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Influence of rearing conditions on subsequent social behaviour of Friesian and Salers heifers from birth to six months of age
Applied Animal Behaviour Science, 12 (1984) 43--52 Elsevier Science Publishers B.V., Amsterdam - - Printed in The Netherlands
43
INFLUENCE OF REARING CONDITIONS ON SUBSEQUENT SOCIAL BEHAVIOUR OF FRIESIAN AND SALERS HEIFERS FROM BIRTH TO SIX MONTHS OF AGE
P. LE NEINDRE and CHRISTINE SOURD
Laboratoire de la Production de viande, Centre de Recherches de Clermont-Ferrand, I.N.R.A., Theix, Sant-Gen}s-Champanelle, 63110 Beaumont (France) (Accepted for publication 18 April 1983)
ABSTRACT Le Neindre, P. and Sourd, C., 1984. Influence of rearing conditions on subsequent social behaviour of Friesian and Salers heifers from birth to six months of age. Appl. Anim. Behav. Sci., 12: 43--52. Social relationships were studied in 4 herds of 2.5-year-old heifers (55 animals in total). Animals of Frieslan (F) or Salers (S) breed were observed at pasture during 144 h. In each breed, half of the females had been either reared by a foster cow (M), or bucketfed and isolated for 10--12 weeks (I). When a year old, animals were allocated into 4 herds, each herd including heifers of 2 experimental treatments. The 4 chosen combinations (FM/FI, SM/SI, SM/FM, SI/FI) allowed us to study the effects of rearing conditions and breed on social behaviour. Non-agonistic interactions were more frequent within Salers groups than within Friesian groups, regardless of rearing conditions. When comparing the 2 rearing conditions (isolated (I) versus mothered (M)), agonistic interactions were more frequent between suckled than between bucket-fed animals, regardless of breed. Hierarchy relationships were assessed by a new method, relying on the notion of hierarchical power, computed from all the individual relationships within a group. Salers heifers had a higher hierarchical power than Friesians. Suckled Salers females were dominant over bucket-fed females of the same breed. By contrast, no significant difference was observed between the 2 corresponding Friesian groups. It would appear, therefore, that bucket-feeding can lead to a disadvantage concerning dominance--subordination relationships in the Salers breed, whereas such an effect is not observed in Friesians. This interaction between breed and rearing conditions may suggest breed differences in the ability of the young to adapt to various rearing systems.
INTRODUCTION
Domestic cattle are raised in many different ways, ranging from intensive systems where rhythms and social environment are mainly determined by humans, to ranching where animals are left free. Farmers select their breeds according to the conditions in which they will be raised. In intensive systems, animals are characterized by high milk production, whereas beef cattle are most commonly bred outdoors. The social conditions in which young 0168-1591/84/$03.00
© 1984 Elsevier Science Publishers B.V.
44
animals are reared vary greatly from one system to another. In dairy farming, the calves are separated from their dam immediately after birth and are reared either in isolation or in groups of animals of the same age. By contrast, in beef production, calves remain with their dam in the herd. However, rearing conditions in the first months of life can influence relationships in adulthood. This has been shown b y Donaldson et al. (1966), Broom and Leaver (1978) and Wamick et al. (1977) for dairy cattle reared in isolation or with other calves of the same age. The development of individual relationships within a herd can also vary with genotype (Donaldson et al., 1966). Therefore, breeds which differ in some physiological factors can also differ in their behavioural ability to adapt to various breeding conditions. We proposed to test such a hypothesis by analyzing the possible influence of breed and social history, up to 6 months of age, on the social relationships of 2.5-year-old heifers. Friesian and Salers breeds were chosen. Salers cattle are bred in hilly and humid parts of the French Massif Central. Calves of this breed are always suckled b y their mothers, even when cows are partially milked in the meantime. By contrast, Friesian cattle are generally reared without their dams. In the present experiment, female calves of these 2 breeds were reared either isolated and bucket~fed, or kept within a group and suckled b y fostercows. The social behaviour of these animals was studied when they were about 2.5 years old, some months before their first parturition. METHODS
Experimental groups We used 27 Salers (S) and 28 Friesian (F) female calves, which were born between 2 November and 3 March. In both breeds, calves were reared according to one of the t w o methods described below until the formation of the final herds, when heifers were a b o u t 16 months old.
Rearing in isolation (I) (without nurse-cow) At birth, female calves were put into individual pens, so that physical contact and visual cues with other animals were not possible. Only acoustic information from other calves was available. Up to 8 weeks after birth, they were fed twice a day with milk in a bucket fitted with a rubber teat and, in addition, received hay, pellets and water. When the calves were between 10 and 12 weeks old, they were put into groups of 4 and, a few days later, they were mustered in 2 herds of mixed breeds. One herd was made of the oldest calves and the second of the youngest ones. These 2 herds were turned o u t to grass in spring, where daily supplementation of pellets was also provided.
Mothered (M) (suckling a foster-cow) To obtain similar rearing conditions for the 2 breeds, all calves were
45 fostered and suckled by an alien primiparous Salers cow, just after the parturition of the foster-cow. For all calves, the fostering procedure took place between the first and the 16th day of life. When there was no foster~ow available immediately, the calf was reared individually, as in the group of isolated ones, until it could be fostered. The foster-cow was isolated with the young to be fostered for periods ranging from 3 to 10 days before she joined the herd of foster cows. For 2 months, the calves suckled only twice a day under human supervision. Out of the suckling periods, cows and calves were kept in separate groups. Thereafter, calves stayed permanently by their dams. As for the calves reared in isolation, they were divided into 2 herds, according to the age of the calves. They were weaned when they were brought back indoors in late autumn, when they were between 7 and 11 months old. All calves were polled when 2 months old. However, polling was not completely successful on all animals, especially for some of the Salers calves, which therefore had short and blunt beginnings of horns (less than 10 cm long). The 4 herds so created were not modified until the end of the second winter, when the heifers were about 16 months old.
