This paper reviews the effects of feeding on milk protein production. It deals, first, with the chemical composition of the milk proteins and the extent to which the composition is influenced by diet, the synthesis of proteins in the mammary gland and the effects of variations in the supply of amino acids and of the energy-yielding nutrients that are absorbed from the gastrointestinal tract. There is then an examination of the impact of changes in dietary energy and protein supply on the content and yield of protein in milk and specific consideration of particular features of ration formulation, including supplementary energy concentrate foods, supplementary lipids and amount and type of supplementary protein foods. Finally, it is argued that the effects of diet on milk protein production are evaluated best simply in terms of milk protein yield; some of the pitfalls of interpreting information on milk protein content in practice are pointed out.

It is concluded that the yield of milk protein is determined by the dietary supply of energy-yielding constituents and protein but that presently employed systems for ration formulation do not provide a satisfactory means of interrelating milk protein yield and the intake of nutrients in the cow's diet.

The problem of demonstrating that animals are consciously aware of their environment or themselves in a similar manner to ourselves has proved to be a relatively intractable one since we have mainly been constrained to rely upon observation of an animal’s behaviour as an index of its awareness. It can usually be argued that even complex behaviours need not necessarily involve an animal being aware of either environmental cues or its response to them. Indeed, simple organisms or computers can perform complex responses to environmental cues when they are clearly not aware of them in the sense that we are ourselves. What can particularly distinguish conscious awareness from simple stimulus-response guided behaviour is the ability of an animal to experience some form of emotional response to an environmental cue or to its own actions. In this review I will summarize some of our experiments on sheep which show that the way their brains process visual and olfactory social and non-social cues from the environment is integrally related to and organized by the emotional significance of what is perceived. I will also argue that the way their brains process complex social stimuli from the environment in order to recognize individuals is very similar to ourselves although these processes are very strongly influenced by changes in their motivational state. From these observations I will maintain that sheep are almost certainly capable of conscious awareness of their environment although perhaps this awareness is mainly restricted to present events and needs with a limited capacity to reflect on the past or future.

Consumer demand for meat is strongly influenced by sensory aspects of meat quality, particularly visual appeal and eating quality. One of the most important of these traits is tenderness which is notoriously complex in origin and hence difficult to control. Potential interactions between diet, pre-slaughter handling, chill rate, muscle shortening during chilling and, therefore, toughness are presented to illustrate the complexity of controlling the trait. The final eating quality result is far from predictable. The Meat and Livestock Commission (MLC) has identified the enhancement of eating quality of beef and pork as important objectives for industry. It has produced and tested blueprint specifications which aim to summarize the ‘best state of the art’ regarding eating quality at each stage of the production and processing chain. The strengths and weaknesses of this approach are discussed. The standard blueprint specification for pork produced an improvement in tenderness of 0.6 scale points (P<0.001, scale = 1 to 8) over random retail purchases of pork chops and a significant reduction in variance. However, considerable residual variation remains, providing the opportunity for greater improvements to be made in the future.

The short-term regulation of intake is thought to be achieved at least in part by signals from the gastrointestinal tract. Infusions of glucose, protein hydrolysate or emulsified fat into the stomach, and of glucose or protein hydrolysate into the duodenum, jejunum or ileum caused pigs to reduce their intake to compensate approximately for the energy infused, probably through the regulation of gastric emptying. Protein or protein hydrolysate infusions also caused a long-term inhibition of intake for 30 h by up to three times the energy infused. During feeding gastric emptying occurred at a constant rate of calories, the rate increasing linearly with body weight; duodenal infusion of glucose slowed gastric emptying to compensate for the infused energy and satiety occurred at a reduced food intake but at the same stomach volume. Duodenal infusion of emulsified fat caused a greater than caloric inhibition of intake, which was blocked by the cholecystokinin (CCK) antagonist L-364,718 and appeared to be mediated through a mono-glyceride-induced CCK release. Emulsified fat infused into the duodenum slowed gastric emptying by more than the energy infused and the gastric volume at satiety was decreased suggesting that the effects of fats on intake are possibly independent of gastric emptying. Since L-364,718 did not increase intake on a normal diet (186 g protein, 20 g fat per kg), CCK may only contribute to satiety in pigs eating high-fat diets.

