By Bruce Schultz, LSU AgCenter
MANGHAM, La. — Post-weaning weight gain for heifers does not have to be constant through their development period, an LSU AgCenter forage specialist said at beef and forage field day on Sept. 21.
Wink Alison advised cattle producers that research has shown that gain can be limited during the first two to three months after weaning and then accelerated so the heifers reach 55-60 percent of their mature weight at the beginning of the breeding season.
This allows use of the relatively lower-quality warm-season grasses early in the development stage and then use cool-season annuals, such as ryegrass, for more rapid gain, he said.
It is essential to continue providing high levels of nutrition after heifers calve to insure re-breeding, Alison said.
A 500-pound female at weaning needs about 180 days to get to the ideal weight to have her first calf. “You’ve really got to do a good job with the warm-season grasses to get to that level,” he said.
A fall calving season is more of a challenge, he said, because heifers have to be developed using warm-season grasses more extensively.
First-bred cows should be allowed onto a pasture before older females to get the more nutritious forage. “When cattle go into a pasture, they’ll eat the highest-quality forage first,” he said.
AgCenter beef cattle specialist Tim Page said obtaining new bulls requires careful consideration, and that means examining the animals’ records — including performance records and expected progeny differences — and studying their physical characteristics. “You’ve got to know what you’re buying in that bull,” he said.
All bulls, even virgin bulls, should be tested for trichomoniasis, he said.
Page advised producers that bulls available for purchase at a large sale are often overconditioned to look good, but they may fail to deliver on high expectations. Show bulls especially are likely to fall short.
Page said one of the first things he considers is a bull’s ability to walk effortlessly and show some athleticism that will be of benefit at breeding time.
AgCenter regional livestock specialist Jason Holmes said producers should only purchase bulls that have been classified Satisfactory Potential Breeders following a complete breeding soundness exam and have their veterinarian perform a breeding soundness exam two to three months before breeding season. “That’s one of the smartest things you can do,” he said.
Producers are sometimes prone to neglect the health of bulls because they are more concerned with their cows, he said.
Generally, a bull can service the same number of cows as its age in months, Holmes said. As a rule, if a bull is 36 months old, he can be turned out on 36 cows.
One option that allows young bulls with superior genetics to contribute to the genetics of the herd is to rotate older, dominant bulls out in the middle one-third of the breeding season and rotate the younger bulls in. In the last one-third of breeding season, the older bulls can be rotated back in.
This “rest” period also provides the opportunity to feed bulls to regain weight lost while in the breeding pasture, he said.
Dr. Jacques Fuselier, AgCenter veterinarian and technical services veterinarian for Merck, said cattle parasites have a negative effect on immunity.
The clear dewormer, avermectin, and the white dewormer, benzemidazole, can be used simultaneously to obtain the best overall results against parasites.
In an intensive or rotational grazing program, removing cattle from a pasture after they’ve eaten grass to about a 6-inch height also reduces the exposure to parasites that climb up the grass leaves, he said.
A fecal egg count can be done to determine if cattle need to be dewormed and if a deworming program is effective. Cattle appearance alone cannot be used as a guide for the presence of parasites, and parasites will affect an entire herd, not just one animal. “Every skinny cow out there does not necessarily have worms,” he said.
Liver flukes have been especially bad this year. A shipment of cattle to an out-of-state buyer resulted in several of the animals dying from the parasite, and that feedlot currently won’t buy Louisiana cattle, Fuselier said.
Flukes are commonly found along the Red River and in other pockets throughout Louisiana.
A liver fluke dewormer is available, but the most popular product, Ivomec Plus, has been removed from the market for at least a year.
AgCenter weed scientist Ron Strahan said smutgrass is the No. 1 weed problem in south Louisiana pastures, and it’s becoming more of a problem in northern parishes.
He showed results of a demonstration of different treatments for smutgrass on a plot at the Goldmine Plantation where the field day was held.
Using a wick bar for applying glyphosate herbicide is effective, but the best control is obtained from the herbicide Velpar. The chemical should be applied just before rain to allow absorption by a plant’s roots, he said.
Soil compaction can prevent effective control, and that probably was a factor for the weak control on the demonstration plots, he said.
Crabgrass can be controlled in bermudagrass pastures with an application of glyphosate four to five days after hay is cut. Strahan also advised that Outrider is a good chemical to control Johnsongrass.
Keith Collins, AgCenter county agent in Richland Parish, conducted a study of hay quality and quantity at Goldmine Plantation. Three 1.12-acre plots were cut at 10 days apart, with first one cut at when the grass was 8-12 inches tall. The second was cut at boot stage at 15-20 inches tall, and the third plot was cut when grass was fully headed at 24-30 inches tall.
The first plot showed the highest total digestible nutrients at 60.7 percent with 1,607 pounds per acre of a mix of bermudagrass and crabgrass harvested on July 18. The second cutting on July 28 had total digestible nutrients of 54.1 percent from 3,268 pounds of hay per acre, and the total digestible nutrients in the final cutting was 50.8 percent at 5,286 pounds per acre. Protein varied from 21 percent in the first cutting, to 12.7 percent in the second cutting and 9.8 percent on the final one, Collins said.