Raising Standard Of Beef Cattle

Press, Volume CIV, Issue 30739, 1 May 1965, Page 8

Raising Standard Of Beef Cattle

It was quite possible to select beef animals which not only had a growth rate much above average but which also had superior conformation, Mr M. G. Bollard, a senior lecturer in animal science at Lincoln College, told beef cattle men attending a beef field day organised by the New Zealand Aberdeen Angus Cattle Breeders’ Association on the property of Mr F. F. Wilding, Te Mania, Hundalee this week.

Mr Bollard was speaking in favour of performance testing and recording in improving beef cattle.

The potential of beef cattle in New Zealand had been barely scratched, said Mr Hollard. The market prospects appeared to be excellent and there certainly had been a marked increase in the number of beef cattle over the years. However, not enough attention seemed to have been paid to efficiency in production of beef. This was common to all beef producing countries but there were moves afoot everywhere to provide the basic data necessary for improvement of beef cattle. Lincoln College believed it could play a useful role in this respect, even if it meant merely repeating other people’s work in the meantime, but in addition it had had the pleasure of the co-operation with Mr Wilding in launching his weight recording scheme and sharing in his enthusiasm for this kind of work.

There were many traits Which were important in beef cattle including calving percentage, growth rate, feed conversion efficiency, type and carcase quality. The show ring had been important and had had far reaching effects on the improvement of beef cattle, and because of the influence of the show ring they had come to recognise the early maturing, well muscled beef carcase of today. In the future the show ring would remain important in breeding beef cattle in seeking better conformation and breed type, but this was only part of beef cattle improvement.

Performance data was essential to evaluate the traits contributing most to efficiency of production. Performance testing must be on a withinherd basis because there was no adequate way of allowing for the difference in the feeding and management between herds, but within herds performance data could be used for-comparing progeny groups not only for growth rate, but for all traits of value. The latter included increased fertility, heavier weaning weights, increased rate of gain and feed conversion efficiency, better conformation and muscling and less wasteful outside fat, and a long productive life span. All these traits were important but breeders would differ in regard to the amount of emphasis placed on each.

There was no doubt, whatever, that tremendous improvement in beef cattle had been made over the last 150 years or so. Modern beef cattle were very different from the long horns of those times. This improvement was a tribute to the breeders concerned. but further improvement in pedigree beef cattle required rather more refined methods.

Genetic improvement was made by selecting the inherently superior stock and by mating these seleceted animals in a well-planned fashion. The rate of progress achieved would depend on the heritability of the character, the selection pressure applied and on the rate of generation turnover.

Sound facts and evidence were essential for a constructive breeding policy. In this regard much data had already been collected overseas. For example, heritability estimates were available for ‘most production

traits. Heritability was the portion of the difference observed between individuals fed and managed alike that could be transmitted to offspring. For example, two bulls might differ in their yearling weight by 1001 b, and with a heritability of 50 per cent for live-weight at this age then 501 b of the observed difference was due to genetic factors.

Heritability figures available were for fertility 10 per cent, birth-weight 40 per cent, weaning weight 30 per cent, growth rate 50 per cent and lean in carcase 60 per cent. On these figures those for growth rate and lean in carcase were particularly high and this meant that substantial progress could be made in breeding for these two traits.

Heritability estimates showed the portion of observed differences that were due to genetic make-up and enabled an assessment to be made of the rate of progress that could be expected from selection.

Fertility, for example, .with a low heritability, could be best improved by paying more attention to feeding levels and disease incidence, whereas growth rate would respond to direct selection. But accurate records were essential. Important Repeatability was an important allied concept. This was the extent to which performances on successive occasions were similar. Mothering ability, for example. was highly repeatable and thus cows which had heavy weaners in one year were likely to have heavy weaners every year

This meant also that culling of cows could safely be carried out on the basis of only one or two records of weaning weights. Further heifer replacements could be selected on the basis of only two or three records for the dams.

There was no doubt, whatever. that conformation was economically important, although opinions and standards of excellence would vary from breeder to breeder. Conformation had a bearing on carcase value, structural soundness and reproductive efficiency.

Longevity was important in beef cattle, but was associated more with herd health, feeding and management than with heritability. Fertility was important, but it was more affected by good feeding of young stock and during the service period by freedom from disease than by any heritable factor.

Mothering ability was important and was moderately heritable. The milk supply of the dam was the big factor involved and this accounted for 50 per cent of the difference in weaning weight between calves. The growth potential of both sire and dam was also important in weaning weight, so it was worthwhile to use bulls which themselves had heavy weights at weaning.

Records could be most efficiently used for these purposes: selecting replacement heifers out of the best cows: selecting heifers sired by through the selection of the bulls which themselves had heavy weaning weights: and culling the lowest 10 to 20 per cent of the cows after one or two records had become available. Great importance could be placed on the performance of the first calf of a heifer because this would give a most useful guide to her performance in later years. Hence culling heifers following the collection of the weight at weaning of her first calf could be a sound practice. Bulls should be selected for breeding if they had heavyweaning weights and a good

- growth rate and then should ■be progeny tested before t being used too widely. It was : herd sire that most genetic • progress would accrue. This ■ was because the sire contriI buted half the genetic makeI up of each calf. Also whereas • 40 per cent of the weaned • heifers would be required for ; replacements, only 1 or 2 per cent of all the weaned bulls • would be required for use f within the herd. Hence much - more discrimination could be t used in the selection of the - sire. : Records could be corrected ■ with appropriate factors to make them more comparable. 1 taking into account the age of the calf at weaning, the sex • of the calf, and the age. and ■ hence the milk supply of the I dam.