Feed supplements may reduce acidosis issues

RESEARCHERS at Aarhus University in Denmark are working on developing feed supplements for dairy cows that reduce the incidence of feed-related diseases and result in better feed utilization.

Dairy cows have the genetic potential to produce more milk than they currently do. In order to utilize this potential, it is critical that cows consume energy-rich feed in the form of feed supplements. However, the allocation of feed supplements can be limited because they may produce ruminal problems in the cow, leading to reduced feed use efficiency, more feed-related diseases and higher nutrient discharges.

With the goal of preventing these occurrences, the Aarhus researchers launched the "Functional Feed Supplements for Effective Dairy Cows" project. The project aims to develop feed supplements that reduce the occurrence of feed-related diseases and improve feed use efficiency, thus curtailing the loss of nutrients to the environment.

Physical structure. The Aarhus researchers attributed acidosis problems in cows mainly to the physical structure of the feed rather than to the starch component of the ration.

"Earlier experiments have shown that the acidosis is localized to the bottom of the rumen and is due to the inability of the pelleted feed to float in the liquid layer of the rumen. This can result in damage to the rumen wall and influence feed use efficiency," Aarhus senior scientist Peter Lund explained.

Lund heads the research project, which includes partners such as DLG, The Knowledge Centre for Agriculture, the Cattle Research Centre and Biomar. They will collaborate closely on utilizing other physical forms of feed supplements to avoid the negative effects on the rumen environment and feed use efficiency.

"Possible alternatives could be lower-density pellets or liquid feeds. As an example, the fishing industry uses feed shapes that result in low effective feed densities. This is a processing technique that potentially may also produce a healthier rumen environment in cows, even at higher feed supplement intakes, as the feed won't result in a local irritation of the rumen wall if it can stay afloat in the rumen liquid," Lund said.

In the project, the researchers focused particularly on dairy operations that use robotic milking machines because using robots to dispense feed supplements is crucial for the overall success of the production system. Different feed supplement flavors will be tested, and new feeding strategies will be produced in addition to generating new knowledge on the best physical form of the supplements, the announcement said.

"If the issues with acidity in the rumen are solved and baits are used in (robotic milking equipment), it should be possible to produce feed rations with a higher concentration of additives that are gentle both on the rumen and on the environment," Lund said. "It will also be possible to sustain a high energy content in both the basic feed and in feed supplements -- for example, in herds using (robotic milkers). This can ensure a greater degree of flexibility in feed ration composition as you can adjust the feed ration to reflect the current price levels for milk, roughage and feed supplements, resulting in a greater financial stability for milk producers."

The Aarhus researchers said they expect that the project will lead to new feeding strategies with higher feed use efficiencies and milk yields.

The project runs until the end of 2016.


Mastitis meeting

More than 420 milk quality, mastitis and udder health researchers, dairy producers and dairy industry partners attended the 52nd National Mastitis Council (NMC) annual meeting Jan. 27-29 in San Diego, Cal.

Discussions at this year's meeting included dairy stockmanship, antimicrobial use and opportunities to improve residue avoidance efforts. Additional topics covered milk quality from around the world, whether somatic cell counts can fall too low and understanding the interactions between teats and liners during the milking process.

Rounding out this year's agenda was a technology transfer session where researchers shared cutting-edge information and solutions for the future of mastitis control.

The 53rd NMC annual meeting is set for Jan. 26-28, 2014, in Ft. Worth, Texas.


Mastitis test

A new on-farm test that identifies subclinical mastitis in individual udder quarters will enable dairy producers to selectively treat cows at dry-off and reduce treatment costs, according to an announcement from Advanced Animal Diagnostics (AAD).

The test, to be marketed as Qscout MLD, identifies, differentiates and counts three primary leukocytes (white blood cells) in milk. Known among scientists as the milk leukocyte differential (MLD), the test automatically assesses the information and indicates whether subclinical mastitis is present before symptoms are even visible to the producer. The test is modeled after the blood leukocyte differential, which has been used in people and companion animals for decades to reliably detect infection, the announcement said.

A recent field trial demonstrated that when the new test is used for diagnosis, selectively treating only cows that test positive for infection is as effective as blanket treatment -- the standard industry practice of administering antibiotics to all cows at dry-off, regardless of disease status, AAD noted.

"Selective dry cow therapy has been shown to have economic benefits, but it hasn't been a practical option because currently available testing methods are either costly and time consuming or they lack accuracy," explained Dr. Mitchell Hockett, AAD director of technical research and the principal investigator of the study. "This study shows that MLD reliably diagnoses subclinical mastitis and effectively guides selective treatment decisions at dry-off."

Study design. The trial results were presented recently during a forum AAD hosted at the NMC annual meeting.

Quarter milk samples were collected within 24 hours of dry-off from 300 Holstein cows that were around 223 days in gestation, AAD reported. Investigators then screened the samples using MLD; they also obtained somatic cell counts and bacterial cultures.

Half of the cows in the study were randomly assigned to a traditional treatment group and had all four quarters dry-treated with the antibiotic cephapirin benzathine, AAD said. The remaining cows were assigned to a selective group, and only those that tested positive for subclinical mastitis in at least one quarter were treated in all four quarters. All cows in the study then had their teats sealed with an internal sealant and treated with a barrier dip.

Investigators collected quarter milk samples for culture 10 days after calving (on day 10).

Trial results. According to the announcement, at 24 hours prior to dry-off and at 10 days after calving, the rate of quarter-level infection, as determined by culture, did not differ significantly between the traditional and selective groups. On day 10, the rate of infection was numerically lower in the selective group.

"We undertook this dry-cow study to put our MLD technology to a tough test," said Joy Parr Drach, AAD president and chief executive officer. "Untreated subclinical disease at dry-off puts a cow at significantly higher risk for developing clinical mastitis later on, so accurate diagnosis is essential to successful selective treatment."

She added, "The results of this study reinforce the diagnostic accuracy of MLD. It shows that (the test) can help producers use antibiotics judiciously at this critical stage of lactation -- and realize the economic benefits of selective treatment -- without increasing infection rates post-calving."


Rumination technology

Dairy producers, veterinarians and nutritionists have long relied on cud chewing as a key monitor of dairy cow health, but until now, rumination hasn't been an easy parameter to track.

SCR Dairy has developed the Heatime HR Tag system that allows dairy producers to track rumination, in addition to activity monitoring, enabling dairy management teams to see deviations from normal activity. Rumination is an indicator of a properly functioning rumen, which can be used as a gauge of animal health.

"Rumination offers an early window for diagnosis since a drop in rumination time frequently precedes any drop in milk production and often occurs before physical symptoms appear," Tom Breunig, U.S. general manager for SCR Dairy, said.

This means dairy producers can monitor rumination time to anticipate potential health concerns before visual signs arise.

Cow heath. According to research that followed cows from dry-off through 150 days in milk, rumination tends to decrease in the last two weeks before calving, drops suddenly at calving and then rapidly increases postpartum, an announcement from SCR Dairy said.

About a week after calving, cows usually reach normal daily rumination time, which stays relatively stable for the remainder of the lactation. Any deviation from a cow's "normal" trend is flagged and can indicate the need to evaluate potential health issues.

Monitoring rumination trends also enables dairy producers to assess a cow's response when an intervention has been made, SCR Dairy noted, which helps more quickly determine when the cow returns to normal. That's because responses often occur in the cow long before the human eye can detect what's really happening.

Volume:85 Issue:10

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