Can Targeted Grazing Reduce Abundance of Invasive Perennial Grass (Kentucky Bluegrass) on Native Mixed-Grass Prairie?

The rapid increase of Poa pratensis L. (Kentucky bluegrass) on North Dakota grasslands during the past 30 yr has negatively impacted ecological services. Kentucky bluegrass grows earlier in the spring than many native grasses, which provides an opportunity to use targeted grazing to reduce Kentucky bluegrass and increase native grasses. A 5 year replicated study used 10 cow-calf pairs or pregnant cows to graze 3-ha paddocks in early to mid-May, early spring, (EARLY) until 30% of the native species were grazed. After 1 June, late spring−early summer, five cow-calf pairs were grazed on 3-ha paddocks (LATE) for twice as long as the EARLY treatment. Biomass was clipped inside and outside of cages after each grazing event and outside cages in the fall. In each paddock, a hundred 10-point frames were taken to determine percent native grass, Kentucky bluegrass, Bromus inermis Leyss. (smooth bromegrass), native forbs, and introduced forbs. After 5 yr, native grass abundance in the EARLY paddocks was 26% greater than in the LATE paddocks. Kentucky bluegrass abundance only differed the second year of the study when the EARLY paddocks had 32% less Kentucky bluegrass than the LATE paddocks. Total biomass was greater in the EARLY paddocks than LATE paddocks in year 2 of the study (886 ± 74 g m⁻² vs. 608 ± 28 g m⁻² for EARLY and LATE, respectively). Targeted grazing by cattle in early spring can increase native grass abundance and, depending on the year, decrease abundance of Kentucky bluegrass. Early spring targeted grazing should be used as a tool in adaptive management programs focusing on reduction of Kentucky bluegrass.     

Are Early Summer Wildfires an Opportunity to Revegetate Exotic Annual Grass–Invaded Plant Communities?

Medusahead (Taeniatherum caput-medusae [L.] Nevski) is an exotic annual grass invading western rangelands. Successful revegetation of invaded-plant communities can be prohibitively expensive because it often requires iterative applications of integrated control and revegetation treatments. Prescribed burning has been used to control medusahead and prepare seedbeds for revegetation, but burning has been constrained by liability concerns and has produced widely varying results. Capitalizing on naturally occurring wildfires could reduce revegetation costs and alleviate liability concerns. Thus, our objective was to determine if early summer wildfires and fall drill seeding could be used as a treatment combination to decrease medusahead and increase perennial and native vegetation. Treatments were evaluated pretreatment and for 3 yr postfire at six sites and included 1) an early summer wildfire combined with a seeding treatment (burn and seed) and 2) a nontreated (no burn, no seed) control. Perennial grass density was 4.6- to 10.0-fold greater in the burn-and-seed treatment compared to the control in the first 3 yr posttreatment (P < 0.05). Exotic annual grass density and cover in the third year posttreatment were lower in the burn-and-seed treatment than in the control (P < 0.05). However, exotic annual grass density was still > 130 individuals · m^?2 in the burn-and-seed treatment. The density of exotic annual grass is of concern because over time medusahead may displace perennial grasses and annual forbs that increased with the burn-and-seed treatment. Though not directly tested in this study, we suggest that, based on other research, the burn-and-seed treatment may need to incorporate a preemergent herbicide application to further suppress medusahead and increase the establishment of seeded vegetation. However, it appears that early summer wildfires may provide an opportunity to reduce the cost of integrated programs to revegetate medusahead-invaded plant communities.     

Forage Quality of Plant Species Consumed by Capybaras (Hydrochoerus hydrochaeris) in the Paraná River Delta,Argentina

The capybara (Hydrochoerus hydrochaeris) is a selective herbivore that may show a preference for certain plant species. Such a preference is likely to be explained by the nutritional benefits hypothesis, stating that the nutritional value of species selected by capybaras is higher than that of avoided ones. Therefore, the objectives of this work are to evaluate the nutritional value of the plant species eaten by capybaras in the Lower Delta of the Paraná River, and to test the nutritional benefits hypothesis by analyzing forage quality. Samples of consumed plant species were collected from habitats located in the study area. We also collected plant species that are very abundant in the field but absent in the capybara’s diet, some of which are consumed by other native herbivores such as coypus (Myocastor coypus). Their nutritional quality was analyzed by estimating the following variables: water content, ash percentage, percentage of organic matter, acid detergent fiber, nitrogen percentage, crude protein, and caloric energy. The protein to fiber ratio was calculated and the water content was determined. The species consumed and not consumed by capybaras had a similar nutritional composition for all the variables analyzed (P  <  0.05). A similar result was observed when comparing within consumed species, except for the caloric energy content, which was significantly higher in species consumed in greater proportion than availability (P  <  0.05). Water content was at its minimum in species consumed in greater proportion than availability, and at its maximum in unconsumed species. No significant differences were found between consumed Poaceae and the rest of the consumed plant species for any of the analyzed variables. Diet selection by capybaras in the studied area may only be partially related to nutritional quality, and there would be other factors involved in foraging, such as physiological mechanisms of the animal or chemical and structural characteristics of food.     

