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Calf control by voice command in a Brazilian dairy
Applied
Animal
Ethology,
Elsevier
Science
Publishers
11 (1983/84) 7-18 B.V., Amsterdam - Printed
7 in The Netherlands
CALF CONTROL BY VOICE COMMAND IN A BRAZILIAN
ROBERT
DAIRY
M. MURPHEY’
Department
of Psychology,
FRANCISCO
A. MOURA
University
for publication
Davis, CA 95616
de Medicina,
Universidade
(U.S.A.)
DUARTE
Departamento de Genktica, Faculdade Ribeirao Preto, S.P. (Brasil)
(Accepted
of California,
de Sab Paula,
14100
23 July 1982)
ABSTRACT Murphey, R.M. and Duarte, F.A.M., 1983. Calf control dairy. Appl. Anim. Ethol., 11: 7-18.
by voice command
in a Brazilian
Brazilian dairymen present calves to their mothers at milking time as a stimulus for milk let-down. The calves are fetched by calling them individually by name. Two crops of Gyr (Bos indicus) calves were observed experimentally. Their responses to the calls were consistent and statistically positive over both observations. Having strangers call the calves resulted in performance decrements, but positive responses still remained well above chance. Randomizing the calling orders had no deleterious effect. Positive responses and the number of calls necessary to elicit a positive response were independent, the latter being related to time of day and level of food deprivation. Calling the calves outside the milking context reduced positive responses dramatically, suggesting that the behavior was, in part, situationspecific. Cows solicit their calves through auditory signals “in nature”, and the husbandrymen’s successful vocal control was probably derived from that preexisting ethological system.
INTRODUCTION
For some cows, particularly those of unselected or “primitive” stock, simple manipulation of the teat is insufficient for milk let-down. The necessary neurohormonal sequence is usually activated by the sight, smell or sound of their calves or calf substitutes (Pollack and Hurnik, 1978). For “modern” dairy breeds, conditioned stimuli, such as the rattling of a milk pail or the attachment of a mechanical device to the teats, usually suffice (Schmidt, 1971). The usual procedure for conducting a milking session (ordenha) in Brazil
‘To whom
correspondence
0304-3762/83/$03.00
should
be addressed.
0 1983 Elsevier
Science
Publishers
B.V.
8
involves matching cows with their calves. When a calf is being sought, it is fetched individually by voice command. Brazilians employ the method in large and small dairies, regardless of the breed being milked or whether the milk is extracted by hand or by machine. This report focuses on the management of calves by voice command in a Brazilian dairy. A BRAZILIAN
ORDENHA
The observations reported here took place intermittently over a period of more than 4 years at the Fazenda Santana da Serra, a dairy located near Mococa, S%o Paulo, Brazil. The cattle were of the Gyr (Bos in&us or Zebu) landrace. Brazilian dairymen widely, if not universally, believe that a Gyr will not let down milk unless her calf or an effigy thereof, such as another calf disguised with the skin of her dead offspring, is physically present. There were 2 ordenhas per day except during one week of each month when the herd was milked 3 times daily while milk-yield and composition measurements were taken. An ordenha began by herding the cows into a shed, where they were tethered in 2 rows, facing feed troughs. The cows were tied at the same spot for every ordenha. Two holding pens, where their calves were restrained, flanked the entrance to the shed (Fig. 1). Typically, a few of the calves stood oriented toward the gate to the pen, while others were standing, milling and lying about in no particular pattern. Generally, the cows farthest from the holding pens were milked first. Because there were 2 rows of cows, 2 holding pens, multiple handlers and occasional disruptive events of a minor nature, the order of milking was not strictly invariant (paired comparisons of the milking orders of five contiguous ordenhas yielded 10 correlation coefficients ranging in value from 0.794 to 0.942, with a median of 0.893). To fetch a calf, a handler unlatched the gate to the holding pen, opened it slightly (Fig. l), and called the name loudly and rapidly an indeterminate number of times. When a calf did not react quickly enough to satisfy the handler, he forced a response by grasping it by an ear or the base of its tail, and guided it briskly to the appropriate cow. When a calf that was not called tried to leave the pen, it was pushed back into the enclosure so as to permit egress for the solicited calf. Upon reaching its mother, the calf was allowed to suckle for approximately 1.5 min while the handler bound the cow’s hind legs tightly together. The calf was then tied to its mother’s front legs within her sight, smell and touch. Finally, the cow was milked by machine, after which the calf was untied and permitted to take the milk remaining in the teats. With respect to the calves’ responses to the calls, at least 3 questions present themselves. (1) Do the calves react reliably? (2) Are the responses specific to a particular name, or to some other aspect of the setting? (3) What is the contextual meaning of the behavior?
Fig. 1. Milking shed at the Fazenda Santana da Serra. A holding pen is in the foreground. Another is located symmetrically across the passageway, outside the left margin of the photograph. The calves’ mothers are tethered in the background. A handler is fetching a calf by name call. The unsolicited calves are not attempting to leave the gate, although some are oriented toward him.
