Effect Of Stocking Rate Research Articles

Modeling weather and stocking rate effects on forage and steer production in northern mixed-grass prairie

Stocking rate (SR) is the primary management factor that influences livestock gains, plant community changes and forage production, as well as economic returns for livestock producers. More effective stocking decision making by ranchers in the semi-arid northern mixed-grass prairie requires clearly understanding forage production and yearling steer weight gain (SWG) responses to SR and high weather variability. The objectives of this study were to: (1) test the Great Plains Framework for Agricultural Resource Management-Range (GPFARM-Range) model for predicting forage production and SWG under three experimental SR treatments and long-term weather conditions on semiarid northern mixed-grass prairie in southeast Wyoming, USA; and (2) quantify the threshold responses of forage production and SWG to SR and the yearly weather variability across years using long-term simulations with SR higher than those experimentally evaluated. We improved upon the GPFARM-Range model to simulate peak standing crop (PSC) and SWG for three experimental SR treatments (low, moderate and high; 0.20, 0.33 and 0.44steerha−1, respectively) from 1982 to 2012 at Cheyenne, Wyoming, USA. The improved model accurately predicted the effects of SR on PSC and SWG across years (root mean square errors from 355 to 387kgha−1 for PSC and from 12.8 to 14.2kghead−1 for SWG). We ran the model with long-term weather data and 50–300% higher SR (0.66–1.76steerha−1) than the high SR experimental treatment. Differential responses of predicted total intake of digestible nutrients (quadratic increase) and metabolic maintenance (linear increase) to these higher SR resulted in a quadratic increase of predicted SWG with SR and high yearly variability at high SR levels. The financially-optimum SR with highest profits was reduced to 0.33steerha−1 for dry or normal seasons and 0.44steerha−1 for wet seasons. Such reduced SR can also benefit land conservation with high PSC and low harvest efficiency. The moderate SR with 25% harvest efficiency was determined between 0.22 and 0.33steerha−1 for dry or normal seasons, or between 0.33 and 0.44steerha−1 for wet seasons. These results provide useful direction for selecting an effective SR to achieve high economic net return with lower yearly variability (risk) and reduced likelihood of rangeland degradation.

Effect of High Stocking Rates on Growth and Survival of the Endangered Rio Grande Silvery Minnow Hybognathus amarus

The endangered Rio Grande silvery minnow Hybognathus amarus was cultured in 2.44-m-diameter outdoor tanks in a 131-day yield trial to assess growth, survival, and percentage of taggable-sized fish (<TEX>${\geq}35mm$</TEX> total length) when stocked at 500/tank (1.07 million/ha), 1,000/tank (2.14 million/ha), and 1,500/tank (3.21 million/ha). At harvest, fish averaged 45.6 mm and 0.94 g in the 500/tank treatment, 42.6 mm and 0.74 g in the 1,000/tank treatment, and 38.4 mm and 0.55 g in the 1,500/tank treatment; the differences were significant (P = 0.05). Survival in the three treatments was 70%, 64%, and 52%, respectively, but the differences were not significant. Percent taggable-sized fish was 86%, 89%, and 65%, respectively, but the differences were not significant. Yield was 672.5 kg/ha, 1,026.6 kg/ha, and 887.8 kg/ha, respectively; yield in the 1,000/tank treatment was significantly greater than that in the 500/tank treatment, but was not significantly greater than that of the 1,500/tank treatment. This facility is a conservation facility and a major goal is to raise fish without formulated feed. Fertilization produced good growth for the first month, but little growth occurred during the second month so supplemental feed had to be used for the final 60 d of the yield trial.

