Astragalus membranaceus root supplementation improves average daily gain, rumen fermentation, serum immunity and antioxidant indices of Tibetan sheep.

The use of antibiotics as supplements in animal feed is restricted due to possible health hazards associated with them. Consequently, there is increasing interest in exploiting natural products to improve health and production of livestock with no detrimental side effects. In this study, we examined the effect of Astragalus membranaceus root (AMT) supplementation on DM intake, growth performance, rumen fermentation and immunity of Tibetan sheep. Twenty-four male Tibetan sheep (31 ±â€¯1.4 kg; 9 months old) were assigned randomly to one of four dietary treatments with different levels of AMT: 0, 20, 50 and 80 g/kg DM (A0, A2, A5 and A8, respectively) in addition to their basal diets. A0 acted as a control group, and measurements were recorded over a 56-d feeding period. Sheep fed with AMT had a higher average daily gain and a lower feed:gain ratio than controls (P < 0.001). Rumen concentrations of NH3-N (P < 0.001), total volatile fatty acids (P = 0.028), acetate (P = 0.017) and propionate (P = 0.031) in A5 and A8 were higher than those in A0. The addition of AMT in the feed significantly increased serum antioxidant and immunity factors of the sheep and increased the concentrations of serum interleukin, immunoglobulin and tumour necrosis factor-α (P = 0.010). We concluded that AMT can be used as a feed additive to improve growth performance and rumen fermentation and enhance the immunity of Tibetan sheep. Some responses exhibited a dose-dependent response, whereas other did not exhibit a pattern, with an increase in AMT. The addition of 50 and 80 g/kg AMT of total DM intake showed the most promising results.

Impact of animal density on cattle nutrition in dry Mediterranean rangelands: a faecal near-IR spectroscopy-aided study.

In the context of determining the sustainable carrying capacity of dry-Mediterranean herbaceous rangelands, we examined the effect of animal density on cattle nutrition, which is fundamental to animal performance and welfare. The effects on dietary components of low (0.56 cows/ha; L) and high (1.11 cows/ha; H) animal densities were monitored for three consecutive years in grazing beef cows. In the dry season (summer and early autumn), cows had free access to N-rich poultry litter (PL) given as a dietary supplement. In each season, near-IR spectroscopy (NIRS) was used to predict the chemical composition of herbage samples (ash, NDF, CP, in vitro dry matter digestibility (IVDMD) and metabolizable energy (ME) content from IVDMD). Near-IR spectroscopy was applied also to faecal samples to determine the chemical composition of the diet selected by the animal, as well as the contents of ash, NDF and CP in the faeces themselves. A faecal-NIRS equation was applied to estimate the dietary proportion of PL. Seasonal categories were green, dry without PL supplementation and dry with it. We found no effects of animal density on nutrition during the green season but effects were apparent when cows consumed dry pasture. Ash content predicted by faecal NIRS was higher in the diet than in plant samples clipped from pasture, which infers that cows ingested soil. Dietary and faecal ash contents were higher (P<0.05) at the H, implying greater soil intake in these animals. During the dry period, dietary contents of ME were higher in L than in H (P<0.05). Poultry litter supplementation was associated with a marked increase (P<0.01) in dietary and faecal CP contents. Poultry litter represented 0.45 and 0.59 of the diet in treatments L and H, respectively (P<0.05). Consequently, treatment H had higher faecal protein (P<0.05). A tendency of higher dietary protein (P=0.08) and lower dietary NDF (P=0.10) in treatment H was probably related to greater PL ingestion. Given that high and sustained rates of poultry litter consumption are detrimental to animal health, the above results cast doubts on the long-term sustainability of the higher of the animal densities tested. Although it may be sustainable vis-à-vis the vegetation, treatment H may have exceeded the boundaries of what is acceptable for cow health. Chemical information revealed with NIRS can be used to evaluate whether animal densities are compatible with animal health and welfare standards and can play a role in determining the carrying capacity of Mediterranean rangelands.

Foraging behavior of two cattle breeds, a whole-year study: II. Spatial distribution by breed and season.

