Competition for Total Mixed Diets Fed for Ad Libitum Intake Using One or Four Cows per Feeding Station

Competition for Total Mixed Diets Fed for Ad Libitum Intake Using One or Four Cows per Feeding Station J. OLOFSSON Department of Animal Nutrition and Management, Swedish University of Agricultural Sciences, Kungsa¨ngen Research Centre, S-753 23 Uppsala, Sweden

regarding feeding space can be found in several countries. The Swedish animal protection law ( 2 1 ) recommends that competition should not exceed 3 cows per feeding place when ad libitum feeding of the forage is practiced. However, regulations pertaining to feeding space do not exist in many countries (e.g., the US). Literature within the area of competition for feed is scarce, and few studies (5, 9 ) with complete control of individual feed intake have been published. Group feeding of cattle inevitably results in some degree of competition for the feed. Even with free access to forage and sufficient spacing at the feeding area, cattle interact in ways that might give some individuals advantages over others in the herd. These interactions are probably not a problem for the animals in a well-designed loose housing system, but, under more divergent conditions, some individuals might be influenced in a negative way. Depending on what form of competition is investigated, different cow characteristics become more or less important for an individual cow to be a winner or a loser. A limited feeding area most likely favors cows that are high in social rank ( 7 ) . The ability to consume feed quickly is also important when area is limited. These traits, together with energy requirements and age, were considered as the most interesting variables when this study was conducted. The aim of the study was to identify the factors determining the outcome of the competition situation and, to some extent, to measure the degree of the effects of competition.

ABSTRACT When dairy cow facilities are being designed, a limited feeding area might be profitable and recommendable if the increased competition for feed does not harm the welfare of the animals or affect production negatively. An experiment was conducted at the University Cattle Research Centre (Uppsala, Sweden) to investigate the performance of individual cows as well as groups of cows. Treatments used 1 or 4 cows per feeding station with a total mixed diet fed for ad libitum intake. The feeding stations were troughs placed on electronic balances and were 1.08 m wide. Sixteen dairy cows were divided into two groups and were studied in an experiment with a change-over design so that each group went through each treatment twice. A computerized feeding system automatically recorded consumption data for feed and water. Video recordings were used to study the social dominance order, the level of aggression at the feeding area, and the time budget of the cows. The mean feed intake increased slightly, but the number of visits to the feeding stations did not change at the higher level of competition. The cows, however, spent significantly less time eating and increased their consumption rate when the competition level increased. The number of displacements at the feeding stations increased dramatically. Cows of low social rank were much more frequently displaced while eating. The effects of dominance value, age, eating rate, and energy requirement of the cows are presented. ( Key words: competition, feed intake, dairy cows, behavior)

MATERIALS AND METHODS

Abbreviation key: DV = dominance value, ECM = energy-corrected milk.

Feeding Laboratory The computerized feeding laboratory at the University Cattle Research Center (Kungsa¨ ngen) was used (14). Feed recording equipment was developed by the Swedish Institute of Agricultural Engineering. The barn was insulated, and the manure was removed with scrapers. The 18 feeding stations at the feeding table were troughs resting on electronic balances at a feeding gate. The troughs measured 0.90 m in width,

INTRODUCTION Limited feeding space might reduce costs of loose housing dairy barns. Recommendations or regulations

Received August 22, 1997. Accepted August 31, 1998. 1999 J Dairy Sci 82:69–79

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0.75 m in length, and 0.35 m in height. Access to each trough was controlled by a horizontal bar that was locked at the feeding gate with electromagnets. Cows with the correct transponder identity only were allowed to enter a station after being recognized by the antenna attached to the bar. By leaning her head against the bar, the cow with the correct identity could swing the bar to a vertical position and reach the feed in the trough. The bar automatically swung back and was locked in a horizontal position when the cow left the station. The stations had a width of 1.08 m, and the cows were partly separated from each other by dividers between each station. These dividers were attached to the feeding gates and had a length of 0.80 m. The distance between dividers was more narrow close to the feeding gate (0.65 m ) than at the end of the dividers (0.90 m), thus, following the shape of the cows. Water was supplied in two troughs equipped with floats to maintain a constant water level. The flow of water was automatically switched off by the use of electromagnetic valves when cows entered the water station, thus making it possible to calculate the amount of water consumed at each visit. Each time a cow visited a feeding station, the computer recorded cow identity, entry and exit times, and initial and final weights of the feed. Water consumption was recorded in the same way. Research Procedure Sixteen Swedish Red and White dairy cows in the middle of first (25%), second (50%), or third lactation (25%), divided in two groups (groups 1 and 2), were fed a total mixed diet for ad libitum intake. Two competition levels for the feeding space: 1 or 4 cows per feeding station (treatments 1 and 2, respectively). The feeding stations used in each treatment were available to all cows in the group. A change-over design was used, and both groups were exposed to each treatment twice (Figure 1). Each treatment period lasted for a week, but data from the initial day of each period were not included in the results. The total mixed diet consisted of 50% precisely chopped grass silage and 50% concentrate, on a DM basis, and contained 11.9 MJ of metabolizable energy and 16.4% CP/kg of DM. The DM content varied between 43 and 48%. The troughs were regularly filled with fresh feed from a feeding wagon with the intention that troughs should not be empty at any time of the day. These fillings occurred during the two milking periods and, if necessary, also at midnight and in the middle of the day. The troughs at treatJournal of Dairy Science Vol. 82, No. 1, 1999