10 OBSERVATION
SET I
Methods
The methods were designed to obtain quantitative descriptions of the calves’ responses to the calls, as well as to assess the importance of the milking order and the presence of a familiar handler. The same 40 calves were observed by one observer in each of 3 ordenhas. Counts were made of the number of positive and forced responses to the calls, as well as the number of unsolicited responses by calves attempting to leave the pen without being called. TABLE I Observation Set I. Number and x2 analyses of calves responding positively and forced to respond when called
Positive responses Forced responses
Session 1
Session 2
Session 3
35 5
20 20
34 6
x2 = 0.105 df=l P > 0.80
Session 1 took place at noon on the day following the one-week, milkyield measurement regime, during which time there had been 3 ordenhas per day. No experimental manipulations were conducted. Session 2 was arranged to simulate what would have been the third, or evening, ordenha of the day had the milk-yield measurement regime been continued. The calves were placed in the holding pens in the same way and at the same hour as they had been during the real ordenhas, but neither their mothers nor the noises of the milking machines were present in the shed. An administrative employee of the dairy, who was not one of the handlers and whose voice was not familiar to the calves in the milking context, called them in the order observed in the first session. Session 3 occurred during the second ordenha, about noon, of the following day. The calves were called by their customary handlers, who employed a randomized calling sequence.
11
Results The results are summarized in Table I. Differences in positive responses between the first and third sessions were insignificant, indicating that the milking order did not affect the outcome. Responses in the second session, when a non-handler called the calves, differed significantly from those of the other 2 sessions. The tendency for some individuals to make unsolicited responses did not account for the general success of the handlers’ calls. The number of times that a calf made an unsolicited response was 21, 8 and 12 for the first, second and third sessions, respectively. In many cases, it was one and the same calf that tried to make unauthorized excursions, time after time, until it finally desisted or was called by the handler at the proper time. Had every calf tried to leave the gate in every trial, whether called or not, the total number of responses would have been N(N + 1)/2 or 820 for each session, whereas the observed number of calves trying to leave the gate, called or not, was 56, 28 and 46 for 3 sessions in order. All three numbers, when compared with the 820 figure, yielded x2’s of greater than 1400 (df = 1, P < 0.001). Moreover, fewer false starts were seen in the third session, when the calling order was random, than in the first session, when it was not. Yet, the number of positive responses remained essentially equal for those 2 sessions. If the calves’ approaches to the gate had been random, the probability that the appropriate calf would respond when called should be the reciprocal of the number of calves in the pen at any given time in the sequence. When the trial-by-trial probabilities are multiplied together (l/N!), the expectancy of a positive response is so small as to be virtually nonexistent over a series of 40 trials. Taking a considerably more liberal view of the problem, and assuming the absolute independence of all trials, summing the probabilities, N-l
_l
c- N-l i=O leads to the expectancy that about 4 calves per session would have made a positive response when called, as opposed to the numbers shown in Table I. Even in the second session, in which positive responses were made by only 50% of the calves, performance was much better than would have been expected on the basis of chance alone (x2 = 15.238, df = 1, P < 0.001). With either method, the calves’ solicited responses were not random, and they were related to the names being called, in that randomizing the calling order and removing the regular handlers and the calves’ mothers still resulted in responses that were specific to particular names.
12 OBSERVATION
SET II
Methods
The Fazenda Santana da Serra was revisited 2 years after Observation Set I had taken place. The time interval allowed an entirely new crop of calves to be available for study. The observations were made at the morning, mid-day and evening ordenhas on 2 days during the milk-yield measurement regime. In addition to the positive and forced responses, as recorded in Observation Set I, a tally was kept of the number of calls preceding a positive response. The same 40 calves were observed in each session. The subjects ranged in age from 61 to 365 days, with a mean of 149 days, on the first day of the observations. On the first or Experimental Day, multiple observers participated in scoring the responses and number of calls. Because the names were called in rapid succession, the tallies of more than one observer were averaged so as to enhance validity. During the morning ordenha (Session l), no experimental manipulations were carried out. Except for the time of day, the procedure was equivalent to that of the first session of Observation Set I. Four observers were present. For the mid-day ordenha (Session 2), the morning milking order was randomized, as had been done in the third session of Observation Set I. Four observers were present. For the evening ordenha (Session 3), a graduate student, who was a “stranger” to the animals except for having served as one of the observers during the previous sessions, and who was from the extreme south of Brazil, where Portuguese is pronounced differently from that spoken at the study site, called the calves (to a maximum of 20 calls per calf) using the order determined by the handlers (its correlation with the order of the morning session was 0.941). Apart from the presence of the calves’ mothers and the noises created by the milking machines, the procedure was similar to that of the second session of Observation Set I. Three observers recorded the data. The second or Control Day took place 3 days after the Experimental Day. Two observers were present during the morning, mid-day and evening ordenhas, keeping accounts of the same variables as those recorded on the Experimental Day. No experimental manipulations were conducted during any of the 3 sessions, as had been the case in Session 1 of the Experimental Day. Results
The positive and forced responses to the handlers’ calls are shown in Table II. A x2 test comparing the 6 positive response cells was not statistically significant (x2 = 5.088, df = 2, P < 0.10). The third session of the Experimental Day (when the graduate student called the calves) accounted for 65.5% of the overall x2. The results were consistent with those of Observation Set I, in that a random milking order did not impede performance, and the poorest
13 TABLE II Observation Set II. Number of calves responding positively and forced to respond when called
Experimental
Day
Control Day
Session 1 (Morning)
Session 2 (Midday)
Session 3 (Evening)
Positive response Forced responses
29 11
33 7
21 19
Positive response Forced responses
36 4
32 8
36 4
responsiveness occurred when a non-handler called the calves. The relationship between age and the number of positive responses was not high ( r = 0.194, df = 38, P > 0.50). Ignoring the calves forced to respond before 20 calls had been made, the probability of a positive response within 20 calls was 0.986 for Sessions 1 and 2 of the Experimental Day. Figure 2 shows the mean number of calls (to a maximum of 20) necessary to elicit a positive response over the 6 sessions. II 10
n 6 7 6 5 4 3 1
MORNlN6 (SESSION
MID-DAY
1)
(SESSIGN2)
OBSERVATION
EVENING (SESSION3)
SEQUENCE
number of calls necessary to elicit a positive response by sessions in Observation Set II. The number of calls was calculated from the observers’ tallies, divided by the number of observers.