Effects of creep grazing and stocking rate on forage selection and nutritive value of the diet for meat goat does and kids on grass/forb pasture

The effects of creep grazing and stocking rate (SR) on forage selection and nutritive value of the diet selected by Spanish does with Boer×Spanish kids and Boer×Spanish does with 3/4 Boer-1/4 Spanish kids were determined using grass/forb pastures. There were four treatments, each replicated, with three stocking rate (SR) treatments and one treatment involving creep grazing. Goats of both types were equally represented in all treatments. Each group of does and kids was allocated to 0.4ha pastures divided into four paddocks that were rotationally grazed in two cycles over a total of 76 days. The three SR were 4 does plus 8 kids (L), 6 does plus 12 kids (M), and 8 does plus 16 kids (H) per 0.4ha pasture. The creep grazing treatment (C) was at the high SR relative to the pasture area common to the does and kids. In this treatment, however, the kids had access to an additional area of a similar 0.4ha pasture sub-divided into four paddocks containing the leguminous tree mimosa (Albizia julibrissin Durazz) planted in rows. A direct observation and simulation method was used to characterize the diet selected by does and kids and obtain representative samples. These samples were evaluated in terms of their CP, NDF, ADF, and ADL concentrations and in vitro true DM digestibility (IVTDMD). There were no significant effects (P>0.10) of stocking rate on botanical composition of the diet selected or its nutritive value. Does and kids selected diets of similar botanical composition and nutritive value for the three treatments without a creep area. When kids were in a creep grazing area, 52.8% of their diet consisted of mimosa leaves leading to an improvement in the overall nutritional value of the diet relative to times when in the base grass/forb pasture (CP 21.9 vs. 19.8%, NDF 34.1 vs. 53.8%, ADF 21.4 vs. 27.5%, and IVTDMD 85.7 vs.79.9%). It was concluded that stocking rate had no impact on diet selection and the nutritive value of the diet of does or kids when grazing forage of low to medium quality. Kids with access to creep areas including mimosa trees, however, preferentially consumed mimosa leaves, thus improving the nutritive value of their diet.

Effects of Stocking Rate on the Variability of Peak Standing Crop in a Desert Steppe of Eurasia Grassland

Proper grazing management practices can generate corresponding compensatory effects on plant community production, which may reduce inter-annual variability of productivity in some grassland ecosystems. However, it remains unclear how grazing influences plant community attributes and the variability of standing crop. We examined the effects of sheep grazing at four stocking rate treatments [control, 0 sheep ha(-1) month(-1); light (LG), 0.15 sheep ha(-1 )month(-1); moderate (MG), 0.30 sheep ha(-1) month(-1); and heavy (HG), 0.45 sheep ha(-1) month(-1)] on standing crop at the community level and partitioned by species and functional groups, in the desert steppe of Inner Mongolia, China. The treatments were arranged in a completely randomized block design over a 9-year period. Standing crop was measured every August from 2004 to 2012. Peak standing crop decreased (P < 0.05) with increasing stocking rate; peak standing crop in the HG treatment decreased 40 % compared to the control. May-July precipitation explained at least 76 % of the variation in peak standing crop. MG and HG treatments resulted in a decrease (P < 0.05) in shrubs, semi-shrubs, and perennials forbs, and an increase (P < 0.05) in perennial bunchgrasses compared to the control. The coefficients of variation at plant functional group and species level in the LG and MG treatments were lower (P < 0.05) than in the control and HG treatments. Peak standing crop variability of the control and HG community were greatest, which suggested that LG and MG have greater ecosystem stability.

Effect of creep feeding and stocking rate on the productivity of beef cattle grazing grasslands

Ninety-six Hereford cow-calf pairs grazing Campo grasslands were used in a 2 × 2 factorial design that evaluated stocking rate (high [H] vs low [L]) and creep feeding (CF; yes or no). Creep-fed calves grazing L had a greater average daily gain (1.07 ± 0.03 kg/d) than CF calves grazing H (0.96 ± 0.03 kg/d; P < 0.05), but L − CF (0.78 ± 0.03 kg/d) and H − CF calves (0.73 ± 0.03 kg/d) had similar average daily gains (P > 0.05). Similarly, L + CF calves were heavier at weaning (172 ± 3 kg) than H + CF calves (160 ± 3 kg), but weaning weights between L − CF (144 ± 3 kg) and H − CF (138 ± 3 kg; P > 0.05) did not differ. Creep-fed calves grazed less (39 ± 10%) than non-supplemented calves (58 ± 15%; P < 0.05). Creep feeding had no effect on milk production, body condition and live weight of the dams, so it had no impact on their reproductive performance. We conclude that CF promotes greater live weight gains and weaning weights of Hereford calves grazing Campo grasslands.

