| Livestock Research for Rural Development 32 (9) 2020 | LRRD Search | LRRD Misssion | Guide for preparation of papers | LRRD Newsletter | Citation of this paper |
In order to have proper grazing management and improvement of husbandry system efficiency, it is necessary to have enough knowledge of sheep diet and plant species cover variations in long-term period. This investigation was carried out in order to draw a clear concept of the sheep diet and plant species cover variations during April to December in Mountainous rangelands of Kalat county, Northwest of Iran. Using an initial study, the region husbandry situations were determined that leaded to identification of five herders with suitable pastoral units. Based on initial study and plants growth season, sampling was conducted in 15-day time point to end of the grazing year in December. The chronic technique was used to determine the percentage of plant species in sheep daily diet. The result of Pearson correlation test showed that the species cover and the species contribution to the sheep diet are related (r= 0.83, P<0.01. Finally the results showed that during April to September period, sheep had higher interest to grasses but in the September to December period, sheep had higher interest to shrubs. while the forbs had constituted little proportion of the sheep diet (5-10%) during April to December.
Keywords: mountainous rangelands, pearson correlation test, plant species
Animal diet is directly influenced by vegetation and animals also strongly affect vegetation that with its understanding, the better rangeland management principles can be attained. Of environmental factors that affect the animal's diet, climate and rangeland condition are important. Climatic conditions have the undeniable effects on the diet of livestock (Askarizadeh et al 2010). Schwartz and Ellis (1981) stated that the season is an influencing factor on the livestock diet and grazing. Van Niekerk and Abubeker (2009) also stated that Rangeland condition and vegetation composition are affecting on the animals diet and various kinds of livestock. Arzani (2009) has stated energy efficiency of different livestock depends on the type of vegetation in the animal’s diet. Actually plant species determine the efficiency of husbandry and play an important role in animal production. So it can be said that the composition, diversity and palatability of different plant species vary throughout the year, and the taste of animals has also short-term and long-term changes. Therefore patterns of vegetation and animal taste variation affect spatial and temporal pattern of grazing and it is necessary to examine them during investigation of the grazing episodes (Fehmi et al 2002 and Butt 2010). Many studies have been done on the livestock diet and vegetation conditions that the following can be noted:
Van rees (1982) stated about seasonal changes of animal taste that plant phenological changes and climatic conditions affect the livestock taste and can cause changes in the livestock diet. He assessed cattle during the 4 months of summer and autumn in southern Australia and found a dramatic and significant change in their diet. Orr et al (1988) investigated the importance of diet in improving meat and wool production in Queensland. By assessing two habitats of desired plant species of native deer, they concluded that despite similarity of vegetation percentage, there was a significant difference between two habitats in weight gain and wool production. Beck and Peek (2005) showed that sheep prefer forbs in spring and summer whereas goats willingly prefer shrubs in all seasons. In free and natural conditions, sheep prefer open environment than goats that these open and without stress environments play an important role in the milk composition richness and protein. Rueda et al (2008) studied sheep grazing behavior in central Spain rangelands. They concluded that spatial pattern of sheep grazing during different seasons is affected by the forage availability. Raoufi Rad et al (2009) has examined the relationship between the animal combination and vegetation composition for optimal management of rangeland. The results showed there is no relationship between percentage of species in sheep diet and percentage of species in the rangeland in terms of production and canopy cover and species grazing by sheep is generally driven by the choice. Ahmadi et al (2009) had examined sheep grazing behavior and diet habits in autumn and winter using chronic technique. The results of grazing cycle and behavior showed that there are no obvious and significant differences between ewes 1, 3 and 5 years in selecting plant species. Askarizadeh et al (2010) investigated sheep and goat diet in various time intervals (July, August and September, in different climatic condition and vegetation). The results of their study showed that goat grazing behavior was stable during the study period but sheep behavior changed based on vegetation changes;, sheep was interested in forbs in August; in July, by dominating grass cover, sheep turned to grazing grasses; in September with approximately equal composition of forbs and grasses, sheep back turned to forbs. These studies indicate that achieving to a complete understanding of animal diet has an important role in determining the effectiveness and efficiency of husbandry system. As long-term study of animal diet is neglected in most cases, a study was done to assess animal diet in long-term with regarding vegetation composition changes.
Khorasan Razavi is a province in northeastern Iran with an area of 118,854 square kilometers, which includes 7% of the total area of the country. The province is located between 929 ˚36 north latitude and ´06 959 east longitude of the Greenwich meridian. The northern boundary of this province is Turkmenistan and North Khorasan province, the southern boundary is South Khorasan and Yazd province, the western boundary is Semnan province and the eastern boundary is Afghanistan. Kalat city with an area of 350269 hectares is located in the northeastern part of Khorasan Razavi province during the longitude of 15, 59 to 30 and 60 and the latitude of 15 and 36 to 59 and 37, which is more than 80% of its area of forest, rangeland and national lands(Figure 1). It has 229255 hectares of pastures with mountainous topography and semi-arid climate. Traditional animal husbandry is one of the main occupations of the people of this region and the sheep breed in this area is Kurdikhorasani.