Environmental enrichment can significantly improve poultry welfare, productivity and profitability by reducing the expression of harmful behaviours, like fear or feather pecking. However, some studies have yielded inconsistent results and many so-called enrichment stimuli elicited little or no interest. This probably reflected the wide array of stimuli used and the paucity of thought given to what a chicken (Gallus gallus domesticus) might find enriching. Clearly, the design of enrichment devices required more critical thought. Our immediate objectives were to establish chickens' specific preferences and thereby guide the development of practical enrichment strategies. First, we established that chicks showed increased use of an environment when it was enriched with simple, manipulable objects. Our use of video playback to assess chickens' responses to specific attributes of selected images then revealed that visual enrichment stimuli should incorporate movement, brightness, colour, and moderate complexity. Next, a survey revealed that almost 50% of the farmers who replied routinely played the radio to their flocks and that the perceived benefits included reduced aggression, improved health and increased productivity. Finally, we showed that a simple device consisting of a bunch of white strings is an extremely attractive pecking stimulus for chicks and adults of various strains of laying hens. Rather than rapidly losing interest in the devices the birds pecked progressively more at them with repeated exposure in short-term experiments. Furthermore, they were still being pecked at 17 and 2 weeks after their incorporation in the home pens of groups of 1-day-old chicks and adult hens, respectively. Even more encouragingly, the provision of string reduced feather pecking in birds of an experimental line showing high levels of this behavioural vice. It also reduced feather damage in caged layers at a commercial farm. The provision of string devices increases the opportunity for the birds to engage in behaviours that are fundamental to their nature, such as exploration and foraging. By maintaining lengthy interest and apparently reducing the expression of damaging feather pecking, string devices also satisfy other critical requirements of effective environmental enrichment. They have the added advantages of low cost, ready availability, ease of installation, and durability.

Collectively, these findings strongly support the hypotheses that extraneous stimulation is important to chickens and that the provision of appropriate visual, auditory and tactile enrichment stimuli can improve their welfare. Projecting images onto the walls of a poultry house could perhaps provide an additional source of visual stimulation, but this requires further investigation. Playing the radio was not only beneficial in terms of welfare and performance but it is probably one of the easiest and most practicable ways of enriching the environment for the birds and the stockpersons. The routine incorporation of string devices in rearing and laying cages is also considered likely to reduce boredom and feather pecking and thereby improve the birds' welfare and productivity. In conclusion, I wholeheartedly recommend the integrated application of string pecking devices and auditory enrichment.

Signs of clinical copper deficiency in ruminant animals include infertility. Blood copper concentrations alone are not an adequate indicator of copper status, as they take no account of the thiomolybdate challenge to the animal. The use of the ratio of caeruloplasmin activity to plasma copper concentration should provide a better indicator of molybdenum induced copper problems. The objectives of this study were to obtain veterinary feedback on the University of Leeds Trace Element Laboratory's (ULTEL) assessment of copper status and responses to any recommended supplementation. Blood samples from 713 female cattle from 114 herds were assessed for copper status, including plasma copper concentrations, serum caeruloplasmin activities and the ratio between the caeruloplasmin and plasma copper (CP/PlCu ratio). On the basis of only plasma copper analysis 95.0 % of the cattle were classified as being of normal copper status using Veterinary Laboratory Agency reference ranges. However, when the CP/PlCu ratio was also considered only 35.6 % of the cattle would be classed as having normal copper status. Appropriate copper supplementation would be required by 30.7 % of the cattle and a further 27.8 % could also benefit from additional copper. Veterinary responses to a questionnaire (80 % returned) indicated that infertility was a major problem in their clients’ herds. Where copper supplementation was recommended and administered an increase infertility was observed. In herds showing poor or lack ofoestrous behaviour/ later embryo loss (signs of clinical copper deficiency), 91.7 % reported that these signs were reduced by copper supplementation. The relevance of the CP/PlCu ratio as a diagnostic aid in the identification of copper responsive infertility has been supported by the responses of the veterinary surgeons.