Can Sheep Control Invasive Forbs Without Compromising Efforts to Restore Native Plants?

Domestic sheep (Ovis aries) are increasingly being used to control non-native invasive plants in areas where restoration is a management goal. However, the efficacy of sheep grazing depends on both its potential for controlling undesirable plants and its ability to promote natives. To date, few studies have investigated impacts of sheep grazing on native forb recovery in North American grasslands. We assessed the impact of sheep on forbs by measuring the number of stems grazed before and after sheep foraged in western Montana, United States. Sheep grazed a higher percentage of non-native than native forbs (70% vs. 23%, respectively), and number of stems grazed was six times higher for non-natives than natives (48 vs. 5, respectively). Sheep preferentially selected the non-native forbs sulphur cinquefoil and yellow salsify over leafy spurge (fi = 2.075; fi = 0.969; fi = 0.969, respectively), as well as the native forbs white prairie aster (fi = 1.090) and blanketflower (fi = 1.000). Selection of native forbs was positively correlated with their pregrazing abundance and increased over the grazing period. Our findings indicate that when using sheep to control invasive forbs, appropriate timing and monitoring of grazing are critical for reducing nontarget impacts to native vegetation.     

Does Cattle Grazing Affect Ant Abundance and Diversity in Temperate Grasslands?

Half of the world's land base is grazed by domesticated livestock. Because of the important functional role of ants in grasslands, it is important to understand the effect of livestock grazing on ant abundance and diversity. The objectives of this study were to examine the effect of cattle grazing and site productivity on the abundance, species richness, and species diversity of ants in Lac du Bois Grasslands Provincial Park, British Columbia, Canada. We hypothesized that the measured ant variables would be lowest in grazed areas and at low site productivity. Pitfall trapping was conducted at four sites: two at each low and high site productivity levels. At each site an ungrazed (fenced exclosure) and grazed transect was sampled during May, July, and August of 2008. Captured ants were preserved in ethanol and identified. Eight genuses of ants were collected: Tapinoma, Camponotus, Formica, Lasius, Aphaenogaster, Myrmica, Solinopsis, and Temnotharox. The mean number of ants per pitfall was higher at high site productivity sites that were grazed (15.10 ±  SE) compared to high productivity sites ungrazed (3.28 ±  SE); grazing at low productivity reduced numbers of ants from 5.07 (± 0.70 SE) to 2.20 (± 0.39 SE) (F = 21.806; P [ 0.001). Tapinoma sessile and A. occidentalis had the greatest numbers in the pitfall traps. Species richness (F = 23.330, P [ 0.001) and diversity (F = 11.764, P = 0.001) followed a similar trend. Because productivity and cattle grazing affect ant diversity and abundance, and ants impact ecosystem functioning, these factors should be considered in management of grasslands.     

Can carotenoids mediate the potentially harmful effects of ultraviolet light in Silurana (Xenopus) tropicalis larvae?

Amphibians have recently experienced unprecedented declines in the wild, the causes of which are often difficult to mitigate. This has increased the importance of ex situ conservation; however, long‐term maintenance and breeding of amphibians in captivity often has limited success. In vertebrates, vitamin D is required for calcium homeostasis and is produced endogenously in skin exposed to ultraviolet (UV) light; however, UV light can be harmful to amphibians in some instances. Carotenoids are dietary pigments that may provide protection from UV light. The aim of this study was to assess the protective capability of carotenoids against the potentially harmful effects of UV light in Silurana (=Xenopus) tropicalis larvae raised in an enhanced or limited UV environment. Tadpole survival and the size and developmental stage reached by the end of the study period were measured. Carotenoids had a significantly positive effect on developmental rate in both UV‐limited and UV‐enhanced environments. Larvae in an enhanced UV environment were significantly larger than those raised under a limited UV environment, irrespective of diet. Carotenoid‐fed larvae tended to have increased survival in relation to those raised without carotenoids, but only in a limited UV environment. Carotenoids appear to provide little protection against UV light in this case. The role of carotenoids in amphibian health has not previously been studied. We show that carotenoid availability significantly influences development and may increase survival in S. (X.) tropicalis larvae. This finding may have important implications for recommendations made on the nutrition of amphibians in captivity.     

