In suckler beef production it is estimated that 55% of the total cost is required to maintain and replace the breeding females while only 1095 of total feed energy intake is stored in the tissue of the calves and cows. The low reproductive rate of the cow is primarily responsible for this low efficiency. Even in a well managed herd, weaning rate Is about 0.95 calves per cow per annum or less. It Is frequently hypothesised that increasing litter size by inducing twin calving would increase output, biological and economic efficiency provided few extra Inputs were required. Although twinning may increase the efficiency of beef production, spontaneous twin-calving is frequently associated with an Increased incidence of calving problems, poor calf survival, retained placentae and longer rebreeding intervals. Such problems related to twin-calving cannot be studied unless the frequency of twinning is increased above the levels that occur spontaneously. Embryo transfer can be used to Increase the frequency of twin calving thus allowing a better assessment of the potential to Increase output. A suckler herd, with a high level of twinning, was established to determine the effects of litter size on calving performance and calf survival rates.

The advent of twinning in suckler cows, through the application of multiple ovulation and embryo transfer techniques has provided a means of increasing the biological efficiency of the suckled calf system of beef production. However, even with improvement in output the need remains for twin-bearing suckler cows to be fed economically. This can be achieved by making effective use of summer and autumn grazing which on most farms provides a high plane of nutrition and allows the cows to increase their body reserves. This generous level of feeding may be followed by more stringent and controlled feeding in winter and early spring, when conserved feeds, grain and by-products are fed. This restriction leads to a reduction in feed costs and also to a depletion of the accumulated resrves.

Recent developments in in vitro fertilization and embryo transfer technology (Lu, et al, 1987) have facilitated the production of twin, continental cross calves from the dairy herd through non-surgical embryo implantation. However, the successful exploitation of this technology in practice requires information on the effects of embryo transfer and/or twinning on animal performance and how these effects may be influenced by feeding and management factors. The objectives of this study were to examine the effects of different management and feed regimes pre- and post-calving on the performance of single- and twin-bearing cows.

A greater use of clover based grassland systems seems likely in future as policies promoting more extensive use of land are adopted by Government at both national and EC level. At Aberdeen a comparison between clover-based and conventionally fertilised systems was carried out over six growing seasons from 1981. The objective was to compare the beef output from two similarly managed farmlets differing only in clover content and fertiliser input. Results are presented here for performance obtained from the grazed swards over this six year period.

It is frequently hypothesised that Increasing the litter size of the beef cow would increase output and biological efficiency. Such hypothesis is supported by the simulation study of Guerra-Martlnez et al (1987), which Indicated that twinning would Increase biological and economic efficiency of beef production by 20 to 25%. However, there is little published data on the comparative growth rates of single-born, single-reared and twin-born and twin-reared beef calves. The objective of the present study was to determine the effect of birth type (single or twin) on growth rate from birth through to beef and on final carcase weight, carcase conformation and fatness level.

Current scientific progress in the understanding of animal welfere is resulting in the possibility of realistic assessments of welfare and the application of such assessments. Understanding has been advanced by the recognition that welfare is not a unitary variable but has different aspects, which may be compromised independently. Some problems which arise, such as injury and disease, also reduce production and may be covered by veterinary and production science. Others, though, such as behavioural restriction and stress, do not affect production so clearly. There is increasing input to these areas from behavioural science and physiology. Ethology has contributed theoretical insights into the control of behaviour, basic knowledge of the behaviour of farm animals and comparisons between different environments (e.g. intensive, extensive and feral). It has also highlighted occurrence of abnormal behaviour, such as stereotypies and cannibalism, in some circumstances. To investigate causes of abnormal behaviour, though, observation must be complemented by experimentation, and by behavioural physiology and neurophysiology. These are now producing notable advances in our understanding of stress. Experimental work is also progressing on motivation for normal behaviour, such as feeding,and for different features in the environment. With increased understanding of different aspects of welfare comes a move away from unrealistic expectations of unitary welfare meesurements or indices, and towards an acceptance that there are scientific grounds for abroader assessment. Further, there is increasing recognition that assessment of welfare has a valid, scientific role in the design end management of housing and husbandry systems for our farm animals.