Effects of stocking rates on gastrointestinal nematode infection levels in a goat/cattle rotational stocking system

Gastrointestinal nematodes (GIN) are increasingly resistant to anthelmintic drugs worldwide, so integrated control methods are more and more needed for the sustainability of small ruminant farming. Such methods rely on knowledge in epidemiology, physiology, and genetics. Ecological studies have highlighted the effect of host density on parasite populations, and in the humid tropics, rotational grazing systems were designed according to the survival of GIN free-living stages. This study aimed to assess the effects of mixed stocking and host stocking rate on host GIN infection level.Four groups of 15–17 Creole male kids were raised on irrigated pasture from weaning (about 3 months) until the age of 7 months, at four partial stocking rates (pSR): 100% (control), 75% (G75), 50% (G50), and 25% (G25) of the total stocking rate of the pasture. The last three groups were associated with weaned Creole heifers to obtain the same overall stocking rate as the control. Animals grazed in a ‘leader’ goat and ‘follower’ cattle design: the G25, G50, and G75 paddocks were split into six plots; each plot was grazed by goats for 1 week and by heifers the following week. The pasture then rested for 4 weeks before the animals were returned for a new grazing sequence. Five control plots were grazed rotationally for 1 week, and rested for 4 weeks. This design was repeated three times a year for a total of 10 repetitions. Average faecal egg counts (FEC) decreased according to a power function of the pSR: FEC=1829pSR3.7. The observed death rate decreased significantly with the pSR (27.6%, 16.4%, 11.9%, and 12.2%). The kids grew faster in G25 (51gd−1) than in G50 (43gd−1) and G75 or control (32gd−1, p<0.05). Heifers were not significantly infected with GIN and grew normally (about 0.48kgd−1).Reducing the pSR by associating a non-host species in a rotational stocking system may be a very promising component of integrated GIN control, at least for the humid tropics.

Effect of Different Stocking Rates on Deyeuxia angustifolia Bog Meadow in Sanjiang Plain of China

This paper investigated the effects of cattle grazing on herbage production and its nutrient and soil characteristics over the grazing season. The grazing experiment was conducted on Deyeuxia angustifolia Bog meadow grassland established in 2010 in Sanjiang Plain. Four grazing treatments were light grazing (LG), moderate grazing (MG), heavy grazing (HG), and a non-grazed exclosure (CK) with corresponding stocking rates of 0.6, 1.0, 1.4, and 0 AU • hm−2 • month−1, selected as three replications. And then found out the optimum carrying capacity after analyzed the nutrition balance between livestock and grassland. Heavy grazing led to a decline in grassland productivity and soil nutrients. The SOM and the TN content in the soil layer of 0–10 cm were much higher than that in the soil layer of 20–30 cm. More attention should be paid to the nutrient changes in the soil layer of 20–30 cm. Currently, studies showed that the reliable carrying capacity in this type of grassland was 1.0 AU • hm−2 • month−1. Inclusion of rangeland health monitoring and optimum stocking rate into grassland management model could facilitate the sustainable development of the grassland.

Detailed description of grazing systems using nonlinear optimisation methods: A model of a pasture-based New Zealand dairy farm

Grazing systems constitute the most extensive land use worldwide. However, economic analysis of these systems has mainly involved the use of linear optimisation methods that provide a general description of the complex processes contained therein. This paper describes a nonlinear optimisation model of a New Zealand dairy farm that incorporates a detailed depiction of key biophysical processes present within grazing systems. The capacity of this optimisation model to provide rich insight into the effects of higher stocking rates within grazing systems is demonstrated in an empirical application. In accordance with system trials, this application shows that higher stocking rates on pasture-based New Zealand dairy farms generally increase pre-grazing pasture biomass, decrease post-grazing pasture biomass, increase pasture utilisation, decrease herbage allowance, decrease intake and energy consumption per cow, decrease milk production per cow, increase milk production per ha, and reduce conception rate. Nevertheless, an intermediate stocking rate is optimal, as greater milk production with a higher stocking rate is not sufficient to offset the associated costs.