Figure 1. The principle research procedure used two cow groups assigned to two treatments in four treatment periods ( a total of eight treatment events). Each feeding station had a total width of 1.08 m, and the total walking area measured 3.2 × 24 m. The number of cubicles matched the number of cows on both treatments.

ment 2 were always filled from the feeding wagon at noon and midnight, and the troughs with lack of feed at treatment 1 mostly could be filled with feed from a trough nearby. However, the feed had been mixed at the same time in both cases. Both treatments were treated as similarly as possible at the feedings. The water levels in the two water troughs were automatically controlled by the use of floats and electromagnetic valves. The cows were milked in a milking parlor twice a day, starting around 0600 and 1500 h. Milk weight and fat, protein, and lactose contents were registered for 3 d/wk. Energy-corrected milk ( ECM; 4% fat) was calculated. Only the last 2 d of registrations in each period were used. The cows were weighed for 2 consecutive d before and after the experiment, and the mean weight together with mean ECM production were used when daily individual energy requirements were calculated: [1.11 × (0.507 × cow weight0.5 + ECM production × 5 ) – 13.6] metabolizable energy, which is according to Swedish recommendations (20). Consumption above the required amount was considered overconsumption. Fluorescent lighting was on between 0600 to 1800 h. This light, together with some daylight, measured approximately 200 lx. A minimum of ordinary lighting (10 lx) was used during night. During videotape recordings, two infrared floodlights (300 W ) were used to illuminate the barn. Feed Consumption Data for feed and water consumption were automatically registered by the computerized system. From the data registered, feed intake, number of

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eating bouts (visits), eating time, consumption rate, and diurnal eating rhythm were calculated. Eating bouts and drinking visits were recalculated into meals with the use of a critical interbout interval of 5 min, which was derived from two separate interval frequency plots (12). Occasionally cows succeeded in pushing feed out of the troughs, resulting in incorrect feed consumption. To correct for these events and to minimize the risk of possible malfunctions in the weighing system, a restriction was given when the data were analyzed. It was assumed that visits shorter than 2 s did not result in feed consumption. Additionally, for visits of 2 s or longer, feed consumption was not allowed to be greater than 0.25 + (eating time – 2 × 0.003) kg of DM. In this way, a visit lasting 10 s had a maximum allowance of 0.274 kg of DM, and, after 10 min, the maximum consumption was set to 2.044 kg of DM. Consumption exceeding this restriction was recalculated with the use of eating time and the approved mean consumption rate for each cow. These corrections were based on studies of consumption data and cow behavior during the experiment and resulted in correction to 1% of the visits to the feed troughs. Social Dominance Order Both groups were recorded continuously for 48 h at the end of each research period with the use of 2 videotape recorders with time-lapse functions (Panasonic AG-6010) and 2 video cameras that were sensitive to infrared light (Ikegami ITC-410 with IR Newicon XQ1276). The recordings were used to investigate the social dominance order among the cows. Behaviors such as butting, pushing, fighting, and threat and avoidance were included when recordings of agonistic behaviors were made ( 4 ) . Butting and pushing were considered to have occurred when one cow, using her head or body, forced another individual to retreat. Fighting between two individuals was recorded when both cows showed physical aggression (i.e., butting) toward the other. The retreating cow was considered to be the loser. Agonistic behaviors between cows without physical contact were considered to be threat and avoidance. In addition, a threat had to be followed by a reaction of avoidance by the opponent in order to be considered as an act of dominance. All of these behaviors had to occur between cows with eye contact or obvious knowledge of the identity of the opponent. Interactions from behind or the side, without eye contact, or the initiation of displacements at the feeding stations did not count as acts of dominance. Each interaction resulted in a point in favor for the winning cow. Two criteria had to be fulfilled to confirm the dominance relationship

between two cows: 1 ) the difference had to be at least 3 points (22), and 2 ) the winning cow had to have at least twice the number of points as the loser. All relationships were documented in a dominance matrix for each cow group (18). Each cow received a dominance value ( DV) , which was the proportion of the known dominance relationships that the cow dominated (16). This index was used when the correlation between social rank and various parameters of cow performance were analyzed. Displacements at Feeding Stations Videotape recordings during the first day and night of the previously mentioned 48 h of recordings were used to get a measurement of the disorder when the cows were eating. Observations were made of events when cows forced another to leave a feeding station. These forced endings of eating bouts could be caused both by physical contact or, in some cases, by threats. Whenever a cow was forced to leave her feeding station, recordings were made of the station number, the identities of the cows, the time of day, and the outcome of the displacement (i.e., whether or not the aggressor entered the feeding station within a minute). Time Budgets The same video recordings were used to document the time budgets for all the individuals in the study. Each cow group was observed for a total of four periods of 24 h, and recordings of eating, drinking, standing, lying, and milking were made every 5 min. A cow was considered to be eating when its head was inside a feeding station. Interruptions shorter than 20 s during eating were omitted (the maximum time for a cow to move directly from one station to another). The same applied to drinking. Cows were recorded as lying down when the chest floor and ventral aspect of trunk touched the floor; otherwise, cows were classified as standing. Access to the feed troughs was not allowed for 2.5 h/d during milking, and the cows were classified as being milked during this time. Statistics and Calculations Statistical analyses were performed using the general linear models and Pearson’s correlation test of SAS (17). Mean values and standard deviations were calculated using the MEANS procedure. Means for crude data were calculated as average daily individual performance within each cow group and Journal of Dairy Science Vol. 82, No. 1, 1999