Can Mowing Substitute for Fire in Semiarid Grassland?

Accumulating data indicate the importance of fire in rangeland systems. Mowing is a common management technique sometimes considered a surrogate for fire. However, direct comparisons of fire and mowing effects are limited. Our objective was to determine whether mowing can substitute for fire in rangeland by comparing effects on plant biomass, composition, cover, soil nutrients, and forage quality. Three disturbance treatments (nontreated control, spring mowing with clipping removal, and spring fire) were randomly assigned to 21 plots (5 × 5 m) each on silty and claypan ecological sites in a completely randomized design, with seven replications per site. Current-yr biomass was similar among control, mowed, and burned treatments (1 003, 974, 1 022 ± 64 kg ● ha^− 1). Mowing shifted functional group composition by reducing C₃ perennial grass 12% and increasing forbs 8%. Non-native species were a larger component of mowed (12%) than control (6%) or burned plots (4%). Fire increased bare ground 35%, reduced litter 32%, and eliminated previous yrs’ growth the first growing season. Plant-available soil N and S more than doubled with fire, and there was a trend for more P in burned plots. Mowing effects were limited to a trend for less soil Fe. Mowing affected 42% of the forage quality variables with a 2% average improvement across all variables. Fire affected 84% of the variables, with a 12% average improvement. Mowing increased forage P and K, whereas fire increased forage concentrations of N, K, P, S, Mg, Fe, Mn, and Cu. Total digestible nutrients increased 1.1% with mowing and 2.1% with fire. In vitro dry matter disappearance increased 2.2% with mowing and 6.7% with fire. Burned plots had greater in vitro fermentation than controls or mowed plots. Although mowing can be a useful management tool, it is not a substitute for the ecological effects of rangeland fire.     

Introduced and Invasive Species in Novel Rangeland Ecosystems: Friends or Foes?

Globally, new combinations of introduced and native plant and animal species have changed rangelands into novel ecosystems. Whereas many rangeland stakeholders (people who use or have an interest in rangelands) view intentional species introductions to improve forage and control erosion as beneficial, others focus on unintended costs, such as increased fire risk, loss of rangeland biodiversity, and threats to conservation efforts, specifically in nature reserves and parks. These conflicting views challenge all rangeland stakeholders, especially those making decisions on how best to manage novel ecosystems. To formulate a conceptual framework for decision making, we examined a wide range of novel ecosystems, created by intentional and unintentional introductions of nonnative species and land-use–facilitated spread of native ones. This framework simply divides decision making into two types: 1) straightforward–certain, and 2) complex–uncertain. We argue that management decisions to retain novel ecosystems are certain when goods and services provided by the system far outweigh the costs of restoration, for example in the case of intensively managed Cenchrus pastures. Decisions to return novel ecosystems to natural systems are also certain when the value of the system is low and restoration is easy and inexpensive as in the case of biocontrol of Opuntia infestations. In contrast, decisions whether to retain or restore novel ecosystems become complex and uncertain in cases where benefits are low and costs of control are high as, for example, in the case of stopping the expansion of Prosopis and Juniperus into semiarid rangelands. Decisions to retain or restore novel ecosystems are also complex and uncertain when, for example, nonnative Eucalyptus trees expand along natural streams, negatively affecting biodiversity, but also providing timber and honey. When decision making is complex and uncertain, we suggest that rangeland managers utilize cost–benefit analyses and hold stakeholder workshops to resolve conflicts.     

Can goats be used as sentinels for tick-borne encephalitis (TBE) in nonendemic areas? Experimental studies and epizootiological observations

A goat flock grazing year-round on a meadow in a "TBE non-risk area" in Thuringia, Germany, with a history of only isolated human TBE cases was examined repeatedly for TBE virus-(TBEV)-specific antibodies and TBEV RNA between October 2008 and December 2009. Surprisingly, TBEV specific antibodies were detected in one goat, which had never left this area. To compare the results of a natural contact to TBEV with a defined contact to TBEV, two goats were immunized experimentally. Both animals developed TBEV-specific antibodies, one goat however in a delayed and reduced manner. In addition, 177 ticks were collected from the meadow in May and June 2009, and were examined by real-time RT-PCR. However, noTBEV RNA could be detected. The results suggest that goats can be used as TBEV sentinels in defined areas. To verify this observation further investigations with a large number of animals are recommended.     

