Fifty Years
Of
Pharmaceutical Technology
And Its Impact On The Beef
We Provide To Consumers
 

 

 

Thomas E. Elam, PhD

President, Strategic Directions

Carmel, Indiana

Rodney L. Preston, PhD
Thorton Professor Emeritus, Texas Tech University
Pagosa Springs, Colorado
August, 2004
 

An independent review of technical literature funded

by the Growth Enhancement Technology Information Team,

an organization of animal health company executives focused on providing the beef industry

with factual information about new animal health technologies.

 

 

 

FIFTY YEARS OF PHARMACEUTICAL TECHNOLOGY

AND ITS IMPACT ON THE BEEF WE PROVIDE TO CONSUMERS[1]

 

Thomas E. Elam, PhD[2] and Rodney L. Preston, PhD[3]

July 20, 2004

Technology is a key factor in keeping beef competitive in the consumer’s food basket.  Technology improves the efficiency of beef production, reduces the cost of production, improves the health and well-being of beef cattle, contributes to maintaining the availability of beef, and has a significant impact on the overall consistency, quality and wholesomeness of beef, all of which lead to providing the consumer with a consistent supply of beef at an affordable price.  In the future, new technology will provide further advances in the production efficiency, animal health and wholesomeness of beef. The benefits from applying technology to providing beef to the consumer can be described in many ways. 

Pharmaceutical technology applied by the beef industry over the past fifty years has been a major contributor to providing the consumer with an affordable and wholesome beef supply.  This technology has improved the overall efficiency with which beef cattle utilize feed and other resources, has enhanced the health and reproduction of cattle, and improved their welfare.[4] 

Annual U.S. beef consumption per person has increased only slightly over the past 50 years (from about 61 lbs. to 65 lbs.[5]) but total beef production increased significantly (from about 13.2 billion pounds to about 27 billion pounds, carcass weight) due to an ever-increasing population.  Thus, the total input of feed and other resources needed to produce this quantity of beef has increased, making improved efficiency of resource use in beef production a paramount consideration.  Partly as a result of improved efficiency, since 1955 the consumer cost per pound of beef has decreased by 26% after adjusting for inflation.  Application of cost-effective technology has been a major factor in the ability of the beef industry to provide this increased supply of beef at an increasingly affordable price. 

The leanness of beef has also greatly improved over the past 50 years, enhancing its wholesomeness and reducing the amount of waste fat.  Carcass fat content has decreased from about 35% to about 27%.  Much of this reduction can be attributed to the introduction of large frame cattle and the use of growth promoting implants.   

Because beef cattle grow at a faster rate that they did 50 years ago (about 3.5 vs. 2.2 lb/day in feedlots), they are harvested on average at a younger age (about 16-20 vs. 24-36 months), which has resulted in younger, more tender beef.  Growth promoting implants and ionophores used in feedlots have made significant contributions to the higher rate of growth in beef cattle (+15 to 20% enhanced growth rate) and improved feed efficiency (+10 to 15%).  Antibiotics have helped control death loss and morbidity.  Parasiticides have reduced losses to parasites that infest cattle, waste feed and slow growth.  Vaccines have reduced disease pressure, further enhancing productivity.  

Consistency in the eating quality of beef remains somewhat of an issue for the industry probably due to the many cattle breed types involved.  Implants have potentially improved consistency because they decrease the animal’s age at harvest.  Future pharmaceutical technology may further improve the consistency of beef. 

It is important to note that none of these technologies alone is responsible for these improvements in beef production.  But taken together they have revolutionized the U.S. beef production system.  In the next section we will look at the details of this productivity increase and its effects on the beef provided to consumers. 

 

Cattle industry productivity, value, prices, and land use – 50 years of progress 

Over the past 50 years the U.S. beef industry has made significant technical progress.  As measured by a simple productivity statistic, pounds of beef produced per total head in the January 1 cattle herd, the efficiency of beef production has increased by over 80%.  As shown in Figure 1, production per head was 137 pounds in 1955, and increased to over 250 pounds in recent years.  The linear trend line regression indicates that there was an average of about 2.3 pounds (about 1.2%) of additional beef produced per head per year over the 50 years. 

Figure 1 [6]^,[7],[8]

In this measure of productivity, U.S. beef production was corrected for beef produced from cattle imported live from Canada and Mexico.  The numbers shown in Figure 1 thus represent an estimate of beef production from the U.S. herd relative to the total size of that herd. [9] 

Increases in productivity in Figure 1 come from two sources: 

1. Increases in the average pounds of beef per head harvested, and
2. Increases in the number of head harvested per head of inventory.

