Free-grazing Sheep Research Articles

Habitat Selection by Free-Grazing Sheep in a Mountain Pasture.

For centuries, mountain grasslands have been part of the grazing cycle of sheep and cattle in extensive management systems in the Pyrenees; however, traditional guided herding has been, in many cases, replaced by free-ranging flocks at these pastures. The goal of this study was to analyze the grazing behavior of free-ranging sheep in mountain pastures using GPS-based tracking systems and Geographic Information Systems. During the summer seasons of 2019, 2020, and 2021, a transterminant flock of free-ranging sheep was tracked with GPS devices attached to collars at the mountain pastures of Collarada mountain (Central Pyrenees, Spain). Preferences for grazing on certain geomorphological features (slope, aspect, and altitude) and different plant communities present in the area were evaluated using the Manly's standardized preference index. The results show that sheep prefer altitudes between 2400 and 2600 m; SE-, SW-, and E-facing sites; and slopes under 20%. The preferred pastures were Festucion eskiae, Primulion intricatae, and Nardion strictae; however, they reject Festucion scopariae communities. This study demonstrates the effectiveness of GPS and GIS technologies in monitoring free-ranging sheep activity, providing valuable data for enhancing pastoral practices and ensuring sustainable pasture use.

GPS monitoring reveals circadian rhythmicity in free-grazing sheep

GPS collars are a technology that is used extensively to monitor livestock due to its versatility. In this study, the main objective was to confirm whether they can detect the circadian rhythmicity that modulates the behavior of free-grazing sheep. The Churra-breed flock that was monitored grazed an approx. 166-ha fenced area within a dehesa ecosystem in the northwestern Iberian Peninsula. Geolocations were recorded every 30 min for two years. Animal activities were categorized based on the speed; an animal was “moving” if the speed was > 0 m/s (the analyzed category), and “resting” if the speed was 0 m/s. Sheep grazing activity in terms of their speed, azimuth, and distance traveled, was subjected to a circadian adjustment derived from the online Cosinor tool. Results reveal that the flock activity, whether based on speed, distance traveled, or azimuth, fit a circadian rhythmicity (p < 0.05). In the summer, particularly July and August, sheep exhibited a significant advance in the acrophase (the time at which the peak of a rhythm occurs), which might have been caused by day length and temperature. In all seasons, flock activity was significantly higher in the diurnal period, while the lowest activity was found in all cases at night, although in the summer sheep activity was high at dawn. In addition, in the day, sheep activity was significantly higher in the fall than it was at other times of the year. The preferred grazing direction of the sheep was non-random, since it was modulated by the contour orientation and the limits of the grazing area. It could be concluded that GPS geolocations allow to demonstrate that free-grazing sheep activity is modulated by a circadian rhythmicity.

Impact of feeding regimens on the composition of gut microbiota and metabolite profiles of plasma and feces from Mongolian sheep.

Mongolian sheep are an indigenous ruminant raised for wool and meat production in China. The gut microbial community plays an important role in animal performance and metabolism. The objective of this study was to investigate the effects of two feeding regimens on the diversity and composition of gut microbiota and metabolite profiles of feces and plasma from Mongolian sheep. A total of 20 Mongolian sheep were assigned to one of two feeding regimens: free grazing (FG) and barn confinement (BC). When samples were collected, the average live weights of the sheep were 31.28 ± 1.56 kg and 34.18 ± 1.87 kg for the FG and BC groups, respectively. At the genus level, the FG group showed higher levels of Bacteroides, RC9_gut_group, Alistipes, Phocaeicola, Barnesiella, and Oscillibacter, and lower levels of Succinivibrio, Treponema, and Prevotella, compared to the BC group. The butyric acid content in feces was lower in the FG group (P > 0.05). Higher levels of palmitic acid, oleic acid, alpha-linolenic acid, L-carnitine, L-citrulline, and L-histidine, and lower levels of L-tyrosine, L-phenylalanine, and L-kynurenine were found in the plasma of the FG sheep. Moreover, there were substantial associations between several gut microbiota genera and alterations in feces and plasma metabolites especially those involved in the metabolism of butyric acid, linolenic acid, and L-tyrosine. Feeding regimens can not only influence the composition of gut microbiota, but also alter metabolic homeaostasis in sheep.