The influence of stocking rate and mixed grazing of Angora goats and Merino sheep on animal and pasture production in southern Australia. 4. Gastrointestinal parasitism

Gastrointestinal nematodes limit the growth, production and welfare of goats but there are few reliable sources of information for recommending management practices across flocks. The effects of animal species (Angora goat, Merino sheep, mixed-grazed goats and mixed-grazed sheep at the ratio of 1 : 1) and stocking rate (SR: 7.5, 10, 12.5 animals/ha) on gastrointestinal parasitism were determined in a replicated experiment on improved annual temperate pastures in southern Australia, from 1981 to 1984. Detailed monitoring of gastrointestinal nematodes was undertaken on animals before, during (five times per year) and at the conclusion of studies using faecal strongyle egg counts (WEC) and total worm counts. Sheep had a greater proportion of nematodes as Teladorsagia spp. and goats a greater incidence of Trichostrongylus spp. Both goats and sheep developed resistance to Nematodirus spp. during the experiment. WEC was similar in goats and sheep at the start of the experimental period but, thereafter, was consistently greater in goats than in sheep. While WEC was highly related to total worm count, the regressions for sheep and goats were different. Increasing the SR increased the WEC of goats and mixed-grazed goats but not of sheep. During the experiment, WEC declined at 7 and 10 animals/ha but increased at 12.5/ha. Mixed grazing with goats provided beneficial effects for sheep at all stocking rates, but the effects for goats were dependent on the stocking rate, being beneficial at 7.5 and 10/ha but harmful at 12.5/ha. The WEC of separately grazed goats were generally higher than the WEC of mixed grazed goats. The WEC of mixed sheep were lower than those of separately grazed sheep. During the experiment, the WEC of mixed grazed sheep declined faster than the WEC of separately grazed sheep but the WEC of separately grazed goats at 12.5/ha and of mixed grazed goats at 10 and 12.5/ha increased. Under the environmental and pastoral conditions examined, Angora wether goats should not be grazed at SR above those recommended for wether sheep. In the present study, the impact of gastrointestinal-nematode infections in goats was reduced at lower SR. Further, mixed grazing of Angora wether goats with wether sheep at or below the recommended SR resulted in reduced gastrointestinal parasitism for both sheep and goats, compared with monospecific grazing conditions. Goats did not represent a gastrointestinal-nematode hazard to sheep.

Effects of year-round stocking rate and stocking method systems on cow-calf production in the gulf coast region of the United States: Costs, returns, and labor considerations

<h2>ABSTRACT</h2> The present research examines the effect of stocking method, i.e., continuous and rotational, and set (fixed) stocking rate on labor requirements, costs, and profits in cow-calf beef production. Two replicates of 4 adjacent pastures each, containing a mixed warm-season, perennial grass sod [common bermudagrass, Cynodon dactylon (L.) Pers.; dallisgrass, Paspalum dilatatum Poir.], were overseeded to ‘Marshall' annual ryegrass [Lolium multiflorum (Lam.)] in the autumn of 2 consecutive years. Within each replicate of 4 pastures, one of the following grazing treatments was randomly assigned each pasture: rotationally stocked (8 paddocks) at a low, medium, or high stocking rate (RL, RM, and RH) and continuously stocked at a moderate stocking rate (CM). Labor activities, expenditures, sales, and equipment usages were recorded throughout the study. On a per-cow basis, total labor usage declined (P < 0.01) in response to increases in stocking rate. However, on a per–0.40 ha basis, total labor usage only tended (P < 0.11) to increase as stocking rate increased. In both bases, total labor usage was greater (P < 0.01) for RM compared with CM. On a per–0.40 ha basis, increases in stocking rate tended (P < 0.08) to result in increased specified expenses, increased (P < 0.01) total sales revenue, and increased (P < 0.05) return over total expenses. Net returns between rotational and continuous stocking methods, at a moderate stocking rate, did not differ (P > 0.90) and would not justify the additional labor associated with rotational grazing management.