To estimate the contribution of both sources, domestic beef production was divided by head of domestic cattle harvested (carcass beef production per head) and harvest was divided by total cattle inventory (harvest/head inventory).  The results (Figure 2) show that both have contributed significantly to the overall increase in productivity.  Since 1955, average carcass weights increased about 42% while head harvested/head of inventory increased by 33%. 

Figure 2 [10]^,[11]

 

As a result of increased productivity, we have been able to about double total beef production (82% increase) from a herd that is today about the same size as it was in 1955.  The major benefits of the increase in productivity are that production costs and prices of beef are much lower and beef production is higher than it would be had technology not advanced.  Since animal waste production is directly related to the size of the total cattle herd, the ability to produce more beef per animal also benefits our environment by substantially reducing the amount animal waste produced per pound of beef produced. 

As shown in Figure 3, the progress in production efficiency since the late 1970’s has allowed increased beef production from a cattle herd that has declined by about 37 million head since 1975.[12] 

Figure 3 [13]

 

International Productivity Comparison and Implications 

The U.S. beef production system is the most efficient in the world when it comes to producing as much beef as possible from each head of cattle in the inventory.  As shown in Figure 4, in 2003 we produced about 253 pounds of beef and veal[14] from each head of inventory.  Canada, using a system essentially identical to that of the U.S., comes in second.  Compared to its major international competitors -- Australia, Brazil, Argentina and New Zealand -- the U.S. is well ahead in productivity. 

The productivity of the U.S. beef industry enables us to produce our beef supply using fewer cattle per pound of beef than any other country.  In the process, we have reduced the number of animals that are needed for our beef supply to a level lower than that implied by the productivity level of any other country of the world.  If one measure of animal welfare is how many cattle have to be born, live and be harvested to produce beef, then arguably, the U.S. is also among the top countries of the world in cattle welfare. 

Figure 4 [15]

Effects of Productivity Increases on Prices and Economic Welfare 

As productivity increases, production costs fall.  As costs fall in a competitive industry, some of those lower costs tend to get passed along to consumers in the form of lower prices.  This has certainly been true for cattle and beef over the past 50 years.  To measure this effect we can look at the productivity measure shown in a prior graph measured against real cattle prices (Figure 5)[16].  To make the data more comparable, both series were indexed to 1955=100.  On that basis productivity has increased to over 180% of 1955 while average annual cattle prices, in real terms, have declined by 40-50% since 1955. 

Figure 5 [17]^,[18]

 

Effects of Cost and Price on Beef Consumption and Production 

Had cattle prices been higher due to higher costs, we know that consumers would have purchased less beef than they did, given the effects of technology on productivity.  How much less depends on the price elasticity of beef.  A recent USDA study[19] placed the beef price elasticity at -0.35, which means a 10% increase in beef price causes a 3.5% decrease in the amount of beef demanded.  If the beef price elasticity is about -0.35, then an 80% increase in retail price (reflecting the absence of the roughly 80% increase in productivity) would cause a 28% decrease in the amount of beef demanded.  If that were the case, with 1955 technology and costs, we can say that 2005 beef production would be only about 17 billion pounds of carcass weight versus an estimated actual production of about 24 billion pounds. 

However, we also have to consider that, to a great extent, consumers would increase spending on alternative meats to replace the lower amount of beef demanded, so the loss of 7 billion pounds of beef production would be offset by increases in the production of alternative meats.  Thus, the higher cost of beef would also result in increased spending on other meats.  The extent to which reduced beef consumption would translate to higher consumption of alternative meats would depend on the cross-price elasticities of beef with respect to other meats. 

For current purposes, we can simply use the estimate of beef production of 17 billion pounds.  To produce 17 billion pounds of beef using 1955 productivity would require a cattle herd of about 126 million head.  The estimated total January 1, 2005 herd is 94.7 million head, or about 31 million head less than what would be implied by 1955 productivity.  Those 31 million extra cattle would need significantly more land, and generate more animal waste, in spite of producing 29% less beef.  That would neither be economically nor environmentally sound. 

 

Effects of Productivity on Resource Use – Land Used by Cattle 

Cattle are the largest users of land in the U.S. food production system.  Pasture for beef cows and stocker cattle, land in feedlots and land in crops used to produce cattle feed account for about 500 million acres[20]^,[21] in the U.S., or about 53% of the total 938 million acres of land in agriculture, including rangeland.  The use of this land involves costs to the industry and creates environmental impacts caused by the presence of cattle and associated activities, such as feedlots. 