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treatment period (see the eight treatment events in Figure 1). Mean cow performances and standard deviations were then calculated within each event. The means for processed data (e.g., consumption per time unit) were calculated using the overall group means for crude data within each treatment event. These within-event data were used when the data were analyzed for significant differences and when the mean performances and standard deviations were calculated for each treatment. The general linear models procedure included the effects of periods, cow groups, and treatments. Data were grouped before the analysis that used the eight treatment events as experimental units. To analyze whether the change of competition level affected the variation between cows, the standard deviations between cows within a treatment were tested for significant differences against the standard deviations in the other treatment. The average increase or decrease of a measurement when changing from treatment 1 to treatment 2 was calculated for each cow. This difference was used to identify cow traits for those cows that were considered winners when the competition for feed increased. The differences between values were considered as significant at P < 0.05 and as having a tendency toward significance at P < 0.1. RESULTS Milk Production On average, the cows produced 28.9 and 29.0 kg of ECM in treatments 1 and 2, respectively. No differences could be found for fat, protein, or lactose contents on a treatment basis. Individual milk production ranged from 18.3 to 37.0 kg of ECM/d. The mean milk production for groups 1 and 2 were 28.7 and 29.3 kg of ECM per cow and day, respectively, and did not differ significantly between the two groups. The ECM production did not correlate significantly with feed consumption, number of meals or visits, eating rate, water consumption variables, DV, or cow age but did show a positive correlation with the time spent eating. This correlation was most evident in treatment 4 ( r = 0.63; n = 16; P = 0.009) and less pronounced in treatment 1 ( r = 0.49; n = 16; P = 0.055). The negative correlation between ECM production and overconsumption of feed ( r = –0.68; n = 16; P = 0.004) remained almost unchanged in both treatments. Social Dominance Order A total of 636 observations of agonistic behaviors were used to determine the social dominance order in Journal of Dairy Science Vol. 82, No. 1, 1999

the two groups of cows. Group 1 appeared to have a linear rank order, and group 2 showed a nonlinear rank order (75% linearity). There was a significant correlation between DV and cow weight ( r = 0.61; n = 16; P = 0.011), but no significant correlation could be found between DV and lactation number. None of the traits of DV, cow age, energy requirement, or basic consumption rate correlated significantly. No evidence could be found to indicate that the social dominance order of the cow groups changed during the experiment. Displacements at Feeding Stations and Water Troughs A total of 1346 enforced endings were recorded at the feeding stations, and 40 enforced displacements were recorded at the water troughs. Changing from treatment 1 to treatment 2 resulted in a greater number of displacements, an increased percentage of aggressors entering the feeding station after the displacement, and a decreased percentage of displacements carried out by dominant cows (Table 1). The displacement data differed between cow groups; group 2, with a nonlinear rank order, was responsible for 62% of the total number of displacements at the feed troughs. This difference between groups was significant ( P = 0.046). No significant correlation could be found between the investigated animal traits and the total number of times that cows were displaced or displaced other cows. The differences among cows in number of displacements were evident as high standard deviations. The enforced endings of visits were highly clustered in time. On average, 45% of displacements at the feeding stations in treatment 1 occurred within 2 h after milking. The corresponding level in treatment 2 was 43%. Most of the displacements during this period in treatment 1 were conducted within the first 0.5 h after milking, after which the cows lay down to rest in their cubicles, and the number of displacements declined with the decline in the number of cows eating. The first 30 min after each milking resulted, on average, in 29.1 displacements in treatment 2 but only 10.5 displacements in treatment 1. Feed Consumption Feed consumption data were based on 21,252 observed eating bouts. When expressed as a mean for the total number of cows, some differences in the consumption measurements could be found (Table 2). The cows consumed slightly more feed, shortened their eating time by 19%, and showed a 27% increase

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COMPETITION FOR TOTAL MIXED RATIONS TABLE 1. Data on forced displacements at feeding stations for 1 and 4 cows per feeding station.1 Displacement variable

Treatment 1 SDM2

SDC3

7.2

3.3

62.4 92.8

10.6 5.0

X Daily individual displacements (no.) Forcer entering station, % Dominant forcer, %

