Breeding objectives

Identifying breeding objectives is fundamental to planned cattle breeding. So who sets breeding objectives? If we are honest with ourselves we will answer ‘I do’. Breeding objectives are the combination of various selection criteria with their respective ‘weightings’ or emphasis that we choose to place on each criterion.

The decision made when choosing bulls for the herd this year will influence the enterprise profitability for the next 10 to 15 years. When buying bulls, or selecting a bull to use in the herd, cattle breeders should make their choice by ‘weighing up’ many factors, including the:

• current herd performance
• environment under which the herd is grazed
• market specifications for the turn-off animals.

Selection is frequently based on intuitive ‘feelings’ about the relative value of a range of traits. These traits include fertility, growth, structure, carcase and temperament, with the producer comparing all the relative traits in all the animals on offer to come to the choice of one, or a few, bull/s or heifers as the case may be. The process of combining a number of attributes or traits into a single breeding decision is setting a breeding objective. The breeding objective should be comprised of all the traits that affect profit plus some indication of the relative emphasis each trait should receive. There is no single bull in a ‘multi vendor sale’ that meets all the needs of producers or their intended markets.

With respect to bull selection, the bull for your herd must first be fertile to pass on the desirable traits to the progeny. Too often beef producers say that they want fertile bulls but pay top dollar for the fattest bull on offer. Reasoning and beauty can get confused! Therefore, the number one criteria must be for a bull to have passed a Bull Breeding Soundness Evaluation as evidenced by an Australian Cattle Veterinarian certificate. The certificate is your passport for greater confidence that he can pass on his desirable genetic traits to produce adequate progeny. For more information see: Bull breeding soundness examination (BBSE). The development of structural soundness genetic differences for leg and hoof conformation and sheath score (in some breeds) will provide marginal benefits in a fertility trait largely influenced by semen quality and mating ability.

To establish the genetic selection criteria, start planning by identifying the relative impact of the various traits affecting: on-farm production requirements; and the market specifications (see table below). An example of these listed criteria across the top of a page could include ‘increasing weaning percentage by 10%‘, ‘increasing weaning weight by 20kg’, ‘increasing P8 fat depth by 5mm’, ‘decreasing calving difficulty by 5%’ and so on. Down the left of the page, list the various selection traits with all honesty; identify which on-farm and market traits are met by the selection criteria. Then across each selection criteria identify how each contributes to your breeding herd performance by satisfying either on-farm or market specifications.

Establishing breeding objectives – areas of significance

The selection decision is based on identifying which bulls, from those available with relevant information, will meet the needs of the herd and enterprise, while balancing the incremental differences in one trait relative to another.

A more definitive method for the process of setting breeding objectives is to qualify the:

• current herd performance for a range of economically important traits
• costs of production in the current herd
• target market specifications
• returns for the traits affecting market specifications
• alternative sires with relevant information to achieve these selection decisions.

A computer program makes easy work for you in matching all the above values. It is called BREEDOBJECT (BREEDOBJECT – Custom Selection Indexes for Cattle) and its output is a $Index that is the combination of the weightings applied to a range of traits identified as important to your production system via a questionnaire. The single $Index is reported as a genetic difference between the animals to which it is applied and quoted as an Estimated Breeding Value (EBV).

Many beef producers have experienced the definite benefits afforded the bull buyer by using the various growth EBVs and fertility EBVs in addition to carcase EBVs. With increased attention to meat quality, more recently, genetic differences have been developed for docility from either: flight speed measures, crush or yard test scores. These are used similar to the regular EBVs with a positive larger Docility EBV being more desirable (available by limited breeds). Since animal temperament is an important component of meat quality, the docility EBV will be incorporated with the DNA markers for tenderness to produce a tenderness EBV in the near future. This is currently available for Brahmans. Likewise for marbling, the ultrasound scan measures for percentage intramuscular fat have been available for some years. However, the introduction of DNA markers for marbling (currently 4) will enable the combination of the ultrasound measure with the DNA result to produce a single EBV for percent intramuscular fat.

Recently, beef producers have had increased opportunity to use new technologies additional to BREEDPLAN EBVs and a Bull Breeding Soundness Evaluation in their selection decision. These technologies include DNA markers for marbling and tenderness, flight speed measures for temperament, feeding pen trials or blood tests for net feed intake and the polled gene test. The often-agonizing question for commercial beef producers is ‘How much emphasis should I place on the various tools when making a selection decision?’ Or do we believe there is a single ‘magic bullet’ that will be the answer to all decisions?

Never before has cattle breeding had so many opportunities for selection. The completion of the cattle genome will further enhance the identification of additional markers to better quantify the attributes of each trait. However, the basic criteria remain the same for setting breeding objectives with the need for beef producers to remain objective and focused on traits that are heritable and of economic importance to their business.

John Bertram, formerly Queensland Government.