The use of land for cattle is roughly proportional to the number of head of cattle required to produce the beef supply.  Technology, by improving the productivity of the cattle herd, has thus helped to reduce the impacts of beef production on land use and the environment.  Technology in many other aspects of agriculture, especially grain production, has also improved the efficiency of land use. 

As has been pointed out, if we were to attempt to produce the current beef supply with 1955 technology we would need a cattle herd about 80% larger than that of today.  Approximately 175 million cattle would be needed, not the current inventory of under 100 million (Figure 5).  Even considering the effects of higher beef prices on beef consumption, the total herd would need to be 126 million head to produce 17 billion pounds of beef in the absence of technical progress. 

Even if the demand/price adjusted estimate of 126 million head and 17 billion pounds of beef is used, there is still a significant effect on resources needed to produce U.S. beef at 1955 technology levels.  Given no increase in stocking rates, the need to pasture and otherwise accommodate a herd of 126 million head, would require us to use about 165 million more acres of land for cattle, or an 18% increase in our total agricultural land use, and that to produce a smaller U.S. beef supply.  This would place an incredible strain on our land inventory and the environment.  We would need to use large amounts of our forests, wetlands and other wild lands for cattle pasture.  The impact on these natural areas would be substantial.  Total animal waste production would also be higher, roughly proportional to the increase in the herd size required, or almost 30% more than presently produced.  In addition, the land use and animal waste production from increased production of alternative meats would exacerbate the effects of these additional cattle. 

Another way to look at the environmental impact is that, since 1975, we have reduced the total cattle inventory by 37 million head.  In the absence of productivity increases, the environmental benefits from the reduced cattle numbers would have been largely lost, with no offsetting increase in beef production. 

Figure 6 [22]^,[23]

 

Over the last 50 years, the cattle industry has raised an increasing proportion of the beef supply in feedlots rather than on pasture and range lands.  A major impact of agricultural technology has been on the amount of land needed to produce the feed required for cattle feedlots.  Given the large increases in the fed beef supply since the 1950’s, most would assume that the amount of land needed to produce increased amounts of feedlot feeds has increased, but, in fact, this is not the case. 

Table 1 is an estimate of the impact on the land used to produce the corn and roughage used for beef cattle feed.  For purposes of this table, it was assumed that all grain used in feedlots is corn and a 50-50 hay/corn silage mixture is used for roughage.  Selected estimates from Table 1 are also shown in Figure 7.

Table 1

Estimated Feedlot Beef Production and Land Used for Corn and Roughage[24]^,[25]

 

 

The overall impact of technology changes for crops and cattle has been to significantly reduce the land used to meet the feed requirements of feedlot beef production, even though there was almost a 200% increase in the pounds of beef produced in feedlots.  Despite the large increase in fed-beef production, the real cost of feedstuffs used was also reduced by about 28%.  The reduction in the real cost of feedstuffs is a significant cost savings to the cattle industry and the beef consumer.  The reduction in acreage required for beef feedstuffs has made more land available to produce crops for other purposes, including grain exports.

Figure 7

 

Summary – What would have happened without cattle industry productivity gains? 

To compare the reality of 2004 to what the world would look like in the absence of cattle productivity gains requires that we know what today would look like without the advances of the last 50 years.  This is not an easy task.  We do not really know what the total U.S. meat production sector would look like now if the cattle industry had its technology frozen in 1955.  But if that had been the case, and alternative meats had continued to improve in production efficiency, we can certainty say that directionally: 

1. Beef production and consumption would be significantly smaller;
2. Cattle and beef prices would be much higher;
3. Cattle industry costs per pound of beef produced would be much higher;
4. The cattle herd would likely be larger than it is, but with lower beef production;
5. The environmental load of the beef industry would be greater;
6. Consumers would need to spend more per pound of beef consumed; and,
7. Alternative meats would have a significantly larger share of the total meat market.

The complex relationships among the meats make estimating the magnitudes of these differences, and the size of the effects of technology very difficult.  What is clear is that the beef industry of the U.S. has been transformed by changing technology.  In 1955, beef production was largely grass-based and beef was produced on small farms.  In 2004, beef is mostly produced from cattle that are fed in large operations. 

Identifying the effects of technology on the cattle and beef market is also a difficult undertaking due to the many interdependencies in the cattle market itself, among the major competing meats, and among the technologies themselves.  A diagram of the major contributors looks something like Figure 8. 

Figure 8

 The beef industry lost market share over the last 50 years, but it is certain that if technology had not changed it would have lost even more.  Despite higher cattle prices in the absence of advancing technology, it is unlikely that the cattle industry would be more profitable today with those higher prices.  Higher costs would offset the higher prices, and the industry would likely be no more, and probably less, profitable than it is now. 