Spatial distributions of 22 mature large-framed Beefmaster × Simford (BS) cross cows and 16 mature small-framed Baladi (BA) cows were determined. Cows were allocated to the same paddock of a Mediterranean pasture and monitored during 6 consecutive seasons: spring (April 2006), summer (June 2006), autumn (September 2006), winter (February 2007), early spring (March 2007), and summer (June 2007). The locations of the cows were determined at 5-min intervals for 3 to 4 d during each season by using Global Positioning System (GPS) collars. The distances between consecutive locations and the average locations of each breed at each hour of the day in each season were calculated. The Lateral Foraging Index (LFI) was calculated as the ratio between the average distance per day travelled by the cows of each breed and the perimeter of the diurnal itinerary of that breed, which was calculated from its hourly average locations. The 2 breeds maintained similar diurnal patterns of foraging and resting, characterized by morning and afternoon foraging, and resting at midday and during the night. In summer this pattern was more distinctive, with longer resting periods and more intense foraging periods than in winter, when the noon rest was shorter and only partial. The diurnal routes differed (P < 0.001) between the breeds in all seasons, in their locations, their travelling time, or both. The BA cows were more active than the BS cows in all seasons: they travelled longer distances (P < 0.001) and foraged for more hours during the day (P < 0.001). For both breeds the LFI was numerically greater in winter and spring (February, and March) than in summer (June and September), and it was numerically greater for BA than for BS cows in most seasons.

Foraging behavior of two cattle breeds, a whole-year study: I. Heat production, activity, and energy costs.

The foraging behavior and energy costs of activity of 19 large-frame Beefmaster × Simford (BS) cross mature cows and 14 small-frame Baladi (BA) mature cows was determined. Cows were allocated to the same paddock of a Mediterranean pasture and were monitored during 5 seasons throughout 2006 and 2007: spring (April 2006), summer (June 2006), autumn (September 2006), winter (February 2007), and early spring (March 2007). Cows were given poultry litter (25% CP, DM basis) as supplemental feed during autumn only. The cows were fitted for 3 to 4 d in each season with global positioning system (GPS) monitors, activity monitors attached to 1 of their hind legs, and heart rate (HR) monitors harnessed to their chests. Oxygen consumption per heart beat was determined for each cow during each season to enable conversion of the diurnal HR patterns to heat production (HP) units. All GPS data of cattle locations and activity and the HR and HP data were synchronized to produce simultaneous 5-min interval records; step length also was calculated for each record. These records provided summaries of partitioning among activities: lying down, standing, foraging, and walking without foraging as well as horizontal and vertical distances walked per day and number of steps taken per day. These attributes were analyzed using multiple regression models to relate these activities to HP and to estimate specific HP costs per unit of each activity. Accordingly, the daily energy costs of activity were calculated for the 2 cattle types in each season as the product of the specific activity and the number of units of each activity per day. The HP level of the large-frame BS cows was greater than that of the small-frame BA cows in winter and lower in spring (P < 0.001); however, the respective HP levels were much closer in summer and autumn, with BA cows having values greater by 3% than those of BS cows. The BA cows were more active than the BS cows during all seasons: they foraged for more hours per day (P < 0.001) and walked longer distances (P < 0.001). The mean specific costs of activity of BA cows were 20% less than those of BS cows (P < 0.001). The BA cows took longer steps during foraging and walking idle compared with BS cows despite their much smaller frame. The BA cows were more efficient in conditions of low herbage quality whereas metabolic rate of BS cows was greater in conditions of high herbage quality.

Energy cost of activities and locomotion of grazing cows: a repeated study in larger plots.

We determined the energy costs associated with the activities of beef cows grazing on Mediterranean foothill rangeland covered with herbaceous vegetation. Our central aim was to compare the energy cost coefficients obtained in this study, using relatively large plots, with those obtained in a previous study conducted on smaller plots. Measurements were performed in 3 seasons: in March on nursing cows grazing a 135-ha plot of high quality herbage (11.4 MJ/kg of ME), and in May and September on nonlactating cows grazing a 78-ha plot of low quality herbage (6.2 MJ/kg of ME). Poultry litter manure was given as a supplement in September. Stocking rates on the respective plots were 2.25 and 1.95 ha/cow; 5, 5, and 7 cows were monitored in the respective months. Heat production was determined by continuous monitoring of the heart rate and measurement of the oxygen consumption per heartbeat. Animal location was tracked with global positioning system (GPS) collars equipped with motion sensors. Activity was determined for 5-min intervals using suitable calibration equations. Horizontal and vertical distances traveled were computed by integrating GPS data and plot maps in a geographic information system. Three models were used to estimate the energy cost coefficients of engaging in a given activity and locomotion. Total daily heat production ranged from 644 (September) to 1,014 kJ.kg of BW(-0.75).d(-1) (March; P = 0.04). Estimates of the energy cost coefficients for activity states (kJ.kg of BW(-0.75).d(-1)) ranged from 42.7 to 46.2 for standing, from 84.5 to 92.4 for walking idle, and from 89.4 to 103.2 for grazing; those for locomotion (kJ.kg of BW(-0.75).d(-1).km(-1)) ranged from 2.8 to 2.9 for horizontal locomotion and from 21.4 to 27.9 for vertical locomotion. Estimated cost coefficients of standing, grazing, and horizontal locomotion derived in the present study from animals on relatively larger plots were similar to those of the previous study based on data from smaller plots, but the energy costs of walking idle and of vertical locomotion were greater in the present study than in the previous one. The differences found are associated with the fact that cows in the present study walked for longer periods of time and traveled longer distances in single uninterrupted bouts of locomotion than those in the previous study.