Formation of the experimental herds for observation of social relationships To study social behaviour in relation to breed and rearing conditions, we created 4 different herds at the end of the second winter. Each of the 4 initial experimental rearing groups (Salers, Isolated (SI, 14 animals); Salers, Mothered (SM, 13 animals); Friesian, Isolated (FI, 15 animals); Friesian, Mothered (FM, 13 animals)) was divided into 2 sub-groups, and 4 new herds were made up with 2 different sub-groups: Herd 1, SI(6)/SM(7); Herd 2, FI(7)/FM(7); Herd 3, FM(6)/SM(6); Herd 4, SI(8)/FI(8) (the number of animals per sub-group are in parentheses). This allowed us to compare the influence of breed (intra-herdcomparisons in Herds 3 and 4) and of rearing conditions (intra-herdcomparison in Herds 1 and 2). Possible interactions between breed and type of rearing were assessed by inter-herdcomparisons.
Method of observation and behavioural elements studied All the animals were identified individually by collars.Each herd was ol~ served between 5 M a y 1980 and 7 July 1980 for 36 h (4 h on one day, plus 2 separate days from dawn to dusk). At this time, the animals were between 27 and 32 months old. Social interactions were noted using a portable taperecorder. A m o n g all the interactions described by Bouissou (1965), we selected those that were the easiest to watch from a distance, in fieldconditions. Due to their low frequency of occurrence, they were laterpooled into 2 categories: agonistic and non-agonistic (Table I).
46 TABLE I Social interactions Menace and avoiding Head butt and flight I Fight Sniffing, flehmen Licking Head play Mounting Head on rump on withers on back
Ag°nisticl
Non-agonistic ~
IAs defined by Bouissou (1965).
Analysis o f results For each herd, the results were summarized in 3 tables corresponding to agonistic relationships, non-agonistic relationships, and total number of interactions between an animal "i" with another animal "j". In the tables, the basic c o m p o n e n t s U is the number of interactions directed from animal "~" toward animal " j " . T h e number of interactions was first analyzed by pair, regardless of their direction (bij = aij + aij) and there were [N(N-1)]/2 pairs per group of N animals. The frequencies of interactions of each herd or of each sub-group were also compared among themselves, using the Kolmogorov--Smirnov test (Siegel, 1956). In the second step of analysis, the direction of the interactions observed between 2 given groups of the same herd was studied. In the first type of analysis, we compared the interactions from Group 1 towards Group 2 with those from Group 2 towards Group 1. In the second type of analysis, we used a method which, as far as we know, has never been employed before in studies of dominance--subordination. An index, which we called "hierarchical power", was computed for each animal, and then used to compare the experimental groups of a same herd, with the Mann--Whitney test. This computation was carried out using the method of Kendall (1955) for analysis of preferences. A two-way table Cij was set up to display the agonistic interactions. When, for 2 given animals i and j, the number of agonistic interactions from i towards ] (aij) was greater than that of j towards i (aji), Cij = 2 and Cji = 0 in the table. If aij = aji, then Cij = Cji = 1. Using this table, and given N as the total number of heifers in the herd, the hierarchical power Pi of a heifer was Pi (k), when h tends towards infinity. Pi (k) was computed by M iterations according to the following formula:
47
v i, P i ( O ) = 1
N
N
N
Pi(k) = X {CijPj(k-1)}× 100 / { 2; X CijPl(k-1)} j=l i=lj=l T A B L E II
Example of computation of the hierarchical power by iterations in the case of 4 animals II(i). Table of agonistic interactions observed between 4 animals A, B, C a n d D
II(ii). Transformation of rough data according to the c o n d i t i o n s for computation o f Pi if aij > aji ~ Cij = 2, Cij = 0 if aii= aji --~ Ci. i = C j j = 1
j
_j
N
N
N
i
A
B
C
D
i
A
B
C
D
P i ( 1 ) = ~ Cii/ y~ ~ Ci] 1--1 i=lj=l
A B C D
-12 20 27
25 -10 13
32 15 -10
18 22 12 --
A B C D
1 0 0 2
2 1 0 0
2 2 1 0
0 2 2 1
100x5016 100×5/16 100x3/16 100x3/16
= = = =
31.2 31.2 18.7 18.7
II(iii). Second iteration
j
N
A B C D
NN
Pi(2) = ~Cijo Pj(1)/ ~ ~ CifPt(1)
i
A
B
C
D
1×31.2 0x31.2 0x31.2 2x31.2
2x31.2 lx31.2 0×31.2 0x31.2
2x18.7 2x18.7 lx18.7 0x18.7
0×18.7 2×18.7 2×18.7 1×18.7
j=l 100×131.0/374.2 100×106.01374.2 100x 56.1 ]374.2 100× 81.1 /374.2
i=I jffil = = = =
35.0 28.3 15.0 21.7
II(iv). T h i r d iteration
J
N
i
NN
~i(3)= x cii.Pi(2)/ r ~ A
B
C
D
j=l
A
lx35.0
2X28.3 2x15.0
0x21.7
100x121.6/370.4= 32.8
B C D
0X35.0 0x35.0 2x35.0
lX28.3 0x28.3 0x28.3
2x21.7 2x21.7 lx18.7
100X101.7]370.4 = 27.5 100x 5 8 . 4 ] 3 7 0 . 4 = 15.8 1 0 0 x 8 8 . 7 ] 3 7 0 . 4 = 23.9
2x15.0 lxlS.0 0x15.0
cifPj(2)
i=1j=1
A t t h e 3rd i t e r a t i o n w e have P A = 32.8, PB = 27.5, PC = 15.8, PD = 23.9. I n a c o n v e n tional r e p r e s e n t a t i o n w e w o u l d have: ~ - * B - * C - * ]~. Therefore, although C is d o m i n a n t
over D, the latter has a greater hierarchical power since he is dominant over A.
