B. Bech Andersen

Performance testing of bulls in AI: Report of a working group of the commission on cattle production

Abstract Performance testing of bulls for AI has been an important factor in cattle-breeding plans in Europe. An EAAP working group was set up to evaluate the standards and to set up new recommendations. The potential traits for testing and selection are described. The main traits are growth rate, feed efficiency, appetite, and carcass properties. Genetic parameters for these traits are given (Table I). The effect of the adaptation period, age and length of test are discussed with particular reference to the role of the feeding system in relation to the correlated responses of selection for growth rate. A survey was undertaken amongst the EAAP countries on facilities for testing, breeds, ownership, housing and feeding systems, starting points and length of tests (Tables II–IX). General recommendations for performance-testing techniques and presentation of results are given for both dairy/dual-purpose and beef breeds. Finally, the need for further research is discussed. This deals both with improvement of testing techniques and the relationship between performance-test results and the productivity/efficiency of male and female progeny in the field.

Comparison of ultrasonic equipment for describing beef carcass characteristics in live cattle (Report on a joint ultrasonic trial carried out in the U.K. and Denmark)

Abstract An experiment was conducted in Britain and in Denmark to obtain information on the potential of different ultrasonic equipment for describing body composition in live cattle. The following machines were tested: the “Scanogram”, the “Danscanner”, the Ohio Nuclear “Sonofluoroscope”, the Philips “Diagnost R” and the Bruel and Kjaer “Revolving transducer system, type 3402”. In Britain, thirty cattle, and in Denmark, twenty cattle, were scanned twice with each instrument. After slaughter, one side of each carcass was separated completely into lean meat, fat and bone. The repeatability of the scanning results was highest at the 1st lumbar vertebra position and higher for fat than muscle measurements. Correlations between ultrasonic measurements and corresponding carcass cut face measurements at 1st lumbar vertebra ranged from 0.52 to 0.81 for fat area and from 0.53 to 0.71 for area of M. longissimus dorsi . The percentage of lean in the carcass was best correlated with fat measurements, whereas muscle area was best correlated with dressing percentage and lean/bone ratio. Between the machines there was only a small difference between the correlations averaged over interpreter, location and origin of cattle. Among the operators, however, there was a preference for the “Danscanner” and “Scanogram”, which are specifically constructed for used on farm animals. It was concluded that those starting scanning work should know the anatomy of the relevant parts of the animal, receive training in the use of the equipment, ensure a good back-up service and arrange periodic checks of the accuracy of their measurements.

In vivo estimation of body composition in young bulls for slaughter. 1. The repeatability and reproducibility of a scoring system, an ultrasonic scanning technique and body measurements

Abstract The repeatability and reproducibility of a scoring system, a scanning technique and body measurements were studied. Almost every trait studied showed significant differences between classifiers, operators, technicians and day of measurement. Repeatabilities, indicating the magnitude of effects of measurement error and day of measurement, were satisfactory (0.6–0.8). Reproducibilities, indicating the additional effect of classifiers, technicians or operators, were also satisfactory, except for fat covering (0.14), muscle area (0.41), width of chest (0.58) and depth of chest (0.30). These low reproducibilities were mainly due to large differences between classifiers, operators and technicians. A valid comparison of different experiments cannot be made on the basis of repeatabilities and reproducibilities themselves, but should be done on the basis of the underlying components of variance.

In vivo estimation of body composition in young bulls for slaughter. 2. the prediction of carcass traits from scores, ultrasonic scanning and body measurements

Abstract The prediction of carcass composition from in vivo scores, ultrasonic scanning and body measurements was studied. Carcass composition differentiated between traits related to the commercial value (fleshiness, fat covering, dressing % and price per kg) and traits determining the composition (% lean, lean/bone, lean/fat ratio). Due to the low variability in the material, relationships between in vivo and carcass characteristics were low. Fleshiness and price per kg of the carcass were best predicted by in vivo scores with residual standard deviations (r.s.d.) of 0.75 class (scale 1–15) and Dfl. 0.24 per kg, respectively. Fat covering and lean/fat ratio were best predicted by in vivo scanning data (r.s.d. 0.82 (scale 1–15) and 0.61). Lean percentage was affected only by weight (r.s.d. 1.78%). Body measurements were poorer predictors than in vivo classification and scanning measurements.

Recent experimental development in ultrasonic measurement of cattle

Abstract Principles of different ultrasonic equipment are described, and a review of the latest experimental results with Krautkramer, Scanogram and SVC equipment is given. It is concluded that the Scanogram equipment provide a good description of the subcutaneous fat layer and the muscle area. The SVC scanner gives the most accurate measurement of the muscle area, and the SVC measurement has the same relation to the carcass composition as the corresponding carcass eye muscle area. Ultrasonic measurements are included in Danish performance tests of potential A.I. bulls.

Main report - E.A.A.P. working group on: efficiency in the dairy cow.

