Previous studies suggest choice of dewormer influences weight gain. Cal Poly State University researchers tested the effects of different pour-on products and routes of administration on grazing performance and carcass characteristics.

A total of 500, single-source stocker cattle were grazed for 105 days. Steers and heifers were processed and weighed at the beginning of the grazing season (average 324 lbs.). Cattle were randomly assigned to five groups, a control and four other groups, each treated either with Cydectin, Ivomec, Eprinex or Dectomax.

Cattle were weighed every 35 days, and fecal samples were collected on 25% of each treatment group to determine fecal egg counts and parasite species present. On day 70, cattle were dewormed with the same product as initially treated. After completion of the grazing season, all cattle were moved to a commercial feedyard and treated with Cydectin Pour-on. Researchers found:

  • Dewormed cattle gained 31.7 lbs. more, on average, than control cattle. No differences were detected in weight gains between dewormers.

  • Fecal egg count data reinforced the opinion that fecal egg counts by themselves aren't particularly useful. For instance, the majority of parasites in this study were identified through larval copro-culture as Cooperia. These parasites don't impair growth until the levels become extremely high. Ostertagia, however, can impair growth even at low numbers.

  • Deworming during the stocker phase didn't affect most carcass traits. Cattle dewormed during the stocker phase produced carcasses that were 13.2 lbs. heavier than non-dewormed cattle.

  • Ribeye area was increased in cattle treated with Cydectin compared to controls.

Jonathon Becket, Dept. of Animal Science, College of Agriculture, San Luis Obispo, CA; 805/756-2419


Bacteriocins — natural antibiotics produced by bacteria as a means of self-defense and commonly found in the rumen — could soon be used to enhance cattle efficiency.

Ron Teather, rumen microbial biotechnology scientist with Agriculture and Agri-Food Canada, Lethbridge, AB, Research Centre, and his colleagues are seeking to identify bacteriocins that can be used to inhibit undesirable rumen bacteria, thus increasing feed efficiency and reducing greenhouse gas emissions from cattle.

In the rumen, each feed component attracts a specialized group of bacteria focused on degrading that component. If the preferred feed of specific bacteriocin-producing bacteria is known, cattle diets can be supplemented to give the bacteriocin-producers an advantage in inhibiting undesirable organisms, Teather says.

Several hundred strains of rumen bacteria that produce different bacteriocins have been identified, he says. Compared to manmade antibiotics, bacteriocins tend to be quite specialized, and have a narrow spectrum of activity and only inhibit one or two other organisms.

What's more, bacteriocins are proteins, he adds. Once they leave the rumen environment, the animal can digest them to supplement its nutrition. There is no residue.

Three specific bacteriocins have been examined on a genetic and molecular level for their potential to enhance rumen metabolism, Teather says.

Coincidentally, a lot of bacteria involved in silage fermentation are bacteriocin-producers. Teather says research is underway to introduce selected bacteriocin-producers into silage in order to produce bacteriocins in the feed itself, but conclusive data won't be available for about two years.

While his research is focused on reducing greenhouse gas emissions from cattle, Teather expects to see improved feed efficiency as a result of introducing bacteriocins in animal rations.

“By shifting rumen fermentation in a direction that will reduce emissions, you make more energy available to the animal instead of losing it as gas,” Teather says. “And the degree to which an animal utilizes the energy in its feed is a measure of efficiency.”

Agriculture and Agri-Food Canada, Lethbridge Research Centre, 403/327-4561


Kansas State University (KSU) researchers want to make a good thing — grain sorghum — even better.

So KSU's Department of Agronomy is establishing the Center of Excellence for Sorghum Improvement (CESI) at the university's Manhattan campus. Research aimed at developing new, improved varieties will also be conducted at the school's various research fields around the state.

Because of its ability to thrive in hot, dry conditions, grain sorghum is one of the most important dryland crops in the central Great Plains, says Dave Mengel, department head. With water availability becoming a growing concern in agricultural policy, sorghum is in a unique position to be a leader in this new agriculture evolution, he adds.

CESI is being formed in cooperation with the Kansas Grain Sorghum Association and the National Grain Sorghum Producers Association. It's hoped CESI will provide the critical mass of scientific expertise in plant breeding, biotechnology, pathology, entomology and physiology to address important production issues in sorghum. These include:

  • Improving yield potential through increased grain fill duration and seed weight,

  • Improving lodging resistance of sorghum and its potential for increased harvestable yield through enhanced stalk strength and rot resistance,

  • Developing and identifying the most efficient, cost-effective sorghum management and production strategies,

  • Improving drought and heat stress tolerance.

Kansas State University

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