Fig. 2. Mean
14
The calves forced to respond prior to 20 calls were omitted from the data. Inspection of Fig. 2 suggests that, while the mean number of calls prior to a positive response increased over the experimental sessions, it also increased over the 3 Control Day sessions. The visual impression was supported by a mean-squares analysis of variance in which the main effects of sessions (F = 21.211, df = 2/234, P < 0.01) and day (F = 28.357, df = l/234, P < 0.01) were statistically significant, but the sessions X day interaction was not (F = 2.542, df = 2/234, P > 0.05). The implication is that the number of calls necessary to elicit a positive response was affected systematically by the time of day for both the Experimental and Control Days. The relationship between calls preceding a positive response and age of the subjects was negative (r = -0.401, df = 38, P < 0.01).
OBSERVATION
SET III
Methods
The observations took place between a mid-day and an evening ordenha in a large, grassy paddock where freshly-chopped sugar cane was available to the calves ad libitum. Their mothers were being kept separately in a nearby pasture. Standing no closer than 15 m to the target animals, a regular handler called the 40 calves observed in Observation Set II, using a maximum of 50 calls per calf and the calling order of Session I of the Experimental Day. The criterion for a positive response was that the target animal had to take at least 4 steps toward the handler upon being called. Four observers tallied the responses. Results
The findings were much less impressive than they were in the previous observation sets. Although the observers reported that many of the subjects looked, listened or otherwise oriented themselves toward the handler when called, only 7 of the 40 calves unequivocally met the criterion, and only one of them did it within 20 calls. The number of calls preceding a criterion response ranged from 10 to 40, with a mean of 28.85. DISCUSSION
The use of the number of positive responses as a dependent variable provided an overly conservative estimate of the strength of the phenomenon under investigation. Had the handlers shown more patience in not forcing the responses, the results might have been more dramatic. The problem was frustratingly noticeable in the early part of Session 1, Experimental Day, Observation Set II, when the handlers apparently thought that the observers
15
were there (possibly at the behest of the owner) to see how efficiently the milking session was being conducted. As a consequence, 7 of the first 10 calves were forced out of the pen without ample opportunity (i.e. a mean of 1.88 calls per calf) to respond to the names, and were not counted as positive responders in our data. As another example, if those calves forced to respond within 20 calls were to be removed from the analysis for the Control Day, Observation Set II, the probability of a positive response would rise from approximately 0.867 to 0.945 (it would increase to 0.986 for Sessions 1 and 2 of the Experimental Day, as mentioned earlier). It was not feasible to interfere with the handlers’ work and impose on their good will more than we had already by asking them to conduct themselves differently, or to modify their procedures in some way that might unpredictably alter the expression of the behavior under study. While the results may have erred toward conservatism, a significant majority of the calves responded appropriately when called by a regular handler, and changing the milking order did not reduce the number of positive reponses in the first two observation sets. When a non-handler called the calves, performance dropped to approximately 50%, which was still well above what would be expected on the basis of chance. Apparently the calves’ responses were conditioned to particular names only in part. Other relevant stimuli might have been the regular handlers’ physical personae, odors, gestures, gazes and sundry qualities of their vocal patterns. In Observation Set I, Session 2, an explanation for the performance decrement was not immediately determinable because at least 3 variables were confounded: (1) the presence of an unfamiliar handler; (2) time of day; (3) an absence of the mothers and noises created by the milking apparatus. The difference was negligible between the calves’ responses in that session and the one in which they were called by the graduate student at the same time of day but with the cows and shed-noises present (x2 = 0.050, df = 1, P < 0.90). Thus, the presence or absence of the calves’ mothers and background noises had no effect, and the general phenomenon was reliable over time with a different sample of subjects. In Observation Set II, the number of calls necessary to elicit a positive response was affected systematically by the time of day, but the number of positive responses was not. A single explanation may account for the apparent independence of the 2 dependent variables. We suggest that the number of positive responses was primarily an operational indicator of leaming, whereas the number of calls was, in addition, a reflection of the degree of food deprivation. Cattle in general, and Zebus in particular, eat little at night (Hafez and Bouissou, 1975; Ruckebusch, 1975). The morning ordenhas began shortly before dawn, a time when the calves should have been the hungriest. As the day progressed, the ordenhas were alternated with periods of ad libitum access to grass and fodder. It follows that motivation to seek nutrients from the mother might decrease over the course of the day, requiring more calls to bring about a response in the evening than in the early
16