In the next section we will explore some of the key technologies shown in Figure 8. 

 

Sources and Magnitudes of Cattle Industry Productivity Change 

How did we increase beef production per animal by some 80% in 50 years?  No one single factor was responsible for this trend.  Rather it was the accumulation of many technological changes that have combined over a period of years to give us this more efficient beef production system. 

Here is a list of some of the major technological contributors: 

              I.      Pharmaceuticals; other animal health products and programs

a.       Antibiotics

b.      Implants

c.       Ionophores

d.      Repartitioning agents

e.       Parasiticides

f.        Vaccines

g.       Estrus regulation

h.       USDA disease/pest eradication programs

           II.      Genetics

a.       Beef

b.      Dairy

         III.      Nutrition

a.       Breeding cattle

b.      Pasture supplementation

c.       Stocker and backgrounder operations

d.      Feedlots

        IV.      Grain yields, and feed costs 

Underlying this list is the fact that the cattle business is a market-oriented, profit-seeking, and price/cost-driven industry that is incredibly competitive.  The result has been that cost-reducing technology is sought out and adopted by the industry, especially the feedlot segment.  Also, because input suppliers see a large and accepting business for new technology for the cattle industry, significant incentives are present to discover and market new products that save cost and resources in the beef production system. 

While the incentives for technology adoption are high, the availability of new pharmaceutical technology has been limited by high costs and long review times for the approval process of the FDA’s Center for Veterinary Medicine.  In recent years the number of innovative, new drugs for animal agriculture has been a slow trickle.  Although cattle have received a high share of the approvals, the total number of truly new animal drugs that have been approved has been less than one per year in recent years.  No new compounds were approved in 2000, 2001 or 2003. 

Table 2 shows the new, novel, drugs approved for the first time by FDA for use in food-producing animals[28].  Since 1986 only 20 new drugs have come onto the market for use in animal agriculture. 

Table 2[29]

New Chemical Entities Approved by FDA/CVM for Food Producing Animals, 1986-2003

 

 

I.a. Animal Health - Antibiotics 

The use of antibiotics in animal agriculture parallels the timeline of their development for human medicine.  As new antibiotics were developed for human uses, they were also used in animals.  In recent years several products were developed exclusively for beef cattle use.  As a result, the spectrum of antibiotic products used in beef cattle today bears little resemblance to that used in human medicine. 

Antibiotics are used in two distinct ways in beef production.  When included in feed at low dose levels, antibiotics can increase growth rates and improve feed efficiency. Because these products are included in feed, their use is generally restricted to feedlots.  Also, antibiotics (generally speaking, injectable products) are used therapeutically to treat sick cattle. 

The era of antibiotic growth promotion in U.S. agriculture began in 1946 with the recognition of substantial growth responses to the inclusion of streptomycin in the chicken feed[30].  At the time, livestock management was changing rapidly from low-performance, high-morbidity, free-range farming to more controlled and intensive husbandry.  Post-war demands for increased food production were high, and the discovery of an unexpected way to accelerate growth was received with enormous interest and enthusiasm by scientists and the livestock industry.  

The benefits of the antibiotic growth promoters are derived from their principal mode of action, which is the manipulation of the microbial flora of the intestinal tract in most species and the rumen in ruminants.  The result of this interaction with the organisms of the gut is improved digestion, metabolism and absorption of an array of essential nutrients, including carbohydrates, proteins, amino acids, minerals and vitamins.  In addition, and as a result of enhanced utilization of their diets, supplemented animals need less feed and produce less waste.  The benefits of antibiotic growth promoters can be broadly categorized into environmental, performance improvement, disease control, prevention of metabolic and fermentation disorders and a set of other related benefits. 

Without antibiotics, cattle divert some of their nutrient intake towards responding to sub-clinical disease challenges that reduce gain and feed efficiency.  The magnitude of this response is variable depending on conditions, but can be as large as 5 to 10 % in feedlot cattle[31]^,[32]. 

Therapeutic uses of antibiotics in cattle result in healthier cattle.  Their use in the treatment of cattle disease situations is not unlike their use in human disease.  This use overcomes bacterial disease, reduces morbidity and mortality, and thereby contributes to both the welfare of cattle and production efficiency.  Examples of this use include various calf diseases, bovine respiratory disease (BRD), and liver abscesses that occur in cattle fed high grain diets.  Quantifying the benefit from this use of antibiotics is difficult because these disease situations are sporadic in occurrence; however it is obvious that antibiotics provide a clear benefit in these situations. 