Effects of year-round stocking rate and stocking method systems on performance of cow-calf pairs in the gulf coast region of the United States

<h2>ABSTRACT</h2> The present research is the second phase (2yr) of a multiyear cow-calf project examining the effect of stocking method, i.e., continuous and rotational, and fixed stocking rate on beef-cattle production. Two sets of 4 adjacent pastures, each containing a mixed warm-season, perennial grass sod [common bermudagrass, Cynodon dactylon (L.) Pers.; dallisgrass, Paspalum dilatatum Poir.], were overseeded to ‘Marshall' annual ryegrass (Lolium multiflorum) in the autumn of 2 consecutive years. Within each set of 4 pastures, 1 of the following grazing treatments was randomly assigned each pasture: rotationally stocked (8 paddocks) at a low, medium, or high stocking rate (RL, RM, and RH) and continuously stocked at a moderate stocking rate (CM). Low, medium, and high stocking rates were 1.25, 2, and 2.75 cows/ha. Brangus cow-calf pairs were stocked on treatment pastures in March 2004. Mean cow BW was greater for RL compared with RM (P < 0.05; 569 vs. 527kg) but did not differ (P > 0.20) for the RM versus RH (522kg) and the RM versus CM (530kg) stocking-treatment comparisons. Calf-adjusted 205-d BW was similar for all treatment contrasts. Pasture weaning BW differed between the RL versus RM (P < 0.01; 238 vs. 394kg/ha) and the RM versus RH (P < 0.01; 394 vs. 583kg/ha) treatment contrasts but was similar for RM and CM (P = 0.23; 394 vs. 437kg/ha). Stocking rate influenced both cow and calf production, but stocking method had little or no effect in the current study.

Effects of year-round stocking rates and stocking methods on performance of cow-calf pairs grazing dallisgrass-common bermudagrass pastures overseeded with annual ryegrass

Beef producers throughout the United States frequently are restricted to a fixed land area that varies considerably in carrying capacity throughout the year. Much of the research that has focused on stocking rate and methods (continuous, rotational) has failed to recognize the inability of most producers to use a variable stocking rate. Two sets of 4 adjacent pastures, each containing a mixed warm-season, perennial grass sod [common bermudagrass, Cynodon dactylon (L.) Pers.; dallisgrass, Paspalum dilatatum Poir.] were overseeded to ‘Marshall’ annual ryegrass (Lolium multiflorum) in the autumn of 3 consecutive years. Within each set of 4 pastures, one of the following grazing treatments was randomly assigned each pasture: continuous stocked at a low, medium, or high stocking rate (CL, CM, and CH) and rotational stocked (8 paddocks) at a high stocking rate (RH). Low, medium, and high stocking rates were 1.25, 2, and 2.75 cows/ha, respectively. Brangus cows and their suckling calves were stocked on treatment pastures in February 1999. Available forage mass tended to be greater (P = 0.10) for CL than CM in the late spring and was greater (P < 0.05) for CL than CM in the summer grazing season. Differences in forage nutritive value were largely associated with the stocking method comparison, favoring CH in the early spring (percent CP, percent in vitro true digestibility, and percent ADF; P < 0.01) and summer (percent CP and percent ADF; P < 0.01) grazing seasons. Cow-calf productivity, as measured by kilograms of calf wean weight per hectare, increased (P < 0.01) in response to increases in stocking rate, but was similar between the continuous and rotational stocking methods at the high stocking rate.

Effects of establishment method and fall stocking rate of wheat pasture on forage mass, forage chemical composition, and performance of growing steers1

Stocking rate is a fundamental variable for managing pastures, and there is a distinct relationship between stocking rate and animal performance for each forage type. This research was conducted to determine the effects of fall stocking rate (SR) and method of establishment of wheat pasture planted into dedicated crop fields on animal performance during the fall and subsequent spring. There was a factorial arrangement of tillage methods used in the establishment of wheat pasture and fall stocking rates. Tillage treatments included 1) CT, seed sown into a prepared seedbed, 2) RT, a single pass with a light disk followed by broadcasting of seed, or 3) NT, direct seeding into the undisturbed stubble of the grazed-out wheat pasture from the previous year. The fixed SR during the fall were 1.9, 2.5, and 3.7 growing beef steers (Bos taurus L.)/ha. In the spring all pastures were grazed at the same fixed SR by steers for graze out. Data were analyzed using the mixed procedure of SAS as a randomized complete block design with field as the experimental unit and year as the block. Forage mass, forage nutritive composition, and animal performance during the fall or spring were not affected (P ≥ 0.14) by tillage method. During the fall grazing season, with increasing SR there were linear (P < 0.01) decreases in BW of steers upon removal from pasture, BW gain per steer, and ADG, whereas grazing-day per hectare and BW gain per hectare increased linearly (P < 0.01) with increasing SR. The carryover effects of fall SR into the spring grazing season decreased (P< 0.01) grazing-day per hectare and tended (P ≤ 0.09) to produce quadratic changes in BW upon removal from pasture and BW gain per hectare. Across the fall and spring grazing seasons, grazing-day per hectare increased linearly (P < 0.01) with greater SR, and BW gain per hectare increased quadratically (P = 0.02) with increased fall SR. A tillage treatment by fall SR interaction (P = 0.10) indicates that although there was no difference (P ≥ 0.12) due to tillage treatment in BW gain per hectare at 1.9 or 2.5 SR, NT fields produced (P ≤ 0.04) more BW gain per hectare than CT or RT at the 3.7 SR. Although increasing SR of growing steers leads to reduced animal performance in the fall and reduced carrying capacity in the spring, NT appears to be capable of withstanding greater fall SR with less impact on total production per hectare than CT or RT.

