Understand Genetics to Manage Your Livestock
Published on Fri, 07/12/2013 - 10:14am
To manage the genetics of beef cow herds, producers should consider several factors in a logical sequence. These factors are production conditions and markets, types of cattle, breeding systems, breeds, and selection of individual breeding animals.
Production Conditions and Marketing
The first factors to consider in a genetic strategy may not be all genetic and should include production conditions and marketing. Genetic strategies for beef cattle should be based primarily on production conditions including the following:
Climate. Climatic conditions range from hot to cold and humid to arid. Cattle types vary in their ability to adapt to different climates. Also, climate affects forage types and, therefore, appropriate levels of cattle production.
Forage conditions. Most beef cattle are maintained on forage, which can vary from abundant to sparse and nourishing to deficient. Cattle also differ in applicability to diverse forage conditions.
Available labor and management skill. Labor will usually range from limited to plentiful and uninformed to knowledgeable. You will also discover that some genetic strategies require more time and expertise than others.
In marketing we need to consider market timing, methods and specifications. If calves are sold at weaning, the producer is paid for weight and in price per pound. The price is most often based on the buyer’s estimate of value beyond weaning. On the other end of the production chain, returns of those retaining ownership to the rail are directly influenced by post-weaning performance and carcass merit.
Fed beef is used primarily for three purposes: “white table cloth” restaurant; “lean” beef; and the commodity or retail market. The first requires high carcass marbling; the second emphasizes leanness; and the last balances marbling and leanness. Different markets call for different genetic strategies.
Unlike most other livestock enterprises, production conditions in beef cattle herds usually cannot be controlled easily or economically. In cow/calf operations, it is more efficient and economical to adapt the operation to the production conditions.
Types of Cattle
The next step is to determine what types of cattle best fit the production conditions and markets. When cattle are not matched to production conditions and markets, performance is reduced, and income drops.
For hot, humid climates, cattle types that originated in such conditions are best adapted. Cattle native to more temperate regions fit better in cooler climates.
The choice of compatible types also depends on forage characteristics:
Sparse: Cattle of small to moderate body size fit best.
Abundant: Larger cows can be maintained, or smaller cows can be maintained at higher stocking rates.
Low quality: Lower milking cattle are best suited. Cows of high milking ability can lose body condition, and reproduction rates can drop.
High quality: Cows can be of higher milking ability; otherwise, forage potential may not be fully realized.
Inconsistent: Easy fleshing types with low to moderate milk are best adapted. Although forage deficiencies can be offset with supplemental feed, cost must be weighed against return.
When selling at weaning, the paramount factors in choice of types are production efficiency and calf value at that point. For retained ownership, efficiency and returns are directly influenced by post-weaning performance and carcass merit.
The next step is to plan a breeding system before considering breeds and selecting breeding stock. The two basic breeding systems are called continuous and terminal. The difference in these systems is their source of replacement females.
In continuous systems, heifers are retained to return to the breeding herd. So, in addition to traits important in market progeny, you should also consider the potential replacement heifers’ environmental adaptability and maternal qualities.
Because no replacement heifers are retained in a terminal system, terminal sires can be selected regardless of how their heifer progeny would perform as brood cows. Replacement females in terminal systems must be either purchased or produced in another herd. When produced in another herd environmental adaptability and maternal characteristics should be considered in designing genetic programs to produce these replacements.
While straight breeding can be done for commercial production, it lacks the advantages of well-planned crossbreeding in heterosis (hybrid vigor), production, efficiency, and, in some cases, marketability. There are practical crossbreeding plans for herds maintained in one or several breeding groups and for one bull herds or thousand cow operations.
Breeds of Cattle
The fourth step is to choose breeds. There are about 75 breeds of cattle in the United States. Some (originally from Europe) perform best in temperate locales. Others (such as the American Brahman, which was created from humped Bos Indicus cattle native to India) are better adapted to tropical environments; and still others are intermediate in adaptability.
Breeds can be logically grouped according to their adaptability and key physical characteristics. These groups include British Beef, Continental Beef, Continental Dual Purpose, Dairy, Bos Indicus and American. Specialty breeds cannot be placed logically in one of these groups because of their unusual genetic features.
Breeds in the American group were formed from a crossbred base of established breeds of two types: tropical adapted (usually Brahman, at levels of 3/8 to 1/2) and temperate adapted (mostly British Beef). In addition to the American group, other combination breeds and composites are being formed. The applicability of combination breeds and composites rests largely on the characteristics of the constituent breeds.
Although breeds should be chosen primarily on the basis of their adaptability to climatic and other production conditions, producers should also consider performance and marketability. For example, in many southern states, calves can be produced most efficiently and without significant price discounts if they are at least 1/4 British, no more than 1/2 Continental, no more than 1/4 Bos Indicus (which could come from sources such as a half-Brahman parent or an American parent), or possibly no more than 1/4 Dairy. For the high quality market, higher percentages of British are applicable. For the lean beef market, less British is more appropriate.
In some situations, producers may deviate from these guidelines. Depending on production conditions and markets, a variety of useful blends can be created within these approximate ranges.
The final step in a sound genetic strategy is to select individual breeding stock. Selection of females certainly affects the genetics of a herd. However, even in a terminal cross, a sire has much more genetic influence than any female. This is because a sire usually is the parent of at least 20 to 25 calves a year, or possibly of many more calves due to artificial insemination. Also, in a continuous system, the genetic composition of a cow herd is determined largely by the sires used over the last three generations. Regardless of the breeding system, sires are the most crucial element in genetic selection.
Sires must be structurally sound, fertile, and active and capable breeders. Ease of calving also is important, especially to breed heifers for their first calves. For sires and dams, limit selection to traits that are economically important and reasonably heritable. Depending on breeding system and market, these traits may include environmental adaptability, soundness, temperament, reproduction, livability, longevity, maternal qualities, body size, rate and efficiency of gain, and carcass merit.
Several methods can be used to select individuals. Some characteristics must be evaluated visually, such as anatomical soundness and visible physical traits affecting market price. However, many traits can be measured objectively, including reproductive features, weight, and body composition or carcass characteristics. Objective methods include performance tests, breeding soundness evaluation, actual carcass measurement or ultrasound estimate, and breed association performance programs.
Genomic techniques – particularly, marker assisted selection and DNA analysis – are being developed. For most production traits, this technology is just now coming into its own and may not be used extensively for genetic selection of beef cattle until further research and development are conducted.
Genetics and Economics
Net income from a beef cattle herd is calculated using this formula:
Net income = (Number of head sold x Sale weight per head x Sale price per pound) – Total cost
Number of head is affected by reproductive efficiency and death loss. However, numbers also vary depending on body size and management system. On fixed resources, producers can maintain more cows of smaller size, resulting in more calves to sell; but average sale weight is likely to be reduced. If weaned calves are retained for grazing, then fewer brood cows must be maintained; sale numbers and price per pound will be lower; and average sale weights will be higher.
Weight per head is influenced by available nutrition (including what comes from milk); environmental effects (such as climate, disease, and sickness); and genetics for growth, environmental adaptability, and resistance to disease and sickness.
Price per pound is determined by the real or perceived value to a buyer at whatever stage of production the herd owner decides to market. Cost of production should include every relevant item, not just outofpocket cash expenses.
The highest net income often does not come from the greatest numbers, the heaviest weights, the highest price, or the lowest cost. The most successful producers develop adapted genetic strategies that optimize and balance these four elements to maximize returns.