morning. It is pertinent to recall that performance fell precipitously in Observation Set III, when the calves were called while they were feeding. The results of Observation Set III suggest that the calves’ responses were situation-specific, but a comparison of the data with those of the other observation sets must be viewed with caution. It is questionable that walking toward the handler in a paddock is equivalent to seeking out the gate in the shed. Moreover, although cattle typically maintain a distance between themselves and humans (Murphey et al., 1980), they also have a tendency to investigate novel objects, including humans, in open field situations (Murphey et al., 1981a, b). Calling the calves in the paddock could have served to orient them toward the caller and attendant observers, with the resulting approach-behavior being more a manifestation of investigatory activity than responses to a called name per se. or alluded to variously in previous The word “learning” was mentioned paragraphs. The observations reported here did not include a formal demonstration that the calves had learned to respond to name calls. Even so, the training procedures, while perhaps inefficient, provided obvious opportunities for reinforced practice. The positive correlation between age and positive responses, and the negative one between age and calls preceding a positive response, were further circumstantial evidence for learning. The directions of the correlations were in accord with the expectation that the older calves should exhibit superior performance by virtue of their having had additional training. As an aside, a calf was called by its mother’s name until it was weaned. A female received her own name upon giving birth to her first calf, after which her nursing young were all called by her name. Although we did not study it systematically, we saw little evidence that the adult cows ever learn their own names, notwithstanding local assurances that they do and the data presented by Albright et al. (1966). CONCLUSION
Most of the calves responded appropriately and reliably when called by name by a familiar handler. At least half of the subjects came when called by a non-handler. The responses appeared to have been conditioned to other, as yet undetermined, stimuli as well as the names. Instrumental conditioning, as such, was not demonstrated in accordance with traditional criteria, but it is reasonable to attribute the calves’ positive responses to learning. More importantly, the observations provided an example of the folk-use of ethological resources in animal husbandry. Lott and Hart (1979) described how Fulani herdsmen in subSaharan Africa make a place for themselves in the dominance hierarchies of their cattle as a means of maintaining behavior control. In the present case, Brazilian dairymen may have become a part of a pre-existing motivational system which they similarly exploit in animal management. It is well known that cows summon their calves by calling them (cf. Dobie, 1941; Schloeth, 1958; Kiley, 1972). In a sense, calves are
17
fetched “by name” “in nature”. Whether they must learn to discriminate their mothers’ calls from those of other cows is unknown, but in any case, the capacity to respond appropriately to a particular auditory signal exists in the absence of human intervention. In successfully soliciting calves by calling them, and in presenting them to their mothers so as to stimulate milk letdown, the handlers were taking advantage of 2 ethological resources. They combined a folk knowledge of a stimulus--response contingency of oxytocin release in milch cows with the preexisting ability of calves to obey specific, voiced commands. The result was an orderly and productive dairy operation. ACKNOWLEDGEMENTS
This research was supported by the Applied Sciences Unit, Department of Scientific Affairs, Organization of American States. We thank Prof. Dale F. Lott for suggesting some of the interpretations contained in the Conclusions section. We also appreciate the invaluable assistance of Irineu Machado Benevides Filho, Lucia Moreno de Souza, Claudia Helena Gadini and Paulo Roberto Nogara Rorato, who served as observers in Observation Sets II and III, as well as the contributions of Washington Coelho Novaes and Maria Cecilia Torres Penedo, who participated in earlier stages of the project. We are especially grateful to the employees of the dairy for their magnanimous hospitality and tolerance. It is with deep sadness that we can offer no more than posthumous homage to the owner of the fazenda, Francisco Figueiredo Barretto, who cooperated unsparingly in this and other research that we have conducted over the course of several years.
REFERENCES Albright, J.L., Gordon, W.P., Black, W.C., Dietrich, J.P. and Snyder, W.W., 1966. Behavioral responses of cows to auditory training. J. Dairy Sci., 49: 104-106. Dobie, J.F., 1941. The Longhorns. Little, Brown and Co., New York. Hafez, E.S.E. and Bouissou, M.F., 1975. The behaviour of cattle. In E.S.E. Hafez (Editor), The Behaviour of Domestic Animals. Williams and Wilkins, Baltimore, pp. 203-245. Kiley, M., 1972. The vocalizations of ungulates, their causations and functions. Z. Tierpsychol., 31: 171-222. Lott, D.F. and Hart, B.L., 1979. Applied ethology in a nomadic cattle culture. Appl. Anim. Ethol., 5: 309-319. Murphey, R.M., Duarte, F.A.M. and Ton-es Penedo, M.C., 1980. Approachability of bovine cattle in pastures: Breed comparisons and a breed x treatment analysis. Behav. Genet., 10: 173-183. Murphey, R.M., Duarte, F.A.M., Novaes, W.C. and Torres Penedo, M.C., 1981a. Age group differences in bovine investigatory behavior. Dev. Psychobiol., 14: 117-125. Murphey, RM., Duarte, F.A.M. and Torres Penedo, M.C., 1981b. Responses of cattle to humans in open spaces: Breed comparisons and approachavoidance relationships. Behav. Genet., 11: 37-48.
18
Pollack, W.E. and Hurnik, J.F., 1978. Effect of calf calls on rate of milk release of dairy cows. J. Dairy Sci., 61: 1624-1626. Ruckebusch, Y., 1975. Feeding and sleep patterns of cows prior to and post parturition. Appl. Anim. Etho!;, 1: 283-292. Schloeth, R., 1958. Uber die Mutterkind-Beziehungen des Halbwilden Camargue-Rindes. Saugetierkdl. Mitt., 6: 145-150. Schmidt, G.H., 1971. Biology of Lactation. Freeman, San Francisco.
