The Utilization of Smooth Bromegrass (Bromus inermis) under Rotational and Strip Grazing Systems of Pasture Management. III. Animal Behavior1, 2

T H E U T I L I Z A T I O N 0]? S M O O T H B R O M E ' G R A S S ( B R O M U S 1 N E R M I S ) UNDER ROTATIONAL

AND STRIP

PASTURE MANAGEMENT.

GRAZING SYSTEMS

OF

I I I . A N I M A L B E H A V I O R ~'2

A. L. BRUNDAGE A~D W. J. SWEETSIAN Department of Ani~al H~sban(Try, Alas~'a AgrimdturaI Experime~t Stt~lio~, l"almcr

The systematic s t u d y of animal activity was initiated by Cory (4) with a detailed analysis of the activities of cattle on the open range. Tribe and Gordon (8) have divided behavior studies into three phases. The first is the anecdotal period, when attempts are made to explain animal behavior on the basis of h u m a n emotions. The second, they call the experimental period, when cows are intensively observed in restricted and u n n a t u r a l enviromnents. The third phase is the modern period when the cows are observed in their n a t u r a l environment with careful attention being given to the explanation of p a r t i c u l a r behavior patterns. Extensive reviews of animal behavior investigations have been presented by Tribe (7) and Hancock (5). Both reviewers stressed the importance of the a d a p t a b i l i t y of the grazing animal. Animal production was considered to be the best measure of the value of a pasture or m a n a g e m e n t system. Behavior studies were indicated for their possible usefulness in explaining some variations in production observed. Their place in pasture investigation was sumnmrized by Tribe: " W i t h o u t making these continuous observations, it would be impossible to appreciate, as we must, the implications of the animals' grazing behavior, but it is these implications that are the reward of the watcher, not the factual data t h a t during a p a r i c u l a r day in a p a r t i c u l a r locality one p a r t i c u l a r animal spent a parti(,ular time grazing, resting, or i d l i n g . " Behavior studies were included in the pasture m a n a g e m e n t experiment to determine the effect, if any, of the p a r t i c u l a r m a n a g e m e n t systems on animal activity and the implications of this activity as regards the pasture-animal complex. EXPERIMENTAL PROCEDURE

Descriptions of the pastures and the m a n a g e m e n t systems employed have been given previously (3). Nine behavior observations were conducted d u r i n g tile 1953 season. The cows were continuously under observation f r o m the time they entered the pasture after morning milking until they were removed for evening milking (a period of a p p r o x i m a t e l y 6 hours). D u r i n g this time the activity of each was a r b i t r a r i l y placed in one of the following categories at Received for publication August 15, 1955. 1Alaska Agricultural Experiment Station Technical Publication 9. -"Data presented are from a thesis submitted by A. L. Brundage to the Graduate t'~aeulty of ihe University of i~.innesota in partial fulfillment of the requirements for a Doctor of Philoso])hy degree.

297

29~

A . L . BRUNDAGE AND W. J, SWEETMAN

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F'I~. 1. P e r cent of ilvlividual time spent g r a z i n g between m o r n i n g and evening milking. Solit!--rot,~timmt, o p e n - - s t r i p grazing.

5-minute intervals: grazing, standing and ruminating, standing and loafing, lying and ruminating, and lying and loafing. These data were presented previously at the 46th annual meeting of the American Society of Animal Production (1). RESULTS AND DISCUSSION Although the original data were for individual animals, herein they have been consolidated for the two management groups for ease in presentation and discussion. In addition, the data presented will be limited to grazing time and pattern. Inasmuch as the observations were of limited duration (6 hours), all the other activities tabulated were directly influenced by grazing time. DAYS ON ~ PASTURE

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FIG. 2. Average per cent of time s p e n t g r a z i n g between m o r n i n g and evening milking f o r two g r o u p s of f o u r cows each. S o l i d - - r o t a t i o n a l , o p e n - - s t r i p grazing.

UTILIZATION

OF S M O O T H B R O M E G R , A S S I N A L A S K A ,

IIA.

299

The individuality of grazing is illustrated in Figure 1, which depicts the grazing time for individuals. The grazing time of an animal relative to that of others tends to remain the same between observations. Figure 2 illustrates how the groups adjusted their grazing habits to changes in the pastures. Both groups steadily increased their total grazing time during the day as the season advanced. Initially, this was related to selection imposed by the increasing maturity of the first growth of herbage with the resultant decrease in total nutritive value. In spite of this decline, the apparcut dry nmtter digestibility of herbage consumed by the cdw under the strip grazing system steadily increased during this period of the 1954 trial (2). These apparently contradictory observations support the conclusion that this animal was actively selecting her diet at this time. The increases in grazing time observed support the conclusion that the selection of a good quality diet from nmture pasture herbage requires more time than from immature herbage. Subsequently, quality and quantity both are factors that influence grazing time later in the season when the cows are regrazing the pasture. Jones (6) suggested that the growth after winter rest was nlore palatable than subsequent

M B

June 2.1955

First qrowth

t~me grazing- 48.9*'..