The impact of therapeutic antibiotics on beef system productivity should not be underestimated.  Without effective therapeutic antibiotics for important cattle diseases, it would be very difficult to maintain large concentrations of cattle in modern feeding operations.  Increased feeding of cattle has been perhaps the most important development in the U.S. cattle industry in the last 50 years.  Despite the co-mingling of cattle in large feedlots and increased hauling distances, annual death loss (about 4%) is about the same today as it was in 1955.  This is largely a testament to the effectiveness of modern antibiotics and vaccines. 

Antibiotic use in livestock continues to be questioned by some from the standpoint of antibiotic resistance and postulated human health risks.  When quantitative risk analysis procedures are applied to available data, the chance of a human health incidence arising from the use of antibiotics in cattle is so small that it is not different from zero risk.  An international panel of medical microbiologists, physicians, veterinarians, animal scientists and risk assessors has recently concluded that, “What has not happened in 50 years of antibiotic use in animals and man, seems unlikely to happen at a rapid rate now.”[33] 

I.b. Animal Health - Implants[34] 

Growth promoting implant products were one of the earliest (1956) and probably the most revolutionary pharmaceutical technology introduced into the beef industry.  Over the past 50 years of use, implants continue to be one of the most effective technologies used in the beef industry.  They provide benefits for every segment involved in beef production from the cow-calf producer through the feedlot phase and even for the packer.  Implant technology can be thought of as hormone replacement, since bulls and implanted steers gain at about the same rate.  With the availability of a wide range of doses and combinations of estrogenic and/or androgenic agents, implants have become almost designer products. While implants tend to be most effective in feedlot cattle, implanting strategies have been effectively applied to other beef production phases as well.  Estimated returns to cattle producers and packers from implant use range from $30 to as much as $67 per head.[35] 

Significant changes in implants and implanting strategies have occurred over time.  Prior to 1987, available implants were estrogenic agents, which metabolically enhanced nutrient use to enhance growth. These products improved feed efficiency 2-8 percent and daily gains from 10-15 percent. In 1987, the androgenic (tissue building) agent, trenbolone acetate, was approved for use in growth promoting implants. This compound had an additive effect with existing estrogenic implants. The androgenic implant enhanced muscle growth and added an additional 4-6 percent to the feed efficiency and 5-8 percent to the daily gains.[36] 

Typical implant programs in feedlot cattle will increase rate of gain 15 to 20% and improve feed efficiency 8 to 12%.  In other words, without implants, feedlot daily gain would be about 2.6 lb per day in steers and 2.4 lb per day in heifers compared to expected gains today of at least 3.1 and 2.7 lb per day, respectively.  Similarly, without implants, feed efficiency would be about 7.0 and 7.1 lb of feed dry matter per lb of gain compared to expected efficiencies today of 6.3 and 6.5, respectively.  Additionally, implants cause a decrease in fat deposition in the beef carcass, an increase in the rib eye area, and an improvement in lean meat growth.  Thus, the cost of gain is decreased, which benefits the cattle producer and carcass improvements are made which eventually benefit both the packer and beef consumer. 

Implant programs provide increased management options which help produce a consistent beef supply from the variety of breed types presently used in the industry.  Implant programs can also be tailored to fit the length of the feeding period.  Depending on the final USDA grade target, leaner carcasses are produced that are more in line with consumer demand, there is less waste fat from the cattle carcasses, marbling score may be reduced, but the eating quality of beef produced using implants is unaffected, especially when cattle are fed to the same USDA grade. 

The Federal Drug Administration (FDA) and several international health organizations (WHO and FAO) have repeatedly stated that there are no human health effects from consuming beef from implanted cattle.[37]^,[38] Despite their proven safety, implants are banned in Europe, and their use in the U.S. and Canada is used by the European Union as a barrier to importation of beef. 

The impact of growth promoting implants on the cattle industry should not be underestimated. If we look around the world, there is no country that feeds cattle in large numbers without using implants.  Europe, in particular, produces a large grain surplus and could feed cattle. However, European social programs designed to protect smaller farms, together with an unwillingness to accept some new technology have made cattle feeding very costly. As a result there is only a small cattle-feeding industry in Europe. 

I.c. Animal Health - Ionophores 

The first ionophore used in cattle was introduced in December 1975.  These compounds work by altering the volatile fatty acid balance in the rumen, reducing production of fermentation waste by-products and increasing the amount of net energy available from feedstuffs.  In doing so they improve feed efficiency and average daily gain and reduce the amount of feed wasted in rumen fermentation.  They work in both feedlot and pasture settings.  Ionophores also reduce coccidiosis and, because they reduce bloat and acidosis that can result from the fermentation of grain starch, feedlots are able to feed higher energy-dense rations.  

