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Open Access Publications from the University of California

Volume 55, Issue 6, 2001


Research on animal-borne parasites and pathogens helps prevent human disease

A large body of basic and applied research conducted at the UC Hopland Research and Extension Center (HREC) has focused on micro- or macroparasites that infest humans, domestic animals and wildlife, including viruses, bacteria, protozoans, helminths and blood-sucking arthropods. Approximately 17 microorganisms detected at the HREC are transmitted by ticks, and of these, at least five cause zoonotic diseases — animal-borne diseases that can be transmitted to people. Scientists working at the HREC identified the basic transmission cycle of the Lyme disease spirochete in the far-western United States. This information now is being used to develop and implement risk-assessment and preventive strategies.

Sheep research offers alternatives to improve production

Scientists working at the UC Hopland Research and Extension Center (HREC) have made important contributions to the sheep industry in breeding and genetics, and in the understanding of animal behavior. A long-term experiment involving HREC was initiated in 1960 to evaluate the effects of selection environment on sheep performance under range conditions. Selectrion of the UC Davis flock, representing the favorable conditions typical of purebred flocks where most breeding rams are raised, resulted in more within-flock improvement in weaning weight than selection under range conditions at Hopland. However, when the UC Davis- and Hopland-selected lines were compared under range conditions at HREC, the two were equal in weaning weight, and the Hopland line was superior in reproduction and total productivity. We concluded that selection should take place in the environment of use. In the late 1970s, investigations were initiated to develop cost-efficient techniques for fostering lambs to unrelated ewes; an effective new method was developed using stockinette jackets and neatsfoot oil to transfer odors. Likewise, research on sexual behavior has resulted in several relatively simple behavioral tests that can be used to determine the performance of rams.

Callipyge meat a tough sell

In 1983, a sheep breeder in Oklahoma noticed a ram with exceptional muscling, especially in the hindquarters. This ram, Solid Gold, was mated to normal ewes, and the condition was passed on to their offspring. Eventually the extra muscling was found to be due to a spontaneous mutation, a natural change in the animal's genetic code. Because the muscle hypertrophy (enlargement) is most pronounced in the hindquarters, the condition was named callipyge, a Greek word meaning “beautiful buttocks.” Needless to say, sheep breeders were immediately interested in the meat production potential of lambs carrying the callipyge gene.

Is there a sire-dam interaction in sperm fertilizing potential?

TO optimize the efficiency of food animal production, a high level of reproductive efficiency is required because producers must spend a large proportion of their resources on the breeding herd. Previous research has demonstrated significant variation in the fertility of males. Our project was designed to evaluate whether there is a male-female interaction in the fertilizing potential of sheep sperm.

Sheep-killing coyotes a continuing dilemma for ranchers

Coyote predation on the UC Hopland Research and Extension Center's research sheep has increased substantially during the last several decades, as it did for commercial sheep producers in the North Coast region. The center has evaluated a variety of lethal and nonlethal predator-control methods in an effort to find a strategy that is cost effective and practical for other producers. The most promising strategy tested was selective removal of only sheep-killing coyotes by use of the livestock protection collar, a tool that was banned in California by Proposition 4, a November 1998 ballot initiative.

Targeting alphas can make coyote control more effective and socially acceptable

Research at the UC Hopland Research and Extension Center (HREC) has improved our understanding of how to reduce sheep depredation while minimizing the impact on coyotes. Analysis of a 14-year data set of HREC coyote-control efforts found that sheep depredation losses were not correlated with the number of coyotes removed in any of three time scales analyzed (yearly, seasonally and monthly) during corresponding intervals for the next 2 years. Field research using radiotelemetry to track coyotes supported and explained this finding. For example, in 1995, dominant “alphas” from four territories were associated with 89% of 74 coyote-killed lambs; “betas” and transients were not associated with any of these kills. Relatively few coyotes were killing sheep, and these animals were difficult to capture by conventional methods at the time of year when depredation was highest. However, selective removal of only the problem alpha coyotes effectively reduced losses at HREC.

Agroforestry is promising for previously cleared hardwood rangelands

Livestock grazing is the primary economic use of most hardwood rangelands in the coastal foothills of California. But owners of these lands may be able to increase revenues by simultaneously producing two crops, trees and sheep. In 1993, we initiated an agroforestry project at the UC Hopland Research and Extension Center to study the ability of three pine species and one hybrid to grow on cleared hardwood rangelands that are grazed by sheep. This study also evaluated the response of planted seedlings to auger and fertilization treatments. After 8 years, tree survival has been high, growth has been vigorous and damage from sheep minimal. Monterey pine and KMX pine, a cross between Monterey and knobcone pine, had the most growth. These results suggest that some pine species are promising for planting on grazing lands in coastal foothills where oaks and other hardwoods have been removed.