Treatment 2

P > F

X

SDM2

SDC3

X

SDC3

4.2

34.9

10.3

16.4

0.007

0.016

24.8 29.7

85.1 62.1

1.2 9.8

8.3 32.4

0.011 0.036

0.003 0.664

1df

= 5; n = 8. deviation of means. 3Standard deviation between cows. 2Standard

in their consumption rate in treatment 2 compared with that in treatment 1. When expressed as a mean for the entire study, cows in group 2 made significantly more visits to the feeding stations ( P = 0.046) than did cows in group 1, but the variation between cows in feed consumption was greater in group 1 ( P = 0.002) than in group 2. The mean day-to-day variation in individual consumption of the total mixed diet, expressed as standard deviation for 12 d, was 1.66 kg of DM per cow in treatment 1 and 2.12 kg of DM in treatment 2. However, these within-cow, day-to-day variations, as well as variation in eating time, eating bouts, and consumption rate, did not show a significant difference between treatments. The mean feed consumption by the cows was 20.8% (0.7 to 61.8%) more than the calculated requirement in treatment 1 and 24.9% (11.0 to 72.0%) more in treatment 2. The correlations between consumption variables and individual traits are accounted for in Table 3, which shows that the age of the cow and the capacity of the individual to eat quickly were more strongly correlated to feed intake than were DV and individual energy requirements. Even so, the dominant cows and cows with a high consumption rate lost less eating time when the competition increased. From that per-

spective, those cows would be considered as being favored by the increased competition. Cow weight was included as a constraint in the calculation of overconsumption; however, the variables of weight and overconsumption were positively correlated ( r = 0.70; n = 16; P = 0.003). The cows had access to the feeding stations for 21.5 h/d and, consequently, the stations were used at 19% of the available time in treatment 1 and 61% in treatment 2. Expressed as means for the entire study, 59% of the visits were followed by a new visit by the same cow within 60 s after the end of the former eating bout. Only 7% of the visits had a time interval longer than 2 h to the next visit by the same cow. These circumstances remained fairly unchanged between treatments. Water Consumption Altogether, 3126 drinking visits were recorded. Water consumption did not differ significantly between treatments. The average cow made 8.3 visits and drank 80.66 kg during 15.59 min/d in treatment 1 and made 7.9 visits and drank 71.89 kg in 15.64 min in treatment 2. The number of calculated meals per day averaged 7.7 and 7.5 in treatments 1 and 2,

TABLE 2. Data on feed consumption variables for 1 and 4 cows per feeding station.1 Consumption variable

Treatment 1

X DMI, kg 22.12 Time spent eating, min 243.23 Eating rate, g of DM/min 93 Bouts, no. 54.4 Meals, no. 11.4

Treatment 2

SDM2 0.46 8.70

SDC3 2.41 31.89

X 22.97 197.89

SDM2 0.69 15.07

4 7.2 0.6

16 21.4 2.1

118 56.0 13.9

8 9.6 0.7

P > F SDC3 2.57 24.48

X 0.102 0.008

SDC3 0.219 0.115

19 17.4 2.5

0.013 0.267 0.000

0.228 0.287 0.168

1df

= 5; n = 8. deviation of means. 3Standard deviation between cows. 2Standard

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OLOFSSON TABLE 3. Pearson’s correlation coefficients between feed consumption variables and the individual cow traits: social dominance value (DV), cow age (months), basic eating rate (grams of DM per minute), and energy requirement (megajoules of metabolizable energy per day). 1 DV

Dependent variable

r

DMI Treatment 1 Treatment 2 Bouts Treatment 1 Treatment 2 Meals Treatment 1 Treatment 2 Eating time Treatment 1 Treatment 2 Eating rate Treatment 1 Treatment 2 Overconsumption Treatment 1 Treatment 2 Treatment difference DMI Bouts Meals Eating time Eating rate Overconsumption 1n

Basic eating rate

Age

P > F

r

P > F

r

P > F

Energy requirement r

P > F

0.21 0.38

0.431 0.150

0.63 0.55

0.009 0.028

0.63 0.78

0.009 0.000

0.47 0.42

0.066 0.109

–0.39 –0.34

0.136 0.199

–0.19 –0.13

0.473 0.635

–0.14 –0.26

0.582 0.331

0.20 0.09

0.452 0.751

–0.51 –0.64

0.041 0.007

–0.10 0.08

0.718 0.779

–0.18 –0.27

0.497 0.301

–0.27 –0.10

0.310 0.724

–0.25 0.24

0.346 0.377

0.07 0.03

0.791 0.901

–0.73 –0.28

0.001 0.316

0.34 0.59

0.199 0.015

0.33 0.08

0.201 0.758

0.40 0.49

0.125 0.056

... 0.78

... 0.000

0.02 –0.16

0.931 0.564

0.20 0.40

0.460 0.126

0.72 0.59

0.002 0.016

0.60 0.69

0.013 0.003

0.57 0.50

0.022 0.049

0.40 0.11 –0.31 0.52 –0.33 0.43

0.129 0.678 0.242 0.041 0.220 0.096

–0.06 0.10 0.16 –0.05 0.24 –0.19

0.814 0.716 0.544 0.842 0.372 0.461

0.43 –0.10 –0.16 0.61 –0.10 0.23

0.092 0.720 0.546 0.011 0.715 0.399

–0.04 –0.16 0.11 0.15 –0.28 0.09

0.897 0.566 0.686 0.590 0.289 0.753

= 16.