Ionophores are currently used extensively in feedlots, stocker operations and in replacement heifer raising operations.  Nearly all feedlot cattle receive an ionophore in the feed from day of arrival to harvest.  A high percentage of replacement heifers will also receive an ionophore.  Pasture supplements can also include ionophores. 

By improving the energy utilization of feeds, ionophores have helped make beef production more efficient and have indirectly aided beef quality by increasing the cost-effectiveness of feeding cattle versus raising them on grass.  In feedlot cattle, ionophores will improve feed efficiency by 6 to 8 percent and daily gain by 1 to 6 percent.  The efficiency response provides an economic benefit to the feedlot producer of about $12 per head.[39]  In stocker cattle and replacement heifers, ionophores improve feed efficiency by 8 to 12 percent and daily gain by 5 to 15 percent.[40] 

Ionophores and implants work together well and, in fact, may work synergistically.  Ionophores make it feasible to feed higher energy diets, and implants act to direct that extra energy into lean meat production.   

I.d. Animal Health – Repartitioning Agents[41] 

The first repartitioning agent for cattle was approved in the U.S. by FDA in 2003.  Repartitioning agents are used in the last part (typically 4-6 weeks) of the feedlot phase of cattle production.  These agents “repartition” the absorbed nutrients towards greater lean meat growth and less fat deposition. While they are being used, rate of gain is increased 17 to 25% and feed efficiency is improved by the same magnitude.  Carcass lean gain is improved almost 70% while a repartitioning agent is being fed.  Gross returns to feedlot cattle producers are about $10 to $17 per head fed.  Net returns will depend on the cost of the drug.  The response to repartitioning agents is additive to that expected from implants and ionophores.  The percentage effects, measured relative to the entire feeding period of 120-140 days, are less than those measured during the approved period of use (last 28-42 days). 

I.e. Animal Health – Parasiticides 

The advent of parasiticides in the 1950’s also represents a major advance in beef cattle rearing.  In their natural, outdoor environment, cattle are subject to infestation by a wide variety of both internal and external parasites.  Though very diverse, parasites have one common effect on cattle – they reduce performance.  Parasites can also cause disease, reduce the value of hides, and in extreme cases can be fatal. 

Internal parasites rob cattle of nutrients from their feed, nutrients that could otherwise be used for growth and development.  They can also attack major organs and reduce the health status of cattle.  In extreme, but rare, cases internal parasites can be fatal. 

Stomach and intestinal worms, tapeworms, liver flukes, lung worms and coccidia are the most common internal parasites of cattle in the U.S.  Their effects are usually insidious and subclinical, such as indigestion and poor feed conversion, less than expected weight gain and, for beef cows, decreased milk production and lower conception rates. Lungworms can cause verminous pneumonia and provide an environment conducive for viral and bacterial pneumonia.   

Today there is a large array of parasiticides that dramatically reduce the impact of these internal pests on beef cattle performance.  However, the evidence on the production effects of this class of products on cattle performance is somewhat scarce.  University studies have shown that the use of an effective control program for beef cattle have the following general effects[42]^{,[43],[44],[45]}:

1. Beef cow weights and body condition scores (BCS) are improved (+20 to 30 pounds and +0.2 to 0.4 BSC),
2. Increases are seen in cow conception rates due to improved body condition scores,
3. Calf weaning weights are increased significantly (20 to 40 pounds), and
4. In heifers there is an increase in growth rate (about 0.1 pounds/day), reduced time to puberty (+33% more reach puberty at 14 months of age) and improved conception rate (25% vs. 56% at 14 months of age),

External parasites of cattle – flies, grubs, lice, and ticks – limit productivity in beef cattle by affecting animals in several ways.  They are a serious threat since they feed on body tissue such as blood, skin and hair.  The wounds and skin irritation produced by these parasites often result in discomfort and irritation for the animal.  More significant, however, is that any blood-sucking or biting parasite may transmit diseases from infected animals to healthy ones.  In addition, these pests also may reduce weight gains, cause losses in milk and meat production, produce general weakness, cause mange and severe dermatitis, and create sites for secondary invasion of disease organisms[46]^,[47],[48].  They can also damage the hide, a valuable by-product of beef production. 

An important economic effect of external parasites on cattle performance has to do with the behavior of cattle as they attempt to avoid them.  The irritation caused by flies, lice and grubs can cause cattle to move about and scratch up against any handy object[49].  This behavior wastes energy and can lead to loss of performance. 