48 The sum total of all the values obtained in a row for one animal gave the first value Pi (1) of its hierarchical power (cf. Table ILl). In the second step, each cell Cij of the table was magnified by the corresponding value obtained for Pj. This was repeated M times, in using the last value obtained for Pi in each magnification. An example of iteration for M = 3 is given in Table II. This method was preferable to those suggested by Brantas (1968), because of its easiness of computation, and also because it made it possible to give a different weight to a given social interaction, depending on the relative hierarchical powers computed in the successive steps of iteration for the 2 animals involved. This is particularly illustrated in Table II, where Animal D, although last in the hierarchy, has a higher hierarchical power than Animal C, because he dominates over Animal A. A FORTRAN programme, available on request, was used to compute the values for Pi(k) from the aij interactions table.
RESULTS
Number of interactions by pair The mean numbers of interactions by pair varied greatly from one herd to another (from 1.69 in FI/FM herd up to 4.11 in SI/SM herd; P ~ 0.05, Table HI). Herds containing both breeds (SI/FI and SM/FM) did not differ significantly from herds containing only one breed. Each sub-group of a given herd (e.g. SI from SI/SM herd) had a mean number of interactions by pair similar to that of its corresponding sub-group in the other herd (SI from SI/FI herd in this case). This was true for all sub-groups, and therefore results were pooled by experimental treatments. These results are given in Table IV. Agonistic behaviour was more frequent in groups of heifers reared TABLE III Number of interactions by pair in the various herds Herd
Number
Mean number of interactions by pair
of pairs
Agonistic
Non-agonistic
Total
SI / SM
78
2.36 a
1.76 a
4.11 a
FI / FM
91
1.09 b
0.60 b
1.69 c
SM ! FM
66
2.08 c
0.97 c
3.05 b
120
1.28 cb
0.97 c
2.25 b
SI / FI
In the same column, means with the same letter as index do not differ significa~ntly (Kolmogorov--Smirnov test, P < 0 . 0 5 ) .
49
TABLE IV Mean number of interactions by pair in relation to rearing conditions and breed Breed
Social relationship
Agonistic
Non-agonistic Total
$alers (S)
Mothered (M) Isolated (I)
2.28 a 1.63 b
1.69 ab 1.77 a
3.97 a 3.40 a
Friesians (F)
Mothered (M) Isolated (I)
2.03 ab 1.06 b
0.97 b 0.49 c
3.00 a 1.55 c
Both
Mothered (M) Isolated (I)
2.15 b 1.33 a
1.33 a 1.09 a
3.48 b 2.43 a
Salers (S) Friesians (F)
Both
1.92 a 1.47 a
1.73 a 0.69 b
3.68 a 2.16 b
For each type of behaviour, figures with the same letter do not differ significantly (Kolmogorov---Smirnovtest, P < 0.05). by a foster-cow (M) than in groups of females which had been bucket-fed (I) (Table IV). Salers females displayed more agonistic behaviour among themselves than did Friesians.
Direction o f interactions We considered only the individual inter-group relationships in each herd, and n o t intra-group interactions. Therefore, we had 2 series of results for each herd: actions of the animals of Group 1 towards animals of Group 2 and vice versa (Table V). The frequency of non-agonistic interactions did not depend on the experimental groups. By contrast, agonistic interactions varied with groups, except in the Friesian herd (FI/FM, 0.36 vs. 0.29, n.s.). Within the Salers herd, heifers reared by a foster-cow (SM) displayed more frequently agonistic behaviour towards bucket-fed heifers (SI) than the opposite (SI towards SM) (P < 0.05; Table V). In herds including both breeds (SM/FM and SI/FI), Salers directed agonistic behaviour more frequently towards Friesians than the Friesians towards the 8alers (P < 0.05}. We studied the relationships between the hierarchical power computed for the heifers and some of their characteristics at the time that the herds were formed: weight, height to withers, age, presence of beginning of horns. This was c o m p u t e d within each group to exclude possible influences of breed and rearing conditions. The hierarchical power was significantly correlated with weight (r = 0.521; P < 0.001}, with height to withers (r = 0 . 5 0 8 ; P < 0.001) and with age (r = 0.388; P < 0.05}. As in the case of agonistic interactions, the mean hierarchical power per group differed in 3 groups o u t o f 4, the only exception concerning the herd of Friesian females (Table VI). However,
5O TABLE V Number of interactions for each animal directed towards animals of a different rearing condition or b r e e d Herd
SI ] SM
Direction of interactions
I ~ M
Interactions Agonistic
Non-agonistic
Total
0.12
0.79
0.91
*
FI / FM
M --, I
2.38
I ~ M
0.47
NS
0.83 0.16 NS
SM / FM
M~ I
0.39
S -* F
1.61
SI / FI
0.31
S -* F
0.92
0.29
2.17 NS
0.44
*
0.75
0.31
0.33
NS 0.68
0.56
*
F -* S
0.63 NS
*
F ~ S
*
3.21
1.23 NS
0.48
*
0.81
*Significant differences, Kolmogorov-Smirnov test, P < 0.05. TABLE VI Influence of breed and rearing conditions on hierarchical power of heifers Herds
FI
FM
SI / SM FI / FM
4¢3 7.4
SM / FM SI / FI
SI **
1016
6.9 6.3
**
**
7.8
I
4.7
SM
10.4