respectively. Cows in group 1, however, had significantly ( P = 0.044 and P = 0.033) fewer visits and meals than group 2 (7.6 and 8.6 visits/d, respectively). The correlation between water consumption and DMI was 0.70 ( n = 16; P = 0.003) in treatment 1 and 0.54 ( n = 16; P = 0.031) in treatment 2. The correlation between water consumption and energy requirements was 0.76 ( n = 16; P = 0.001) in treatment 1 and 0.67 ( n = 16; P = 0.005) in treatment 2. No other significant correlation was found between drinking

variables and cow traits, such as DV, cow age, energy requirement, or basic feed consumption rate. Time Budgets The study of the time budgets revealed that the cows altered their behavior when the competition for the total mixed diet increased. A significant decrease in eating time was compensated by a significant increase in time spent standing (Table 4), especially

TABLE 4. Data on average time budget for 1 and 4 cows per feeding station.1 Activity

Lying Eating Standing Milking Drinking

Treatment 1 X 56.7 17.2 14.8 10.3 1.1

1df

SDM2 1.9 1.0 1.6 0.3 0.2

Treatment 2 SDC3 5.1 2.4 3.7 ... 0.6

= 5; n = 8. deviation of means. 3Standard deviation between cows. 2Standard

Journal of Dairy Science Vol. 82, No. 1, 1999

X 55.4 13.8 19.4 10.3 1.1

(%) SDM2 1.8 0.6 1.4 0.3 0.2

P > F SDC3 5.6 2.1 4.6 ... 0.6

X 0.286 0.012 0.021 ... 0.890

SDC3 0.511 0.705 0.298 ... 0.590

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TABLE 5. Pearson’s correlation coefficients between time budget variables and the individual cow traits: social dominance value (DV), cow age (months), basic eating rate (grams of DM per minute), and energy requirement (megajoules of metabolizable energy per day). 1 DV

Dependent variable Lying Treatment 1 Treatment 2 Standing Treatment 1 Treatment 2 Eating Treatment 1 Treatment 2 Drinking Treatment 1 Treatment 2 Treatment difference Lying Standing Eating Drinking 1n

Basic eating rate

Age

r

P > F

r

P > F

–0.02 –0.16

0.937 0.560

–0.18 –0.03

0.497 0.899

0.31 –0.16

0.237 0.562

0.25 –0.00

–0.40 0.02

0.124 0.946

–0.12 –0.41 0.27 –0.47 0.56 –0.28

r

Energy requirement

P > F

r

P > F

0.45 0.32

0.083 0.227

–0.45 –0.45

0.082 0.080

0.360 0.997

–0.13 –0.15

0.642 0.587

0.39 0.18

0.200 0.508

–0.04 –0.07

0.882 0.809

–0.67 –0.46

0.005 0.075

0.35 0.74

0.185 0.001

0.649 0.116

0.15 –0.07

0.578 0.806

–0.22 –0.41

0.411 0.116

0.27 0.40

0.304 0.122

0.320 0.068 0.025 0.296

–0.30 –0.23 –0.02 –0.22

0.261 0.390 0.948 0.419

–0.12 –0.04 0.39 –0.18

0.651 0.870 0.130 0.503

–0.07 –0.12 0.34 0.12

0.794 0.659 0.202 0.653

= 16.

for cows with low DV. These and other correlations between time budget variables and investigated individual traits are shown in Table 5. The cows redistributed their behaviors when the competition for feed increased, and the diurnal change in the allocation of feed consumption was the most obvious. In treatment 1, 43% of the eating time was spent during the hour immediately before and 1 h after milkings. Because of the restricted eating space at the higher competition level, only 24% of the total eating time was spent during this period in treatment 2. The extra feedings at noon and midnight did not result in any differences between the two treatments regarding the behaviors of standing, feeding, drinking, or lying.

The distribution of drinking and resting behaviors did not significantly change over the 24-h period, but the distribution of eating and standing did change (Table 6). When the competition increased from 1 to 4 cows per feeding station, a significantly higher proportion of the feed consumption occurred during the night (1800 to 0600 h). The cows also spent a significantly smaller proportion of time standing during the night in treatment 2 than they did in treatment 1. In Table 7, the correlations between cow traits and the night share of each behavior are presented, showing significant effects of increasing the competition level for DV and basic eating rate. When the competition level increased, cows of low social rank tended to adjust behaviors to a greater

TABLE 6. Proportion of each behavior recorded during the day (0600 to 1800 h ) and the night (1800 to 0600 h ) for 1 and 4 cows per feeding station.1 Treatment 1 Behavior Lying Standing Eating Drinking

Day 39.7 39.6 62.7 50.5

Night 60.3 60.4 37.3 49.5

SDM2 1.3 2.4 3.7 5.3

Treatment 2 SDC3 4.2 10.6 7.6 36.9

Day (%) 39.8 46.1 58.8 52.0

Night 60.2 53.9 41.2 48.0

SDM2 1.2 2.9 3.6 8.1

SDC3

P > F

4.5 9.8 11.6 34.5

X 0.847 0.044 0.023 0.697

SDC3 0.609 0.208 0.074 0.590

1df

= 5; n = 8. deviation of means. 3Standard deviation between cows. 2Standard

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OLOFSSON TABLE 7. Pearson’s correlation coefficients between the percentage night share (1800 to 0600 h ) of each time budget variable and the individual cow traits: social dominance value (DV), cow age (months), basic eating rate (grams of DM per minute), and energy requirement (megajoules of metabolizable energy per day). 1