Effect of Stocking Rate on Soil-Atmosphere CH4 Flux during Spring Freeze-Thaw Cycles in a Northern Desert Steppe, China

BackgroundMethane (CH4) uptake by steppe soils is affected by a range of specific factors and is a complex process. Increased stocking rate promotes steppe degradation, with unclear consequences for gas exchanges. To assess the effects of grazing management on CH4 uptake in desert steppes, we investigated soil-atmosphere CH4 exchange during the winter-spring transition period.Methodology/Main FindingThe experiment was conducted at twelve grazing plots denoting four treatments defined along a grazing gradient with three replications: non-grazing (0 sheep/ha, NG), light grazing (0.75 sheep/ha, LG), moderate grazing (1.50 sheep/ha, MG) and heavy grazing (2.25 sheep/ha, HG). Using an automatic cavity ring-down spectrophotometer, we measured CH4 fluxes from March 1 to April 29 in 2010 and March 2 to April 27 in 2011. According to the status of soil freeze-thaw cycles (positive and negative soil temperatures occurred in alternation), the experiment was divided into periods I and II. Results indicate that mean CH4 uptake in period I (7.51 µg CH4–C m−2 h−1) was significantly lower than uptake in period II (83.07 µg CH4–C m−2 h−1). Averaged over 2 years, CH4 fluxes during the freeze-thaw period were −84.76 µg CH4–C m−2 h−1 (NG), −88.76 µg CH4–C m−2 h−1 (LG), −64.77 µg CH4–C m−2 h−1 (MG) and −28.80 µg CH4–C m−2 h−1 (HG).Conclusions/SignificanceCH4 uptake activity is affected by freeze-thaw cycles and stocking rates. CH4 uptake is correlated with the moisture content and temperature of soil. MG and HG decreases CH4 uptake while LG exerts a considerable positive impact on CH4 uptake during spring freeze-thaw cycles in the northern desert steppe in China.

Bird community responses to cattle stocking rates in a Pacific Northwest bunchgrass prairie

In 2006–2010, effects of four different cattle stocking rates (0, 14.4, 28.8, and 43.2 animal unit months) were compared, representing 0%, 20%, 32%, and 46% utilization of vegetation by domestic livestock, on vegetation structure (as indexed by visual obstruction), and songbird population and apparent nest density, community composition, and diversity in a Pacific Northwest bunchgrass prairie in northeastern Oregon, USA. Overall paddock-level visual obstruction decreased and structural heterogeneity increased with increasing stocking rates, and those effects carried over 1 year after grazing had ceased. Most species were able to locate nesting sites regardless of differences in visual obstruction, except western meadowlark and vesper sparrow, for which obstruction was lower in paddocks with higher stocking rates. Apparent nest density for grasshopper sparrows was negatively affected by higher stocking rates. Grazing effects on absolute songbird population density were restricted to negative effects of higher stocking rates on savannah sparrows, but this relationship was not observed until 1 year after grazing had ceased. Songbird community composition differed between control and heavily-grazed paddocks, driven by an increase in the proportion of horned larks and a decrease in the proportion of savannah sparrows in heavily-grazed paddocks from pre-treatment to post-treatment years. Bird diversity indices were unaffected by stocking rate. Negative effects of high stocking rates on densities of two species and the absence of any clear positive effect for the other three species suggest high stocking rates as applied in this experiment may not provide suitable habitat for all grassland songbirds. The absence of negative responses of density to low and moderate stocking rates suggests these grazing regimes generally provided suitable habitat for all species.