Mann--Whitney test. *Significant difference, P < 0.05. **Significant difference, P < 0.01. it is difficult t o relate this t o specific effects o f t h e rearing c o n d i t i o n s and breed, since these 2 factors have m o d i f i e d b o t h t h e physical characteristics o f t h e animals (Table V I I ) a n d t h e hierarchical p o w e r s i m u l t a n e o u s l y , especially in t h e Salers h e r d (SI/SM). O n t h e o t h e r h a n d , physical factors (i.e. weight and height t o withers) m a y n o t be t h e o n l y ones responsible for t h e difference o f hierarchical p o w e r f o u n d b e t w e e n t h e 2 groups o f t h e Salers h e r d (SI/SM). When using intra-group linear regression, the t h e o r e t i c a l dif-
51 TABLE VII Weight and height to withers of heifers according to breed and rearing conditions Experimental group
Mean weight (kg) FI
/ FM
SI / SM
Height to withers (cm) SI
3~(117)
SM/FM SI/FI
356/
317//<_._.Z.__..~
/ FI/FM
SM
(118) ~ *
t/(125)
3~(118) 3~(118)
3~(117)
-
34~(123) 3~(120)
Mann--Whitney test. *Significant difference, P < 0.05. ference due to physical factors should be 1.5 or 2.4, depending on whether weight or height to withers is used. By contrast, the observed difference was 6.3 to the advantage of the group reared with a foster cow. The presence of horns had no effect on the intra-group hierarchical power. DISCUSSION AND CONCLUSION It is clear from our results that breed has a marked influence on social behaviour. Friesians were socially less active than Salers. In addition, Salers clearly dominated Friesians. This breed difference was not modified by rearing conditions and is probably of genetic origin. This is supported by Beilharz et al. (1966) and Dickson et al. (1970), who observed heritabilities of the dominance index of 0.4 and 0.3, respectively. Breeders of Friesian dairy cows thus appear to have selected animals with a low social activity and a low dominance index, since such animals are likely to adapt more easily than other cows to the frequent human manipulations of dairy breeding. In both breeds, heifers reared without a foster-cow were less active than those that were suckled. On the other hand, the influence of rearing conditions on the hierarchical power varied with the breed. Suckled Salers females were dominant over bucket-fed animals of the same breed. This effect could result, at least partially, from physical differences, such as body weight and height to withers, influencing hierarchical power, due to difficulties of rearing Salers calves in isolation. By contrast to what was observed in the Salers breed, rearing conditions were not found to have any effect on Friesian heifers. Donaldson et al. (1966), Warnick et al. (1977) and Broom and
52
Leaver (1978) f o u n d t h a t dairy animals reared in isolation from 10 weeks to 10 months were dominated by those reared in a group. It is possible that group rearing increased the agonistic behaviour of their animals, although this was n o t the case in our study. Furthermore, the length and intensity of isolation in our study may n o t have been as complete as in other studies, and our isolated animals were grouped with fostered animals only a few months after the end o f their period of isolation. The effects of the interaction between rearing conditions and genotype on social behaviour are in agreement with other findings on the behaviour of these two breeds. Friesian calves consume larger quantities of colostrum than Salers and drink more easily from a bucket (Le Neindre et al., 1979). They also eat solid food sooner and in larger amounts than Salers calves (P. Le Neindre, unpublished results). All these results tend to suggest that Friesian calves are better adapted to being reared in isolation from birth, and that later consequences are much less important than for Salers calves. These behavioural differences between Friesian and Salers heifers can probably be found between the two main types of cattle, namely suckling cattle (especially those of beef breeds) and dairy cattle. ACKNOWLEDGEMENTS We are grateful to Doctors P. Poindron and G.B. Martin for the English translation of the manuscript.
REFERENCES Beilharz, R.G., Butcher, D.F. and Freeman, A.E., 1966. Social Dominance and Milk Production in Holsteins. J. Dairy Sci., 49: 887--892. Bouissou, M.F., 1965. Observations sur la hi~rarchie sociale chez les bovins domestiques. Ann. Biol. Anita. Biochim. Biophys., 5: 327--339. Brantas, J.C., 1968. On the dominance order in Friesian Dutch dairy cows. Z. Tierz. Z(ichtungs biol., 84: 127--151. Broom, D.M. and Leaver, J.D., 1978. Effects of group-rearing conditions or partial isolation on later social behaviour of calves. Anim. Behav., 26: 1255--1263. Dickson, D.P., Barr, G.R., Johnson, L.P. and Wieckert, D.A., 1970. Social Dominance and Temperament of Holstein Cows. J. Dairy Sci., 53 : 904--907. Donaldson, S.L., Black, W.C. and Albright, J.L., 1966. The effects of early feeding and rearing experiences on the dominance, aggressive, and submissive behavior in young heifer calves. Am. Zool., 6: 554--560. Kendall, M.G., 1955. Further contributions to the theory of paired comparisons. Biometrics, 11: 43--62. Le Neindre, P., Menard, M.F. and Garel, J.P., 1979. Suckling and drinking behaviour of newborn calves of beef and dairy cows. Ann. Rech. Vet., 10: 211--212. Siegel, S., 1956. Non-parametric statistics for the behavioral sciences. McGraw Hill, New York. Warnick, V.D., Arave, C.W. and Mickelsen, C.H., 1977. Effect of group, individual and isolated rearing of calves on weight gain and behaviour. J. Dairy Sci., 60: 947---953.