Dependent variable Lying Treatment 1 Treatment 2 Standing Treatment 1 Treatment 2 Eating Treatment 1 Treatment 2 Drinking Treatment 1 Treatment 2 Treatment difference Lying Standing Eating Drinking 1n

DV

Basic eating rate

Age

Energy requirement

r

P > F

r

P > F

r

P > F

r

P > F

–0.01 –0.06

0.976 0.835

–0.08 0.10

0.769 0.701

0.24 –0.06

0.371 0.817

–0.44 –0.33

0.089 0.212

–0.05 0.43

0.868 0.097

–0.03 0.16

0.920 0.816

–0.50 –0.06

0.050 0.816

0.43 0.50

0.098 0.051

–0.09 –0.57

0.753 0.022

0.05 0.10

0.867 0.721

0.01 0.07

0.977 0.787

0.44 0.05

0.089 0.850

–0.22 0.33

0.410 0.211

0.43 0.20

0.099 0.452

0.08 0.13

0.778 0.623

0.15 0.01

0.586 0.980

–0.05 0.49 –0.54 0.49

0.845 0.055 0.029 0.055

–0.02 0.20 0.07 –0.19

0.927 0.464 0.792 0.490

–0.34 0.55 0.07 0.05

0.197 0.027 0.798 0.843

0.13 –0.03 –0.25 –0.12

0.630 0.911 0.351 0.656

= 16.

extent than did the more dominant cows. Instead of eating, the subordinate cows were observed standing and lying to a greater extent around the two milkings when eating normally was preferred. DISCUSSION The use of feeding stations in this study was necessary in order to gather data for feed and water consumption, but the feeding stations differed somewhat from the feeding tables or feed bunks commonly used on dairy farms. The difference is especially pronounced regarding the width of each feeding station and the use of extended dividers between each cow. However, the low and open construction of the feeding station minimized the difference from feeding directly at a feeding table. The general observations and effects of limited space in this study are probably relevant in all cases. The addition of fresh feed will most likely stimulate a cow to eat. Therefore, it is important that feeding occur in a similar way for different treatments. In this study, the troughs at treatment 2 were always filled directly from the feeding wagon at the additional feedings at noon and midnight, and the feed level in the troughs in treatment 1 mostly were adjusted by moving feed from one trough to another. The freshness of the feed was assumed to be almost the same because the feed in the feeding wagon was Journal of Dairy Science Vol. 82, No. 1, 1999

mixed at the same time as the feed already placed in the troughs. All other routines at feeding were similar in both treatments. Most studies of competition for roughage or total mixed diets have been made of groups, without possibilities to register eating behavior of individuals, but, during recent years, the number of studies trying to obtain complete control of individual performance has increased. In this study, the average feed consumption increased when the number of cows per feeding station was changed from 1 to 4. This increase corresponds well to results published by Elizalde ( 5 ) , who compared different levels of competition for silage using 1, 3, 5, 7, or 9 low producing cows per feeding gate. Elizalde found that the average cow reduced her silage intake both in the absence of competition and at the highest level of competition. The highest average intake was found with 7 cows per feeding gate. Friend et al. ( 7 ) reported a 16% increase in consumption of a total mixed diet when the length of the feed bunk was decreased from 0.5 to 0.25 m per cow. Another experiment published in the same article compared 0.1, 0.2, 0.3, 0.4 and 0.5 m of feed bunk per cow and resulted in the highest consumption of a complete ration at 0.3 m of feed bunk per cow. The average feed intake, however, was reduced by 11% as feed bunk space per cow went from 0.5 to 0.1 m. In a study of yearling dairy heifers eating from a feed

COMPETITION FOR TOTAL MIXED RATIONS

bunk with 0.81, 0.41, 0.27, or 0.2 m of space per heifer, Keys et al. ( 1 0 ) reported the highest average daily intake of the total mixed diet at 0.2 m of feedbunk per heifer. In contrast, Leaver and Yarrow ( 1 1 ) found a 5% reduction in the average consumption of maize silage by heifers when feed bunk space was changed from 0.4 to 0.2 m per heifer. Reynolds and Campling ( 1 5 ) found no differences in the consumption of grass silage that was offered for ad libitum intake to 11 cows from 6 or 11 mangers. Hopster and Wierenga ( 9 ) found that total roughage intake did not differ significantly between a situation with 12 eating places for 16 dairy cows and a situation in which the number of feeding places matched the number of cows. Henneberg et al. ( 8 ) also found no differences in total feed intake when stocking densities of 1, 2, or 3 dairy cows per feeding place were compared, and Frank and Magnusson ( 6 ) found no differences for 1 or 3 cows per feeding place with a total mixed diet. Even if the data from the experiment do not provide information about consumption over time within an eating bout, observations indicated that the cows did not have a genuinely higher consumption rate when competition for the feed increased. Instead, the average consumption rate of the cow was mainly increased by means of a more effective use of the feeding station, (i. e., eliminating noneating time at the station). The increase in consumption rate was therefore not thought to be extreme. The decreasing eating time with limited feed space is well documented (5, 6, 8, 10, 11, 15). In experiments using 6 or 17 feeding places per 17 heifers, Metz et al. ( 1 3 ) found an average decrease in total eating time at the higher competition level for the roughage. This change in consumption time was clearly correlated with social rank. The heifers of highest social rank increased their total eating time when the feeding space became limited. Increased consumption rates at higher competition levels for the feed have been reported or could be estimated from reported data (5, 6, 7, 8, 10, 11, 15). The record of the number of visits or eating bouts does not adequately describe how cows alter their eating frequency, because the computerized feeding system records a new visit each time a cow puts its head inside the station. An extreme situation arises when a cow scratches her head against the bar at the feeding gate. These noneating events, together with all short breaks that occur naturally while eating, are corrected for when eating bouts are recalculated into meals. The change in the number of daily meals when the competition for feed increases is not constant. An