Vegetation Production Responses to October Grazing in the Nebraska Sandhills

Abstract Understanding the long-term effect of summer grazing date and fall stocking rate on herbage production is critical to extending the grazing season in the Nebraska Sandhills. A study was conducted from 1997 to 2002 at the Gudmundsen Sandhills Laboratory located near Whitman, Nebraska, to determine the herbage production response to summer grazing date and October stocking rate on two different sites. Site 1 was dominated by warm-season grasses and site 2 was dominated by cool-season graminoids. At each site, three 0.37-ha pastures were constructed in each of four blocks before application of summer grazing treatments. Pastures in each block were grazed at 0.5 animal-unit months (AUM) · ha −1 in June or July, or were deferred from summer grazing. Following summer grazing treatments, October stocking rate treatments (no grazing or 1.0, 2.0, or 3.0 AUM · ha −1 ) were applied to subunits of each summer grazing date pasture during mid-October. Vegetation was sampled in each pasture in mid-June and mid-August and sorted by functional group to determine the effect of 5 yr of grazing treatments on herbage production and residual herbage. Herbage production was not affected by summer or October grazing treatments on the warm-season grass–dominated site. Increasing October stocking rate, however, reduced cool-season graminoid production and subsequent herbage production 25% by year 5 of the study. Residual herbage at both sites at the end of the October grazing periods explained as much as 16% to 34% of subsequent year’s herbage production. Grazing managers in the Nebraska Sandhills can extend the grazing season by lightly stocking pastures in the summer to facilitate additional fall grazing. Heavy stocking in October over several years on cool-season–, but not warm-season–, dominated sites will reduce production of cool-season graminoids on these sites.

The Effect of Stocking Rate on Soil Glomalin under Traditional and Mixed Grazing Systems in a Temperate Steppe

Abstract It is of great importance to maintain the soil health in grassland ecosystem. Glomalin, a secretion of the Arbuscular mycorrhizal fungi (AMF), was proved to be a useful biochemical parameter to evaluate the soil fertility. Present study designed a field experiment to investigate the effect of stocking rate on soil glomalin under traditional and mixed grazing systems in a temperate steppe of China. The results showed that grazing system significantly affected the amount of glomalin, and higher values of total glomalin (TG), total glomalin storage (TGs) and a higher ratio of (TGs) to soil organic carbon storage (TGs/SOCs) were found during the mixed system (MS), however, lower values of easily extractable glomalin (EEG) and soil organic carbon (SOCs) were achieved. In traditional system (TS), higher values of TG, TGs and TGs/SOCs were found in the control (S0) and light grazing treatments (S3). The obtained results indicate that light or moderate grazing would favorable to grassland and compared with TS, MS was a preferable grazing system to the maintenance of grassland ecosystem.

Effect of supplementary feed and stocking rate on the production of ostriches

This study was conducted to determine the effect of two different levels of supplementary feed and two different stocking rates on the production of grazing ostriches. One hundred and seventy ostriches were randomly allocated to four groups and kept on irrigated lucerne pasture with or without supplementary feed from approximately 58 kg to a target weight of 95 kg. The ostriches rotationally grazed lucerne pasture at one of two stocking rates, i.e. 15 birds/ha or 10 birds/ha and were fed one of two levels of supplement i.e. 0 g or 800 g feed/d formulated according to the nutrient requirements of the relevant group of birds. Data were analyzed by ANOVA. There was no interaction between the supplementary feed and stocking rate regarding mean live weight at 54 weeks of age and feed conversion ration (FCR). Data were provided as the two main effects of level of supplementation and stocking rate. Significant differences in mean live weight at 54 weeks of age and FCR of the birds were observed between the different levels of supplementary feed. The parameters measured for the two different stocking rates used in this study (10 birds/ha vs . 15 birds/ha) did not differ from each other and did not influence either mean live weight at 54 weeks of age, average daily gain (ADG) or FCR. The two groups which received 800 g supplementary feed/d reached slaughter weight (95 kg) within the set of 54 weeks of grazing for the trial, while the two groups which received no supplementary feed did not achieve slaughter weight by 54 weeks on the pasture. Ostriches receiving supplementation of 800 g/bird/day had significantly better FCR’s than birds receiving no supplementation. There was a significant interaction between level of supplementary feed and stocking rate regarding ADG of the birds. As stocking rate increased, average daily gains of birds receiving no supplementary feed declined. This study indicates that ostriches being kept on grazing and receiving supplementary feed will exhibit improved and faster growth rates than ostriches which only have access to grazing and receive no supplementary feed.

