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Tips for minimizing dark cutters

Practical tips for handlers looking to cut the incidence of this costly problem

An extremely frustrating problem when shipping finished feedlot cattle is the incidence of dark cutters — those graded B4 — or, to a lesser degree, bruising or trim losses experienced at the packing plant. I’m sure we don’t know all the causes of dark cutters yet, but this article will explore some of the causes and give producers some ways to minimize their occurrence.

The dark cutter is an aesthetic thing as it has been found that meat tenderness is not affected. But the dark cutter looks dark compared to red, juicy meat. Most of this meat goes for institutional usage, hence the lower price.

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Intact bulls have the highest incidence of dark cutters, followed by steers. Contrary to what a lot of people think, heifers can be dark cutters as well. It is not worth taking the chance of having any intact bulls in a group of market animals. Not only do they have a much higher incidence of dark cutters, they also can stir up the entire group, resulting in a higher incidence of dark cutters.

Most feedlots take great efforts to check all incoming cattle so stags from improper castration can be dealt with early in the feeding period. Purebred breeders culling yearling bulls can castrate them with pain killers. The risk from blood loss is fairly low. But if fed out, the incidence of dark cutters in these intact bulls can be as high as 25 to 30 per cent and the economic losses can be huge. Producers selling bulls are often paid only 50 per cent of the animal’s potential value. It is well worth the risk to castrate unless you are doing on-farm slaughter where transportation is not an issue.

Good implanting technique is important. Most of the riding occurs early if implants are crushed, but conditions such as infected implant sites lead to uneven absorption of product and increased riding may result. Riding in the feedlot is never a good thing. Just as stags or intact bulls are a problem, the bullers will cause excessive riding and may need to be removed permanently. Oddball conditions such as hermaphrodites (intersex animals) or freemartin heifers may need to be removed or segregated. They often are very mixed up hormonally and may act aggressively or ride frequently.

When transporting to the slaughterhouse, try to keep everything the same as normal until loading. Some feedlots that use horses for pen checking try to have feedlot workers on horses for loading, as the cattle do not recognize that as something different. Just loading with people on foot drove up the incidence of dark cutters.

An absolute no-no is mixing cattle. If taking cattle from small groups, use the dividers in the trailer and make a conscious effort to keep them separate. Send instructions to keep groups separate at the plant.

Any fluctuations in temperature can increase the incidence of dark cutters. The highest incidence in the U.S. occurs in the months of March and April, with the least in December. Temperature fluctuations occur in those months. As well, young heifers will be cycling more, which will definitely drive up the incidence. If you are using MGA to suppress heat in the heifers, make sure to be extremely tight to the 48-hour withdrawal. If you go over this time period, the rash of cycling activity and riding will drive up the dark cutters big time, as the heifers have essentially been synchronized.

Research on cattle fatigue syndrome supports the adage that shipping in really hot weather and moving and running cattle longer distances can lead to dark cutters at the very least. Downer cattle are the worst-case scenario.

While loading, handle cattle as quietly as possible. Minimize the use of prods, whips or other devices. This can really be said for handling at any time. Making sure the loading chute is level facilitates loading to a large degree. You should not need to use a prod on more than five per cent of the animals if the chute is designed properly. If you are diligent in this, the bruising losses and hide damage will also be minimized.

The right flooring minimizes slipping on the way to the plant. Anything which reduces shrink such as feeding a good water supply with electrolytes or vitamin E as an antioxidant helps reduce shrink, and secondarily, should help with dark cutters.

There is also a product called DeStress that is mixed in water. It has been shown to decrease weight loss from dehydration and reduce dark cutters as a secondary benefit. Dark cutters result from low energy levels. So with cattle that are hypoglycemic and experience temperature swings in the fall and spring, there will be more dark cutters. DeStress has natural sugars to counteract low energy and amino acids.

Grade also goes with the incidence of dark cutters. It has been found that the key is the 50 per cent AAA. Below that, dark cutters can be as high as four to five times the rate as above 50 per cent.

The frequency of dark cutters will increase as the distance to the plant increases. There is also a difference in the frequency of dark cutters between plants. Some of this is tied into the distance the large plants draw cattle from but there are other factors. Animal behaviourist and plant handling designer Dr. Temple Grandin and other researchers believe 80 per cent of the contributing factors which lead to dark cutters, bruising and other carcass damage occurs before the cattle arrive at the plant. Factors at the plant such as rough handling or weekend cattle are the straws that break the camel’s back, so to speak.

Most of the management changes are within your control. Handling improvements that reduce bruises such as changing maladjusted alley stops and removing protruding bolts also decrease dark cutters. Always analyze your processing and implanting techniques. Always be vigilant of stags or uncastrated bulls and properly castrate them as soon as possible. Marketing intact yearling bulls may be a recipe for disaster when it comes to dark cutters. Many of the same issues that may cause bulling in the feeding period can lead to the dark cutters. However, dark cutters happen within a day of the butchering process, usually before arriving at the packing plant.

Temperament of cattle can also have a big influence on dark cutters and these can be selected for. Do the economics at your feedlot and figure out what it takes to use preventatives, low-stress handling and other tips I have mentioned. By implementing these strategies, hopefully we can keep the incidence of dark cutters and the economic downgrades they bring to a very low level.

About the author

Contributor

Roy Lewis is an Alberta-based veterinarian specializing in large-animal practice. He is also a part-time technical services vet for Merck Animal Health.

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