43
INFLUENCE OF REARING CONDITIONS ON SUBSEQUENT SOCIAL BEHAVIOUR OF FRIESIAN AND SALERS HEIFERS FROM BIRTH TO SIX MONTHS OF AGE
P. LE NEINDRE and CHRISTINE SOURD
Laboratoire de la Production de viande, Centre de Recherches de Clermont-Ferrand, I.N.R.A., Theix, Sant-Gen}s-Champanelle, 63110 Beaumont (France) (Accepted for publication 18 April 1983)
ABSTRACT Le Neindre, P. and Sourd, C., 1984. Influence of rearing conditions on subsequent social behaviour of Friesian and Salers heifers from birth to six months of age. Appl. Anim. Behav. Sci., 12: 43--52. Social relationships were studied in 4 herds of 2.5-year-old heifers (55 animals in total). Animals of Frieslan (F) or Salers (S) breed were observed at pasture during 144 h. In each breed, half of the females had been either reared by a foster cow (M), or bucketfed and isolated for 10--12 weeks (I). When a year old, animals were allocated into 4 herds, each herd including heifers of 2 experimental treatments. The 4 chosen combinations (FM/FI, SM/SI, SM/FM, SI/FI) allowed us to study the effects of rearing conditions and breed on social behaviour. Non-agonistic interactions were more frequent within Salers groups than within Friesian groups, regardless of rearing conditions. When comparing the 2 rearing conditions (isolated (I) versus mothered (M)), agonistic interactions were more frequent between suckled than between bucket-fed animals, regardless of breed. Hierarchy relationships were assessed by a new method, relying on the notion of hierarchical power, computed from all the individual relationships within a group. Salers heifers had a higher hierarchical power than Friesians. Suckled Salers females were dominant over bucket-fed females of the same breed. By contrast, no significant difference was observed between the 2 corresponding Friesian groups. It would appear, therefore, that bucket-feeding can lead to a disadvantage concerning dominance--subordination relationships in the Salers breed, whereas such an effect is not observed in Friesians. This interaction between breed and rearing conditions may suggest breed differences in the ability of the young to adapt to various rearing systems.
INTRODUCTION
Domestic cattle are raised in many different ways, ranging from intensive systems where rhythms and social environment are mainly determined by humans, to ranching where animals are left free. Farmers select their breeds according to the conditions in which they will be raised. In intensive systems, animals are characterized by high milk production, whereas beef cattle are most commonly bred outdoors. The social conditions in which young 0168-1591/84/$03.00
© 1984 Elsevier Science Publishers B.V.
44
animals are reared vary greatly from one system to another. In dairy farming, the calves are separated from their dam immediately after birth and are reared either in isolation or in groups of animals of the same age. By contrast, in beef production, calves remain with their dam in the herd. However, rearing conditions in the first months of life can influence relationships in adulthood. This has been shown b y Donaldson et al. (1966), Broom and Leaver (1978) and Wamick et al. (1977) for dairy cattle reared in isolation or with other calves of the same age. The development of individual relationships within a herd can also vary with genotype (Donaldson et al., 1966). Therefore, breeds which differ in some physiological factors can also differ in their behavioural ability to adapt to various breeding conditions. We proposed to test such a hypothesis by analyzing the possible influence of breed and social history, up to 6 months of age, on the social relationships of 2.5-year-old heifers. Friesian and Salers breeds were chosen. Salers cattle are bred in hilly and humid parts of the French Massif Central. Calves of this breed are always suckled b y their mothers, even when cows are partially milked in the meantime. By contrast, Friesian cattle are generally reared without their dams. In the present experiment, female calves of these 2 breeds were reared either isolated and bucket~fed, or kept within a group and suckled b y fostercows. The social behaviour of these animals was studied when they were about 2.5 years old, some months before their first parturition. METHODS
Experimental groups We used 27 Salers (S) and 28 Friesian (F) female calves, which were born between 2 November and 3 March. In both breeds, calves were reared according to one of the t w o methods described below until the formation of the final herds, when heifers were a b o u t 16 months old.
Rearing in isolation (I) (without nurse-cow) At birth, female calves were put into individual pens, so that physical contact and visual cues with other animals were not possible. Only acoustic information from other calves was available. Up to 8 weeks after birth, they were fed twice a day with milk in a bucket fitted with a rubber teat and, in addition, received hay, pellets and water. When the calves were between 10 and 12 weeks old, they were put into groups of 4 and, a few days later, they were mustered in 2 herds of mixed breeds. One herd was made of the oldest calves and the second of the youngest ones. These 2 herds were turned o u t to grass in spring, where daily supplementation of pellets was also provided.
Mothered (M) (suckling a foster-cow) To obtain similar rearing conditions for the 2 breeds, all calves were
45 fostered and suckled by an alien primiparous Salers cow, just after the parturition of the foster-cow. For all calves, the fostering procedure took place between the first and the 16th day of life. When there was no foster~ow available immediately, the calf was reared individually, as in the group of isolated ones, until it could be fostered. The foster-cow was isolated with the young to be fostered for periods ranging from 3 to 10 days before she joined the herd of foster cows. For 2 months, the calves suckled only twice a day under human supervision. Out of the suckling periods, cows and calves were kept in separate groups. Thereafter, calves stayed permanently by their dams. As for the calves reared in isolation, they were divided into 2 herds, according to the age of the calves. They were weaned when they were brought back indoors in late autumn, when they were between 7 and 11 months old. All calves were polled when 2 months old. However, polling was not completely successful on all animals, especially for some of the Salers calves, which therefore had short and blunt beginnings of horns (less than 10 cm long). The 4 herds so created were not modified until the end of the second winter, when the heifers were about 16 months old.