The role of trace element deficiencies in the causation of clinical diseases is often questioned because of the poor correlations which are found between the trace element status of the animal or its diet and the incidence of disease. The most striking example is that relating to the copper (Cu) nutrition of sheep, in which concentrate diets containing 8 mg Cu/kg DM can cause poisoning (Hogan, Money and Blayney, 1968) while pastures containing twice as much Cu can cause a deficiency disease (swayback) to develop (Allcroft and Lewis, 1957; Alloway, 1973). Unidentified stress factors are often invoked to explain such anomalies. However, the poor relationships between nutritional status and disease incidence reflect the inadequacies of past methods of assessing the extent that a trace element is absorbed from the diet and its functional activity in the animal and the fact that requirements vary during an animal's life. The object of this paper is to re-emphasize the nutritional component of trace element disorders by looking at the quantitative and functional basis of trace element requirements, the factors which predispose animals to deficiencies and how these might be countered.

During the 1st week of life the energy contained in the body of the average piglet increases by a factor between four and five. To achieve this increase the piglet must ingest metabolizable energy (ME) at a rate which is about four times its maintenance requirement. Well over half the ME supplied in the milk of the sow is in the form of emulsified fat. Whilst the piglet is being suckled, its intake is controlled by litter size, availability of teats and productiveness of the mammary gland. At 3 weeks of age the normal piglet requires about 7.8 MJ digestible energy to sustain a live growth rate of 280 g/day. At this stage the growth comprises about 40 g protein and about 68 g fat. This means that the required intake for a newly weaned piglet on a typical starter diet should be about 475 g/day. In practice such intakes are rarely achieved for several days, therefore weaning causes severe disruption of intake and of the growth curve and there are other factors involved including social disturbance and stress. Further problems are caused by the provision of diets which are unsuited to the physiology of the piglet's immature digestive tract. The sudden loss of the IgA component and indeed other protective factors contained in the dam's milk can be extremely serious, and the reduction in food intake is effectively a defence strategy by the piglet to cope with its new circumstances and try to maintain physiological homoeostasis. In some circumstances the use of antibacterial agents, organic acids or probiotics may be beneficial, but the approach is less reliable than careful formulation of the diet to avoid provocative ingredients such as soya-bean and rapeseed meal.

Decreasing the proportion of long forage in mixed diets from 400 to 100 g/kg at constant digestible energy intakes reduces milk fat content by approximately 5 g/kg for every 100 g/kg decrease in hay. This response varies widely and a safe minimum diet composition to maintain approximately 40 g fat/kg milk from Friesian cows in mid-lactation is approximately 450 g long forage/kg or 220 g acid-detergent fibre/kg dry matter. This, however, would reduce milk yields. With barley-based concentrates, milk yield increases as the proportion of hay in the diet is reduced, with the result that the reduction in the yield of fat is less than the fall in its concentration. Milk fat content is higher when ground maize, which is a slowly fermented starch source, or fodder beet or fibrous by-products replace rapidly fermented starch sources such as barley in low-roughage diets. Milk yield, however, is lower. Supplementary fats and oils generally increase milk yield but their effects on milk fat content and yield vary widely.

Increasing the intake of high-concentrate diets of fixed composition increases the yield of milk but reduces its fat content. Increasing the number of meals per 24 h reduces this milk fat depression without affecting milk yield. Thus, advice on milk fat production must take account of the level of intake, the pattern of feeding and the diet composition.

In most situations, the avoidance of low milk fat content requires control of rumen fermentation to prevent high proportions of propionic acid. However, with frequent feeding during the 24 h, high propionic acid in the rumen has less effect on milk fat. It appears that high plasma insulin concentration is the main factor reducing milk fat production.

The release of insulin is stimulated by the peaks of propionate, which are produced after large meals of concentrates but not by the steady supply of propionate associated with frequent feeding.

Available knowledge can permit wide variation in milk fat production by dietary manipulation with reasonable accuracy but the future aim should be for more direct intervention at metabolic control points.

Livestock systems are comprised of sets of complex interconnected processes each with their own outputs eg growth, yield, animal health, welfare and environmental emissions. Livestock management decisions are currently based almost entirely on the judgement and experience of the stockman who has to estimate or guess the likely effects of any control action.

An integrated management system for a livestock production enterprise would be one which controlled all relevant processes. For example if the purpose of the system was to regulate nutritional input in order to control animal growth and pollutant emissions, the controller would calculate input values which would enable growth and emissions criteria to be satisfied simultaneously.

The essential components of an integrated management system are sensors and models. Developments in sensor technology will make available increasing amounts of information relevant to monitoring animals and their environment. Model-based control systems are particularly appropriate for accommodating the variability of most livestock production processes. Models exist for most of the economically important and scientifically interesting processes in livestock production. However the requirements of a process model that is to be incorporated into a controller are different from those of a model which is aimed at demonstrating understanding of the process. Areas where process models are lacking include those involving interactions between production and environmental factors.