There is a common misperception that economics is about money. People holding this view will expect a paper on the economic aspects of animal welfare to quote various financial figures representing the effects on the costs of production, or on the consumer prices of animal products, from adjustments in production methods designed to ‘improve’ the welfare of farm livestock. Under such a view it would seem that better animal welfare is a cost to people, but a benefit to animals.

However, this is too simplistic a view of what economics is really about. Economic analysis is built up from a model that treats all economic activity as a series of resource-using processes undertaken to benefit people (considered collectively, not any particular subgroup) . Livestock production is one such economic process. It takes resources (land, feed, labour, animals, veterinary services, etc) and transforms them into commodities that people want - milk, meat, eggs, wool, etc. In economic terms, livestock production is simply the exploitation of animals for human benefit. Logically, any change in this process which is subject to decision (as opposed to factors outside human control) will only take place if people want it.

There is mounting concern for the welfare of farm animals in all the countries of the European Community and the members states of the Council of Europe. The rapid increase in intensive management systems of poultry, pigs, cattle and fur-bearing animals has been the subject of heated debate in every European country. The publication of Ruth Harrison's book, Animal Machines, a quarter of a century ago, can now be seen as the starting point for the increasing demands for legislation to control what are seen to be new and unnecessarily restrictive ways of keeping farm animals. In the United Kingdom, as long ago as 1965, the Brambell Committee made recommendations that were largely ignored. Animal welfare societies increasingly called for legislation to control the situation. Society generally, on the other hand, welcomed the provision of cheap eggs, cheap poultry meat and relatively cheap dairy products.

It is likely that returns from lamb production in future will depend, much more than at present, on producing leaner carcasses. There are several short-term changes in management which could produce leaner carcasses. However, In the longer term genetic Improvement, particularly by within-breed selection In terminal sire breeds, is likely to provide permanent, cumulative and cost-effective benefits In carcass composition. In the early 1980s a research project was started at the Edinburgh School of Agriculture, using Suffolk sheep, to examine the genetic potential for Improving carcass composition In terminal sires. The work commenced with an evaluation of techniques for in vivo measurement of carcass composition (Simm, 1987) and derivation of selection indices to incorporate In vivo measurements (Simm and Dingwall, 1989). Since 1985 In vivo measurement and Index selection have been practised In the experimental flock, which now numbers about 220 ewes. This paper reports the interim results of selection.

Selection is an important component of animal breeding theory. Directional selection is used extensively in animal breeding programmes as a method of obtaining genetic improvement. Much of the theory used to explain the consequences of selection assumes that the quantitative traits under consideration, eg. leanness or index scores, are under the control of many genes with small effects (polygenes). However, many traits are under the control of both polygenes and a major gene. Conventionally, the expected response to index selection is taken to be R=ih2σp, where σP is the phenotypic standard deviation of the index, h2 its heritability and i the intensity of selection. The intensity of selection is the expected mean of the index scores of the selected animals and has been tabulated by Falconer (1989).

In the UK feed accounts for 0.80 to 0.90 of the variable costs of dairy production. In recent years the imposition of milk quotas has served to emphasise the importance of efficient milk and milk solids production. In field progeny testing schemes, sires’ transmitting ability or breeding value can be predicted for milk production traits, but not for feed Intake or for efficiency of milk production. As breeders continue to select on production traits, using sires of high genetic merit for production, the important question then is, ‘what correlated response occurs in gross efficiency and in feed consumption?’.

Litter size in swine, although lowly heritable, has been receiving increasing interest especially with the availability of computer programs to allow estimation of genetic merit for this trait using family information. Genetic changes in a trait over time can be monitored by estimating best linear unbiased prediction (BLUP) of breeding value for individuals exhibiting the trait. Data from a recording programme within a Canadian province allowed estimation of genetic and phenotypic trends for three measures of litter size.

Data from purebred Yorkshire and Landrace litters were obtained from the Quebec Record of Performance Sow Productivity Program. First parity litters born between 1977 and 1987 were analysed for total numbers born, numbers born alive and numbers weaned. Data were edited to include only herds with ten or more litters in Yorkshire and 40 or more litters in Landrace. Also, in order to reduce the number of records further, due to computing limitations, a sow was only allowed one daughter per full-sib family. A total of 2024 Yorkshire gilts (from 467 sires and 1539 dams) and 1920 Landrace gilts (from 421 sires and 1436 dams) provided records.

