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Real-Time Ultrasound Helps Define Lysine: Calorie Ratio Requriements

Real-time ultrasound fat and lean measurements in growing pigs can be used to accurately predict growth and lysine:calorie ratio requirements, according to a Kansas State University study.

Determining an accurate lysine:calorie ratio will ensure the right amount of lysine is provided in diets that vary in energy density.

The study's objective was to determine lysine:calorie ratio requirements for growing-finishing pigs raised under commercial conditions. The researchers compared the traditional lysine titration technique and real-timeultrasound.

Researchers completed two experiments using 240 gilts and 240 barrows with initial weights of 60 lb. and 75 lb., respectively. The experiments were conducted under commercial conditions to model the lysine:calorie ratio requirements of growing-finishing pigs based on protein and lipid accretion rates from real-time ultrasound estimations.

In both studies, pigs were selected from the ongoing experiment in which growth performance and carcass characteristics were measured, evaluated and compared. The dietary treatments (Table 1 and 2) consisted of eight diets arranged in a 2 x 4 factorial with zero and 6% added choice white grease and four lysine:calorie ratios in each of the four phases of growth. Total lysine content of the diets is presented in Table 3 and 4.

In each study, five pigs from each of 48 pens were randomly selected, weighed, tagged and scanned within a week of placement in the finishing barn and then every three weeks until they were marketed at an average of 240 lb.

Growth and real-time ultrasound data were used to calculate daily body weight gain and fat and protein (muscle) deposition rates. Subsequently, daily requirements for metabolizable energy and total lysine were calculated to model lysine:calorie ratio requirements.

The modeled lipid and protein accretion rates effectively predicted the difference between treatments in agreement with the growth performance data.

In both experiments, protein and lipid accretion rates were greater for lysine:calorie ratio diets 3 and 4. In addition, the treatments with greater protein accretion (lysine:calorie ratio diets 3 and 4) and greater requirement for total lysine, also demonstrated increased lysine:calorie requirements when compared to lysine:calorie ratio diets 1 and 2.

The modeled lysine:calorie ratios accurately predicted the actual lysine:calorie ratio requirements observed from the growth performance data in both experiments.

Researchers: Manuel De La Llata, Steve Dritz, Mike Tokach, Robert Goodband and Jim Nelssen, Kansas State University, Manhattan, KS. Phone De La Llata at (785) 532-1270 or e-mail

Improper Feed Grinding Drains Efficiency of Smaller Pork Producers

Despite cheap feedstuffs, an Ohio study of producer feed processing practices reveals smaller producers may be losing the battle for efficiency.

But it doesn't have to be that way, says David Meeker, the former coordinator of the Ohio Pork Industry Center. Proper hammer mill maintenance and operation can yield good results.

In the study, a majority of smaller producers (56%) used a screen that is 1/2 in. or larger in their hammer mills when grinding feed. This produces average grain particle sizes larger than the target of 700 microns for ground corn. Reaching that target of 700 microns is best achieved in a hammer mill with a 3/16-in. screen.

Table 3 shows this distinction belongs to producers feeding less than 2,000 hogs/year, 39% of producers surveyed.

"This appears to be one of the contributing factors to greater efficiencies in larger operations that does not have to be accepted. With proper attention to detail, any size operation can grind feed properly," say Ohio Pork Industry Center staff.

Ohio State University (OSU) extension agents helped conduct the 1999 OSU Swine Team Project to shed some light on how pork producers and commercial feed mills are doing with feed processing.

More than 60 producers and commercial feed mills submitted ground corn samples from 28 counties in Ohio.

Five screens were used to analyze feed. Low range in variability of microns is desired, with most in the range of 500 to 1,000 microns, the team reports.

Kansas State University research shows the best range for feed to be digested and used by the pig is when feed is ground in the 600 to 800 micron range. Microns smaller than 600-800 increase incidence of gastric ulcers. A 1.2% improvement in feed conversion is realized for every 100-micron reduction in grain particle size to the optimum range. It's worth 40-50 cents/pig, researchers say.

Consistency in grain particle size also helps ensure proper feed mixing, unloading, augering and feeding down in feeders, adds the Ohio team.

Table 1 represents screen sizes producers use in on-farm hammer mills and other feed grinding systems and the resulting grain particle sizes. There were 13 samples taken of feed processing using roller mills. Feed particle size ranged from 634 microns to 785 microns.

Differences in particle sizes are influenced by flow rate of corn to the grinder, screen condition, number and condition of hammers, tip speed of hammers, moisture content of corn and sometimes corn varieties.

Starting with average particle size of 746 microns and an 1/8-in. screen, average particle size increases each time the screen size increases (Table 1). This data says in order to grind corn in a hammer mill to 700-800 microns, use a 3/16-in. screen or smaller. This will increase energy costs and labor, but the gains in feed efficiency more than offset those costs.

Table 2 compares average micron size of corn for on-farm feed processing vs. commercial milling practices. It shows the commercial mill doing a better job.

In a head-on comparison of on-farm vs. commercial hammer mills, the commercial mills averaged 730 microns while on-farm mills averaged 1,069 microns.

Researchers: Dale Ricker, Steve Moeller and David Meeker, former coordinator; Ohio Pork Industry Center. Phone Ricker at (419) 253-6294.