Domestic sheep have a strong social tendency. However, the nature of social relationships varies with season, breed, and size of enclosure. Ewes occupy a smaller home-range, with larger subgroup sizes, in the winter compared with the summer months (Lawrence and Wood-Gush, 1988a). Domestication has apparently led to a reduction in nearest neighbour (NN) distances from feral (Soay) sheep, who do not have strong flocking behaviour, to Merinos with NN distances of less than 2 m (Arnold, 1985). The social choices made by ewes affect their foraging behaviour and may have significant effects on production (Lawrence and Wood-Gush, 1988b). The aim of this study was to examine the social choices of a hill and a lowland breed of ewe when grazing two different environments in spring and summer of 1995 and 1996. The influence of lamb genotype on the behaviour of the ewes was also investigated.

In sub-Saharan Africa (SSA), the association of crops and livestock in mixed farming systems generally benefits both enterprises. This paper focuses on the main contributions of livestock to crop production: the use of manure and animal draught power to produce crops and the investment of income from livestock into technologies that benefit crop production. In low-input, grazing-based feeding operations, manure is a vital soil fertility amendment. In these systems, penning livestock overnight on fields, fallow between cropping periods, returns both manure and urine to the soil and results in much higher crop yields than if manure only is gathered from stalls and spread onto fields. However, most farmers have insufficient manure to sustain food production. Nutrient harvests often exceed nutrient inputs, requiring a much greater use of fertilizers to arrest soil nutrient depletion. The opposite may be true for mixed farming where livestock are given food in confinement. In these emerging systems, the continuous importation of food (and fertilizer) can result in nutrient surpluses with subsequent soil nutrient build-up and loss. The contribution of animal power to crop production is relatively new in Africa. Animal power affects the amount of land cultivated by farmers, crop selection, the yield per farm and per ha, and on the participation and work load of people (family members and outside labour) involved in crop production and its associated activities. In addition to the impacts of manure and draught power on crop production, income derived from livestock is often invested in inputs that enhance crop production. At the ‘micro’ level, livestock income influences crop production (1) directly by allowing households to invest in productive inputs such as fertilizer, hired labour, and carts and (2) indirectly by allowing poor households to improve their nutritional status and, therefore, the productivity of their most important resource, their own labour. At the ‘macro’ level, increased livestock exports have a large stimulating effect on the demand for locally produced goods and services, particularly basic food crops. Thus, increasing the productivity of the livestock sector, including an emphasis on the policy and institutional environment influencing marketing and trade, is an important element of a development strategy focused on stimulating economic growth and alleviating poverty.

The concept of ‘coping strategies’ has received increasing attention over the last few years. Benus et al. (1991) reported two major types of strategy in rodents. These were the so-called active and passive strategies. The active strategy consists of being aggressive, forming behavioural routines and showing low responsiveness to changes in the environment, the passive strategy involves being low aggressive, flexible and responsive to changes in the environment. Hessing et al. (1993) reported similar findings in pigs. These strategies have potential implications for pig husbandry, since they may be more or less adaptive in specific farming environments.

Lamb has some positive attributes so far as consumers are concerned i.e. high levels of tenderness and flavour, a low incidence of quality problems (such as PSE muscle in pigs) and a ‘natural’ image. However, a major reduction in fatness of the meat on display in supermarkets is seen as essential to maintain sales in the UK and increase them abroad. Analyses of lamb cuts on retail sale shows that insufficient trimming is or can be done to produce a lean product. An increase in carcass weight would allow more scope for new methods of butchery and presentation. Changes in the way that lamb is marketed are essential in order to reduce carcass fatness. More use of carcass classification and an objective scheme can provide the basis for grading which penalizes over-fat carcasses. Tenderness and flavour can both be modified by changes on the farm and in processing. Chilling rate and ageing/conditioning are major factors controlling tenderness and diet is important in producing desirable flavour. There is considerable scope for improving eating characteristics by ensuring that the factors which affect them are at appropriate levels. However, the major factor in increasing consumer appeal remains a reduction in the fat content of lamb.

