Exploiting Terminal Traits
Limousin and Piedmontese germplasm may be best exploited as terminal sires without creating problems with excessive birth weight, calving difficulty and calving problems in crosses with Herefords.
Researchers at the USDA Livestock and Range Research Laboratory, Miles City, MT, compared the three breeds for economically important traits.
Cattle from these breeds of larger mature size tend to grow more rapidly and be older at a given level of fatness. Hereford, Limousin and Piedmontese are of approximately equal mature size and yet may vary in body composition at a given degree of maturity.
Crossbred cows were bred to Hereford, Limousin or Piedmontese sires. Male calves were followed through harvest. Female calves were group-fed and used to examine nutritional effects on age at puberty.
Hereford-sired calves had shorter gestation periods and weighed less at birth than either Limousin- or Piedmontese-sired calves.
Limousin-sired calves tended to grow more rapidly than Hereford-sired calves. By the finishing phase, Limousin- and Hereford-sired calves had greater average daily gains than Piedmontese-sired calves.
Differences in dry matter intake among breeds of sire were relatively small.
Differences in carcass weight, longissimus muscle area, fat depth and percentage kidney, pelvic and heart fat resulted in a clear stratification of USDA yield grade between breeds of sire.
Hereford-sired calves had more marbling than progeny of Limousin or Piedmontese sires. However, shear forces from steaks of Piedmontese-sired calves was less than for progeny of Limousin or Hereford sires.
Hereford- and Piedmontese-sired heifers were younger at puberty than Limousin-sired heifers. Within breeds of similar mature size and growth rate, ample variation exists in age at puberty and body composition at an approximately equal degree of maturity.
Within breeds of similar mature size and growth rate, ample variation exists in body composition and age at puberty at an approximately equal degree of maturity. This contraindicates use of these breed resources in rotational crossbreeding systems.
For more information contact Mike MacNeil, USDA, at 406/232-4970 or e-mail [email protected] .
Tools For Calving Ease
Calving difficulty costs the U.S. beef and dairy cattle industries more than $400 million annually. But producers have dramatically reduced dystocia and resulting deaths of calves and their mothers, say research scientists at the USDA Livestock and Range Research Laboratory in Miles City, MT.
Previously, ARS physiologist Robert Bellows and his colleagues found that feeding heifers to maximize growth from weaning to breeding increased skeletal and pelvic size. This helps reduce dystocia. They further showed that large, high-gaining sires produce calves with large birth weights.
Based on this information, geneticists developed selection tools to improve calving ease. Additionally, breeders stopped selecting primarily for weaning weight and looked closely at keeping birth weight under control.
Now laboratory scientists are focusing on hormonal and genetic influences.
They've discovered that cows with difficulty calving have different estrogen and progesterone levels than cows that don't need assistance. They also have evidence that a gene on chromosome 2 may influence birth weight without influencing subsequent growth.
Eventually, this information may yield more tools to help cows deliver calves easily.
For more information contact Kathryn Barry Stelljes at 510/559-6069 or e-mail [email protected] .
Protein in Cattle Diets
Feeding too much protein is a waste of money and can lead to environmental problems through increased nitrogen in animal waste Scientists at New Mexico State University's Clayton Livestock Research Center are looking for optimal levels of a protein equivalent in feedlot diets. Their research is part of a large-scale study in the Southwest to examine how nutrients in feed affect both cattle and the environment.
Because natural protein sources like cottonseed meal are an expensive part of the ration, feedlots use urea as a protein equivalent. Urea is converted to microbial protein in the animals' digestive tracts.
Cattle at Clayton are being fed diets with 11.5, 13 and 14.5% crude protein. One group's diet contains 100% urea, one is 50% urea and 50% cottonseed meal, and another is 100% cottonseed meal.
So far, it appears daily gain is increasing with higher crude protein, says Glen Duff, Clayton superintendent. However, the relationship is more complicated than that, so the midpoint of 13% crude protein may turn out to be the best ration.
Researchers want to see which protein source works best. Urea is outperforming a mixture of urea and natural protein sources in the experiments. Duff thinks the urea is having a buffering effect, changing the pH levels in the rumen.
Protein levels might be stepped down as cattle get older and heavier.
Environmental engineers will study waste samples from each research site to determine how feed nutrients affect nitrogen in animal waste and its potential for contamination.
For more information contact Glenn Duff, 505/374-2566 or e-mail [email protected] .
Tasco-Forage Improves Shelf Life
Length of time that cuts of meat remain in retail display is largely determined by visual changes in color. Consumers prefer beef cuts with a cherry red bloom. Increased color stability that results from treating fescue with Tasco™ forage could improve profitability for the retail meat industry.
