One of the key principles in Stephen Covey's book "Seven Habits of Highly Effective People" is to start with the goal in mind. This management approach is aptly applied to the development of a breeding system.
Determination of the breeding program goal(s) involves a careful evaluation of the production resources at the farm or ranch as well as the demands of the market channel(s) through which cattle are sold. Beef cattle producers must address a number of considerations as they design a mating system appropriate to their individual enterprise. The following factors should be considered:
* What is the most appropriate grazing system for the enterprise? What are the issues associated with duration, frequency and timing of the grazing system that may limit or be in conflict with the mating system alternatives?
* What proportion of total farm income is derived from the cow/calf enterprise and what times of the year do other enterprises compete for a producer's time?
* What is the cost and availability of labor?
* How much complexity can be effectively handled by management?
* How important is simplicity?
* What is the availability of bulls from desired breeds or composites?
* What is the feasibility and cost effectiveness of utilizing artificial insemination?
* What is the marketing plan for the enterprise?
Producers have a variety of mating system alternatives from which to choose. The most simple approach is straight breeding throughout the herd. The primary advantage is, of course, convenience.
But, the producer gives up the opportunity to make effective use of two powerful genetic tools - heterosis and breed complementarity. Effective crossbreeding systems take advantage of both of these genetic tools.
Heterosis is the performance advantage of crossbred progeny as compared to the average of the parental breeds involved in the cross for a particular trait. In essence, the value of heterosis is manifested in the ability of a crossbred animal to better deal with stress.
Heterosis is expressed individually in crossbred progeny, maternally via the use of crossbred females and paternally through the use of crossbred or composite bulls. Reproductive performance, calf survival and cow longevity are traits where the benefits of heterosis are greatest. Moderate positive effects are also obtained in the growth traits (Table 1).
The concept of breed complementarity is founded on the premise that no single breed excels in all economically important traits. As such, the careful matching of breed strengths and weaknesses can yield progeny with the optimal combination of traits. However, implementation of an effective crossing system requires thorough planning, may increase the intensity of management and must account for the resource limitations of a particular farm or ranch.
The goal at the ranch is to assure that the cowherd is well matched to the environment with particular attention to the forage resource. It's important to recognize that crossbreeding is not a "silver bullet" for cattle breeders. In fact, crossbreeding efforts may fail to produce favorable outcomes.
The late Bob DeBaca suggested that the primary reasons for failures in crossbreeding were:
* Over-use of individual beef cattle breeds that have too much in them - too much growth, milk, birth weight or mature size.
* The mating system was either too complicated or wasn't implemented in a systematic manner.
* Seedstock producers failed to develop the expertise and service orientation to assist their clients in development of effective crossbreeding systems.
* The use of poor quality bulls in a crossing system will not yield desired results. Selection of bulls must be based on an objective set of criteria that allows the identification of superior sires.
Producers should keep two general targets in mind when developing a mating system - what are the requirements for profitability at the cowherd level (typically involves cost controls), and what are the requirements of the market place?
One of the most significant challenges facing commercial producers is that of overcoming the genetic antagonisms between maternal and carcass traits that were described in the article "Can Both Be Achieved?" on page 6. As such, producers should critically evaluate the environmental and market risks as well as the resource limitations associated with their enterprises.
The selection of breeds and sires within those breeds should be made with a goal of matching the genetic potential of the cowherd to the available resources. For example, a cow-calf enterprise in the semi-arid West is likely to have vastly different forage availability than a herd in northern Missouri.
Montana State University's Don Kress, and Mike MacNeil at USDA's Fort Keogh Livestock and Range Research Laboratory in Miles City, MT, illustrate the process of matching biological type to environmental conditions in Figure 1. Ranges in annual precipitation are utilized to delineate acceptable levels of milk and mature size.
When rainfall is limited (<12 in.), the options in cow size and level of lactation are limited to cows with mature weight less than 1,100 lbs. and milk production less than 15 lbs./day.At the upper end of the precipitation scale, larger cows capable of higher milk production may be acceptable.
In essence, as forage availability becomes more limited, the risk of reproductive failure due to mismatched biological type increases. Additionally, if producers are participating in marketing systems that require conformance to a specific set of post-mortem targets, then it becomes more important for producers to match their selection strategy and mating system to those criteria.
The benefits and requirements/drawbacks associated with a variety of crossbreeding systems are outlined in Table 2. The use of either two- or three-breed rotation systems (Figure 2) yields a relatively high level of heterosis for pounds of calf weaned per cow exposed to mating.
The most notable challenges associated with these systems include the need for multiple breeding pastures and a narrower range of breeds from which to choose due to the fact that daughters from each rotation are maintained as replacements. Furthermore, the male calves from these systems tend to be moderate in growth rate and carcass cutability. Thus, marketing flexibility may be reduced.
The use of disciplined terminal crossbreeding systems (Figure 3) is under-utilized. The inclusion of a terminal sire cross in a herd using a rotational system overcomes the shortcomings associated with the rotational system alternatives. All progeny from the terminal cross are marketed with none being retained as breeding females.
Note that in Table 3, the degree of conformance to the generally accepted carcass targets (70% YG 1 and 2, and 70% Choice or better) is highest in composite populations that are composed of 50% British breed and 50% Continental breed influence. This ratio can also be optimized in about 75% of the progeny produced by terminal sires in terminal crossing systems involving either rotational cross or composite maternal populations.
In terminal crossing systems involving British maternal populations and Continental terminal sires, steer progeny from British breeds are well suited to market targets emphasizing quality grade. Meanwhile, steers and heifers from the terminal sire breeds are more optimal for targets emphasizing the combination of yield grade and quality grade (=70% each). In many regions of the country, especially where the need for Bos indicus influence is important, the terminal cross may well be a British breed bull.
The selection of the proper breeding system is essential to hitting both the cowherd and market animal objectives and will contribute significantly to the overall sustainability and profitability of the farm or ranch.