Split-Time AI: Using Estrus Detection Aids to Optimize Timed Artificial Insemination

Timed AI pregnancy rates can be optimized through use of a split-time AI approach following administration of the 14-day CIDR-PG protocol for heifers and the 7-day CO-Synch + CIDR protocol for mature cows. Using split-time AI, insemination of non-estrous females is delayed until 20 to 24 hours after the scheduled time for fixed-time AI. Estrotect estrus detection aids applied at the time of PG administration allow producers to determine the estrous status of females and inseminate at the optimal time.

The development of protocols that effectively facilitate synchronization of estrus and ovulation has enabled producers to increase the use of fixed-time artificial insemination (FTAI) in beef heifers and cows, rather than performing artificial insemination (AI) on the basis of detected estrus. In this approach, AI is performed at a predetermined time following prostaglandin F2a (PG) administration. Previous research efforts have evaluated several protocols to determine the appropriate time at which to perform FTAI. For example, following the 14-day CIDR-PG protocol for heifers, the pregnancy rate to FTAI is highest when FTAI is performed 66 hours after PG administration. Acceptable pregnancy rates can be obtained using FTAI following several protocols; however, a proportion of females undergoing estrus synchronization do not express estrus prior to FTAI. To account for these non-estrous animals, all cows and heifers are administered gonadotropin-releasing hormone (GnRH) at FTAI to ensure that ovulation is induced. However, endocrine changes associated with estrus expression are known to positively influence fertility, and pregnancy rates are on average 27 percent lower among females that fail to express estrus prior to FTAI (Perry and Smith, 2015).

A complete copy of the article is available through MU Extension.

Beef Forage Tour 2016 September 17 - start time 1:30

What You’ll See & Hear:

Cow-Calf Operations

Stocker Operation

Spring & Fall Calvers

Corrals and Working Chutes

Novel Endophyte Fescue   

Kentucky 31 Fescue

Bermuda Pasture

Young Cattle Producers

Computer Records

Hay Storage

Ammoniation of Fescue

Health Programs 

A flyer with complete information with stops listed. 


2016 Ozark Empire Fair Hay Show Winners

Two Barry Countians have taken first place honors the winners of the 2016 Hay Show at the fair.

Matt Cupps

     Placed first in Class I


Marcia Moreland

       Placed First in Class II


Congratulations Matt and Marcia



53rd Annual Filed Day

Sept. 10, 2016

9:00 to 2:00 p.m.

  • Beef
  • Dairy
  • Horticulture
  • Pollinators
  • Large and small Ruminants
  • Agronomy
  • Farm Technology




October 18,19,20, 2016

Missouri State University Shealy Farm,
Fair Grove, MO

A 3-day seminar on Management-intensive Grazing
for economic and environmental




Irrigation Advice from MU Extension
Natural Resource Engineering Specialist

Questions and answers on irrigation in Missouri


July Rains On Toxic Tall-Fescue Pastures Add Heat Stress to Cows

Sourcr: Craig Roberts, 573-882-0481

COLUMBIA, Mo. – “In this heat, remove cattle from toxic tall-fescue pastures,” says Craig Roberts, University of Missouri Extension forage specialist. “Get them onto nontoxic grass with shade and plenty of water.”

While rain in July benefits corn and soybeans, it spurs growth of toxic tall fescue. Livestock farmers must be alert to heat stress added by toxins in the lush grass.

“We had our worst gains on calves when grazing toxic fescue in a hot, wet July. Those calves gained only one-third pound per day,” Roberts says of research at the MU Southwest Center, Mount Vernon.

Calves on nontoxic grass gained three times as much.

Heat stress affects not only gains but other growth as well. There are many research papers on what heat stress does to bulls and cows, Roberts says. Heat affects conception and pregnancy.

Cool-season grasses usually go dormant in July, but rains this year kept grass growing.

“Lush Kentucky 31 fescue in summer looks good, but is toxic,” Roberts says. K-31 contains a fungus between plant cell walls creating ergovaline, a toxin. That is a vasoconstrictor that cuts blood flow to body extremities, which slows cooling.

Heat-stressed cattle stop eating to seek shade or to stand in a pond. “Cattle try to cool down,” Roberts says. “That is good for the cattle, but it reduces feed intake and slows gains.”

To those who don’t know tall fescue, the green growing grass in July looks like a bonus. MU forage agronomists urge producers to remove cattle from toxic fescue pastures.

Warm-season grasses that thrive in summer offer alternatives.

The problem becomes what to do with toxic fescue left standing.

“It makes hay, not grazing,” Roberts advises.

“Ergovaline isn’t a stable compound, like a protein. It breaks down when exposed to sun and air,” he says.

“About a third of the toxin goes away in the first week after mowing. The toxin continues to fade in a stored bale, but at a slower rate. By winter feeding time, the toxin in hay will be lowered by about half.”

The best long-range plan is to replace toxic fescue with a new novel-endophyte variety.

Plentiful July growth creates a problem for trimming pastures back to prepare for fall-grown stockpile. Existing growth must be removed by mid-August.

That’s time to spread nitrogen to boost to fall growth. For the longest fall growing season, producers should apply fertilizer before the first fall rains arrive.

The pasture should be about 4 inches tall when nitrogen is added. Usually, paddocks are grazed down, but this year the grass should be mowed and baled. That clears the field for fresh fall growth that starts with September rains.

Stockpiled pasture can be grazed late into winter. Stockpile reduces the need for feeding baled hay to the herd in winter.

One strategy is to graze the stockpile first while the baled hay continues to decline in toxicity.

Information on novel-endophyte fescue seeding is at www.grasslandrenewal.org. Or contact a regional agronomist through a local MU Extension center.









New laws that may impact you will take effect December 31, 2016

What is VFD?

How will I obtain VFD feed?

Do I need to have VFD feed? Why?

Get answers to these questions