However, the major economic burden of external parasites is the diseases they may spread.  Without effective control, the losses from these parasites and the diseases they spread would be significant. 

As is the case with internal parasites, there is today a wide range of products for control of external parasites.  Unfortunately there is very little scientific evidence on the monetary value of cattle performance effects of external parasites. 

I.f. Animal Health – Vaccines[50]^,[51] 

Vaccines used against bacterial and viral diseases, and bacterial toxins are the oldest pharmaceutical technology applied to cattle.  The first vaccine was against blackleg caused by the toxin produced by Clostridium novyi in cattle. 

Over the years, many vaccines have been developed against specific bacterial and viral disease problems in cattle.  This technology is prophylactic in nature since the antigens used are for specific disease situations which may or may not be present in a given cattle herd or in the feedlot.  Obviously, if the disease entity is not present, there will be no benefit from the vaccine.  On the other hand, if the disease is present, or if an outbreak occurs, the benefit can be very great.  In addition to blackleg, common vaccines used in cattle production include infectious bovine rhinotracheitis (IBR), bovine viral diarrhea (BVD), bovine respiratory syncytial virus (BRSV), parainfluenza, clostridium perfringens, haemophilus, pasteurella, leptospira and certain combinations of the above.  Several vaccines against Escherichia coli O157:H7 are under development and could eventually have major food safety implications for the beef industry. 

Due to the nature of their use, it is very difficult to quantify the production efficiency benefits resulting from the use of vaccines.  However, a healthy animal will always perform better than one that is, or has been, ill.  Vaccine use also reduces the performance variability of feedlot cattle.  To the extent that vaccines prevent the onset of clinical and subclinical disease, they contribute significantly to the efficiency of beef production and also to animal welfare. 

I.g. Animal Health – Estrus Regulation 

There are several products used to regulate estrus in feedlot heifers and breeding female cattle.  Melengestrol acetate (MGA) has been shown to improve rate of gain and feed conversion in feedlot heifers.  In feedlot heifers the use of an estrus suppression product improves average daily gain and feed efficiency by about 3 to 7%.[52]^,[53]  Fed heifers do less riding and bulling when estrus is not present, so there's less dust, less bruising and increased beef quality. 

Other products, such as prostaglandins, are used in breeding heifers and cows to bring them into estrus at the same time, thus shortening the calving season and producing more uniform calves at weaning.  Use of artificial insemination is also facilitated and genetic improvement is enhanced when estrus is synchronized. 

I.h. Animal Health – USDA Disease/Pest Eradication Programs[54] 

USDA, with the cooperation of the cattle industry, has helped eradicate or sharply reduce the prevalence of several important diseases in cattle.  Contagious bovine pleuropneumonia was eradicated in 1892, the screwworm in 1966, the cattle fever tick in 1943 and foot and mouth disease in the 1930’s.  Ongoing programs include bovine tuberculosis and brucellosis (37 states are currently disease-free).  Though several of the programs pre-date 1955, they are all important milestones in the improving health status of the U.S. cattle herd. 

Currently, emphasis is being placed on preventing the re-occurrence of BSE.  Strict rules have been imposed by the FDA on the feeding of ruminant derived feed ingredients to cattle and USDA is screening selected, older, cattle for the disease. 

II.a. Genetics – Beef 

The genetics of beef cattle over the last 50 years, as applied by the industry, is probably best described as a directionless process.  Early in the past 50 years, three breeds constituted the majority of the beef cattle produced in the U.S., namely Hereford, Angus and Shorthorn.  The beef type at that time was described as compact, or compressed.  The cattle were of small frame and were quite fat at market weights.  The advent of quarter-inch trimming of fat on carcasses brought about an awareness of cattle that were too fat.  The benefits of crossbreeding through heterosis began the development of composite lines of cattle (Santa Gertrudis, Braford, Brangus, “black-baldies,” etc.).  Large frame, exotic European breeds (Charolais, Simmental, Limousine, etc.) were introduced that increased rate of gain, improved feed efficiency, increased mature size and carcass weight.  Because of weight limitations, achieving a desired USDA grade without creating a carcass weight that was too heavy to “fit the box” became a major problem for the industry.  As a result, the present beef cattle in the U.S. are a diverse population that presents challenges and opportunities in the production of a consistent supply of beef. 

Genetic measures have been introduced to improve certain aspects of the production process.  Bull test stations identified sires that were above average in rate-of-gain with less fat thickness.  Quantitative measures, such as expected progeny differences (EPDs), gave projected performance values for certain traits such as rate of gain and carcass characteristics. 

