by: Bob Weaber, Ph.D.
Kansas State University

Improvement of the economic position of the farm or ranch is an ongoing process for many commercial cow-calf producers. Profitability may be enhanced by increasing the volume of production (i.e. the pounds of calves you market) and/or the value of products you sell (improving quality).

The reduction of production costs, and thus breakeven prices, can also improve profitability. For commercial beef producers, the implementation of technologies and breeding systems that increase the quality and volume of production and/or reduce the input costs is essential to maintain or improve the competitive position of the operation. Profitability is influenced by these factors concurrently.

Efficiency is the proportion of outputs to inputs and is frequently used by beef producers. There are many different ‘efficiencies' that affect beef production, especially at the cow-calf level. Some of these efficiencies are observed at the individual animal level and some observed at the system or herd level. The various efficiencies can be categorized into with measures of biological or economic efficiency.

Improvement in individual animal efficiency, especially during the postweaning growing or finishing phases, may or may not improve efficiency at the herd or system level, and may have undesirable correlated response in traits of cows.

So, why is improvement in feed efficiency important and why does the beef industry focus on it? During the growing and finishing phase of production, a one percent improvement in feed efficiency has the same economic impact as a three percent increase in rate of gain.

The traits that beef producers routinely record are outputs, which determine the value of product sold and not the inputs defining the cost of beef production. The inability to routinely measure feed intake and feed efficiency on large numbers of cattle has precluded the efficient application of se lection despite moderate 08-0.46).

Role of growth and lactation potential on ME efficiency and ME requirements

Mature cow weight and lactation potential play a key role in determining annual nutrient requirements for cows. Increasing average cow mature weights from 1,000 pounds to 1,400 pounds, approximately the change we've observed over the last 30 years, increases nutrient requirements by 27 percent. Increasing lactation potential from 10 pounds to 30 pounds per day at peak results in a 16 percent increase in nutrient requirements.

These increases in potential have the opportunity to be associated with increases in output, but they also have the potential to undermine a cows fitness in a given production environment. Increases in mature weight and lactation drive up maintenance requirements. Optimization of growth and lactation genetics, and ultimately profitability, requires understanding the marginal revenues and marginal costs associated with these attributes.

The associated change in maintenance requirement due to mature weight change is distinctly different from the change increased weight has on maintenance energy or metabolic efficiency. Metabolic rate does not scale linearly with mass or weight. Instead, it increases exponentially by the 3/4 power.

Thus, warm-blooded animals with larger mass are more metabolically efficient than ones of small mass. The principle reason for these phenomena is relationship between surface area of the animal and it's mass. Large animals have less surface area per unit mass enabling them to conserve heat more effectively. So, large cows are more efficient users of maintenance energy but have higher requirements.

The key then is finding cows with appropriate levels of mature weight and lactation potential (or biological type) for your production environment. Note that managerial (i.e. reducing supplemental feed stuffs) or environmental (i.e. drought) changes that alter nutrient availability may substantially change the fitness of your existing cows. Care should be taken in sire selection for production of replacement females such that their growth, mature weight and lactation potential are appropriate.

Value of heterosis in improving biological efficiency

One of the only, yet very effective ways to improve biological efficiency of beef cattle production systems is through the use of planned crossbreeding systems to leverage heterosis, especially maternal heterosis, and breed complementarity.

Heterosis refers to the superiority of the crossbred animal relative to the average of its straight-bred parents. Heterosis results from the increase in the heterozygosity of a crossbred animal's genetic makeup. Heterozygosity refers to a state where an animal has two different forms of a gene.

It is believed that heterosis is the result of gene dominance and the recovery from accumulated inbreeding depression of pure breeds. Heterosis is, therefore, dependent on an animal having two different copies or a gene. The level of heterozygosity an animal has depends on the random inheritance of copies of genes from its parents.

In general, animals, which are crosses of unrelated breeds, such as Limousin and Brahman exhibit higher levels of heterosis, due to more heterozygosity, than do crosses of more genetically similar breeds such as a cross of Angus and Hereford.

Heterosis generates the largest improvement in lowly heritable traits. Moderate improvements due to heterosis are seen in moderately heritable traits. Little or no heterosis is observed in highly heritable traits. Heritability is the proportion of the observable variation in a trait between animals that is due to the genetics that are passed between generations and the variation observed in the animal's phenotypes, which are the result of genetic and environmental effects.

Traits such as reproduction and longevity have low heritability. These traits respond very slowly to selection since a large portion or the variation observed in them is due to environmental factors and a small percentage is due to genetic differences. Heterosis generated through crossbreeding can significantly improve an animal's performance for lowly heritable traits. Crossbreeding has been shown to be an efficient method to improve reproductive efficiency and productivity in beef cattle.