Striped Bass, Morone saxatilis, Egg Incubation in Large Volume Jars

The standard McDonald jar was compared with a large volume jar for striped bass, Morone saxatilis, egg incubation. The McDonald jar measured 16 cm in diameter by 45 cm in height and had a volume of 6 L. The experimental jar measured 0.4 m in diameter by 1.3 m in height and had a volume of 200 L. The hypothesis is that there is no difference in percent survival of fry hatched in experimental jars compared with McDonald jars. Striped bass brood fish were collected from the Coosa River and spawned using the dry spawn method of fertilization. Four McDonald jars were stocked with approximately 150 g of eggs each. Post-hatch survival was estimated at 48, 96, and 144 h. Stocking rates resulted in an average egg loading rate (±1 SE) in McDonald jars of 21.9 ± 0.03 eggs/mL and in experimental jars of 10.9 ± 0.57 eggs/mL. The major finding of this study was that average fry survival was 37.3 ± 4.49% for McDonald jars and 34.2 ± 3.80% for experimental jars. Although survival in experimental jars was slightly less than in McDonald jars, the effect of container volume on survival to 48 h (F = 6.57; df = 1,5; P > 0.05), 96 h (F = 0.02; df = 1, 4; P > 0.89), and 144 h (F = 3.50; df = 1, 4; P > 0.13) was not statistically significant. Mean survival between replicates ranged from 14.7 to 60.1% in McDonald jars and from 10.1 to 54.4% in experimental jars. No effect of initial stocking rate on survival (t = 0.06; df = 10; P > 0.95) was detected. Experimental jars allowed for incubation of a greater number of eggs in less than half the floor space of McDonald jars. As hatchery production is often limited by space or water supply, experimental jars offer an alternative to extending spawning activities, thereby reducing labor and operations cost. As survival was similar to McDonald jars, the experimental jar is suitable for striped bass egg incubation.

Stocking rate effects on metabolizable energy intake and grazing behaviour of Tan sheep in steppe grassland on the Loess Plateau of Northwest China

SUMMARYA simulated grazing system was set up in Huanxian County, Gansu province, on the Loess Plateau of Northwest China, involving the purchase of 18-month-old wether lambs in June of each year atc. 20 kg body weight (BW) and sale 6 months later atc. 35 kg BW. Three stocking rate (SR) treatments of 2·7, 5·3 and 8·7 wether lambs/ha were evaluated on geographically separated warm season (WS) and cold season (CS) paddocksc. 1 km apart; 3 years' data are reported (2004–2006). The metabolizable energy (ME) yield of the grazing system, calculated from the weight of animals fed and their weight gain, averaged 1·7, 3·3 and 4·7 GJ/ha/year for 2004, 2005 and 2006, respectively, in the WS and 0·9, 1·9, and 2·7 GJ/ha/year, respectively, in the CS for SR of 2·7, 5·3 and 8·7 animals/ha. Detailed grazing behaviour records were kept in order to elucidate intake dynamics. In these grazing systems, bite weight was typicallyc. 0·04 g/bite, lower than for temperate grazing systems at comparable herbage mass. A hypothesis for further study is proposed that this may relate to the distribution of a similar herbage mass over a greater sward height range in steppe vegetation than in temperate grass pasture. Sheep increased their bite rate (bites/min) and the number of steps/min at higher SR to compensate, such that intake/animal was reduced by not more than 10% with a threefold increase in SR. At higher SR, herbage ground cover on grazed plots was still lower than on ungrazed plots, 1 year after a 90-day summer grazing period or a 48-day winter grazing period. The significance of the findings for management of these systems is briefly discussed.