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increase in the number of meals at a higher level of competition has been found in two studies (5, 8), which agrees with results from this study. Others (3, 5 ) have reported no difference or fewer meals in situations of higher competition ( 2 ) . A large part of the displacements performed by subordinate cows was carried out in a paired relationship of two cows. In such cases, very little violence occurred. The clustering of displacements in time (most interactions occurred during the first 30 min after each milking) indicated the high degree of need and motivation of the dairy cow to eat after milking. In treatment 1, the intensity was much higher at the beginning of each eating period after which intensity declined. Cows normally consumed feed for about 30 min after milking; then, one by one, they chose to rest in their cubicles. Fewer cows eating resulted in fewer displacements. Another situation arose in treatment 2 in which the stations were occupied for much longer after each milking. The cows usually did not rest until they were satiated, and the displacement rate was quite high as long as at least 3 cows had an interest in eating from the two available stations. A few of the mentioned studies (6, 8, 13) of competition include observations on displacements and, in all cases, an increase in the number of displacements is reported. The increase of displacements in this experiment was exceptionally high and was, in my opinion, the most serious argument against the use of 4 cows per feeding station. There might, however, be fewer displacements per feeding station in a larger group, because the probability of finding an available feeding station most likely would increase as the number of stations increases. When the competition is increased from 1 to 4 cows per feeding place, the cows altered their average eating rhythm by spending significantly less time eating and more time standing without eating. Socially dominant cows were recorded as being those cows that gained eating time at the higher competition level while subordinate cows were forced to alter the allocation of their feed consumption to less preferred hours of the day. The basic consumption rate of cows did not seem to affect the time budget to any great extent, but cows with a high energy requirement were observed eating longer than others in treatment 4. Most references used in the discussion mention the time budget by means of consumption over the 24-h period. Albright and Timmons ( 2 ) , however, studied the time budget in approximately the same way as the procedure in the present experiment. They found a small increase in standing time and a decrease in the time spent resting and eating when Journal of Dairy Science Vol. 82, No. 1, 1999

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the competition level increased. No differences were reported as being significant. Collis ( 3 ) reported no differences in eating, standing, or resting behaviors, but Hopster and Wierenga ( 9 ) showed that the subordinate cows, to a greater extent than the dominant cows, altered their consumption rhythm and consumed more feed at night. Milk production is a very difficult variable to secure in a short-term experiment. Two days of milk recordings per research period (research week) were considered to be enough (19), but a longer period of adaptation before each research period would be preferred. Because of the overall high overconsumption of feed, milk production could not be assumed to differ between the two competition levels, and, because the composition of the feed remained the same throughout the experiment, differences in milk production would be assumed to be due to factors other than feed intake. The differences between the two competition levels in different behavioral variables are, therefore, not likely to affect milk production. Albright ( 1 ) reviewed a study by Speicher of approximately 600 cows with 0.61 and 0.46 m of bunk space per cow. No differences could be found in milk production, conception rate, health of the cows, behavior, or labor input between these two levels of competition. None of the reviewed articles reported a significant difference in milk production after cows were changed from low to high competition for feed. With nonlactating heifers, however, a significant decrease in daily weight gain appeared in situations of increased competition (10, 13).

a long feed consumption time and the preferred time budget. The individual consumption rate had an effect on a cow’s chance to keep a long feed consumption time and possibly also to maintain high DMI. Cow age had very little influence on the effects of competition and individual energy requirement as a cow trait did not seem to be crucial when the outcome of the higher competition was determined. No evidence has been found to indicate a decrease in milk production or negative effects on cow health when competition for feed increased, either in this rather short study or elsewhere. The decrease in eating time cannot be assumed to affect the cows to any great extent because the capacity to adjust to a more effective use of the feeding stations is apparent, nor do the fairly small differences in time budgets of other behaviors discourage the use of the higher competition level. The most serious question might be whether it is defensible to subject cows to a situation in which the number of forced endings of visits at the feeding stations is almost five times higher than in the less crowded situation with 1 cow per feeding station. ACKNOWLEDGMENTS This study was a part of the research program, Dairy Cow Management and Well-being, coordinated by Hans Wiktorsson and financially supported by the Swedish Council for Forestry and Agricultural Research (Sweden). REFERENCES