Formation of the experimental herds for observation of social relationships To study social behaviour in relation to breed and rearing conditions, we created 4 different herds at the end of the second winter. Each of the 4 initial experimental rearing groups (Salers, Isolated (SI, 14 animals); Salers, Mothered (SM, 13 animals); Friesian, Isolated (FI, 15 animals); Friesian, Mothered (FM, 13 animals)) was divided into 2 sub-groups, and 4 new herds were made up with 2 different sub-groups: Herd 1, SI(6)/SM(7); Herd 2, FI(7)/FM(7); Herd 3, FM(6)/SM(6); Herd 4, SI(8)/FI(8) (the number of animals per sub-group are in parentheses). This allowed us to compare the influence of breed (intra-herdcomparisons in Herds 3 and 4) and of rearing conditions (intra-herdcomparison in Herds 1 and 2). Possible interactions between breed and type of rearing were assessed by inter-herdcomparisons.
Method of observation and behavioural elements studied All the animals were identified individually by collars.Each herd was ol~ served between 5 M a y 1980 and 7 July 1980 for 36 h (4 h on one day, plus 2 separate days from dawn to dusk). At this time, the animals were between 27 and 32 months old. Social interactions were noted using a portable taperecorder. A m o n g all the interactions described by Bouissou (1965), we selected those that were the easiest to watch from a distance, in fieldconditions. Due to their low frequency of occurrence, they were laterpooled into 2 categories: agonistic and non-agonistic (Table I).
46 TABLE I Social interactions Menace and avoiding Head butt and flight I Fight Sniffing, flehmen Licking Head play Mounting Head on rump on withers on back
Ag°nisticl
Non-agonistic ~
IAs defined by Bouissou (1965).
Analysis o f results For each herd, the results were summarized in 3 tables corresponding to agonistic relationships, non-agonistic relationships, and total number of interactions between an animal "i" with another animal "j". In the tables, the basic c o m p o n e n t s U is the number of interactions directed from animal "~" toward animal " j " . T h e number of interactions was first analyzed by pair, regardless of their direction (bij = aij + aij) and there were [N(N-1)]/2 pairs per group of N animals. The frequencies of interactions of each herd or of each sub-group were also compared among themselves, using the Kolmogorov--Smirnov test (Siegel, 1956). In the second step of analysis, the direction of the interactions observed between 2 given groups of the same herd was studied. In the first type of analysis, we compared the interactions from Group 1 towards Group 2 with those from Group 2 towards Group 1. In the second type of analysis, we used a method which, as far as we know, has never been employed before in studies of dominance--subordination. An index, which we called "hierarchical power", was computed for each animal, and then used to compare the experimental groups of a same herd, with the Mann--Whitney test. This computation was carried out using the method of Kendall (1955) for analysis of preferences. A two-way table Cij was set up to display the agonistic interactions. When, for 2 given animals i and j, the number of agonistic interactions from i towards ] (aij) was greater than that of j towards i (aji), Cij = 2 and Cji = 0 in the table. If aij = aji, then Cij = Cji = 1. Using this table, and given N as the total number of heifers in the herd, the hierarchical power Pi of a heifer was Pi (k), when h tends towards infinity. Pi (k) was computed by M iterations according to the following formula:
47
v i, P i ( O ) = 1
N
N
N
Pi(k) = X {CijPj(k-1)}× 100 / { 2; X CijPl(k-1)} j=l i=lj=l T A B L E II
Example of computation of the hierarchical power by iterations in the case of 4 animals II(i). Table of agonistic interactions observed between 4 animals A, B, C a n d D
II(ii). Transformation of rough data according to the c o n d i t i o n s for computation o f Pi if aij > aji ~ Cij = 2, Cij = 0 if aii= aji --~ Ci. i = C j j = 1
j
_j
N
N
N
i
A
B
C
D
i
A
B
C
D
P i ( 1 ) = ~ Cii/ y~ ~ Ci] 1--1 i=lj=l
A B C D
-12 20 27
25 -10 13
32 15 -10
18 22 12 --
A B C D
1 0 0 2
2 1 0 0
2 2 1 0
0 2 2 1
100x5016 100×5/16 100x3/16 100x3/16
= = = =
31.2 31.2 18.7 18.7
II(iii). Second iteration
j
N
A B C D
NN
Pi(2) = ~Cijo Pj(1)/ ~ ~ CifPt(1)
i
A
B
C
D
1×31.2 0x31.2 0x31.2 2x31.2
2x31.2 lx31.2 0×31.2 0x31.2
2x18.7 2x18.7 lx18.7 0x18.7
0×18.7 2×18.7 2×18.7 1×18.7
j=l 100×131.0/374.2 100×106.01374.2 100x 56.1 ]374.2 100× 81.1 /374.2
i=I jffil = = = =
35.0 28.3 15.0 21.7
II(iv). T h i r d iteration
J
N
i
NN
~i(3)= x cii.Pi(2)/ r ~ A
B
C
D
j=l
A
lx35.0
2X28.3 2x15.0
0x21.7
100x121.6/370.4= 32.8
B C D
0X35.0 0x35.0 2x35.0
lX28.3 0x28.3 0x28.3
2x21.7 2x21.7 lx18.7
100X101.7]370.4 = 27.5 100x 5 8 . 4 ] 3 7 0 . 4 = 15.8 1 0 0 x 8 8 . 7 ] 3 7 0 . 4 = 23.9
2x15.0 lxlS.0 0x15.0
cifPj(2)
i=1j=1
A t t h e 3rd i t e r a t i o n w e have P A = 32.8, PB = 27.5, PC = 15.8, PD = 23.9. I n a c o n v e n tional r e p r e s e n t a t i o n w e w o u l d have: ~ - * B - * C - * ]~. Therefore, although C is d o m i n a n t
over D, the latter has a greater hierarchical power since he is dominant over A.