Grazing behavior and energy costs of activity: a comparison between two types of cattle.

The grazing behavior, diet intake, and energy costs of activity of 2 types of cows grazing a Mediterranean pasture were compared. Fifteen large-frame Beefmaster x Simford (BM) cross cows and 13 small Baladi (Ba) mature cows were allocated to the paddock and monitored during 3 seasons throughout 2006; spring (April), summer (June), and autumn (September). Cows were not given supplemental feed during the spring and summer, but had free access to a poultry litter supplement (25% CP, DM basis) during the autumn. Fecal output and digesta kinetics and feed intake were estimated using indigestible double-marker technique. Cows were fitted for 3 to 4 d in each season with global positioning system (GPS) monitors, with activity monitors attached to one of their hind legs, and with heart rate (HR) monitors harnessed to their chests. Oxygen consumption per heart beat was determined for each cow during each season to enable conversion of the diurnal HR patterns to heat production (HP) units. All the GPS data of cattle locations and the activity, HR, and HP data were synchronized to produce a simultaneous record at 5-min intervals. Partition of time spent by the cows lying down, standing, grazing, and walking without grazing, the horizontal and vertical distances walked per day, and the number of steps taken per day were summed from these records. Multiple regression models were adjusted to refer these activities to the HP and to estimate the specific HP costs per unit of each activity. Accordingly, the daily energy costs of activity were calculated for the 2 cattle breeds on each season as the product of the specific activity and the number of units of each activity per day. Feed intake by Ba cows per unit of metabolic BW was greater (P < 0.001) than that of BM cows in both spring and summer and their apparent selection of greater-quality herbage in spring was greater (P < 0.1) than that of BM cows. The smaller framed Ba cows grazed more hours per day and walked longer distances than the BM cows among all seasons. The specific costs for locomotion were less for the Ba cows.

Energy cost of cows' grazing activity: Use of the heart rate method and the Global Positioning System for direct field estimation.

This study with grazing beef cows on the range was designed to explore the possibility of determining incremental energy expenditure (EE) in standing, traveling, and grazing relative to that in lying down, by means of continuous monitoring of EE, location, and activity by the heart-rate method, with Global Positioning System (GPS) collars, and by motion sensors in the GPS collars, respectively. Cows were observed on Mediterranean foothill rangeland covered with herbaceous vegetation through 4 seasons of the year. There were 2 stocking rate treatments, and 14 statistical models were evaluated, including one that was a stepwise model. Total daily EE (TEE) was affected by many interdependent factors apart from activity, including season, stocking rate, herbage quality, standing biomass, and reproductive state of the cow. Each model included all activity variables, plus some of the other factors. Across seasons and treatments TEE, in kJ/(kg of BW(0.75) . d), ranged from 469 in densely stocked, nonlactating cows in June to 1,092 in sparsely stocked, lactating cows in April. The cows' daily vertical and horizontal movements ranged from 75 to 174 m and from 1.5 to 4.2 km, respectively. Within a day, time spent traveling (without grazing) ranged from 0 to 32 min, and grazing time ranged from 4.4 to 12.1 h. Cows spent less time grazing (P < 0.001) in the summer, when herbage quality was low, than in winter and spring. Relative to the baseline EE while lying down, the daily increment incurred by grazing ranged from 13 to 48 kJ/(kg of BW(0.75) . d), and that incurred by grazing, standing, and traveling combined ranged from 38 to 74 kJ/(kg of BW(0.75) . d) or 5.8 to 11.4% of TEE. In conclusion, the estimates of activity costs yielded by 11 of the models were similar to one another, whereas those yielded by the stepwise model and the remaining 2 models were 20% smaller. The cost of grazing activity was estimated to be 6.14 J/(kg of BW(0.75) . m), and that of locomotion during grazing was 6.07 J/(kg of BW(0.75) . m), which agree with values obtained for animals and humans by means of a treadmill. The experimental and statistical approach tested here yielded fairly reliable estimations of energy costs of activities in grazing cows.