Factors which affect the carcass composition of beef cattle include breed type, plane of nutrition and slaughter weight. With increasing weight, the relative proportions of the carcass joints and tissues change and if these changes were known or could be predicted then cattle could be slaughtered at the desired carcass composition. Dairy bred calves for beef production can be classified into three breed categories -straightbred Friesians, early maturing beef breed x Friesians and late maturing beef breed x Friesians. The objectives of the present study were to compare the changes in carcass composition associated with changes in slaughter weight in Friesian (FF), Hereford x Friesian (HF) and Charolais x Friesian (CF) steers and to determine the effects of dietary metabolisable energy (ME) content.

The application of milk quotas has stressed the importance of maximising the financial margin per litre of quota as well as those margins calculated on a per cow or a per hectare basis. Since quotas were Introduced there has been a move towards exploiting the value of high quality forage by reducing the amounts of compound feed supplementation. However, low amounts of compound feeding in early lactation can cause ketosis or can reduce fertility. So many farmers with autumn calving cows have tended to feed high amounts of compounds for the first three months of lactation and then, about the end of the calendar year, decide whether changes in feeding are necessary to meet quota targets for the last quarter of the year.

Milk producers in the UK are paid according to their production of milk fat, protein and lactose. The production quota system also includes an element restricting fat production. It is therefore important to be able to predict the changes in production of milk solids arising from changes in feed inputs. There are few published predictive models for this purpose (e.g. Sporndly 1989, Emery, 1978) and none under UK conditions. This is a preliminary study to identify and quantify some of the factors affecting yields of milk constituents as a first stage in the development of predictive models.

Previous research at the Agricultural Research Institute of Northern Ireland has shown that equivalent milk yields can be obtained by feeding high levels of low-protein supplementary concentrate or low levels of high-protein supplementary concentrate. The latter may be due to an increase in dry matter intake and thus energy available for milk yield (an indirect effect) or an increase in amino acid supply from increased protein in the diet (a direct effect) or a combination of these. The experiment compared the effect of varying levels of protein supplement on rumen fermentation characteristics in lactating dairy cows.

There is evidence from a range of experiments of increases in milk production, including improvements in milk protein content, to additional dietary inclusions of low degradability ‘animal’ protein sources. This experiment was designed to examine the effect of stage of lactation on the response of dairy cows to increased dietary protein.

The continuous design experiment was conducted with 20 individually fed autumn calved dairy cows and four heifers over the first 26 weeks of lactation. The animals were fed initially a ‘standard diet’ of silage ad libitum and 8 kg (freshweight) of concentrate per day up to the 14th day of lactation. The cows were then allocated to four balanced groups of five cows (and one heifer) on the basis of lactation number, body weight and current milk yield. The data recorded during the first 14 days were used for subsequent covariance analysis.

Augmenting the supply of specific amino acids to pigs and poultry is straightforward cbinpared with ruminants where fermentation in the forestomach may reduce the proportion of the supplement which ultimately reaches the small intestine. Recently there have been several attempts to develop amino acid supplements which escape rumen degradation, thus optimising the increase in duodenal amino acid supply. The work reported in this study provides an in vivo assessment of one such product - namely lysine and methionine coated with a pH sensitive polymer.

Major changes have taken place in the British pig slaughter population over the past 10 years. There has been a dramatic change in average fatness, entire males have almost replaced castrated males and specialist Meat Sire lines are having an increasingly significant effect. MLC's First Stotfold Trial was carried out to examine the effects of these various factors and provide a database of information for decision-making by the major breeding companies and the industry as a whole.

The introduction of new breeds, genetic progress in traditional breeds and the slaughter of entire males have helped reduce average P2 backfats by 0.5mm per year over the last 10 years. In the early 1980's, there was growing industry concern over the possible reduction in eating quality by the production of very lean pigs and entire males. The Meat and Livestock Commission's first Stotfold trial included an examination of these issues.