The study compared the impact of feeding different energy supplements (barley, molassed sugar beet and fat) prior to calving and the effects of feeding supplemental fat post-partum, on subsequent production and reproductive efficiency of dairy cows. Forty-eight multiparous Holstein-Friesian dairy cows were assigned to one of two groups, six weeks prior to expected calving date and fed a grass based total mixed ration according to ME requirements for late gestation. Group 1 was supplemented with barley (B) or molassed sugar beet feed (SB) prior to calving and was then given a high starch lactation ration. Group 2 was supplemented with either fat (F) or no supplement (C) pre partum, and was then given a similar lactation ration as Group 1 but supplemented with fat. Lactation rations were fed through to week-20 post partum and the cows were monitored during this period. Milk yield (P<0.002) and milkfat (P<0.02) production were higher and milk protein concentration (P<0.001) was lower in Group 2. The number of days to first rise in progesterone following parturition was greater (P<0.01) in Group 2. Due to the design of the study, effects of prepartum supplementation were only evaluated within each lactation ration group. Conception rate to first service was higher (P<0.001) for B than SB supplemented cows in Group 1 and higher (P<0.02) for F than C supplemented cows in Group 2. Services per conception were lower (P=0.06) for B than SB supplemented cows in Group 1 and lower (P<0.05) for F than C supplemented cows in Group 2. Overall pregnancy rates and days open were not significantly different between the groups. The data shows that pre-partum nutrition had an important role in determining subsequent fertility. Despite having negative effects early post partum, supplementing with fat did not affect overall reproductive performance but it did improve milk production.

A review of physiology and behaviour–based studies on the function of stereotypic behaviour indicates contradiction and inconsistency within the literature. By considering appropriate neurochemical data alongside an existing model of motivation (Hughes and Duncan, 1988), a greater understanding of the function of stereotypy may be gained. The Hughes and Duncan model (1988), described stereotypies as highly motivated appetitive behaviours performed repeatedly in an environment where consummatory goals are denied. Moreover, appetitive behaviours activate reward circuitry such as the ventral tegmental area and nucleus accumbens and are thus considered to have a reward value associated with their performance (Carr, 2002; Jones et al., 1990). Stress induced sensitisation of reward circuitry may result in appetitive ‘stereotypies’ having increased reward value, perhaps becoming consummatory in their own right. In such a scenario, stereotypic behaviour could function as a coping tool, allowing the animal to counter the effects of an aversive environment.

In vitro techniques are widely used to predict the nutritive value of foods for farm animals. However, food evaluation systems are moving towards systems based on nutrient flows rather than on energy or protein. Nutrients are supplied via the digestive tract and presently available in vitro methods are inadequate to simulate the complicated and non-steady-state processes in this tract. This is partly due the lack of adequate in vivo reference values and partly due to a too-high degree of standardization and simplification. Future developments should therefore aim to develop in vitro systems which closely monitor the dynamics of the digestive processes. Adequate interpretation of the results may require sophisticated mathematical models.

The rôle of voluntary food intake, measured as daily food consumption on ad libitum feeding from 30 to 90 kg live weight, in future selection strategy is reviewed. Intake shows a heritability of 0.3, and genetic correlations of 0.6 with growth rate and –0.4 with leanness. Low genetic correlations between test station and commercial farm performance are reported for growth rate (0.27) and backfat (0.41) which arise either from genotype × feeding level interactions, or from individual feeding at stations. Selection for rate of lean growth appears to lead to a primary increase in rate of protein deposition, whereas selection for efficiency of lean growth appears to lead to a reduction in rate of fat deposition via a decline in intake. Continued reduction in intake may limit further improvement in lean growth rate and sow productivity. As optimum fatness is approached, the selection emphasis is expected to swing towards rate of lean growth to reduce total food used for maintenance. To determine the optimum selection regime, a knowledge is required of the genetic relationship between intake and lean growth rate. Meanwhile, the optimum selection regime may involve ad libitum group feeding with electronic recording of individual food intake. In the long term, exogenous or endogenous growth promoters could remove the need for selection against backfat, and necessitate a radical genetic increase in intake.

To develop sustainable grazing systems, an understanding of the complex interactions between competing plant species and grazing herbivores is needed. An understanding of dietary preference is a prerequisite to predicting how much and from which plant species animals select. This work initially concentrated on dietary preferences of sheep grazing perennial ryegrass and white clover swards and was then extended to other animal species to test the generality of our findings.