To a better knowledge of cattle growth

Press, Issue 32535, 19 February 1971, Page 13

To a better knowledge of cattle growth

From a better knowledge of the body composition of beef animals people would have a better understanding of how to produce a greater variety of beef, and in Australia he believed that their future would depend on a greater ability to take advantage of markets that cropped up, Professor R. M. Butterfield, dean of the faculty of veterinary science and professor of anatomy at Sydney University, told a meeting held at Lincoln College this week under the auspices of the Beef Breeders’ Research Committee and the New Zealand Sheep and Beef Cattle Survey.

Professor Butterfield who was discussing the. results of work involving individual muscle dissection of beef animals, said that if it was desired to keep an animal for a particular purpose then it should be selected for that purpose. But while geneticists and many stud breeders agreed that to make progress in selection the number of criteria that were selected for must be kept to a minimum, when an examination was made of the standards of excellence of breeds of livestock it was found that the opposite state of affairs existed, with a mass of criteria spelt out to ensure that progress, if any, would be very slow. Why did the stud breeder cling to this system which guaranteed only slow change? He was no fool. He did it because noone had yet convinced him that he could safely depart from the system that would, at least, guarantee the sale of bulls which were good to look at in the eyes of those who had been calibrated in the same system. It was necessary to convince the breeder that he could reduce the number of selection criteria without landing himself in trouble. It was here that anatomical studies of the process of growth could play a large part in defining just how animals grew and what could safely be done to alter this growth. It should not be forgotten that everything in anima! production resulted from this process of growth, about which very little was known.

The basis of much of the work they had done in Sydney and Brisbane had been an individual muscle dissection technique, he said. They claimed no originality in this approach to body composition research and in tact the first use of it seemed to have been made in New Zealand at Ruakura by Miss Walker. It had disadvantages in the eyes of some people. It was slow and tedious to them and it was also claimed that the meat trade dealt in meat and not muscles and therefore it was a method that was out of touch with the industry. But Professor Butterfield said that by dealing with individual muscles and bones and with fat in various specific locations they were able to piece together the functional systems and it soon became clear that within these systems there were definite patterns of growth which were never revealed to the worker whose efforts were confined to cuts of meat.

To illustrate the pathway by which they became involved in the use of anatomical techniques, Professor Butterfield recalled the study of a single characteristic of beef carcases. He said that many people had been concerned at the inroads Brahman cattle were making into the cattle population of Queensland about 10 years ago—they were interested in the effect that these odd-shaped animals would have on the proportions of red meat which would be available from various parts of the C&TC&S6. A dissection of a group of Brahman cattle and a group of British Polled Hereford cattle and a group of the worst looking steers from a property where no new bulls had been introduced for at least 70 years showed that in all cases 56 per cent of the total muscle weight was from the expensive regions of the carcase. At first it seemed that this was a surprising result, but it now seemed quite sensible. All steers performed similar functions—they all walked and in fact did little else. Would ft be expected that they would develop very differently in a system whose prime function was that of locomotion? From this he believed that they could say that if an animal had well developed muscles on one part of its body it would

have well developed muscles all over its body. This then should help considerably in reducing the number of criteria that were looked for in an ideal beast. There was no need to place great emphasis on development in one region or another. Professor Butterfield said that the best place to get a visual indication of whether there was muscle development and not just fat was on the forearm rather than anywhere else. This was an area that a lot of good butchers looked at. Reporting on a further study to see how muscles grew in young cattle, he said it soon became apparent that there was a marked relationship between the growth of any muscle and its function, so that in the case of the muscles of the abdominal wall there was a group of muscles which did not have a great deal of use in the calf at birth but whose function developed rapidly as the calf started to fill its digestive tract with food. So in the calf immediately after birth there were muscles growing at all sorts of different rates but by the time the calf had quadrupled its birth weight and was about 200 to 2501 b it had reached a stage where nearly all of the muscles in the body had settled down to grow at a very uniform rate. From here on they were dealing with one large mass of muscle all growing at about the same rate, except for some muscles of the neck, which in the entire animal were affected by puberty and began to grow at a more rapid rate in the male. There could, therefore, be no advantage from a muscle weight distribution point of view in slaughtering animals at any particular weight once they had gone past this very early stage. This had been the theoretical basis on which

they had developed their interest in the growth of meat animals. The question was now how they could manipulate the growth of animals to make the best use of their carcases without interfering with other productive characteristics. By the same process of dissection of a lot of other cattle they had decided how they could alter cattle if it was in their interests to do so to suit markets for beef. And with the wide variety of markets becoming available this was surely the secret of success in the beef industry. Looking at the factors which affected the body composition of the beef animal, Professor Butterfield said that the first of these were genetic factors and the first among these was early maturity. By this they meant an animal which reached a mature stage of development of body tissue at a low body weight—it began to lay down body fat having largely completed its growth of body muscle and bone. This had been and still was a very desirable characteristic in cattle under many conditions, for in spite of the genera! clamour for lean

meat there was nevertheless a requirement from most consumers that a certain level of fatness be reached to give them the optimum quality in meat. These early maturing types of cattle had proved to be extremely valuable in those areas of the world where the nutrition was of a stopgo nature.

The limitation of these early maturing cattle, however, Was under conditions where the available foodstuff was in such constant and heavy supply that they tended to over-fatten at weights which were too light for economic marketing. So late maturity was all. the rage these day. These were animals which were capable of absorbing a very constant and heavy nutritional intake without becomint over fat at light weights. The Friesian was an example of this type of cattle. However, people were also now very concerned to obtain other breeds of cattle with late maturing characteristics along with heavier muscle development, and so such animals as the Charolais, Limousine, Chianina, etc., were becoming popular. A third late maturing type were the double muscled cattle, which were genetic freaks and which had particular advantages in certain specialised markets, but in this context Professor Butterfield added a word of warning—it was not terribly difficult to breed the ideal carcase but it was not of much advantage if the ideal animal was bom dead. Turning to nutritional factors, Professor Butterworth described experiments to study the effect of fast versus slow growth on body composition. Three groups of calves were fed at very different rates but they found again at the same weights these calves had the same proportions of muscle, and it was also found that the rate of growth did not affect the ratio between muscle and bone. “Undoubtedly there are important differences in bone shape and length between the treatments, but their weight relationship held good." ,