by Sally Colby
Beef producers with cattle nearing the end of the finishing cycle are finding themselves stuck holding animals past their ideal slaughter weight. Dr. Dan Loy, professor of animal science and director of the Iowa Beef Center, has some tips for cattlemen forced to hold cattle during plant slow downs and closures. Loy said that while heavier carcass weights have been an ongoing trend, the current situation is unprecedented.
“Carcass weights increasing is nothing new,” said Loy, “but the trend looks like it’s continuing, and given the current situation, likely to be above the line.” Under the Defense Production Act, plants will open with enhanced worker protection, distancing and slower line speeds.
Increased carcass weights come at a cost. “A 1,600-plus-pound steer will take about 10-and-a-quarter pounds of feed dry matter per pound of gain,” said Loy. “That continues to increase as they get heavier. The 1,700- and 1,800-pound weights are beyond the scope of data but feed intake will be higher.”
Fortunately, the net energy system works. “It’s the basis for all of the growth models and various software programs,” said Loy. “We have a lot of experience using that to predict performance of beef cattle and also program and develop predicted performance.”
Nutritionists can predict ADG and weight based strictly on feed intake. “We’re monitoring current performance based on feed consumption and net energy of feed,” said Loy, “and we can predict final weight within 1%. The nutritionist can predict performance, and can also program the rate of growth with programmed feeding and backgrounding programs to stage cattle coming into feedlots. Now we’re looking at potentially using the same technology and tools to program cattle on the back side.”
To slow the rate of gain, Loy recommends backing down a ration or two from the step-up ration to a conservative finishing program. Assuming cattle continue to eat 25 pounds of DM per day, the number of pounds gained over a two-month period will decrease by around 35 to 40 pounds.
However, such a program isn’t without problems. Loy said in numerous studies involving various levels of roughage fed to finishing steers, cattle on higher roughage rations ate more feed but gained the same. “If we use this approach, we have to moderate intake and manage that,” he said. “We can maintain cattle at their current weight; the problem is that steers are probably still growing in muscle and bone, so if we just maintain their weight, they’re going to lose some fat and marble.” A limited or managed intake program should be considered if there’s sufficient bunk space and bunk management.
To slow cattle while maintaining sufficient growth for marbling involves a backgrounding ration for finishing – one that maintains two to 2.5 pounds/day gain in a 60-day period. “We’re still going to put on 100 to 150 pounds, but we’ll slow the rate down and still produce quality beef by the time cattle go to market,” Loy said. “This isn’t too much unlike when my grandfather fed cattle with high levels of corn silage.”
Dr. Dan Thompson, department chair of animal science, Iowa State University, discussed some of the welfare concerns associated with feeding heavier cattle. The major issue that surfaces during longer summer days is atypical interstitial pneumonia (AIP). The issue is more prevalent in heifers and occurs more in long-day cattle in summer. “There are a lot of theories about why we see this – pathogens, septicemia, dust interaction, heat stress,” he said. “Most AIP mortalities occur at about 150 to 160 days on feed, and most occur in summer when it gets hot – June, July and August.”
Thompson said animals with AIP will appear to be sway-backed and bowed in the front legs. “Their lungs are overloaded and full of infiltrate,” he said. “Where there’s supposed to be air, there’s fluid. You can hear an expiatory grunt, and a lot of them die next to the water tank because they’re so out of breath and in such acute respiratory distress that they can’t take a drink.”
AIP was once thought to have a single cause, such as dust or other underlying factors, and could be solved with aspirin. But there’s no treatment for AIP, and the mortality is about 50%. Thompson said the best option for dealing with AIP is to take the animal to a local locker; they won’t be condemned because it’s non-infectious.
Bruising is commonly seen in heavy cattle going to slaughter. Larger animals are more easily bruised because their hips are higher. The hauler’s trailer should be built for fat cattle, and preferably modified so animals don’t catch their tailheads as they jump down into the belly. Loy suggests extending the top deck forward and placing the top deck loading ramp so it flips to the side rather than under the top of the lower deck. Cattle should be handled carefully to prevent bruising at both loading and unloading.
Another serious problem with heavy cattle going to slaughter is fatigued cattle syndrome. Heavy cattle with more finish simply can’t endure being run around at home for load out.
“The big thing with fatigued cattle syndrome is not due to injury or joint issues,” said Thompson. “It’s due to stress and exhaustion as a result of moving.” Lactic acid accumulates in the muscles, and animals become so stiff they can’t move, and are condemned at the plant.
The best way to prevent fatigued cattle syndrome during warm weather shipping is to go slowly. Factors such as heat stress, time of loading and animal size can’t be controlled, but handlers can control the way cattle are handled, the speed at which they’re moved and the degree of introduced stress through impatient handling.
Thompson said one of the biggest problems in animal welfare today is the length of time animals stand on the truck at the plant prior to being unloaded. He urges packer partners and the USDA to figure out a way to provide shade or fans for waiting cattle, and to get animals off the truck more efficiently.
“Control what can be controlled,” said Thompson. “Have the proper trailers and adaptations, and take time to load trucks and haul carefully.”