Animal
Ethology,
Elsevier
Science
Publishers
11 (1983/84) 7-18 B.V., Amsterdam - Printed
7 in The Netherlands
CALF CONTROL BY VOICE COMMAND IN A BRAZILIAN
ROBERT
DAIRY
M. MURPHEY’
Department
of Psychology,
FRANCISCO
A. MOURA
University
for publication
Davis, CA 95616
de Medicina,
Universidade
(U.S.A.)
DUARTE
Departamento de Genktica, Faculdade Ribeirao Preto, S.P. (Brasil)
(Accepted
of California,
de Sab Paula,
14100
23 July 1982)
ABSTRACT Murphey, R.M. and Duarte, F.A.M., 1983. Calf control dairy. Appl. Anim. Ethol., 11: 7-18.
by voice command
in a Brazilian
Brazilian dairymen present calves to their mothers at milking time as a stimulus for milk let-down. The calves are fetched by calling them individually by name. Two crops of Gyr (Bos indicus) calves were observed experimentally. Their responses to the calls were consistent and statistically positive over both observations. Having strangers call the calves resulted in performance decrements, but positive responses still remained well above chance. Randomizing the calling orders had no deleterious effect. Positive responses and the number of calls necessary to elicit a positive response were independent, the latter being related to time of day and level of food deprivation. Calling the calves outside the milking context reduced positive responses dramatically, suggesting that the behavior was, in part, situationspecific. Cows solicit their calves through auditory signals “in nature”, and the husbandrymen’s successful vocal control was probably derived from that preexisting ethological system.
INTRODUCTION
For some cows, particularly those of unselected or “primitive” stock, simple manipulation of the teat is insufficient for milk let-down. The necessary neurohormonal sequence is usually activated by the sight, smell or sound of their calves or calf substitutes (Pollack and Hurnik, 1978). For “modern” dairy breeds, conditioned stimuli, such as the rattling of a milk pail or the attachment of a mechanical device to the teats, usually suffice (Schmidt, 1971). The usual procedure for conducting a milking session (ordenha) in Brazil
‘To whom
correspondence
0304-3762/83/$03.00
should
be addressed.
0 1983 Elsevier
Science
Publishers
B.V.
8
involves matching cows with their calves. When a calf is being sought, it is fetched individually by voice command. Brazilians employ the method in large and small dairies, regardless of the breed being milked or whether the milk is extracted by hand or by machine. This report focuses on the management of calves by voice command in a Brazilian dairy. A BRAZILIAN
ORDENHA
The observations reported here took place intermittently over a period of more than 4 years at the Fazenda Santana da Serra, a dairy located near Mococa, S%o Paulo, Brazil. The cattle were of the Gyr (Bos in&us or Zebu) landrace. Brazilian dairymen widely, if not universally, believe that a Gyr will not let down milk unless her calf or an effigy thereof, such as another calf disguised with the skin of her dead offspring, is physically present. There were 2 ordenhas per day except during one week of each month when the herd was milked 3 times daily while milk-yield and composition measurements were taken. An ordenha began by herding the cows into a shed, where they were tethered in 2 rows, facing feed troughs. The cows were tied at the same spot for every ordenha. Two holding pens, where their calves were restrained, flanked the entrance to the shed (Fig. 1). Typically, a few of the calves stood oriented toward the gate to the pen, while others were standing, milling and lying about in no particular pattern. Generally, the cows farthest from the holding pens were milked first. Because there were 2 rows of cows, 2 holding pens, multiple handlers and occasional disruptive events of a minor nature, the order of milking was not strictly invariant (paired comparisons of the milking orders of five contiguous ordenhas yielded 10 correlation coefficients ranging in value from 0.794 to 0.942, with a median of 0.893). To fetch a calf, a handler unlatched the gate to the holding pen, opened it slightly (Fig. l), and called the name loudly and rapidly an indeterminate number of times. When a calf did not react quickly enough to satisfy the handler, he forced a response by grasping it by an ear or the base of its tail, and guided it briskly to the appropriate cow. When a calf that was not called tried to leave the pen, it was pushed back into the enclosure so as to permit egress for the solicited calf. Upon reaching its mother, the calf was allowed to suckle for approximately 1.5 min while the handler bound the cow’s hind legs tightly together. The calf was then tied to its mother’s front legs within her sight, smell and touch. Finally, the cow was milked by machine, after which the calf was untied and permitted to take the milk remaining in the teats. With respect to the calves’ responses to the calls, at least 3 questions present themselves. (1) Do the calves react reliably? (2) Are the responses specific to a particular name, or to some other aspect of the setting? (3) What is the contextual meaning of the behavior?
Fig. 1. Milking shed at the Fazenda Santana da Serra. A holding pen is in the foreground. Another is located symmetrically across the passageway, outside the left margin of the photograph. The calves’ mothers are tethered in the background. A handler is fetching a calf by name call. The unsolicited calves are not attempting to leave the gate, although some are oriented toward him.