Improvements in cow-calf production due to heterosis are attributable to having both a cross bred cow and a crossbred calf. The heterosis generated in calves that are the progeny of straightbred parents of different breeds or crossbred parents is called individual heterosis.

While this type of heterosis has important effects on economically important traits, it only accounts for approximately one-third of the total economic benefits of having crossbred cows and calves. Thus if you only have crossbred calves (i.e. straight bred cows) you're missing the biggest share of economic benefit from crossbreeding.

Individual heterosis improves performance in a number of traits measured on calves including survival and growth. For example, individual heterosis can improve weaning weights by nearly four percent, which on a 500 pound weaned calf is 20 pounds.

Why is it so important to have crossbred cows?

The production of crossbred calves yields advantages in both heterosis and the blending of desirable traits from two or more breeds. However, the largest economic benefit of crossbreeding to commercial producers comes from having crossbred cows.

Maternal heterosis improves both the environment a cow provides for her calf as well as improves the longevity and durability of the cow. The improvement of the maternal environment a cow provides for her calf is manifested in the improvements in calf survivability to weaning and increased weaning weight. Crossbred cows exhibit improvements in calving rate of nearly four percent and an increase in longevity of more than one year due to heterotic effects.

Heterosis results in increases in lifetime productivity of approximately one calf and 600 pounds of calf weaning weight over the lifetime of the cow. Crossbreeding can have positive effects on a ranch's bottom line by not only increasing the quality and gross pay weight or calves produced but also by increasing the durability and productivity of the cow factory. Crossbred cows maybe the only free lunch in the world.

The effects of maternal heterosis on the economic measures or cow-calf production have been shown to be very positive. The added value of maternal heterosis ranges from approximately $50/cow/year to nearly $100/cow/year depending on the amount of maternal heterosis retained in the cowherd (Ritchie, 1998). Maternal heterosis accounted for an increase in net profit per cow of nearly $75/cow/year (Davis et al., 1994).

Their results suggested that the benefits of maternal heterosis on profit were primarily the reduced cost per cow exposed. Crossbred cows had higher reproductive rates, longer productive lives, and required fewer replacements than straight bred cows in their study. All of these factors contribute to reduced cost per cow exposed. Further, they found increased outputs, including growth and milk yield, were offset by increased costs.

How can I harness the power of breed complementarity?

Breed complementarity is the effect of combining breeds that have different strengths. When considering cross breeding from the standpoint of producing replacement females, one could select breeds that have complementary maternal traits such that females are most ideally matched with their production environment.

Matings to produce calves for market should focus on complementing the traits of the cows and fine -tuning calf performance (growth and carcass traits) to the market place.

There is an abundance of research that describes the core competencies (biological type) of many of today's commonly used beef breeds. Traits are typically combined into groupings such as maternal/reproduction, growth and carcass.

When selecting animals for a crossbreeding system, their breed should be your first consideration. What breeds you select for inclusion in your mating program will be dependent on a number of factors including the current breed composition of your cow herd, your forage and production environment, your replacement female development system, and your calf marketing endpoint. All of these factors help determine the relative importance of traits for each production phase.

What are the keys to successful crossbreeding programs?

Many of the challenges that have been associated with crossbreeding systems in the past are the result of undisciplined implementation of the system. With that in mind, one should be cautious to select a mating system that matches the amount of labor and expertise available to appropriately implement the system.

Crossbreeding systems range in complexity from very simple programs such as the use of hybrid genetics, which are as easy to use as straight breeding, to elaborate rotational crossbreeding systems with four or more breed inputs. The biggest keys to success are the thoughtful construction of a plan and the sticking to it! Be sure to set attainable goals. Discipline is essential.

Modify cows or modify environment?

Historically, supplemental feedstuffs have been relatively inexpensive compared to current costs. In fact, much of the early motivation to develop farmer owned confinement feeding systems, common in the Midwest, was to add value to coarse grains by feeding it to cattle. Present costs for supplemental feed stuffs, fertilizer and fuel inputs have many producers reconsidering their production model and moving towards systems with reduced inputs. Indeed producers are evaluating modification of the cow rather than modification of the production environment.

It seems that in the short run, the most effective way to improve efficiency at the production or herd level is through selection for cows of the appropriate biological type that fit their production environment. Further, these cows should likely be crossbred cows to leverage the benefits or maternal heterosis and breed complementarity.

In the intermediate to long run, seedstock and ultimately commercial producers should select for animals, that optimize efficiency to the enterprise's market endpoints. Such a two pronged approach leverages efficiency gains due to additive and non-additive genetics that affect animal efficiency of feed utilization as well as biological efficiency, respectively.

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