Agricultural Research Service (ARS) scientists are investigating ways to boost fertility in beef cattle. They've discovered that the follicle, the egg-releasing structure within the ovary, must reach full maturity to maximize pregnancy's chance of success.
Researchers Tom Geary, reproductive physiologist at the ARS Fort Keogh Livestock and Range Research Laboratory in Miles City, MT, and Michael Smith, University of Missouri reproductive physiologist, are conducting the studies.
They're still researching which hormonal cues enable the follicle to attain maturity, but their findings are already important for livestock producers who want to artificially inseminate (AI) their beef cows at the same time.
In one recent study, they found that when cows are allowed to naturally ovulate, it didn't matter what size their follicles were. Their bodies intuitively knew when they were ready to release the eggs.
Producers use the hormone GnRH to induce ovulation. The study points out, however, that if the hormone is injected before the follicle is mature enough, pregnancy has a lower chance of success.
Geary says follicular cells may not be fully developed at the time of induced ovulation because inadequate estrogen is being produced. He's studying if extra estrogen helps coax follicle maturity along.
— USDA-ARS News Service
Arkansas and Kansas researchers collaborated on a review of 39 research papers on weight shrink during transportation. They found shrink comes from two sources — loss of fill (urine and feces) and tissue shrink.
During the first 3-4 hours, shrink averages about 1% of body weight/hour. After 10 hours, it's as little as 0.1%/hour.
Handling procedures affect the rate of shrink, and higher shrink occurs when there are problems with gathering, sorting and loading calves. Shrink also occurs with nervous, excitable calves, though researchers couldn't find clear evidence that fresh-weaned calves influenced shrink rates.
Researchers say allowing cattle to graze before moving them helps minimize shrink during the first few hours of transport. Cattle shipped long distances, and losing 7-9% of their body weight, could recover about half that immediately when allowed to eat and drink after shipping. It takes about 10 days to recover the remaining lost weight, however.
Researchers also noted that as the amount of transit shrink increases, so does the level of bovine respiratory disease (Prof. Anim. Sci. 17:247).
— Texas A&M Beef Cattle Browsing
An Oklahoma pilot project aims to examine the feasibility of providing online, real-time, groundwater-depth data to inform Oklahoma residents about drought conditions.
ARS geologist John Daniel is heading the project, which will offer localized water-table readings through the existing statewide meteorological network.
The network, called Oklahoma Mesonet, comprises more than 110 automated weather stations and provides data on air temperature, wind, rainfall, humidity, solar radiation and solar temperature.
Funded by the U.S. Bureau of Reclamation, the project focuses on two groundwater observation wells drilled at existing Mesonet stations. The well at the El Reno site is 15-20 ft. below the surface while water at the Acme site is at 45-50 ft.
Measurements at the wells will help interpret water level changes and explain the impact of drought on groundwater supply, Daniel says.
View data at www.mesonet.org/public.
— USDA-ARS News Service
Rotation grazing boosts cropland fertility, according to ARS animal scientist John Stuedemann and ecologist Alan Franzluebbers. The researchers found that carbon stored in the soil during the first five years from when bermudagrass was planted, was two to three times greater when the grass was grazed than when it was harvested for hay or left unharvested.
More carbon in the soil means less escapes in the atmosphere. This is beneficial because carbon dioxide concentration in the air has been rising and it is a contributor to the “greenhouse effect” and possibly to global warming.
ARS researchers in Watkinsville, GA, found that adding cattle grazing to crop rotation systems can be beneficial by enriching the soil with carbon and other nutrients. They envision a system that adds cattle into crop farming systems in the Southeast — where, for example, raising calves on pasture could be added into a crop rotation with corn or wheat.
Researchers have found that putting as little as 10% of existing cropland into a grazing rotation could significantly reduce costs. The lower costs come from reduced inputs from herbicides and generating additional income from livestock.
— USDA-ARS News Service
In some locales, dryland alfalfa has stopped growing, reports Bruce Anderson, University of Nebraska-Lincoln professor of agronomy.
As the alfalfa continues to be dormant, Anderson says it will slowly lose feed value and tonnage due to continued maturation, as well as leaf loss from insect feeding, diseases and age. But a yield of at least ½-ton/acre is needed to justify the fuel, labor and other expense of harvesting hay, he adds.
Grazing could be relatively cheap if portable electric fence is available, and transporting cattle or water isn't a concern. Plus, dry, bloomed-out alfalfa has a pretty low risk for bloat
But if grazing or cutting can't be justified, Anderson says, it's probably best to leave the alfalfa alone.
Shredding or haying will provide a cleaner, higher quality hay once the alfalfa receives enough rain for regrowth. In most cases, it's not worth it when the cost and time involved in shredding or haying are considered.
— University of Nebraska-Lincoln