)
# This is the recorded time in which the animal consumes an average of 1 kg of dry matter (DM) in 24 hours.
Acta agriculturae Slovenica, 121/3 – 20256
M. SIMEONOV and D. L. HARMON
cattle, allow for the possibility that cow‘s milk contains 
opiate-like substances that play a key role in the calf ‘s 
attachment to the mother. 
At weaning, the NR lambs were subjected to both 
psychological (separation from the mother) and physi-
cal stress (the introduction of a new type of feeding and 
husbandry). These lambs spent more time standing and 
moving and less time lying down, playing and eating 
compared to the AR lambs (Figure 3), suggesting that 
the rearing method before weaning affects behaviour 
(p < 0.01). According to Pascual-Alonso et al. (2015) 
artificial rearing before weaning creates a positive hu-
man-animal relationship reducing stress and improving 
lamb welfare. In this case, when lambs are artificially 
reared, human is accepted as a social substitute , which 
relieves the stress of weaning (Boivin et al., 2000). 
De et al. (2017) describes lying down as a fac-
tor of rest and as an indicator of good animal welfare. 
This could support our results, namely the AR lambs 
  
  
 
 
 
b
ns
a
a
a
a
b b b
a
b
b b b
a a a
0
5
10
15
20
25
30
35
40
21 22 23
(Wea-
ning)
24 25 26 27 28 29
St
an
di
ng
, %
Age of lambs, day
a
Natural rearing Artificial rearing
a
a
a
a
a
a
a a
a
b
b
b
b b
b b b b
0
5
10
15
20
25
30
35
40
21 22 23
(Wea-
ning)
24 25 26 27 28 29
M
ov
em
en
t, 
%
Age of lambs, day
b
Natural rearing Artificial rearing
a
b
b
b b
b
a
a a
a
25
30
35
40
45
50
55
60
21 22 23
(Wea-
ning)
24 25 26 27 28 29
Ly
in
g,
 %
Age of lambs, day
c
Natural rearing Artificial rearing
a
b b
b
b
b
b b
b
a a a
a a
a a
0
5
10
15
20
25
30
21 22 23
(Wea-
ning)
24 25 26 27 28 29
Pl
ay
, %
Age of lambs, day
d
Natural rearing Artificial rearing
a, b Differences between groups were significant at p < 0.05
Figure 3: Behaviour of the lambs during the study period
Behavior, min/h NR AR SEM p-value
Standing 10.56 4.23 0.534 *
Movement 15.31 10.28 0.435 *
Lying 26.52 30.01 0.433 *
Play 2.17 5.14 0.193 *
Meal 5.44 10.34 0.341 *
Table 4: Behaviour of the naturally (NR) versus the artifi-
cially reared (AR) lambs after weaning
* p < 0.01
Acta agriculturae Slovenica, 121/3 – 2025 7
Determining the influence of rearing method on lamb weaning behaviour
spent 12% more time lying down after weaning than 
NR lambs (Table 4). The possible reason for this is that 
during the first days after weaning, the NR lambs await 
their social behaviour in the first days after weaning 
and spend much of their time standing or moving (Fig-
ure 3ab).
Play behaviour is an indicator of animal welfare 
in which the individual behaves in a spontaneous and 
flexible manner (Burghardt, 2005).It is an indicator of 
animal welfare (Oliveira et al., 2010), evident when 
they are healthy, fed and stress-free (Burghardt, 2005). 
Abrupt weaning, lack of milk and loss of social patterns 
are stressful for animals (Damián et al., 2013; de Melo 
et al., 2022). In calves, the change in behaviour may 
last several weeks (Veissier & LeNeindre, 1989). In our 
study, play behaviour in NR lambs completely stopped 
on the first day after weaning, and gradually increased 
thereafter (Figure 3d). This shows that the change in 
behaviour and the occurence of anxiety in the animals 
in our study happens in the first 24 hours after wean-
ing, while in other studies it lasted up to few days after 
weaning in lambs and calves (Veissier & Le Neindre, 
1989; Boland et al., 2008; Norouzian, 2015).
In our study, abrupt weaning further increased 
emotional stress in the NR lambs, which was also con-
firmed in the study by Norouzian (2015), where the ani-
mals were weaned at 6 weeks of age. The author found 
that the lambs that were weaned by withdrawing part 
of the milk for a week showed lowerarousal, which lead 
to less stress, compared to quickly weaned animals. 
The reason for this according to de Melo & Ungerfeld 
(2016), is that social, emotional, and nutritional chang-
es occurr that increase cortisol levels (Mohapatra et 
al., 2021). This is described as a physiological response 
to stress, in which cortisol levels rise (Mears & Brown, 
1997) and energy expenditure increases in the animals‘ 
not yet stabilised physiological state to the new living 
environment (de Melo et al., 2022).
Yau & Potenza (2013) indicated that emotional 
stress increases the animals‘ appetite, which was not the 
case in our study, in which the NR lambs spent less time 
feeding (Figure 2, Table 3). In our study, abrupt weaning 
of NR lambs not only affected body weight and growth, 
but also dramatically increased locomotor activity and 
standing at the expense of resting, eating, and play time. 
This indicates a change in behaviour and the onset of 
anxiety associated with weaning and separation from 
the dam. This requires further research and in-depth 
studies on the behavioural responses associated with 
separation from the dam and how we can mitigate its 
negative effects in early-weaned lambs. 
5 CONCLUSION
In the study, AR lambs were found to have a higher 
ADG after weaning at 23 days of age, indicating that 
stress on this indicator is lower in AR lambs.
Natural rearing of lambs prior to weaning and 
early weaning (23 days of age), resulted in lambsspend-
ing less time and makeing fewer attempts to consume 
dry feed.
Early weaning of NR lambs was found to cause 
psychological and physical stress due to anticipation of 
their social model, where they spend a large part of the 
time standing and moving, and less time lying down 
and playing, compared with AR lambs. This shows that 
the method of rearing before weaning has a significant 
influence on the behaviour of NR lambs. This warrants 
further research into factors that influence behaviour 
and its control in early weaned lambs.
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