- Author: Lauren Hallett
- Author: Katharine Suding
Over the last few years Californians have grappled with how to manage lands during times of both drought and plentiful rainfall. At SFREC and on Central Valley rangelands, one question is whether management that promotes high forage in wet years alters ecosystem resilience in dry years. For example, promoting highly productive grasses is a common goal. While drought years can negatively affect productive grasses, less productive species, particularly forbs like filaree, do relatively well in drought years due to decreased competition. Over the last several years the Suding lab and SFREC crew have been building ever-larger drought manipulations to test how different management practices, and associated species mixes, affect forage across good and bad rainfall years.
In the first iteration of this project, we looked at how grazing practices and rainfall interact to affect forage over dry and wet years. We hypothesized that grazing practices that maintained a diverse mix of grasses and forbs would promote more stable forage across wet and dry conditions. To test this, we first varied grazing intensity over four years within a pasture to describe how grazing alters grass and forb abundances (Figure 1a). Second, we implemented rainout shelters and irrigation over three years to create “dry” and “wet” plots within areas of different grazing histories (Figure 1b). We found that moderate grazing practices maintained a diverse mix of grass and forb species. This mixture better maintained vegetation cover and biomass across rainfall conditions compared to low-grazed areas dominated only by grasses (Figure 2) (Hallett, Stein, Suding conditionally accepted, Oecologia).
In the second iteration of this project, we are exploring how rainfall timing alters grassland diversity and forage production. We hypothesized that early-season drought will alter which species recruit that year, with higher forb abundance in dry falls and higher grass abundance in wet years, whereas late-season drought would reduce overall production. To test this, we have implemented large shelters with roofs that are pulled in place to create early-season, late-season and continuous drought as well as a control (Figure 3). We are finding that periodic early-season drought helps to maintain forb diversity in California rangelands. Working with Dr. Whendee Silver, we are also testing the effect of rainfall timing on nutrient cycling and greenhouse gas emissions. We are finding that previous-season rainfall as well as current season alters greenhouse gas emissions, which may be important for managing rangelands for multiple ecosystem services going into the future.
- Author: Nikolai Schweitzer
The Sierra Foothill Research and Extension Center in Browns Valley, CA utilizes 130 acres of summer irrigated pasture for cattle grazing. SFREC's irrigation water is supplied by a local water district via pipelines and open ditch distribution sources. The irrigation delivery system applies water through sprinklers, open ditches, and gated pipes. Each irrigated pasture at SFREC is managed for 1) Forage Production, 2) Water Quality, and 3) Soil Quality.
SFREC staff measures forage production in 15 enclosed cages throughout five different irrigated pastures. The treatments within each cage include leaving 4-6 inches of residual grass and measuring Total Forage Production (TFP). Guidelines for general irrigation and pasture management production based on past and current research recommend leaving 4 to 6 inches of residue/grass growth after each grazing period. The basis of this recommendation is to increase forage production (by leaving increased amounts of foliar surface area), improve root development, decrease weeds, cause less stress for forage grasses and increase water infiltration. Total Forage Production is measured by clipping the grass all the way to the ground. This center project is measuring the two treatments (4-6 inches & TFP) on their respective pounds/acre production. Each month (from April through October) forage is clipped from each cage, dried, and weighed (pounds/acre). After the samples are clipped, each enclosed area is leveled to its prescriptive treatment.
During the last two years of field sampling on irrigated pasture at SFREC, there was an increase in forage diversity in the Total Forage Production subplot. Clovers, birdsfoot trefoil, and filaree became increasingly abundant due to the increased sunlight and less crowding from competitive grasses. While the increase in clover and other forbes growth lends to an increase in forage quality, there is an overall decrease in forage production per acre in the TFP treatments when compared to the treatments with 4-6 inches of residual grass.
Numerous other factors can potentially impact irrigated pasture forage growth. Fertilization (rates, composition, timing), irrigation (frequency, amount, duration), grazing (stocking density, class/age of animal), species composition, physical structures (water location, loafing areas, rubbing zones, mineral location), soil properties, aspect, and slope, are other important components to manage or consider.
- Author: Mckenna Kane
Over the past several months, Dr. John Angelos of UC Davis School of Veterinary Medicine has been working on a vaccine for one of the cattle industry's most widespread diseases: infectious bovine keratoconjunctivitis (IBK), commonly known as pinkeye. IBK is caused by an infection of Moraxella bovis in the eye that leads to corneal ulcers, scarring and, in extreme cases, permanent blindness.
According to Dr. Angelos, the disease presents an economic loss for the producer due to the cost of labor to treat the infection, the cost of the antibiotic treatment as well as reduced weight gains. He also notes the disease has certain animal welfare considerations; it can be extremely painful for the infected animal. Currently, there is not an effective vaccine to prevent the painful disease, only a costly treatment.
Dr. Angelos has been working on this vaccine since April, but the vaccine has been developing since the early 2000s. This summer, Dr. Angelos is testing the effectiveness of an intranasal vaccine, rather than the subcutaneous version of previous studies. His hypothesis states “calves vaccinated intranasally with Moraxella bovis cytotoxin (MbxA) will have a significantly reduced cumulative proportion of corneal ulcerations associated with naturally occurring IBK versus control calves.”The team collected blood and tear samples from approximately 180 animals at the UC Sierra Foothill Research and Extension Center and administered either the vaccine or a placebo assigned to the animal. In order to keep the results unbiased, Dr. Angelos did not know which vaccine he was giving to the animals; they were labeled “A” or “B.”
Each week thereafter, he and several students have examined the entire herd, noting those with active cases of pinkeye. If an animal shows signs of pinkeye, an innocuous stain is administered in the eye to see the ulcer, a measurement and a picture are taken to monitor the ulcer from week to week. At the end of the study, animals with active cases of pinkeye will be given antibiotics to cure the pinkeye.
Ultimately, the goal of the research is to create a vaccine that will prevent the disease from occurring. Dr. Angelos explained that although this vaccine has made great advancements, it will need to have subsequent testing and trials to determine if it is viable in the industry. In the video below, Dr. Angelos explains his research and the role of the Sierra Foothill Research and Extension Center in developing a vaccine for infectious bovine keratoconjunctivitis.
- Author: Megan G Osbourn
In the latest Research Spotlight, Glenn Nader, Livestock and Natural Resources Advisor, describes the project currently underway at SFREC to test the efficacy of utilizing rice strawlage as a supplement for beef cattle. In past studies, rice strawlage has greatly increased the laboratory nutritional quality of rice straw. The strawlage process, could greatly impact both California livestock and rice operations. It also could have potential worldwide impacts, as rice straw is one of the world's largest cereal residues produced. The current use of rice straw in the dry form has very limited applications in animal feeding systems.
For more information on rice strawlage research, click here.
- Contributor: Maddison Easley
- Contributor: Nikolai Schweitzer
- Contributor: Erica Spotswood
While data is still being collected and analyzed, Spotswood shared some observations from the research conducted thus far. “We do not yet know the effects of grazing, but results from our first year of data indicate that medusahead does well in places with higher soil moisture, and with more grass cover. We also know from some experiments that cows can definitely move seeds around. The seeds attach to their fur, but don't stay on very long, and they probably drop most of them within the first 20 feet of picking them up,” said Spotswood.
Check out the video for details!
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Dispersal Vectors and Risk Assessment of Noxious Weed Spread