June 7,1953

First growth

time grozing-580%

June 25,[9,53 First growth

hme qrazincJ-639%

duly 9,t953

Secondgrowth

time grezing-559%

Second growth

time grozing-62.5%

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August 6,1953

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time grazmg-65.7%

August tS,195S

Third growth

time 9roztng-67,4%

Sept, 8,1953

Thb'd gl'owth

time grozing-6~0%

Sept. IO,19SS

Fourth growth

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H

3

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. I 40

. time groztng-Tt,2%

. .80 . .120. . 160 . . 200 . . 240 .

2 ~0' I o3' '

560

MINUTES ON PASTURE

~IG. 3. Gl"aZillgpatterns between morning and evening milking of a group of four cows oi1 strip grazing.

:~00

A. L. B R U N D A G E

A N D W. J . S W E E T M A N

growth, even though the latter might be of equal leafiness. In addition to this, selective grazing is employed to avoid consumption of material soiled by dung and urine. The grazing time is also increased as a result of the physical nature or quantity of the herbage. When subsequent growth is sparse, the quantity consumed in any one bite is reduced, increasing the number of bites required per unit of consumption. The distribution of the grazing time for the strip grazed group (Figure 3) appeared to be influenced by advancing season also. The initial period of grazing was steadily lengthened as the season progressed. Grazing activity was definite during this period, and aimless walking was kept at a minimum. The fact that initial grazing time during observation 4, when they were on lush second growth, was comparable to the initial times during observations 1 and 2, when they were on lush first growth, suggests that its length is determined by the satisfaction of the hunger urge, for initial time was increased on material of poor quality and ou material of reduced quantity and quality. Postponement , f hunger satisfaction might result from the intake of material of lower nutri-

N U M B E R

June 2,1953

F~rS| doy Qn expo~ment

ti~e g~zinQ-45.5%

June 7,195,3

L~st dayon Ist growth

time grazing-51.0%

J~ne 25,1953

Fourth day on tS! growth

lime Qrozing-571%

July 9,1953

Lost d~y On 2 ~

growth time Qmzmg-6tO%

OF G Am;luSt 6,|953 LaS! d~r ~m 2r.d ~p~wth time l~Zll~-764%

$

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F

N

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h

O'

'"o

A~uSt | ~ 1 ~ 3

LOOt doy On ~d

~Owth tM~ ~oZtng*736%

Sq~t. 8,1953

First cloy on 3td

~owlh

Sept |0,1953

First day on 4 ~

g~owth tim grozing-GS.6%

time ~azing- 58,0 %

. .SO. . iL~O . . .IGO. . 200 . . . 240 . . .260. MINUT[$

~0

~;o

ON pASTURE

FIc. 4. Grazing patterns betweell morning and evening milking of a group of four cows on rotntional grazing.

U T I L I Z A T I O N OIt1 S M O O T H B R O M E G R A S S I N A L A S K A .

III.

301

rive value, lowered intake per unit of time as a result of reduction in quality and quantity, or an interaction of the two. Grazing was always more sporadic in the afternoon. Often, one or more animals would be engaged in other activities while their mates were grazing. This suggests that the lengthening of the initial grazing period was an adequate adjustment enabling the grazing cows to satisfy their major needs during the morning. Data are unavailable to show how these animals responded to the depleted strip when they returned to the pasture after the evening milking. The effect of advancing season upon the distribution of grazing time (Figure 4) for cows that grazed rotationally was modified by the degree of defoliation a paddock had undergone prior to tile observation. When the animals were grazing an area which had undergone little or no defoliation previously, the grazing patterns were similar to those observed with the strip-grazed group. This suggests that a comparatively effective and lasting degree of satisfaction was obtained during the initial grazing period. When defoliation of an area was nearly complete, grazing during the morning appeared to be conducted under protest. On two occasions the animals refused to graze when they entered the pasture. Instead. they gathered at the fence separating the two groups and complained audibly for several minutes. When they did graze, they were very restless and failed to graze in any one area for more than a few minutes before moving on to completely new territory. The grazing during the afternoon was more compulsory, as the animals reduced their restless wandering and concentrated on grazing the remaining herbage. These observations suggest that the animals failed to receive any lasting degree of satisfaction from their morning's grazing activity and were forced to graze actively during the afternoon to make up this deficit. The average lactation curves indicate that nutrient intake under these grazing conditions was inadequate, for daily production declined sharply during the last few days on a paddock (3). Total dry matter intake and digestibility also decreased during this time (2). Thus, the responses of the animals to this environment were inadequate. Their recovery was dependent upon a change in environment, in this case movement to a new paddock, rather than adaptation. The grazing behavior of the cow whose time was estimated (Figure 1, obser~ation 7) was unique. Her entire nlorning was spent listlessly standing, or lying down. Absolutely no interest was expressed in grazing, and very little walking was done. There was no rumination during the entire observation. Her grazing time was 36.1% of the total time on pasture, and this was done during late afternoon. It was discovered during the evening milking that she was suffering from acute mastitis. This had not been observed during the morning milking. This is an example of the effect of illness upon a grazing cow. In addition to being disturbed by the illness itself, her physiological balance is further impaired b y a reduction in nutrient intake. It emphasizes the importance of providing conditions whereby nutrient intake will be enhanced in addition to treating the illness directly. In the above instance there was no indication that she derived