48 The sum total of all the values obtained in a row for one animal gave the first value Pi (1) of its hierarchical power (cf. Table ILl). In the second step, each cell Cij of the table was magnified by the corresponding value obtained for Pj. This was repeated M times, in using the last value obtained for Pi in each magnification. An example of iteration for M = 3 is given in Table II. This method was preferable to those suggested by Brantas (1968), because of its easiness of computation, and also because it made it possible to give a different weight to a given social interaction, depending on the relative hierarchical powers computed in the successive steps of iteration for the 2 animals involved. This is particularly illustrated in Table II, where Animal D, although last in the hierarchy, has a higher hierarchical power than Animal C, because he dominates over Animal A. A FORTRAN programme, available on request, was used to compute the values for Pi(k) from the aij interactions table.
RESULTS
Number of interactions by pair The mean numbers of interactions by pair varied greatly from one herd to another (from 1.69 in FI/FM herd up to 4.11 in SI/SM herd; P ~ 0.05, Table HI). Herds containing both breeds (SI/FI and SM/FM) did not differ significantly from herds containing only one breed. Each sub-group of a given herd (e.g. SI from SI/SM herd) had a mean number of interactions by pair similar to that of its corresponding sub-group in the other herd (SI from SI/FI herd in this case). This was true for all sub-groups, and therefore results were pooled by experimental treatments. These results are given in Table IV. Agonistic behaviour was more frequent in groups of heifers reared TABLE III Number of interactions by pair in the various herds Herd
Number
Mean number of interactions by pair
of pairs
Agonistic
Non-agonistic
Total
SI / SM
78
2.36 a
1.76 a
4.11 a
FI / FM
91
1.09 b
0.60 b
1.69 c
SM ! FM
66
2.08 c
0.97 c
3.05 b
120
1.28 cb
0.97 c
2.25 b
SI / FI
In the same column, means with the same letter as index do not differ significa~ntly (Kolmogorov--Smirnov test, P < 0 . 0 5 ) .
49
TABLE IV Mean number of interactions by pair in relation to rearing conditions and breed Breed
Social relationship
Agonistic
Non-agonistic Total
$alers (S)
Mothered (M) Isolated (I)
2.28 a 1.63 b
1.69 ab 1.77 a
3.97 a 3.40 a
Friesians (F)
Mothered (M) Isolated (I)
2.03 ab 1.06 b
0.97 b 0.49 c
3.00 a 1.55 c
Both
Mothered (M) Isolated (I)
2.15 b 1.33 a
1.33 a 1.09 a
3.48 b 2.43 a
Salers (S) Friesians (F)
Both
1.92 a 1.47 a
1.73 a 0.69 b
3.68 a 2.16 b
For each type of behaviour, figures with the same letter do not differ significantly (Kolmogorov---Smirnovtest, P < 0.05). by a foster-cow (M) than in groups of females which had been bucket-fed (I) (Table IV). Salers females displayed more agonistic behaviour among themselves than did Friesians.
Direction o f interactions We considered only the individual inter-group relationships in each herd, and n o t intra-group interactions. Therefore, we had 2 series of results for each herd: actions of the animals of Group 1 towards animals of Group 2 and vice versa (Table V). The frequency of non-agonistic interactions did not depend on the experimental groups. By contrast, agonistic interactions varied with groups, except in the Friesian herd (FI/FM, 0.36 vs. 0.29, n.s.). Within the Salers herd, heifers reared by a foster-cow (SM) displayed more frequently agonistic behaviour towards bucket-fed heifers (SI) than the opposite (SI towards SM) (P < 0.05; Table V). In herds including both breeds (SM/FM and SI/FI), Salers directed agonistic behaviour more frequently towards Friesians than the Friesians towards the 8alers (P < 0.05}. We studied the relationships between the hierarchical power computed for the heifers and some of their characteristics at the time that the herds were formed: weight, height to withers, age, presence of beginning of horns. This was c o m p u t e d within each group to exclude possible influences of breed and rearing conditions. The hierarchical power was significantly correlated with weight (r = 0.521; P < 0.001}, with height to withers (r = 0 . 5 0 8 ; P < 0.001) and with age (r = 0.388; P < 0.05}. As in the case of agonistic interactions, the mean hierarchical power per group differed in 3 groups o u t o f 4, the only exception concerning the herd of Friesian females (Table VI). However,
5O TABLE V Number of interactions for each animal directed towards animals of a different rearing condition or b r e e d Herd
SI ] SM
Direction of interactions
I ~ M
Interactions Agonistic
Non-agonistic
Total
0.12
0.79
0.91
*
FI / FM
M --, I
2.38
I ~ M
0.47
NS
0.83 0.16 NS
SM / FM
M~ I
0.39
S -* F
1.61
SI / FI
0.31
S -* F
0.92
0.29
2.17 NS
0.44
*
0.75
0.31
0.33
NS 0.68
0.56
*
F -* S
0.63 NS
*
F ~ S
*
3.21
1.23 NS
0.48
*
0.81
*Significant differences, Kolmogorov-Smirnov test, P < 0.05. TABLE VI Influence of breed and rearing conditions on hierarchical power of heifers Herds
FI
FM
SI / SM FI / FM
4¢3 7.4
SM / FM SI / FI
SI **
1016
6.9 6.3
**
**
7.8
I
4.7
SM
10.4
