By. A. T. Stubbs
YOUR day at the bull sale could be one of the most important, from a cattle breeding point of view, that you will spend this year. In the few brief moments of bidding for a bull you may be determining 80% of the genetic future of at least part of your herd. Since a bull may sire so many more progeny in his lifetime than a cow can produce in hers, his influence on future calf crops is much greater than that of individual cows. Add to this the fact that bulls can be selected much more intensively, or putting it another way, can be culled much more heavily than heifers because relatively few are required as replacements, then it can be seen that the genetic influence of the bull is of first importance in a breeding programme. Most breeders have a good idea of what they are going to look for in bulls. Let us take a look at the points to consider, decide on their importance and see how they may be checked out.
FERTILITY – Clearly the bull must be fertile, and highly fertile at that. While the heritability of fertility is not generally considered to be high and it is well known that management, particularly nutritional factors, largely governs herd fertility, there is substantial evidence to show that sub-fertility can be, and is passed on genetically. For this reason, it is prudent to carry out whatever checks can be made. An examination of the lifetime calving record of the bull’s dam is advisable, taking note of both regularity of calving and of date of calving, or calving interval. Semen testing for fertility is usually carried out prior to using bulls in the breeding herd. It does not replace the need to examine the dam’s record.
GROWTH RATE – This factor is linked with overall feed efficiency and with profitability, and therefore merits the close attention of the breeder. It is also a factor which is highly heritable so that if superior bulls are selected, they may be expected to make relatively large improvements in the growth rate of their calf crops. How can such bulls be identified? Mass per day of age relative to other bulls in the breeder’s own herd is the only satisfactory measure available to the buyer. In the Beef Performance Testing Scheme, yearling mass per day of age (adjusted 550-day mass) is expressed as a ratio, in a similar manner to weaner mass. Differences in feeding levels between herds may make comparisons of mass per day of age bulls from different herds invalid: use of the ratio, however, indicates the superiority of a bull within its own herd group. Again it is advisable to enquire as to the size of the group because high ratios are less meaningful in small groups than in large ones. Information on a bull’s sire e.g. progeny test is valuable, but it is seldom available. Large mature size is often thought to be a desirable feature. The important economic trait, however, is growth rate at a young age. Because more than 70% of total nutrients are used for cow maintenance, large cow size can be a disadvantage unless the cows are proportionately productive.
MUSCLING – Conformation is the most common criterion of bull selection. It is the most readily available and easier to apply. It is also the most subjective since no measurements are involved. The ideal carcass conformation is a well-muscled one and the term “cutability” has been coined to denote the proportion of high-quality lean meat cuts in a carcass. The breeder’s aim is to be able to select bulls with high “cutability”. To do this he must be able to distinguish between muscle and fat deposits in the live animal. It should be noted that certain aspects of “blockiness”, often considered as desirable in the British breeds particularly, are a reflection of fatness, not muscling. It is necessary to concentrate on a few conformation points which are relatively little affected by fat and which reflect muscling. Bulls that are relatively well-muscled are unlikely to be as “square”, deep and smooth as bulls with a high ratio of fat to muscle.
FUNCTIONAL EFFICIENCY – Under this heading one considers the capability of a bull to perform his reproductive function over an extended lifetime. Lest it be assumed that “most bulls should be alright”, some very disturbing results of tests of a sample of bulls commercially available in the USA and in South Africa have shown up surprisingly high numbers of defective animals; of nearly 11 000 bulls examined in Colorado, some 20% had defects which mad them either questionable or unsatisfactory for breeding purposes. NO data is available for this country and one can but hope that the problem is less widespread. Nevertheless, close attention should be paid to functional efficiency points. Testes should be checked by palpation, when they should move easily within the scrotum; there should be no sign of unnatural hardness, swelling, or hypoplasia. [Note: these days we check semen morphology which offers a more accurate measure of testicular function]. Legs are particularly important and should be strong and free moving neither too straight in the hock nor sickle-hocked. Abnormalities occurring in other parts of the body e.g. mouth, back, or eyes may be sufficient reason for rejection of a bull. A degree of masculinity is required, in proportion to age and varying with breed standards. Evidence from South Africa incriminates over fatness as a factor reducing fertility and there would seem to be good reason to discriminate against over-fat bulls.
There are of course many other breeds and conformation points and the emphasis given to these will largely be a matter of individual preference. One of the criteria not mentioned so far is pedigree. For a few buyers pedigree has a place, but it should not take precedence over performance test information. Pedigrees seldom contain economically–important performance information. Bear in mind that a great-grandfather contributes only one-eighth of the genetic make-up of a bull and, in fact, has very little influence indeed. The key factors of fertility, milk production, and growth-rate depend on their assessment on some form of records. Clearly, the bull breeder who keeps good records is in a much better position to supply the information requested by the buyer. Since the only real reason for the existence of the bull breeder is to generate and supply good genetic material to the commercial producer, one would expect his breeding criteria to be very similar to that of the commercial man. In this respect, many buyers could be disappointed if they sought detailed performance records on sale bulls-for the simple reason that often no such records exists. It is interesting to reflect on the super-efficient poultry industry where performance records are the basis of their high powered genetic improvement programs; and to compare that situation with beef production, where too many bull breeders who partly control the genetic resources of the national herd, keep few or no performance records at all. But perhaps not enough commercial producers ask to see records of the bulls they buy! It is surprising how many breeders use excellent cow records then proceed to buy the all-important bull with no performance information at all.
To return to the practical steps in buying a bull, a buyer has to put all the foregoing points together into a “PURCHASE PLAN” The suggested approach may be summarized as follows:
Aim: To buy a good bull, highly rated for economically important characteristics. The aim can best be achieved by a combination of “eyeballing” the bulls and casting a critical eye over their records.
“Eyeball” available bulls to get a general impression
Fertility: Check dams’ fertility records number of calves and calving intervals which should be 365 days or less on average..
Growth rate: Check bulls own 550 day ratios and numbers in ratios. Aim over 100, but check proportion of bull calf crop previously culled.
Having drawn up a “short list” of bulls based on performance records, return to the bulls and “eyeball” for:
Muscling and other conformation points.
To some buyers this “PURCHASE PLAN” may seem unnecessarily detailed, but is it not worth spending a little extra time when buying the key breeding animals on which the genetic future of the herd so largely depends?
A. T. Stubbs, Chief of Animal Production. Conex, July 1975 – Although her husband Tony wrote the above article, permission to use it was granted by Carmen Stubbs. It must be noted that Carmen has been working with and breeding Mashonas for 56 years in her own capacity and is a highly respected cattle woman and breeder. She remains a outspoken and passionate advocate for this breed, maintaining the outlook that she has always had, being that apart from having excellent traits and characteristics, these cattle just look right at home, here in Zimbabwe. She also stresses the importance of record-keeping, and Herdmaster records for her herd go back as far as her foundation herd of 17 cows and one bull.
Photographs provided by Maree Osborne and Margot Worswick