Tasco is an Ascophyllum nodosum brown seaweed-based product that has increased antioxidant activity in both plants and animals.
Endophyte-infected and uninfected tall fescue (Festuca arundinacea) pastures in Virginia and Mississippi were treated with 3 lbs. Tasco/acre in April and July. Beef steers grazed the pastures from April to October prior to transportation to Texas Tech for finishing in the feedlot.
After fabrication, steaks were wrapped with polyvinyl chloride film, subjected to simulated retail display for up to three days. Color was evaluated daily by a trained panel.
Steaks from Mississippi steers that grazed Tasco-treated fescue retained higher color scores throughout retail display.
Steaks were more uniform and had less discoloration and less browning if they were from steers that had grazed Tasco-treated fescue.
Vitamin E in liver was increased and serum Vitamin E was decreased in steers that had grazed the treated pastures.
The endophyte in tall fescue may decrease uniformity and increase lean discoloration of beef steaks. These experiments indicated that Tasco applied to tall fescue during the grazing season can improve color stability and extend beef shelf-life, particularly in cattle grazing infected tall fescue.
The mode of action of Tasco is not clear, but antioxidants and specific vitamins may be involved. Color stability may be related to effects on specific vitamins, including vitamin E.
For more information contact Vivien Allen, Texas Tech, at 806/742-2837 or [email protected]@ttu.edu .
Vitamin D & Tenderness
Meat tenderness can be influenced by numerous techniques. Increased levels of calcium (Ca2+) — through postmortem injection, infusion or marination — have been shown to improve the tenderness of cooked meat products.
Oral supplementation of feeder cattle with vitamin D3 effectively increases serum Ca2+ and has been thought to increase muscle Ca2+ content and thus the tenderness of cooked beef.
This research indicates that supplementing cattle with vitamin D3 does not influence cooked beef tenderness, which is in disagreement with previous work.
Individual Charolais × Hereford heifers were supplemented with one of seven levels of vitamin D3. Feedlot performance, serum Ca2+ levels, and carcass data were collected and loin steaks were used to obtain Warner-Bratzler shear force values of steaks.
Cattle supplemented with D3 plus CaCO3 had lower daily feed intake and reduced average daily gains compared with controls during the eight-day supplementation period.
Supplemented cattle had numerically higher dressing percentages, possibly due to less fill at the time of slaughter, because carcass weights and USDA yield grades did not differ across treatment groups.
Although blood serum Ca2+ was increased, supplementation with any level of vitamin D3 for any length of time up to eight days did not improve Warner-Bratzler shear force.
Oral D3 supplementation (at high or low doses) for two to eight days pre-slaughter increased serum Ca2+ concentration but did not improve cooked tenderness.
More work is necessary to determine whether D3 impacts beef tenderness. And, if so, whether the positive impact of tenderness outweighs the negative effect on feedlot performance and results in tenderness improvements sufficient to offset the cost of D3 supplementation.
For more information contact John Scanga, Department of Animal Sciences, Colorado State University, 970/491-6244 or [email protected] .
The Ultimate Beneficiaries
Some tend to think that producers are the targets of agricultural research. But most researchers tend to look further up the line.
“Consumers are the ultimate benefactors of the application of technology in production, processing and marketing of beef and all agricultural products,” says Bob Bellows.
He recently retired after more than 30 years as a USDA-Agricultural Research Service associate at the Fort Keogh Livestock and Range Research Laboratory, Miles City, MT.
“The fact that U.S. consumers spend only 11% of their total income to purchase food is testimony to the success of this technology adoption,” he explains.
Looking back over the span of Bellows' research career, there have been tremendous advances in the areas of beef cattle reproduction, nutrition, genetics, plant science and product quality.
These advances have resulted in improved production efficiency and more and better products available to the consumer.
But, the future places an even greater burden on the shoulders of the agricultural research community.
“The extent of technology adoption across the beef industry — particularly in cow/calf production — is relatively low and must increase if U.S. producers are to remain competitive nationally and internationally,” Bellows says.
Bellows stresses that this fact must be considered as a strong argument for public funding for agricultural research.
“Animal scientists must work to ensure that the voice of animal agriculture is heard and remains a strong economic force,” he adds.
Ironically, the American beef industry is under ever-increasing scrutiny from its consumers — both nationally and internationally.
“Our products must be safe, nutritious, healthful and produced in an ethical and environmentally sustainable manner,” says Bellows. “Decision-makers from producers to regulators must make decisions based on sound science.”
— By Clint Peck