GENETICS

Cattle breeds and beef genetic testing

The Ways We Graze

Not All Cows Dine The Same

If left on their own, cattle and wild ungulates like to hang around the water hole and graze the dickens out of riparian areas. This fact has caused more than a few cowboys to scratch their heads and wonder if they can breed a critter that'll head for the high country when the grass greens up.

If left on their own, cattle and wild ungulates like to hang around the water hole and graze the dickens out of riparian areas. This fact has caused more than a few cowboys to scratch their heads and wonder if they can breed a critter that’ll head for the high country when the grass greens up.

By: Jaime Pullman

What makes cattle good at grazing? Is one breed better designed for grazing than another?

Recently a reader asked WR if cattle bred to live off western grasses could survive easily on the grasses of the east, and vice versa. The answer depends on a multitude of factors, but the key is adaptation. When cattle evolved as grazing animals, their job was simply to survive and reproduce. Domestication asked them to produce within the limits of their environment and climate. Today, cattle genetics from across the world can be easily exchanged, and animals are moved thousands of miles within a day. This provides unique opportunities for introducing heterosis and improving various traits. But this type of movement comes with problems, as well.

According to geneticists and producers from a 2004 National Beef Cattle Evaluation Consortium meeting report,“A gene pool conferring adaptation to past and distant environments confers less than optimum adaptation to current and, indeed, to future conditions.” The report continues, “In many instances, management systems and environments are changing more rapidly than animal populations can adapt to such changes through natural selection… While providing many benefits to efficient livestock production, movement of genes into new environments also can reduce adaptation of a resident herd to its unique conditions and challenges.” As a result, the report suggests “Rapidly increased genetic potential for production may be achieved at the expense of decreased genetic merit for adaptation” (fertility and survival). 

Breeds of cattle don’t exhibit remarkably different grazing habits in general, but they are each best adapted to graze under the conditions in which the breed developed. During the early 1990s, researchers from the Northern Agricultural Research Center in Havre, Montana, found that different biological cattle types do not significantly differ in the amount of time or distance they traveled when grazing rangeland.

However, the bite rate did differ among breed groups (a bite is defined as that tearing sound heard as the forage is pulled from the stems – bite rate is the number of bites in a given period of time). The larger, higher-producing biological types had a higher bite rate. The researchers proposed that the increased bite rate might be a response that, essentially, allowed each breed to get the right amount of intake for their breed-specific needs.

Introduction to a new environment would require the individual microflora to adjust to new forage, but that adjustment would occur over time to improve feed efficiency. Other stressors, including changes in terrain, heat, humidity, and altitude require longerterm adaptation.

The genetic grazing ability of an animal, while an important consideration, is less important than climate, forage conditions, available labor and management skill. Choosing the best cattle type for a climate is most successful if you consider the climate in which the breed developed, and the ability of the cattle to adapt to the environment. Cattle native to temperate regions do well in cooler conditions, for example. Which brings us back to adaptation. There are about 75 different cattle breeds in the US and most can be grouped according to their place of origin (Bos taurus, Bos indicus, etc), and some assumptions about their ability to adapt to different climates can be made from that information.

According to Dr. William Pinchak, a professor at Texas A&M AgriLife Research who has more than 30 years experience as a grazing beef cattle nutritionist, every genotype and environment exists across wide regions. If you break up the country by region, some sections will have different forages than others. For example, in some sections there may be greater amounts of tall fescue and perennial ryegrass. Humidity, temperatures, and precipitation can vary significantly across small distances. Even small changes can impact cattle that are adapted to one environment when they are moved to another.

Dr. Pinchak says, “Generally, cattle highly adapted to hot humid environments do not fare well in colder, dry environments. Similarly, cattle from the Northern third to half of the West take a year or two to adapt to the Southern Great Plains region. Northern latitude western cattle are usually selected for higher growth potential and body size than southern cattle and are fed hay, silage, etc. for up to six months per year to meet genetic potential for performance.”

Sparse forage suits cattle of small to moderate size best, while abundant forage can maintain larger cattle or a greater number of smaller cattle. When forage is low quality, lower milking cattle are best, since those that have high milking ability can lose body condition which may result in a drop in reproductive ability, unlike in a high quality forage situation. Inconsistent forage situations are most adapted by easy fleshing cattle types with low to moderate milk production.

Body size is also important because smaller cows tend to do less damage to grass paddocks, particularly during wet weather. There is also some evidence that smaller cattle are more mobile and are less impacted by heat stress than larger cattle.

Many of the traits improved through heterosis are especially important in grazing systems, including productivity, longevity, and fertility. This can be achieved by using high quality sires and breeding to large-gene-pool breeds. Genetics of cows is very important, but in terminal breeding situations, sire choice will have the broadest genetic impact on a herd.

Though research has shown some differences among breeds in the way grazing occurs, there is no evidence that one breed is generally more adept at grazing than another, except that some excel under certain conditions. But even under those particular conditions, the genetics of one group of animals within the breed may be significantly different to others. Research completed in the 1990s by New Mexico State University researchers found significant among breed and within-breed genetic variation in diet selection, which changes how range is utilized and managed.

This is why many experts recommend using large population breeds because sire selection options will typically provide the most genetic progress. Beef cattle diets are primarily pasture and stored forages, but pasture is the most economical feed program. It is also very sustainable when grazing cattle numbers align with the right amount of forage, the right type forage, and all at the right time. For this to happen, management is key.

STAY-AWAY-FROM-STREAM GENE
According to the 2004 National Beef Cattle Evaluation Consortium report, because cattle and wild ungulates prefer grazing near streams, preventing the over-utilization of riparian zones before adequate grazing of upland terrain is highly important. Research suggests that this type of problem can, at least in part, be solved through genetic selection.

A Montana State University study published in 2004 found that Tarentaise cattle, which are native to the alpine region of France, spent a higher proportion of time grazing on slopes distant from water sources than Hereford cattle, which are native to the British Isles. In addition, the researchers observed heritable variation within the Hereford breed to graze steeper, drier range areas.

Dr. Pinchak says, “We risk a lot in the beef cattle industry when broad generalizations are made.” He says the West versus East question can only be answered precisely if geographic location, forage/pasture type, winter feeding program and, most importantly, ownership and management objectives are identified. With our knowledge of genetics constantly developing, producers now have an opportunity to use both management techniques and genetic selection to improve forage utilization.

There is no one perfect breed, even under perfect conditions, but genetics can be selected to improve on the situation you have. Understanding the demands of your environment and climate on your cattle, and the ability of the cattle to adapt to those conditions, can make the best salable product within the challenges you face, regardless of your grazing situation.

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