Monitoring shows vegetation change at multiple scales

Several historical data sets from the UC Hopland Research and Extension Center (HREC) provide valuable information on vegetation dynamics at multiple spatial and temporal scales. An early botanical survey by Harold Heady and Al Murphy provides a baseline for examining landscape-level changes in species richness and distribution over 50 years. We conducted a floristic survey between 1995 and 1999 and found gains and losses of native and non-native species abundance across the field station. On two sites where sheep were removed in 1958, permanent transects provide valuable information about plant community responses to protection from livestock grazing; in the oak understory, native perennial blue wildrye increased steadily, while in grasslands native purple needlegrass was less abundant after 43 years. On a cleared watershed, originally diverse in hardwood species, we found that only interior live oak and coast live oak were significantly reestablished after 30 years.

Carefully timed burning can control barb goatgrass

Barb goatgrass is a noxious annual grass that is rapidly invading California's grassland ecosystems. No effective control strategies for managing barb goatgrass have been available that do not simultaneously injure other more desirable grass and broadleaf species. In our study at the UC Hopland Research and Extension Center, we conducted prescribed burning in late spring or early summer before barb goatgrass seeds had reached maturation. One year of prescribed burning was not sufficient to control re-establishment the following year. However, 2 years of complete burning gave effective control of barb goatgrass while increasing native perennial grass cover and native species richness, particularly legumes. The success of the goatgrass control was directly proportional to the completeness of the second-year burn.

Animals and fungi can affect goatgrass establishment

The establishment of barb goatgrass is greatly affected by its interactions with other species in California grassland. For example, goatgrass establishment is enhanced by a fungus, Ulocladium atrum. This fungus is visible as black lesions on the surface of the seedhead; it helps break down the tough, woody seedhead surrounding goatgrass seeds. This speeds up germination and leads to a 65% increase in goatgrass bio-mass at the end of the growing season.

Plant species provide vital ecosystem functions for sustainable agriculture, rangeland management and restoration

Plants respond to and change their environments, actively altering factors such as soil stability, nutrient and water availability, and the distribution of pests and beneficial organisms. By identifying the functions associated with different species and the effects they have on their ecosystems, managers can use plants as tools in agriculture, range management and restoration, since they will be able to choose plants more effectively and anticipate unintended consequences of vegetation changes. Because cover crops have been used in agricultural settings for years, much is known about their functioning and response to environmental conditions and management practices. Much less is known about plants in natural systems, yet this information can be critical to range management and restoration. We compare what is known about grassland plant functions in California by reviewing the extensive research that has been undertaken at the UC Hopland Research and Extension Center.

Australian varieties improve pasture in long-term annual legume trials

More than 50 Australian legume varieties for rangeland have been introduced commercially since the mid-1980s, but none of them had been tested for their adaptability to California. To determine their viability, in 1990 we planted a number of these varieties at the UC Hopland Research and Extension Center, along with some that were already popular in California. We evaluated them over the course of 10 years, and in 1997 planted 16 more varieties that had been subsequently introduced. Many of the cultivars planted in 1990 persisted to cover more than 50% of the plots, while others covered a smaller portion and several disappeared completely. Our evaluation shows which of the new cultivars are likely to improve rangeland in Northern California coastal areas.

Watershed research examines rangeland management effects on water quality

Oak- and annual grass-dominated rangelands in California occupy 7.4 million acres, often occurring at the state's urban, wildland and agricultural interface. Rapidly changing land uses in these ecosystems have watershed-scale impacts that are the subject of intense debate among policy-makers, environmentalists and landowners. Watershed research conducted at the UC Hopland Research and Extension Center (HREC) between the 1950s and 1980s provided valuable information for predicting the effects of watershed management activities — such as converting oak and chaparral to grasslands — on water quantity and quality, slope stability and erosion. The research illustrated that conversion from woodland to grassland significantly impacts the hydrology and sediment dynamics of watersheds, suggesting that land-use changes such as vineyards and urban expansion must be evaluated carefully. Preliminary data from a new series of watershed studies initiated at HREC in 1998 indicate that livestock grazing does not significantly increase nutrient and sediment levels in stream water, but that current fecal coliform standards may be exceeded during storm events.