(02/21/20) ALEXANDRIA, La. — Young bulls should be gaining weight as they approach the breeding season at a rate of 1.5 to 2 pounds per day, an LSU AgCenter ruminant nutritionist advised at crop and cattle forum held Feb. 18 in Alexandria.
Guillermo Scaglia said yearling bulls can lose 100 to 400 pounds during breeding season, and they will need to recover their weight with a combination of good pasture or hay and cracked corn or other concentrate.
But he said a high-energy diet with large portions of corn or other grain could negatively affect breeding performance, so producers must carefully consider feeding regimes.
The bull-to-cow ratio is an important consideration, too. Scaglia said older bulls can service more cows. A bull that is 24 months old can handle 24 cows, and a 3-year-old bull about 36 cows, he said. But a bull 12 to 15 months of age will only be able to service 10 to 12 cows.
He said it’s a myth that muscular bulls and bulls with big neck crests among other characteristics have superior libido, or desire to mate. Also, he indicated that many people always consider replacing bulls that look thin in the middle of the breeding season.
“Maybe these bulls are thin because they are doing their job,” he said. “However, consult a veterinarian if there is any risk of the bull losing weight because of an illness. Otherwise, he is probably doing what he is supposed to do.”
Semen quality in bulls start to decline when they are 6 to 7 years old, he said, and they also will start to lose social dominance to younger bulls around that age. He recommended an annual breeding soundness exam for all bulls.
Ashley Edwards, AgCenter agent and coordinator for animal sciences, said cows should maintain a body condition score of 5 to 6.
She said a survey of cattle owners showed they lack the time and added labor to use techniques such as artificial insemination to improve their herds. Many owners say they can afford such practices; “they just do not have the time,” she said.
Artificial insemination has a success rate of about 40 to 65%, she said.
Cows can be induced into estrus with hormones costing $6 to $30, she said.
Ron Strahan, AgCenter weed scientist, warned that several plants are poisonous to cattle, including butterweed, sicklepod and lantana, but he said Perilla mint is particularly toxic.
“This is one you definitely want to get out of your pasture,” he said. “We have cattle that die every year from this plant.”
He said a new herbicide, Duracor, can be used to kill clover, dogfennel, horsenettle and marsh elder.
Another new herbicide, Rezilon, is a good pre-emergence herbicide for crabgrass, volunteer ryegrass and goosegrass.
Strahan said broomsedge remains a problem with no known herbicide control. He will be evaluating the use of glyphosate applied with a weed wiper this year.
Sebe Brown, AgCenter entomologist, said this year’s mild winter has been favorable for insect pests.
“You need to be prepared for red-banded stinkbugs,” Brown said, adding that the insect can be controlled with bifenthrin.
Brown also recommended that farmers use an insecticidal seed treatment when they are planting in fields where cover crops have been grown.
He said several seed treatments are available for cotton to protect against thrips. Gaucho combined with Orthene provides the best-yielding cotton, he said.
Josh Copes, LSU AgCenter agronomist, said corn variety trials last year showed irrigated corn yielded an average of 208 bushels per acre compared to 179 bushels on dry land.
Daniel Stephenson, AgCenter weed scientist, said farmers need to ensure weed seed are not moved to new locations by harvesting equipment.
“When harvesting, try to avoid areas with high populations of weeds,” he said. “Equipment is one of the best ways to move weeds to new areas.”
Stephenson said farmers should be mindful of staying on the defensive against weeds even after a crop is harvested.
“Controlling weeds after harvest is an investment in the future,” he said.
Keeping soybean fields weed-free for the first five weeks of a crop will result in maximized yields, he said.
Burndown of fields should be carried out four to six weeks before planting, he said. If weeds such as glyphosate-resistant Italian ryegrass are not controlled before planting corn, “there’s no herbicide that’s going to save you,” he said.
Boyd Padgett, AgCenter plant pathologist, said fungicides can be effective on rust diseases in wheat. But he said resistant varieties offer good protection and should be the first line of defense.
He said scab is the major disease facing Louisiana wheat in the past four of five years. Some fields weren’t harvested in previous years because of the disease.
“Probably the reduction in acreage is due in part to this disease,” he said.
He said corn also can be susceptible to the scab fungus, so rotating corn with wheat could increase the risk of this disease.
Northern corn leaf blight starts at the bottom of corn plants, so getting fungicides to the bottom of the canopy is critical to control the disease, he said.
Padgett said farmers should spray fungicides only when needed because treatment is not always cost-effective.
“Don’t spray just to spray,” he said. “Spray only when you need to.”