Assisted Reproduction in Horses: What Can Be Learned from Assisted Reproduction in Cattle?

Researchers and practitioners of assisted reproduction in horses have borrowed heavily from similar bovine practices over the years. However, most procedures required species-specific experiments for optimization. Furthermore, the flow of information occurs in both directions; some procedures, for example, vitrification of embryos and intracytoplasmic sperm injection, were made efficacious in horses before cattle. The great advantage of research in cattle is the availability of large numbers of animals and embryos for testing hypotheses economically. Objectives of cattle breeding generally are more scientific than those concerning horses, and it is likely that much can be learned in the future from genetic tools being developed for cattle breeding. A genetic advantage of cattle breeding over horse breeding is the extremely large genetic and phenotypic databases of some breeds, which can be matched to genomic information.     

Is poly(ADP-ribose) polymerase involved in bovine placental retention?

Poly(ADP-ribose) polymerase (PARP) is the enzyme which utilises NAD to synthesise poly(ADP-ribose) polymers. This process appears in response to DNA lesions. Oxidative stress, which might be involved in bovine placental retention, is the reason for oxidative DNA injury. In this mini-review, the relationship between PARP activity and bovine placental retention is discussed. The results of our experiments on PARP activity in placental tissues showed that the enzyme of 113 kDa and its cleavage products were present in retained as well as released fetal membranes. Western blotting technique showed different intensities in the staining of bands which might suggest different activities of the enzyme.     

Risk Factors for Incisional Complications after Exploratory Celiotomy in Horses: Do Skin Staples Increase the Risk?

Objective: To assess risk factors for celiotomy incisional infection in horses, especially the use of staples for skin closure. Study Design: Case series. Animals: Horses (n=356) that had 1 exploratory celiotomy for colic and survived >2 weeks after surgery between March 1, 2004 and December 31, 2007. Methods: Incisions were classified as “normal” (no complication, only edema, serous drainage lasting <24 hours) or as “surgical site infection (SSI)” (persistent serosanguinous drainage or purulent drainage with or without positive bacterial culture). All possible risk factors, including method of skin closure (monofilament sutures or staples), were statistically analyzed using univariate and multivariate logistic regression. Results: Of 356 horses, 303 (85%) had normal wound healing and 53 (15%) developed a SSI (purulent: 48 [14%]; persistent serosanguinous: 5 [1%]). Bacterial cultures were positive in 33 of 40 cases. Factors significantly associated with SSI in the multivariate analysis were: use of staples for skin closure (odds ratio [OR] 3.85, P<.001) and surgical site closure by a 1st or 2nd year resident (OR 2.20, P=.016). Lavage of the linea alba with sterile saline solution after closure was a protective factor (OR 0.38, P=.004). Conclusion: Use of staples for skin closure and less experienced surgeons closing the abdomen are risk factors for incisional infection. Incisional lavage after linea alba closure was a protective factor. Clinical Relevance: Despite their ease and speed of application, skin staples can lead to an increase in celiotomy wound complications in horses.     

Strongylus vulgaris (Looss, 1900) in horses in Italy: is it still a problem?

A post-mortem survey was carried out on 46 Sardinian horses to evaluate the presence of Strongylus vulgaris and associated pathology. Horses were from local farms and had been treated with broad-spectrum anthelmintics at least 3 times a year. Examination of the cranial mesenteric arterial system (CMAS) showed parasite-induced lesions in all horses. S. vulgaris larvae were found in 39% of examined arteries, while their detection rate in coprocultures was 4%. Histology, carried out on 26 horses, showed mainly chronic and chronic-active lesions. Histometry showed a significant increase in thickness of the arterial wall, in particular of the intima tunic and adventitia tunic of the ileocolic artery and its colic branch. MCV, MCHC and alpha2, beta and gamma globulins were increased in horses with S. vulgaris larvae in the arteries, while the albumin/globulin ratio was decreased. Horses that were positive on faecal examination showed decreased values for RBC, PCV and the albumin/globulin ratio. Although several studies have shown a dramatic decrease of S. vulgaris infection worldwide, our data show that this parasite continues to exert its pathogenic role, even when its detection rate is quite low within the strongyle population infecting horses.