10 OBSERVATION
SET I
Methods
The methods were designed to obtain quantitative descriptions of the calves’ responses to the calls, as well as to assess the importance of the milking order and the presence of a familiar handler. The same 40 calves were observed by one observer in each of 3 ordenhas. Counts were made of the number of positive and forced responses to the calls, as well as the number of unsolicited responses by calves attempting to leave the pen without being called. TABLE I Observation Set I. Number and x2 analyses of calves responding positively and forced to respond when called
Positive responses Forced responses
Session 1
Session 2
Session 3
35 5
20 20
34 6
x2 = 0.105 df=l P > 0.80
Session 1 took place at noon on the day following the one-week, milkyield measurement regime, during which time there had been 3 ordenhas per day. No experimental manipulations were conducted. Session 2 was arranged to simulate what would have been the third, or evening, ordenha of the day had the milk-yield measurement regime been continued. The calves were placed in the holding pens in the same way and at the same hour as they had been during the real ordenhas, but neither their mothers nor the noises of the milking machines were present in the shed. An administrative employee of the dairy, who was not one of the handlers and whose voice was not familiar to the calves in the milking context, called them in the order observed in the first session. Session 3 occurred during the second ordenha, about noon, of the following day. The calves were called by their customary handlers, who employed a randomized calling sequence.
11
Results The results are summarized in Table I. Differences in positive responses between the first and third sessions were insignificant, indicating that the milking order did not affect the outcome. Responses in the second session, when a non-handler called the calves, differed significantly from those of the other 2 sessions. The tendency for some individuals to make unsolicited responses did not account for the general success of the handlers’ calls. The number of times that a calf made an unsolicited response was 21, 8 and 12 for the first, second and third sessions, respectively. In many cases, it was one and the same calf that tried to make unauthorized excursions, time after time, until it finally desisted or was called by the handler at the proper time. Had every calf tried to leave the gate in every trial, whether called or not, the total number of responses would have been N(N + 1)/2 or 820 for each session, whereas the observed number of calves trying to leave the gate, called or not, was 56, 28 and 46 for 3 sessions in order. All three numbers, when compared with the 820 figure, yielded x2’s of greater than 1400 (df = 1, P < 0.001). Moreover, fewer false starts were seen in the third session, when the calling order was random, than in the first session, when it was not. Yet, the number of positive responses remained essentially equal for those 2 sessions. If the calves’ approaches to the gate had been random, the probability that the appropriate calf would respond when called should be the reciprocal of the number of calves in the pen at any given time in the sequence. When the trial-by-trial probabilities are multiplied together (l/N!), the expectancy of a positive response is so small as to be virtually nonexistent over a series of 40 trials. Taking a considerably more liberal view of the problem, and assuming the absolute independence of all trials, summing the probabilities, N-l
_l
c- N-l i=O leads to the expectancy that about 4 calves per session would have made a positive response when called, as opposed to the numbers shown in Table I. Even in the second session, in which positive responses were made by only 50% of the calves, performance was much better than would have been expected on the basis of chance alone (x2 = 15.238, df = 1, P < 0.001). With either method, the calves’ solicited responses were not random, and they were related to the names being called, in that randomizing the calling order and removing the regular handlers and the calves’ mothers still resulted in responses that were specific to particular names.
12 OBSERVATION
SET II
Methods
The Fazenda Santana da Serra was revisited 2 years after Observation Set I had taken place. The time interval allowed an entirely new crop of calves to be available for study. The observations were made at the morning, mid-day and evening ordenhas on 2 days during the milk-yield measurement regime. In addition to the positive and forced responses, as recorded in Observation Set I, a tally was kept of the number of calls preceding a positive response. The same 40 calves were observed in each session. The subjects ranged in age from 61 to 365 days, with a mean of 149 days, on the first day of the observations. On the first or Experimental Day, multiple observers participated in scoring the responses and number of calls. Because the names were called in rapid succession, the tallies of more than one observer were averaged so as to enhance validity. During the morning ordenha (Session l), no experimental manipulations were carried out. Except for the time of day, the procedure was equivalent to that of the first session of Observation Set I. Four observers were present. For the mid-day ordenha (Session 2), the morning milking order was randomized, as had been done in the third session of Observation Set I. Four observers were present. For the evening ordenha (Session 3), a graduate student, who was a “stranger” to the animals except for having served as one of the observers during the previous sessions, and who was from the extreme south of Brazil, where Portuguese is pronounced differently from that spoken at the study site, called the calves (to a maximum of 20 calls per calf) using the order determined by the handlers (its correlation with the order of the morning session was 0.941). Apart from the presence of the calves’ mothers and the noises created by the milking machines, the procedure was similar to that of the second session of Observation Set I. Three observers recorded the data. The second or Control Day took place 3 days after the Experimental Day. Two observers were present during the morning, mid-day and evening ordenhas, keeping accounts of the same variables as those recorded on the Experimental Day. No experimental manipulations were conducted during any of the 3 sessions, as had been the case in Session 1 of the Experimental Day. Results
The positive and forced responses to the handlers’ calls are shown in Table II. A x2 test comparing the 6 positive response cells was not statistically significant (x2 = 5.088, df = 2, P < 0.10). The third session of the Experimental Day (when the graduate student called the calves) accounted for 65.5% of the overall x2. The results were consistent with those of Observation Set I, in that a random milking order did not impede performance, and the poorest
13 TABLE II Observation Set II. Number of calves responding positively and forced to respond when called
Experimental
Day
Control Day
Session 1 (Morning)
Session 2 (Midday)
Session 3 (Evening)
Positive response Forced responses
29 11
33 7
21 19
Positive response Forced responses
36 4
32 8
36 4
responsiveness occurred when a non-handler called the calves. The relationship between age and the number of positive responses was not high ( r = 0.194, df = 38, P > 0.50). Ignoring the calves forced to respond before 20 calls had been made, the probability of a positive response within 20 calls was 0.986 for Sessions 1 and 2 of the Experimental Day. Figure 2 shows the mean number of calls (to a maximum of 20) necessary to elicit a positive response over the 6 sessions. II 10
n 6 7 6 5 4 3 1
MORNlN6 (SESSION
MID-DAY
1)
(SESSIGN2)
OBSERVATION
EVENING (SESSION3)
SEQUENCE
number of calls necessary to elicit a positive response by sessions in Observation Set II. The number of calls was calculated from the observers’ tallies, divided by the number of observers.