30~

A. L. B R U N D A G E AND W. J. S W E E T M A N

a n y benefit f r o m b e i n g on p a s t u r e . the illness.

Being there may have actually complicated

SUMMARY AND CONCLUSIONS

N i n e c o n t i n u o u s b e h a v i o r o b s e r v a t i o n s h a v e been c o n d u c t e d on two g r o u p s o f d a i r y cows g r a z i n g s m o o t h b r o m e g r a s s u n d e r r o t a t i o n a l a n d s t r i p g r a z i n g syst e m s o f m a n a g e m e n t . T h e t o t a l g r a z i n g t i m e of b o t h g r o u p s i n c r e a s e d w i t h a d v a n c i n g season. This has b e e n a t t r i b u t e d to i n c r e a s i n g p l a n t m a t u r i t y during" i n i t i a l g r a z i n g a n d to s o i l i n g a n d r e d u c e d a v a i l a b l e h e r b a g e d u r i n g s u b s e q u e n t g r a z i n g . A d v a n c i n g season also r e s u l t e d in a n i n c r e a s e in i n i t i a l g r a z i n g t i m e f o r t h e g r o u p u n d e r t h e s t r i p g r a z i n g s y s t e m . This was a p p a r e n t l y s a t i s f a c t o r y compensation for reduced palatability and availability, for afternoon grazing a c t i v i t y r e m a i n e d r e l a t i v e l y c o n s t a n t o v e r t h e e x p e r i m e n t , T h e p a t t e r n of g r a z i n g a c t i v i t y f o r the r o t a t i o n a l l y g r a z e d a n i m a l s was i n f l u e n c e d b y the d e g r e e of p r e v i o u s d e f o l i a t i o n of a p a d d o c k p r i o r to t h e o b s e r v a t i o n i n a d d i t i o n to a d v a n c i n g season. W h e n g r a z i n g a n e a r l y d e p l e t e d area, the p e r i o d of i n t e n s e g r a z i n g a c t i v i t y was s h i f t e d to t h e a f t e r n o o n . REFERENCES (1)

(2)

(3)

(4) (5) (6) (7) (8)

A. I~. Continuous Behavior Studies of Grazing Dairy Cattle. J. A~imal Sci., 12: 939. 1953. ]~RUNDAGE,A. L., SW~ETi~IAN,W. J., AND BULA, ]~. J. The Utilization of Smooth Bromegrass (Brom~s iy~ermis) under Rotational and Strip Grazing Systems of Pasture Management. II. Digestibility-Intake Studies. J. Dairy ScL, 39: 287. 1956. BRUNDAGE,A. L., SIVEET~,fAN,W. J., HOD(~SON,~{. J., AND BULA, R. J. The Utilization of ~mooth Bromegrass (Brom~s i~termis) under Rotational and Strip Grazing Systems of Pasture Management. I. Aninml and Pasture Production. J. Dairy Sci., 39: 280. 1956. CoRY, V. L. Activities of Livestock on the Range. Texas Agr. Expt. Sta.. B~dl. 367. 1927. H.xxC0CK, J. Grazing Behaviour of Cattle. Animal Breed. Abstr., 21: 1. 1953. JaNus, L. Measurement of Palatability. Proc. 6th Intern. Grassland Congr., 2: 1348. 1952. TRIBE, D. E. The Behaviour of the Grazing Animal: A Critical Review of Present Knowledge. J. Brit. Grassland Sac., 5: 209. 1950. T~I~, D. E., _~XD GORDON, J. G. The Critical Approach in Grazing Behaviour Studies. Brit. J. Animal Behaviour, 1: 12. 1953. ]~RVNDAGE,