Mann--Whitney test. *Significant difference, P < 0.05. **Significant difference, P < 0.01. it is difficult t o relate this t o specific effects o f t h e rearing c o n d i t i o n s and breed, since these 2 factors have m o d i f i e d b o t h t h e physical characteristics o f t h e animals (Table V I I ) a n d t h e hierarchical p o w e r s i m u l t a n e o u s l y , especially in t h e Salers h e r d (SI/SM). O n t h e o t h e r h a n d , physical factors (i.e. weight and height t o withers) m a y n o t be t h e o n l y ones responsible for t h e difference o f hierarchical p o w e r f o u n d b e t w e e n t h e 2 groups o f t h e Salers h e r d (SI/SM). When using intra-group linear regression, the t h e o r e t i c a l dif-
51 TABLE VII Weight and height to withers of heifers according to breed and rearing conditions Experimental group
Mean weight (kg) FI
/ FM
SI / SM
Height to withers (cm) SI
3~(117)
SM/FM SI/FI
356/
317//<_._.Z.__..~
/ FI/FM
SM
(118) ~ *
t/(125)
3~(118) 3~(118)
3~(117)
-
34~(123) 3~(120)
Mann--Whitney test. *Significant difference, P < 0.05. ference due to physical factors should be 1.5 or 2.4, depending on whether weight or height to withers is used. By contrast, the observed difference was 6.3 to the advantage of the group reared with a foster cow. The presence of horns had no effect on the intra-group hierarchical power. DISCUSSION AND CONCLUSION It is clear from our results that breed has a marked influence on social behaviour. Friesians were socially less active than Salers. In addition, Salers clearly dominated Friesians. This breed difference was not modified by rearing conditions and is probably of genetic origin. This is supported by Beilharz et al. (1966) and Dickson et al. (1970), who observed heritabilities of the dominance index of 0.4 and 0.3, respectively. Breeders of Friesian dairy cows thus appear to have selected animals with a low social activity and a low dominance index, since such animals are likely to adapt more easily than other cows to the frequent human manipulations of dairy breeding. In both breeds, heifers reared without a foster-cow were less active than those that were suckled. On the other hand, the influence of rearing conditions on the hierarchical power varied with the breed. Suckled Salers females were dominant over bucket-fed animals of the same breed. This effect could result, at least partially, from physical differences, such as body weight and height to withers, influencing hierarchical power, due to difficulties of rearing Salers calves in isolation. By contrast to what was observed in the Salers breed, rearing conditions were not found to have any effect on Friesian heifers. Donaldson et al. (1966), Warnick et al. (1977) and Broom and
52
Leaver (1978) f o u n d t h a t dairy animals reared in isolation from 10 weeks to 10 months were dominated by those reared in a group. It is possible that group rearing increased the agonistic behaviour of their animals, although this was n o t the case in our study. Furthermore, the length and intensity of isolation in our study may n o t have been as complete as in other studies, and our isolated animals were grouped with fostered animals only a few months after the end o f their period of isolation. The effects of the interaction between rearing conditions and genotype on social behaviour are in agreement with other findings on the behaviour of these two breeds. Friesian calves consume larger quantities of colostrum than Salers and drink more easily from a bucket (Le Neindre et al., 1979). They also eat solid food sooner and in larger amounts than Salers calves (P. Le Neindre, unpublished results). All these results tend to suggest that Friesian calves are better adapted to being reared in isolation from birth, and that later consequences are much less important than for Salers calves. These behavioural differences between Friesian and Salers heifers can probably be found between the two main types of cattle, namely suckling cattle (especially those of beef breeds) and dairy cattle. ACKNOWLEDGEMENTS We are grateful to Doctors P. Poindron and G.B. Martin for the English translation of the manuscript.
REFERENCES Beilharz, R.G., Butcher, D.F. and Freeman, A.E., 1966. Social Dominance and Milk Production in Holsteins. J. Dairy Sci., 49: 887--892. Bouissou, M.F., 1965. Observations sur la hi~rarchie sociale chez les bovins domestiques. Ann. Biol. Anita. Biochim. Biophys., 5: 327--339. Brantas, J.C., 1968. On the dominance order in Friesian Dutch dairy cows. Z. Tierz. Z(ichtungs biol., 84: 127--151. Broom, D.M. and Leaver, J.D., 1978. Effects of group-rearing conditions or partial isolation on later social behaviour of calves. Anim. Behav., 26: 1255--1263. Dickson, D.P., Barr, G.R., Johnson, L.P. and Wieckert, D.A., 1970. Social Dominance and Temperament of Holstein Cows. J. Dairy Sci., 53 : 904--907. Donaldson, S.L., Black, W.C. and Albright, J.L., 1966. The effects of early feeding and rearing experiences on the dominance, aggressive, and submissive behavior in young heifer calves. Am. Zool., 6: 554--560. Kendall, M.G., 1955. Further contributions to the theory of paired comparisons. Biometrics, 11: 43--62. Le Neindre, P., Menard, M.F. and Garel, J.P., 1979. Suckling and drinking behaviour of newborn calves of beef and dairy cows. Ann. Rech. Vet., 10: 211--212. Siegel, S., 1956. Non-parametric statistics for the behavioral sciences. McGraw Hill, New York. Warnick, V.D., Arave, C.W. and Mickelsen, C.H., 1977. Effect of group, individual and isolated rearing of calves on weight gain and behaviour. J. Dairy Sci., 60: 947---953.