Presently, considerable effort is being directed towards gene mapping and marker technology.  This will enable the identification of gene combinations that relate to growth, efficiency and the eating qualities of beef such as tenderness. 

II.b. Genetics – Dairy

 It may not seem obvious that genetic improvement of dairy cattle has helped the productivity of the beef industry, but it has, in fact, been a contributor.  Dairy cattle produce beef as a by-product of milk production.  If the number of dairy cattle can be reduced via increased milk production efficiency, there will be more specialized resources available for beef production. 

Dairy cattle genetics have helped improve milk production from about 6,000 pounds per cow in the mid 1950’s to about 19,000 pounds in 2004-2005[55].  By more than tripling the milk-per-cow, we have been able to dramatically reduce the number of dairy cattle required to produce the U.S. milk supply.  In doing so, the dairy industry made “room” for a larger beef cowherd.  As a result of advances in milk cow productivity since 1955, the dairy herd has shrunk from 23.5 million head to 9.1 million.  During that same time period, the beef cowherd grew from 25.7 to 32.7 million head.  Figure 9 shows the decline of the dairy cowherd since 1955 and the increase in the beef cowherd.

Figure 9 [56]

 

Genetic improvement in dairy cattle has proceeded faster than has been the case for beef for a very simple reason.  In beef cattle, the genetic traits used for selection are many and complex and results are often unpredictable.  In dairy cattle, genetic focus is on one trait – milk per cow – and the results are easy to measure and unambiguous. 

III.a. Nutrition – Breeding Cattle[57] 

With the introduction of larger, exotic, breeds of cattle, weight at puberty was heavier and cow-calf producers had difficulty getting heifers to calve at two years of age using conventional feeding programs.  Research demonstrated the importance of feeding adequate energy to achieve pubertal weights in time for breeding first-calf heifers at 13-14 months.  Recently, the beneficial role of fat additions to the diet on reproductive performance has been demonstrated.  Furthermore, the importance of achieving a minimum body condition score at calving through dietary energy management and the ability of cows to return to estrus in time to be bred and maintain a yearly calving performance has greatly facilitated the incorporation of larger frame cattle into the national cow herd. 

III.b. Nutrition – Pasture Cattle 

Over the past 50 years there have been major advances in the understanding of the role of nutrition in pasture cattle performance.  As a result, the use of pasture supplements containing vitamins, minerals and other nutritional elements missing in natural pastures has become commonplace.  In many cases, pasture supplements also contain energy and protein to make up for seasonal deficiencies in grass.[58]  Ionophores are also used in some supplements. 

The benefits are increased weaning weights in calves and improved reproductive performance in cows.  The magnitudes of these benefits depend to a great extent on the effects of weather on forage quality, and are highly variable. 

III.c. Nutrition – Backgrounder and Stocker Operations 

Over the past 50 years, programs for managing the transition of cattle from a pasture environment to the feedlot have been improved.  Known as backgrounding and stocker programs, these management systems are designed to put low cost weight on weaned calves prior to shipment to feedlots.  The difference between the programs is that stocker operations are more intensively managed for higher weight gains whereas backgrounding programs maximize the utilization of roughages, pastures and crop residues.   

Both of these systems involve feeding hay, grain and protein supplements to young animals on pasture.  Vaccines, antibiotics, implants, parasiticides and feed additives, especially ionophores, are commonly used.  The normal target is to have cattle gain 1-2.5 pounds a day versus less than a pound that would be gained on pasture alone.[59] 

The performance benefit is that cattle arrive at the feedlot, younger, heavier, and in better condition and health than animals that remain on pasture with no supplementation or health management. 

III.d. Nutrition – Feedlot Cattle 

Feedlot nutrition research, results and application have been taking place continuously over the past 50 years.  In addition to better defining the nutrient requirements of beef cattle that have been the source of information for updating the National Research Council (NRC) Nutrient Requirements of Beef Cattle, research has also quantified the relationship between nutrient intake, especially energy and to some extent protein, and the productive performance of beef cattle.  Predicted feed and energy intakes, and resulting growth rates translate into live weights, feed efficiencies and harvest weights to achieve USDA grade endpoints.  Thus, when cattle are placed in the feedlot, closeouts can be predicted and break-even points determined, facilitating the hedging of cattle to lock in profit margins.

Nutrition technology has helped convert cattle from roughage/pasture/range diets to high concentrate diets fed in the feedlot.  Pharmaceutical products play an important role in making this conversion a success.  The ability to feed cattle diets high in grain is a more economical way of supplying cattle dietary energy than via roughage.  The feedlot system also permits higher rates of growth that allow cattle to be harv