Cattle sector grappling with genetic link to feed efficiency

NASHVILLE, Tenn. — Few beef producers have selected cattle for feed efficiency because it is a difficult quality to measure among large groups of animals.

Improved bovine DNA evaluations may provide easier ways to unravel valuable qualities like feed efficiency and disease resistance and link them to sire selection information.

As genomic technology marches forward, many producers feel left behind. They say they do not understand the math behind expected progeny differences or genomic breeding values that could tell them which individuals carry the genes for marbling, colour or best rate of gain, said scientists during an education session at the recent National Cattlemen’s Beef Association annual meeting in Nashville.

But with rising feed costs and more competition for land, producers need to find those animals with better than average performance in pastures or feedlots to save money.

Feed efficiency is the ratio of live weight gain to dry matter intake.

Swine and poultry have made great gains in this field but cattle lag behind.

“The genetics for feed efficiency have been largely untapped. There is the potential to improve but we as an industry have not done that,” said beef specialist Dan Shike of the University of Illinois.

Across the breeds, improvements have been made in weaning and yearling weights so finding the genes for feed efficiency should be the next big discovery.

Most producers already select for increased dry matter intake without realizing it because they seek animals that gain more, said researcher Matt Spangler of the University of Nebraska.

“It is intriguing why an animal is fed the same as its contemporaries and gains more or less,” he said.

The U.S. beef cattle evaluation study is looking at thousands of sires to tie genomic tools to expected progeny differences and develop molecular breeding values. Using genomic information already collected by the American Angus Association, genomically enhanced expected progeny differences are available.

“Does it work? Yes, we know it works. Does it work well enough that I would pay for it? That is a whole other story,” said Spangler.

The American Angus Association has created genomically enhanced expected progeny differences on 16 traits, including calving ease, carcass weight, marbling scores, scrotal circumference, birth, weaning and yearling weights. Other purebred associations have also embarked on this research because bull buyers need to know if certain qualities can be found across the breeds.

The work is still in the early stages and variation exists among breeds. There is not enough information on some breeds to know which bulls carry the most desirable qualities.

“By and large this technology is not robust across breeds and we suffer from a lack of genetic tools to focus on input traits,” Spangler said.

On a practical level producers tend to focus on better gain, improved carcass gain and profit but a one percent improvement in feed efficiency has the same economic impact as three percent improvement in the rate of gain.

“We really need to think about the input side,” said Shike.

Feed costs amount to 50 to 70 percent of costs for the average operation and when corn hit $7 per bushel last year, the figure rose to 80 percent of a feedlot’s cost.

A feed efficiency improvement of 10 percent would reduce feed costs by $1.2 billion in the United States.

Selecting heavily for feed efficiency could have some negative effects.

“Selecting for rate of gain will increase mature cow size and selecting for rate of gain will add to the feed cost of the cow herd,” Shike said.

His research includes studying cows at different ages and sizes to compare milk production, hip height and body condition score as well as individual dry matter intake.

“There’s tons of variation so there is potential for selection. Can we select for improved feed efficiency in the feedlot without having negative impacts on the cow? he said.

They have divided cows into different types. A high maintenance cow is one with high milk production, high visceral organ weight, high body lean mass and low body fat mass. Gelbvieh, Simmental and other continental breeds fit into this category.

A low maintenance cow produces moderate milk, weighs less and probably has more body fat like the Angus, Hereford and Red Poll.

Selecting for the low maintenance cow does not mean they are the most efficient.

The cow type should be selected based on feed sources and the environment it lives in. If there is less feed available, the low maintenance cows do well, whereas abundant feed supplies favour larger, heavier milking types.

“Their systems are geared for high production and if you have the available resources, they will be the more efficient cow at that particular level,” he said.

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