Abstract In both scientific work and in the planning of breeding programmes, feeding schemes etc., the definitions of biological and economic efficiency and optimization procedures are important. So too is knowledge and understanding of the relationships between the variables involved. Therefore, the Commission on Animal Genetics and the Commission on Animal Nutrition within the European Association of Animal Production set up a working group with the purpose of stimulating the development and use of a common language (definitions etc.) among animal geneticists and nutritionists working on increased efficiency in the dairy cow for production of milk, milk fat, milk protein, and the connected beef production. Efficiency can be defined as the ratio of output/input, with output and input given in a variety of units, biological, physical or financial. Using the term “efficiency” requires a clear definition, both of the term chosen and of the system studied. Definitions concerning nutrition and breeding are given and recommended with respect to primary and secondary traits as well as an overall selection index. A few examples are: (1) residual food intake, a minus b, estimated energy in feed intake, minus estimated energy in products (milk, gain and foetus) and for maintenance; (2) feed efficiency, b/a; (3) economic efficiency, the net income per unit of product (e.g. milk). The improvement in biological efficiency is important, and research has to be focused on the underlying processes such as rumen function, utilization of digested and metabolized energy and the partitioning of feed energy between milk and body tissue. Knowledge about genetic variation between animals for these different biological processes is very limited, and should be studied in relation to the composition of feed ration, the feeding strategy and the physiological state of the animal. One-sided genetic selection for milk yield capacity is seen to have a negative effect on feed efficiency, reproduction and health, while the feed intake capacity does not keep step with the requirements for the increasing yield. Under these circumstances the net income per kg milk is decreasing, when calculating according to the overall economic efficiency. Therefore it seems essential to include secondary traits in dairy-cattle breeding programmes. This, however, requires extensive and demanding field data recording, and more research is needed to explore the effect of direct selection for improved feed efficiency and feed intake capacity and to develop a consistent approach to indexing for multiple trait selection. The issue is complex, and there is a great need for cooperation between countries and institutes.

Performance testing of bulls for efficiency and beef traits in dairy and dual-purpose cattle. Report of an E.A.A.P. working group

Abstract The working group conducted a seminar in Wageningen, The Netherlands, in April 1987. The objectives of the seminar were: 1. (1) a review and an exchange of results and experiments about performance testing of bulls in dairy and dual-purpose breeds; 2. (2) recommendations for testing procedures and further research needs. The comparison of performance test results with male progeny under different environments showed a clear positive relationship. It was concluded that performance tests should be comparable with the prevailing conditions the progeny have to fulfil, especially with regard to test period length and feeding intensity. Preliminary results from Denmark and The Netherlands about the relationship between performance test results and female progeny for feed efficiency indicated a slight positive relationship. Metabolic and immunological parameters (in connection with a challenge) of young sires may provide indications to metabolic stability in production and diseases. The estimation of breeding values for beef were discussed. The economic aspects of beef production in dairy and dual-purpose breeds were discussed under the EEC-situation with milk quotas. The studies presented showed that performance testing of young bulls is a useful approach to improve the efficiency of production. The papers of the seminar are available as E.A.A.P.-publication No. 34 (ISBN: 90-220-0924-6).

Offal components, body fat partition, carcass composition and carcass tissues distribution in Danish Friesian cull cows of different age and body condition

Abstract Quantification of offal components, carcass composition and partition of major tissues (fat, lean and bone) in cull cows of different age and body condition class is the goal of this study. For this purpose 98 Danish Friesian cull cows were divided according to their chronological age into three groups: “very young” ( 4.5 yrs) and three body condition classes: “thin”, “normal” and “fat”. After slaughter offal components including emptied gut were weighed and the carcass was jointed into first, second and third quality cut groups. They were dissected into lean, fatty tissue and bone. “Very young”, “young” and “mature” cows, independent of their condition class showed little variation in their carcass composition, body fat partition between carcass and offals and bone and fat distribution between categories of major cuts (P>0.05). However, “mature” cows had significantly lower percentage of total lean in the first quality cuts and greater percentage in the third quality cuts. Independent of the cows age, improvement of body condition resulted in a lower percentage of total fat in the carcass but more around the kidneys and intestines. The carcass has less lean and bone and more fat with proportionally less lean and fat occurring in the first quality cuts.

Performance testing of future A.I. bulls for growth rate, feed efficiency and muscularity. Genetic parameters, adjustment for systematic environmental factors, selection indices

Abstract Based on data from 2217 bulls distributed among 296 sires and four breeds from the Danish performance testing system, genetic parameters have been estimated for growth rate, feed efficiency and muscularity. Muscularity was measured on the live animal with ultrasonic equipment. The heritability of daily gain and muscle area was estimated at 0.53 and 0.71 respectively. The estimate of the genetic correlation between daily gain and muscle area was negative (−0.30). This is probably caused by the large gene import from North America giving higher daily gain and lower muscle area. When correcting for systematic environmental factors it was necessary to use linear models, instead of the often used rolling average for each trait and test station, to avoid bias from single heavily used bull sires. Selection on a multiple trait index for daily gain and muscle area simultaneously resulted in a 1.6–2.7 times higher total expected economic progress, compared to selection on daily gain or muscle area alone. The multiple trait index did not change birth weight. The total economic response was insensitive to changes in the economic weights, while the correlated responses in daily gain and muscle area were very sensitive. Hence if the economic weights chosen do not deviate too much from the true weights, biological considerations (which type of animal is desired from a biological point of view) rather than economical considerations determine which economic weight should be used in the index.

Cattle breed comparison and crossbreeding trials in Europe; A survey prepared by a working party of the European association for animal production

Abstract A Working Party of the European Association for Animal Production surveyed the breed comparison and crossbreeding trials which were being carried out in Europe. The survey summarizes the experimental work in the different countries and gives details on 86 separate projects concerned with breed and strain evaluation in pure and crossbreeding situations. The paper gives a general summary of the survey and recommendations on the methodology for future experiments. More detailed abstracts of the individual trials included in the survey are obtainable on request.