Fig. 2. Mean
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The calves forced to respond prior to 20 calls were omitted from the data. Inspection of Fig. 2 suggests that, while the mean number of calls prior to a positive response increased over the experimental sessions, it also increased over the 3 Control Day sessions. The visual impression was supported by a mean-squares analysis of variance in which the main effects of sessions (F = 21.211, df = 2/234, P < 0.01) and day (F = 28.357, df = l/234, P < 0.01) were statistically significant, but the sessions X day interaction was not (F = 2.542, df = 2/234, P > 0.05). The implication is that the number of calls necessary to elicit a positive response was affected systematically by the time of day for both the Experimental and Control Days. The relationship between calls preceding a positive response and age of the subjects was negative (r = -0.401, df = 38, P < 0.01).
OBSERVATION
SET III
Methods
The observations took place between a mid-day and an evening ordenha in a large, grassy paddock where freshly-chopped sugar cane was available to the calves ad libitum. Their mothers were being kept separately in a nearby pasture. Standing no closer than 15 m to the target animals, a regular handler called the 40 calves observed in Observation Set II, using a maximum of 50 calls per calf and the calling order of Session I of the Experimental Day. The criterion for a positive response was that the target animal had to take at least 4 steps toward the handler upon being called. Four observers tallied the responses. Results
The findings were much less impressive than they were in the previous observation sets. Although the observers reported that many of the subjects looked, listened or otherwise oriented themselves toward the handler when called, only 7 of the 40 calves unequivocally met the criterion, and only one of them did it within 20 calls. The number of calls preceding a criterion response ranged from 10 to 40, with a mean of 28.85. DISCUSSION
The use of the number of positive responses as a dependent variable provided an overly conservative estimate of the strength of the phenomenon under investigation. Had the handlers shown more patience in not forcing the responses, the results might have been more dramatic. The problem was frustratingly noticeable in the early part of Session 1, Experimental Day, Observation Set II, when the handlers apparently thought that the observers
15
were there (possibly at the behest of the owner) to see how efficiently the milking session was being conducted. As a consequence, 7 of the first 10 calves were forced out of the pen without ample opportunity (i.e. a mean of 1.88 calls per calf) to respond to the names, and were not counted as positive responders in our data. As another example, if those calves forced to respond within 20 calls were to be removed from the analysis for the Control Day, Observation Set II, the probability of a positive response would rise from approximately 0.867 to 0.945 (it would increase to 0.986 for Sessions 1 and 2 of the Experimental Day, as mentioned earlier). It was not feasible to interfere with the handlers’ work and impose on their good will more than we had already by asking them to conduct themselves differently, or to modify their procedures in some way that might unpredictably alter the expression of the behavior under study. While the results may have erred toward conservatism, a significant majority of the calves responded appropriately when called by a regular handler, and changing the milking order did not reduce the number of positive reponses in the first two observation sets. When a non-handler called the calves, performance dropped to approximately 50%, which was still well above what would be expected on the basis of chance. Apparently the calves’ responses were conditioned to particular names only in part. Other relevant stimuli might have been the regular handlers’ physical personae, odors, gestures, gazes and sundry qualities of their vocal patterns. In Observation Set I, Session 2, an explanation for the performance decrement was not immediately determinable because at least 3 variables were confounded: (1) the presence of an unfamiliar handler; (2) time of day; (3) an absence of the mothers and noises created by the milking apparatus. The difference was negligible between the calves’ responses in that session and the one in which they were called by the graduate student at the same time of day but with the cows and shed-noises present (x2 = 0.050, df = 1, P < 0.90). Thus, the presence or absence of the calves’ mothers and background noises had no effect, and the general phenomenon was reliable over time with a different sample of subjects. In Observation Set II, the number of calls necessary to elicit a positive response was affected systematically by the time of day, but the number of positive responses was not. A single explanation may account for the apparent independence of the 2 dependent variables. We suggest that the number of positive responses was primarily an operational indicator of leaming, whereas the number of calls was, in addition, a reflection of the degree of food deprivation. Cattle in general, and Zebus in particular, eat little at night (Hafez and Bouissou, 1975; Ruckebusch, 1975). The morning ordenhas began shortly before dawn, a time when the calves should have been the hungriest. As the day progressed, the ordenhas were alternated with periods of ad libitum access to grass and fodder. It follows that motivation to seek nutrients from the mother might decrease over the course of the day, requiring more calls to bring about a response in the evening than in the early
16