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| Figure 1. Location of Kalat County, Iran |
Due to the extensive rangelands, an initial study was conducted to fully understand the region situation. Based on this initial study, five herder were identified that are in the region annually and their pastoral units area were 350 to 450 ha (the mean area of region pastoral units is about 300 to 500 ha). Sampling, due to the presence of livestock in rangelands has started from the first half of April and continued until the first half of December. During the sampling, dominant growth forms, vegetation composition and animal forage preference were recorded in 15-day intervals. To determine the animal forage preference, the chronic technique was used, so that while animal was grazing, feeding time on each plant species was records. This was daily done during the 270 days of livestock presence in the rangeland. To show the time variation of livestock grazing on one species, the time of animal grazing on each species was calculated in terms of min/day with the total grazing time. By dividing one species grazing time on the total grazing duration, contribution of each species to the animal diet will be determined. Based on some studies (Barani et al 2003; Askerizadeh 2010), the adult ewes that compose the main part of the herd during the year, were selected as animal samples. Due to the inherent behavior of sheep, to monitor the animal activities, random selection of animal creates a smaller bias to data (Haghiyan et al 2013). To carry out the monitoring, by standing in the appropriate distance from the herd so that the normal activity of herd is not disturbed, One animal (adult ewe) in the vision range was examined and upon its removal from perspective, another ewe in perspective was monitored.
Assessing vegetation and animal diet showed that there were substantial changes in vegetation and plant species contribution to animal diet during the 9-month.
Pearson correlation test showed, generally there is a significant relation between percentage of species cover and its contribution to the sheep diet (r= 0.83, P<0.01) but each species has different trend in in animal diet during the 9-month period.
The results of the study showed that despite shrubs cover was more than grasses during the period April to July, sheep is more interested in grass in the period April to July, so grasses had a greater proportion of the sheep diet. In July to September grasses cover was more than shrubs and sheep is more interested in grasses. With reduction in grasses quality and quantity in the period September to December, sheep taste changed to shrubs. Forbs with regards to their coverage and its trifle variation, had almost included a constant proportion of the sheep diet (Figure 2 and 3).
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| Figure 2. The share of plant growth forms in sheep's diet(feed) |
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| Figure 3. Cover percentage of Vegetative forms |
Long term (9-months) assessment showed that proportion of grasses, shrubs, and forbs had respectively contributed 45-50, 40-45, and 5-10 percent in the sheep diet, meanwhile, their cover percentage were 35- 40, 40- 45, and 5 respectively (Figure 4).
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| Figure 4. Average of vegetative forms, percentage in sheep diet and average of cover percentage in 9 month period |
Assessing vegetation and animal diet in all three regions showed that there were substantial changes in vegetation and plant species contribution to the animal diet over the 9 months period. Pearson correlation test showed that the species cover percentage and their contributions to the sheep diet are generally related but each species and growth form had their own patterns in animal diet during the 9 months period. Generally with reduction in grasses cover, their contribution to the sheep diet is declined (Raoufi Rad et al 2009 and Haghiyan et al 2013). Decreasing grasses water and freshness in the period September to December can be another reason for reduction in Sheep willingness to grasses (Ahmadi et al 2009). In the forbs, with their cover increment, their contribution to the sheep diet had increased (Askarizadeh et al 2010). Based on the field observations, it can be said that low cover of forbs like Medicago littolaris is the reason of low contribution of forbs to animal diet; otherwise sheep is highly interested in forbs. Although shrubs had no significant changes in cover percentage, but their proportion in the sheep diet were different over the 9 months period. It shows in the long-term assessments, Shrub species should be studied separately while forb and grasses had the same pattern during the period. It can be concluded too that, in the period April to September (spring and summer), grasses are considered more than shrubs by livestock due to freshness and quality, although their cover is less than shrubs. In September (the end of summer), there were a substantial increase and decrease in shrubs and grasses contribution to animal diet respectively. The increasing trend was continued during the period September to December, so that shrubs contribution to the sheep diet increased to 70 percent and grasses contribution decreased to less than 30 percent. Meanwhile, the average proportion of grass in the sheep diet was 55-65 percent in the period April to September and the average proportion of grass in the sheep diet was 30-40 percent in September. The results show that season and vegetation composition have a large influence on sheep selection for plant species to graze (Schwartz and Ellis 1981; Van Niekerk and Abubeker 2009). It can conclude that assessment of vegetation, its changes, and animals’ diet should be done in long-term studies so that palatability and animals’ interest to different species get clearly distinguished and it can be possible to understand the diet of livestock and measure husbandry system efficiency and effectiveness.
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