CONCLUSIONS On average, an increase in competition from 1 to 4 cows per feeding station led to a significantly shorter eating time, longer standing times without eating, higher eating rates, increased number of meals, more displacements at the feeding stations, more aggressors entering the feeding station after the displacements, and fewer displacements conducted by dominant aggressors. In treatment 2, the cows spent a greater share of their feed consumption time during the night leading to a decrease in the share of standing time during the dark hours. Even if all of the investigated cow traits showed significant correlations of interest with a number of variables of feed consumption and behavior, it can be concluded that the cow traits showed less significant effects on cow performance when competition was increased from 1 to 4 cows per feeding station. The DV of a cow had impact on the possibility to maintain Journal of Dairy Science Vol. 82, No. 1, 1999

1 Albright, J. L. 1993. Feeding behavior of dairy cattle. J. Dairy Sci. 76:485–498. 2 Albright, L. D., and M. B. Timmons. 1984. Behavior of dairy cattle in free stall housing. Trans. ASAE 1119–1126. 3 Collis, K. A., M. J. Vagg, P. T. Gleed, C. M. Copp, and B. F. Sansom. 1980. The effects of reducing manger space on dairy cow behaviour and production. Vet. Rec. 107:197–198. 4 Dickson, D. P., G. R. Barr, and D. A. Wieckert. 1967. Social relationship of dairy cows in a feed lot. Behaviour 29:195–203. 5 Elizalde, H. F. 1993. Studies on the effects of chemical and physical characteristics of grass silage and degree of competition per feeding space on the feeding behaviour of lactating dairy cows. Ph. D. Diss., Queens Univ. Belfast, Belfast, United Kingdom. 6 Frank, B., and M. Magnusson. 1994. Feeding strategies with total mixed ration for loose-housed dairy cows with different feeding space. Rep. 91, Dep. Agric. Biosys. Technol., Lund, Sweden. 7 Friend, T. H., C. E. Polan, and M. L. McGilliard. 1977. Free stall and feed bunk requirements relative to behavior, production and individual intake in dairy cows. J. Dairy Sci. 60: 108–116. 8 Henneberg, U., L. Munksgaard, E. S. Kristensen, S. P. Konggaard, and V. Østergaard. 1986. Malkekoens adfærd og produktion ved forskellig belægning i sengestalde. Beretning fra stat-

COMPETITION FOR TOTAL MIXED RATIONS ens husdyrbrugsforsøg 613, Natl. Inst. Anim. Sci., Frederiksberg, Denmark. 9 Hopster, H., and H. K. Wierenga. 1986. De invloed van overbezetting op de individuele ruwvoeropname van melkkoeien. Rep. B-267. Res. Ins. Anim. Prod., Schoonord, The Netherlands. 10 Keys, J. E., R. E. Pearson, and P. D. Thompson. 1978. Effect of feedbunk stocking density on weight gains and feeding behavior of yearling Holstein heifers. J. Dairy. Sci. 61:448–454. 11 Leaver, J. D., and N. H. Yarrow. 1977. The intake of maize silage by self-fed heifers allowed restricted access. J. Br. Grassl. Soc. 32:165–169. 12 Metz, J. H. 1975. Time patterns of feeding and rumination in domestic cattle. Meded. Landbouwhogesch. 75-12, Agric. Univ., Wageningen, The Netherlands. 13 Metz, J.H.M., P. Mekking, H. J. Blokhuis, and H.E.B. Branje. 1979. Sociale effecten van de vermindering van het aantal eetplaatsen in een ligboxenstal. Bedrijfsontwikkeling 10:61–65. 14 Nilsson, E., and C. Ekfa¨ldt. 1991. Foderstyrningslaboratoriet i lo¨sdriftsladuga˚rden pa˚ Kungsa¨ngens fo¨rso¨ksga˚rd. Rep. 127, Swedish. Inst. Agric. Eng., Uppsala. Sweden.

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15 Reynolds, V. S., and R. C. Campling. 1981. Competition for feed between dairy cows. Anim. Prod. 32:366. 16 Sambraus, H. H. 1975. Beobachtungen und u¨berlegungen zur socialordnung von rindern. Zu¨chtungskunde 47:8–14. 17 SAS User’s Guide: Statistics, Version 5 Edition. 1985. SAS Inst., Inc., Cary, NC. 18 Schein, M. W., and M. H. Fohrman. 1955. Social dominance relationships in a herd of dairy cattle. Br. J. Anim. Behav. 3: 45–55. 19 Schu¨ler, D. 1992. Studies on the necessary measuring frequency for feed intake and milk performance data in feeding experiments with dairy cows. Arch. Anim. Nutr. 42:317–323. 20 Swedish Board of Agriculture. 1994. Code of Statutes 1994:2, Jo¨nko¨ping, Sweden. 21 Spo¨rndly, R., ed. 1995. Fodertabeller fo¨r idisslare 1995. Dep. Anim. Nutr. Manage. Rep. 235 Swed. Univ. Agric. Sci., Uppsala, Sweden. 22 Wierenga, H. K. 1990. Social dominance in dairy cattle and the influences of housing and management. Appl. Anim. Behav. Sci. 27:201–229.

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