P.P. Semenye
P.O. Box 252, Maseno, Kenya
Introduction
Materials and methods
Results
Discussion
Conclusions
Acknowledgements
References
Abstract
The grazing behaviour of Maasai cattle was influenced by season, area and grazing orbit. In a grazing day the cattle spent 1, 8, 14, 15 and 62% of their time drinking, ruminating, resting, walking and grazing respectively. The mean length of the grazing day of Maasai cattle is defined, as from the time they left their bomas in the morning until they returned for the night; this duration was 10.8 ± 0.6 and 10.4 ± 0.6 hours for cattle and calves respectively. The mean grazing orbit was 15.5 and 10.8 km for adult cattle and calves respectively. A vibracorder proved quite accurate in timing cattle activities.
Daily intake of grazing cattle is determined by the product of time spent grazing, the rate of biting and forage intake per bite (Hodgson, 1982). It therefore follows that grazing time influences intake directly, while other grazing habits such as drinking, ruminating, playing and resting may influence intake either positively or negatively. In Africa pastoral herdsman exercise a major influence on the grazing behaviour of their cattle through herding. By herding, man decides when and where cattle are to go for grazing. So the skill of a herdsman coupled with environmental factors are the determinants of a successful grazing day in terms of forage intake.
The endeavour to understand the grazing behaviour of the Maasai cattle was part of a study of the Maasai pastoral production system. This study was initiated by the International Livestock Centre for Africa (ILCA). The study was carried out in three group ranches which were selected on the bases of their ecology and development gradients in Kajiado District, Kenya.
The five-minute method was used to study grazing behaviour, as suggested by Hancock (1953) and used by Lampkin et al. (1958) at Muguga, Kenya. At the end of each five-minute period, an observation was made and the behaviour of each selected animal recorded. Behaviour activities recorded were: species of grass or browse grazed, resting while either standing or lying, ruminating while standing or lying, walking and drinking. With the exception of the species grazed the other behaviour patterns were confirmed if they continued for ten or more seconds.
In theory, a total of 144 observations could be made from 7.05 to 19.05 hours which is the normal daylight period in Kenya at this latitude. However, the grazing period does not always extend over the entire daylight period, but rather is modified according to the schedule and needs of the individual livestock owner. In each herd, three animals were selected according to the role each cow appeared to play in the herd: the herd leader, an ordinary cow and a laggard. Each animal selected was followed by one observer during the entire grazing day.
The observers used pedometers to monitor the distance covered during each grazing day. At the end of each day the distance walked was taken as the average of the three pedometers used. Pedometers were calibrated regularly against a known distance. A vibracorder was used as described by Stobbs (1970) to monitor total time spent actively, in grazing, walking, drinking and ruminating. For statistical analysis, SPSS and least squares procedures of Harvey (1977) were used.
Grazing Day Length
The mean length of the grazing day of Maasai cattle, defined as from the time they left their bomas in the morning until they returned for the night, was 10.8 ± 0.6 and 10.4 ± 0.6 hours for adult cattle and calves respectively. The difference between the adults and the calves of 0.4 hour was not significant (P>0.05).
Although the 28 grazing days recorded by the five-minute method and the vibracorder did not overlap entirely, the latter also recorded an average of 10.6 ± 0.8 hours. During green seasons grazing days were longer than during dry ones; the averages for the green and the dry were 11.1 ± 0.4 and 10.3 ± 0.8 hours respectively but the difference was not significant (P > 0.05). The measurements of the grazing day with an ordinary watch and the vibracorder were very similar and the differences between them were within the experimental error. A vibracorder had the advantage over human observers that, once the instrument was set with a chart covering seven days' records, it needed no further handling until the expiry of the seven days. The vibracorder also recorded night activities between 18.30 to 07.30 hours. The average duration of night activity for the green and dry seasons was 2.0 ± 1.3 hours and the seasonal difference was not significant (P>0.05). The night activity was assumed to be mainly rumination. Total time spent ruminating on the average was 2.8 hours divided into 2 hours at night and 0.8 hours during the day.
Distance Walked per Grazing Day
The mean distance walked per grazing orbit was 15.5 ± 5.0 and 10.8 ± 4.8 km for adult cattle and calves respectively. Hence adult cattle walked 4.7 km more than calves. The difference was 36% of the overall mean and significant (P<0.05). This difference in walking distance between the calves and the adult cattle was due to grazing management. Calves grazed in reserved areas near the homestead (Olopololi), while the adults utilised the communal grazing areas. Calves had more opportunity for high intake since in the homestead herbage was relatively more abundant than in the communal areas, necessitating less walking in search of forage. For the adult cattle the distance walked was dependent on the herder's skills, on the grazing orbit followed, and whether it was a watering day or not.
Specific Grazing Habits
The overall percentage time spent in a grazing day in specific activities were 1, 8, 14, 15 and 62% in drinking, ruminating, resting, walking and grazing respectively. The percentage time spent was different between seasons, areas and grazing orbits and there were significant interactions of season x area and season x grazing orbit.
Seasonal effects were highly significant (P<0.01) while animal type was not (P>0.05) for any of the activities. The coefficient of variations of the activities were large, and they ranged from 23 to 98.
Table 1 presents various activities as affected by seasonal changes. More time was spent drinking in the green than in the dry and the dry/green seasons. Cattle ruminated less in the green than in the other two seasons, while rumination time during the day was 8% longer in the dry than in the green season. Cattle rested 13% of the day longer in the dry than in the green or dry/green seasons, but they walked for a longer period in the green and dry/green than dry season. Proportion of time spent on grazing was longest in the green season (66%), followed by dry/green (62%) and 57% for the dry season.