The ecological adaptability of cloned sheep to free-grazing in the Tengger Desert of Inner Mongolia, China

Since the birth of the first cloned sheep, somatic cell nuclear transfer technology has been success- fully used to clone a variety of mammals. Cloned livestock have no apparent health risks, and the quality and safety of the cloned animal products are similar to non-cloned animals. The social behavior and environmental adapt- ability of postnatal cloned animals, especially when used for grassland farm production purposes, is unknown. In the present study, the cloned Dorper sheep equipped with GPS location devices were free-grazed in a harsh natural environment similar to conditions commonly experienced by Mongolian sheep. The main findings of this research were as follows. (1) Under free-grazing conditions, the cloned sheep showed excellent climatic and ecological adaptability. In extreme temperature conditions ranging from -30 to 40°C, the cloned sheep maintained acceptable body condition and behaved as other sheep. (2) The cloned sheep quickly adapted from a herd feeding strategy to the harsh environment and quickly exhibited a grazing regi- men as other free-grazing sheep. (3) The cloned sheep exhibited free-grazing patterns and social behavior as other sheep. (4) The cloned sheep in the harsh environment thrived and produced healthy lambs. Overall, the cloned Dorper sheep exhibited excellent ecological adaptation, which is an important consideration for breeding meat sheep by cloning. The Dorper sheep readily adapted to the free-grazing conditions on the Mongolian plateau grass- land, which attests to their ability to withstand harsh environmental conditions.

Food intake by free-grazing sheep and resource productivity

A study was conducted in the Middle Atlas Region, Morocco, to investigate habitat use by free-grazing sheep during December 1985, and May, July and September 1986. Movements of free-grazing sheep were observed and recorded. With advance in season, grazing time per unit area (GTA) varied among plant communities. GTA in plant communities was as high as 72 min ha −1 and as low as 3 min ha −1 ( P < 0.05). Intake (g dry matter per ewe per day) was different among the 11 patches and depended on season ( P < 0.05), i.e. 815, 1249, 1279 and 968 in December, May, July and September, respectively. Ingestion parameters, i.e. rate of biting and mass per bite, varied according to plant communities ( P < 0.05) and season ( P < 0.05). Sheep tended to compensate for a decrease in the availability of feed by changing the rate of biting and bite size.

Feeding station behavior of free-grazing sheep

A study was conducted in the Middle Atlas Region, Morocco, to investigate the feeding station (FS) behavior of free-grazing sheep during November 1986 and April, June and September 1987. Behaviors observed and recorded were number of FS min −1, time elapsed per FS (T/FS), bites/FS and dry matter intake per FS (DMI/FS). The number of FS min −1 was highest in April ( P < 0.05), while DMI/FS peaked in June ( P < 0.05). The time spent per FS was the same ( P > 0.05), regardless of season. Fewer FS min −1 were recorded in shrubby plant communities than in herbaceous plant communities ( P < 0.05). Both T/FS and DMI/FS varied among plant communities ( P < 0.01 and 0.05, respectively). Biting rate at a FS differed among plant communities at different times of the year ( P < 0.05).

Use of habitats by free-grazing sheep

A study of habitat use by free-grazing sheep was conducted in the Timahdit Station, Morocco, during spring, summer and autumn of 1985. Sheep movements through plant communities were observed and recorded by tracking animals all day long during 6 days in three different areas each season. Grazing time per unit area (GTA) for plant communities in Area 1 varied from 4 to 70 min ha −1 and was influenced by season. In Area 2, there was an interaction season × plant communities ( P < 0.05). Use ranged from 1 to 116 min ha −1. A similar interaction also occurred in Area 3. GTA in plant communities was as high as 35 and as low as 0 min ha −1. Foraging velocity (rate of walking) varied mainly with advance in season. Walking rate averaged 17, 22 and 24 steps min −1 for spring, summer and autumn, respectively. The three areas offered three different cases. Sheep used Area 1 by cueing on a unique area with high-quality resources all the year. In Area 2, a plant community that contained a novel plant determined sheep grazing behavior in the spring.