morning. It is pertinent to recall that performance fell precipitously in Observation Set III, when the calves were called while they were feeding. The results of Observation Set III suggest that the calves’ responses were situation-specific, but a comparison of the data with those of the other observation sets must be viewed with caution. It is questionable that walking toward the handler in a paddock is equivalent to seeking out the gate in the shed. Moreover, although cattle typically maintain a distance between themselves and humans (Murphey et al., 1980), they also have a tendency to investigate novel objects, including humans, in open field situations (Murphey et al., 1981a, b). Calling the calves in the paddock could have served to orient them toward the caller and attendant observers, with the resulting approach-behavior being more a manifestation of investigatory activity than responses to a called name per se. or alluded to variously in previous The word “learning” was mentioned paragraphs. The observations reported here did not include a formal demonstration that the calves had learned to respond to name calls. Even so, the training procedures, while perhaps inefficient, provided obvious opportunities for reinforced practice. The positive correlation between age and positive responses, and the negative one between age and calls preceding a positive response, were further circumstantial evidence for learning. The directions of the correlations were in accord with the expectation that the older calves should exhibit superior performance by virtue of their having had additional training. As an aside, a calf was called by its mother’s name until it was weaned. A female received her own name upon giving birth to her first calf, after which her nursing young were all called by her name. Although we did not study it systematically, we saw little evidence that the adult cows ever learn their own names, notwithstanding local assurances that they do and the data presented by Albright et al. (1966). CONCLUSION
Most of the calves responded appropriately and reliably when called by name by a familiar handler. At least half of the subjects came when called by a non-handler. The responses appeared to have been conditioned to other, as yet undetermined, stimuli as well as the names. Instrumental conditioning, as such, was not demonstrated in accordance with traditional criteria, but it is reasonable to attribute the calves’ positive responses to learning. More importantly, the observations provided an example of the folk-use of ethological resources in animal husbandry. Lott and Hart (1979) described how Fulani herdsmen in subSaharan Africa make a place for themselves in the dominance hierarchies of their cattle as a means of maintaining behavior control. In the present case, Brazilian dairymen may have become a part of a pre-existing motivational system which they similarly exploit in animal management. It is well known that cows summon their calves by calling them (cf. Dobie, 1941; Schloeth, 1958; Kiley, 1972). In a sense, calves are
17
fetched “by name” “in nature”. Whether they must learn to discriminate their mothers’ calls from those of other cows is unknown, but in any case, the capacity to respond appropriately to a particular auditory signal exists in the absence of human intervention. In successfully soliciting calves by calling them, and in presenting them to their mothers so as to stimulate milk letdown, the handlers were taking advantage of 2 ethological resources. They combined a folk knowledge of a stimulus--response contingency of oxytocin release in milch cows with the preexisting ability of calves to obey specific, voiced commands. The result was an orderly and productive dairy operation. ACKNOWLEDGEMENTS
This research was supported by the Applied Sciences Unit, Department of Scientific Affairs, Organization of American States. We thank Prof. Dale F. Lott for suggesting some of the interpretations contained in the Conclusions section. We also appreciate the invaluable assistance of Irineu Machado Benevides Filho, Lucia Moreno de Souza, Claudia Helena Gadini and Paulo Roberto Nogara Rorato, who served as observers in Observation Sets II and III, as well as the contributions of Washington Coelho Novaes and Maria Cecilia Torres Penedo, who participated in earlier stages of the project. We are especially grateful to the employees of the dairy for their magnanimous hospitality and tolerance. It is with deep sadness that we can offer no more than posthumous homage to the owner of the fazenda, Francisco Figueiredo Barretto, who cooperated unsparingly in this and other research that we have conducted over the course of several years.
REFERENCES Albright, J.L., Gordon, W.P., Black, W.C., Dietrich, J.P. and Snyder, W.W., 1966. Behavioral responses of cows to auditory training. J. Dairy Sci., 49: 104-106. Dobie, J.F., 1941. The Longhorns. Little, Brown and Co., New York. Hafez, E.S.E. and Bouissou, M.F., 1975. The behaviour of cattle. In E.S.E. Hafez (Editor), The Behaviour of Domestic Animals. Williams and Wilkins, Baltimore, pp. 203-245. Kiley, M., 1972. The vocalizations of ungulates, their causations and functions. Z. Tierpsychol., 31: 171-222. Lott, D.F. and Hart, B.L., 1979. Applied ethology in a nomadic cattle culture. Appl. Anim. Ethol., 5: 309-319. Murphey, R.M., Duarte, F.A.M. and Ton-es Penedo, M.C., 1980. Approachability of bovine cattle in pastures: Breed comparisons and a breed x treatment analysis. Behav. Genet., 10: 173-183. Murphey, R.M., Duarte, F.A.M., Novaes, W.C. and Torres Penedo, M.C., 1981a. Age group differences in bovine investigatory behavior. Dev. Psychobiol., 14: 117-125. Murphey, RM., Duarte, F.A.M. and Torres Penedo, M.C., 1981b. Responses of cattle to humans in open spaces: Breed comparisons and approachavoidance relationships. Behav. Genet., 11: 37-48.
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Pollack, W.E. and Hurnik, J.F., 1978. Effect of calf calls on rate of milk release of dairy cows. J. Dairy Sci., 61: 1624-1626. Ruckebusch, Y., 1975. Feeding and sleep patterns of cows prior to and post parturition. Appl. Anim. Etho!;, 1: 283-292. Schloeth, R., 1958. Uber die Mutterkind-Beziehungen des Halbwilden Camargue-Rindes. Saugetierkdl. Mitt., 6: 145-150. Schmidt, G.H., 1971. Biology of Lactation. Freeman, San Francisco.