Ratios between rumination and grazing time were 1:8, 1:9, 1:17 and 1:5 for the overall mean, dry/green, green and dry respectively. Although this calculation of the rumination to grazing time ratio was only for the day-light period when viewed together with Table 1, a trend emerged linked to forage quantity and intake. Grazing and ruminating times appeared to be interrelated; low quality forage in the dry season resulted in longer ruminating and shorter grazing (intake) time, while the reverse was found in the better conditions of the green season. It is accepted that intake is limited by forage quality. But in this production system it appeared that rumination time was negatively related to intake.
Table 1. Percentage of grazing day spent on different activities by season.
|
Season |
N |
Drinking |
Ruminating |
Resting |
Walking |
Grazing |
|
Overall mean |
61 |
1 |
8 |
14 |
15 |
62 |
|
(6) |
(48) |
(84) |
(90) |
(372) |
||
|
(0.1) |
(0.8) |
(1.4) |
(1.5) |
(6.1) |
||
|
Dry/green Feb/Mar 1983 |
21 |
1b |
7a |
13a |
17a |
62ab |
|
(6) |
(42) |
(78) |
(102) |
(372) |
||
|
(0.1) |
(0.7) |
(1.3) |
(1.7) |
(6.2) |
||
|
Green May/June 1983 |
28 |
3a |
4c |
8b |
19a |
66a |
|
(18) |
(24) |
(48) |
(114) |
(396) |
||
|
(0.3) |
(0.4) |
(0.8) |
(1.9) |
(6.6) |
||
|
Dry Sept/Oct 1983 |
12 |
1b |
12b |
21c |
9 |
57 |
|
(6) |
(72) |
(126) |
(54) |
(342) |
||
|
(0.1) |
(1.2) |
(2.1) |
(0.9) |
(5.7) |
abc Except for the overall means other means having no superscript letter in common differ at the P£ 0.05. (In brackets = time in hours).
That the vibracorder can be used successfully to record grazing time (Stobbs, 1970) was confirmed in this present study. It has many obvious logistics advantages over observers with watches. It is a tool that could be used to compare herdsman and their herds. The vibracorder was also effective in recording time spent on rumination during the night. Therefore the total ruminating time was calculated by adding the night time recorded by the vibracorder to that of the day time recorded by observers. The total ruminating time in 24 hours of 2.8 hours fell at the lower end of the range of 2.5 to 10.4 hours, reported by Harker et al (1953) and van Soest (1982).
Maasai cattle walked shorter distances than pastoral Fulani cattle in northern Nigeria studied by van Raay and de Leeuw (1974) who recorded daily averages ranging from 16 to 30 km. Maasai cattle walked less because of better grazing resources due to the bimodal rainfall and a greater degree of sedentarisation and a closer spacing of water sources, all leading to a lesser need for walking.
The percentage time spent grazing of 62% or 6.7 hours was intermediate between times reported for herded cattle (65 to 89%, Semenye 1981; Otchere, 1986) and non-herded cattle (55%, Harker et al., 1953; Lampkin et al., 1958; Lampkin and Quarterman, 1962).
Lack of significant difference between animal types within a single herd means that the behaviours for the three different categories were similar. In a situation where cattle are not herded, similarity between the categories is less likely. Where cattle are herded the influence of the herder dominated the individual expression of cattle. However, when it came to behaviour on which the herder had less influence such as rumination, significant differences between grazing areas were observed due to differences in forage quality and water availability. Rumination time is known to vary with the forage quality (Hancock, 1953; van Soest, 1982), which varied across areas and seasons.
More time was spent drinking in the green season, when there was plenty of surface water. Reasons have been advanced above for expecting longer rumination periods in the dry season when forage was at its lowest quality. Since they had access to forage of high quality and plenty of water in the green season, cattle should enjoy more resting time instead of less. However, it is possible that more resting occurred in the dry/green and dry seasons than in the green because of higher prevailing temperatures and the desire of either the cattle or the herder to avoid unnecessary effort. With increasing temperature, cattle rest for longer periods by seeking shade. The trials of Lampkin and Quarterman (1962) with steers at Muguga and Mariakani with temperatures below and above 30°C respectively, showed that time spent under the shade was much greater in the hotter environment. A similar seasonal trend in walking time was observed, but it should be noted that in the dry season cattle devoted their entire walking time simply to walking whereas in other seasons grazing and walking occurred simultaneously in some instances. Cattle grazed for the shortest time in the dry season, when quantity and quality of forage were lowest but spent a relatively longer period in rumination.
The Maasai herdsman herded their cattle with great skill despite severe limitations of livestock facilities such as adequate water sources, troughs and dips; and lack of paddocks and perimeter fences. The need for increasing the length of the grazing day to enhance intake was uppermost in their minds. However, due to predators this was not possible, hence the total grazing time coincided with sunrise and sunset.
Rumination time was found to vary with the forage quality. Therefore, in dry seasons longer rumination time necessitated by poor forage quality could limit intake.
A vibracorder timing of grazing days was found to be as accurate as watch timing. Due to the convenience of a vibracorder over observers, it is an ideal tool for grazing behaviour studies.
The author wishes to thank ILCA for funds supporting this research, the pastoralists for allowing me to study their cattle, Drs. A. Carles, A. Said, J. Lambourne and Mr. P. de Leeuw for advice and guidance, Messrs. P. Chara, E. Rugema, T. Tukai and E. Wacira for their good work as field assistants and Ms. P. Pacha for typing the manuscript.
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