Herding and forage ingestion by sheep

A study was conducted in the Middle Atlas Region, Morocco, to investigate the impact of herding on ingestion and distance walked by sheep during spring (March–April), summer (June–July) and autumn (October–November) 1985. Stocking rate was considered to be light. Treatments were free-grazing (FG), normal-herded (NH) and fast-herded (FH) sheep. Fast-herded, NH and FG sheep travelled 11.4, 6.3 and 5.9 km/day, respectively (SE=1.2). Grazing time averaged 508±42 min/day for all treatments and seasons. The percentage grass, grass-like plants, forbs and shrubs in the diet was similar among treatments ( P>0.05), but animals ate more ( P<0.05) grass in spring (Sp) than summer (Su) or autumn (A). Percentage of shrubs in the diet was different in all seasons ( P>0.05), i.e. 3.7, 16.7 and 25.3%, respectively (SE=2.0). Diversity and selectivity indices did not vary among treatments ( P>0.05), but increased ( P>0.05) between Sp and Su (SE=0.14 and 0.03, respectively). The index of similarity between treatments, i.e. FG vs. NH, FG vs. FH or NH vs. FH, was 0.971, 0.990 and 0.986, respectively. Composition of neutral detergent fiber (NDF), acid detergent fiber (ADF) and lignin (ADL), crude protein (CP), ash and in vitro organic matter digestibility (IVDMD) in simulated diets were similar among treatment groups ( P>0.05), but NDF, ADF and ADL increased ( P<0.05) with advance in season and CP and IVDMD declined ( P<0.05). Dry matter intake (g/LW 0.75/day) was lower for FH (72) than for FG or NH (81 and 82, respectively) (SE=3.0). This study demonstrated the ability of sheep to compensate for any adverse effect of herding when resources are not limiting.

Studies on the nutritive value of the diet selected by grazing sheep. II. Some sources of error when sampling oesophageally fistulated sheep at pasture

Some possible sources of error when sampling oesophageally fistulated sheep at pasture were examined in eleven trials. Samples collected from sheep asted for varying periods of up to 22 hours did not differ significantly in nitrogen content from samples collected from unfasted sheep. There was no significant difference between the nitrogen content of extrusa collected at the start of a 30-minute period and that of extrusa collected at the end of the period. Sheep transferred from a perennial ryegrass/clover pasture to a native pasture for three months ingested herbage containing 3·80% nitrogen when returned to the original pasture. Control sheep which had remained on the ryegrass/clover pasture selected material containing 3·33% nitrogen. In a further trial sheep transferred from a ryegrass/clover pasture to a Phalaris/ clover pasture consumed herbage with an organic matter digestibility of 70·8 % which contained 3·44 % nitrogen. The material consumed by similar sheep which had grazed the Phalaris/clover pasture for 18 months was 71·5% digestible and contained 3·63% nitrogen.Diurnal changes in the digestibility and nitrogen content of the diet of free-grazing sheep were observed in two trials. Diurnal changes in nitrogen content were similar on different days but changes in digestibility were relatively smaller and less repeatable between days.Consistent differences in the composition of the diet selected by individual sheep and selected on different days were observed in a further five trials. Variation between sheep and between days in the nitrogen content of the diet was ±5·6% and ±7·4% respectively, both estimates being expressed as coefficients of variation. Corresponding estimates for digestibility, calculated as standard deviations, were ±1·6 and ±1·3 units. The implications of these results when sampling oesophageally fistulated sheep at pasture are considered.

Diurnal Variation in the Diet selected by Free-grazing Sheep

THE use of oesophageal fistulae has facilitated work on the diet selected by grazing ruminants. Three experiments at this laboratory with free-grazing sheep have shown marked diurnal changes in the nitrogen content of the diet selected by Merino wethers.