bluuebunny/crossref_metadata_2025 huggingface dataset:
Tests of Chemical Substances for Mutagenic Action
Authors: Auerbach C. , Robson J. M.
Published: June 2019

Thediscovery in 1941 (Auerbach and Robson, first published in 1946) that mustard gas (β-β′-dichloro-diethyl-sulphide), (ClCH2.CH2)2S, is comparable to X-rays in its capacity to produce mutations and chromosome rearrangements naturally raised the question as to what special properties of mustard gas enable it to act in this manner. There are indications (Auerbach and Robson, 1947) that the mutagenic effects of mustard gas are due to a direct action on the chromosomes, and not to an indirect oneviathe cytoplasm. This suggests that a selective and specific chemical reaction occurs between mustard gas and the genie material. It appeared possible that a systematic survey of substances chemically related to mustard gas might reveal a chemical group or structural arrangement responsible for the mutagenic action. This in its turn might also throw some light on the other component of the reaction, the gene or chromosome, and on the process of mutation itself.

The substances, to be tested were, with one exception, chosen on account of their chemical and pharmacological similarity to mustard gas. They were:

(1) N-methyl di-(2-chloroethyl) amine, CH3.N(CH2.CH2Cl)2, one of the so-called nitrogen mustards. This is a liquid with strong vesicant action. It decomposes fairly rapidly in water. Its hydrochloride is a solid, soluble in water and forming a stable solution. This solution proved useful in certain tests in which it was convenient to apply a mutagenic substance in aqueous solution.
A Comparative Study of the Chromosome Structure and Behaviour in Three Different Genera of Indian Grasshoppers
Authors: Ray-Chaudhuri S. R. , Dutt M. K. , Greenwood A. W.
Published: June 2019

The Acrididæ are characterised by a very uniform karyotype. With a few exceptions, the species so far studied contain 23 chromosomes in the male, which are very similar in size and structure. Attempts to deduce the probable mechanism of speciation within the Acrididæ were restricted only to metrical studies of chromosomes. Recently, however, Coleman (1943) has established in two species the subterminal position of the primary constriction or centromere and the variation in the length of the two arms in different chromosomes of the same karyotype. In the present paper additional evidence is presented which shows a linear differentiation of some chromosomes of the Acrididæ. Furthermore, in view of the fact that chromosome behaviour during meiosis is a more reliable criterion of ascertaining linear differentiation, the meiosis was studied in three genera.

Three species belonging to three different genera were studied. They are Spathosternum prasiniferum Walker, Oxya sp. and Phlœoba sp. The former two belong to the sub-family Catantopinæ and the latter one to Acrididæ. Adult male specimens have been captured from the field adjoining the Biological Departments, Calcutta University, mostly in the months of August and September 1943–44. The testes were dissected out in Ringer's solution (cold-blooded formula) and fixed in Medium Flemming, Belling's, and Kahle's fixatives. The two latter were very suitable for smear preparations. Sections were cut at 25 to 30 micra in thickness and stained in iodine-crystal violet and in Heidenhain's hæmatoxylin. A 2 per cent, solution of safranin also gave good results. Squash preparations were stained by Feulgen's method. Diplotene stages in Phlœoba were studied from temporary aceto-carmine preparations.
Further Observations on Placental Fusion in Mice, and a Report of a Case in the Rat
Authors: Carr J. G.
Published: June 2019

An account was previously given of the discovery of two cases of placental fusion in mice, and it was suggested that this condition might occur fairly frequently. This has been amply borne out by subsequent experience, as fourteen other examples have been found while working with mice, and in addition it has once been found in the rat. From this additional material further information about the types of developmental abnormalities that may result from this condition has been gathered. Since the last paper, Owen (1945) has found that commingling of the fœtal circulations in cattle twins can result in the transfer of erythrocyte precursors between partners, resulting in animals exhibiting blood-groups bearing no relation to their genotype. Similar transfers in mice would lead to confusion in many genetic experiments, especially in transplantation experiments with tumours.

No genetical basis for the condition is apparent from the data available. It has been, noted in three matings of CBA mice, two of C3H mice, eight C3♂ × CBA♀, and three stock mice, the proportions being roughly related to the relative numbers of each type examined at the time of littering. The frequency is rather less than 1 per cent, of all placentas seen. The only common feature, to which attention was also drawn in the previous paper, has been that the fusion occurred always in conditions of uterine crowding due to large litter size. The smallest litter size in which this fusion was found was five, but in this case five placentas were present in one horn. Whenever labour was observed, it appeared to be difficult and prolonged. Once, by good fortune, delivery was timed approximately. A CBA mouse was found to have delivered two young, and two more were born within the next ten minutes. Nothing further appeared for two hours and ten minutes, when a live pair with fused placentas was delivered with some distress. The last two of the litter, making eight in all, were delivered within twenty minutes of the completion of the birth of the fused pair
XV.—The Life-history and Ecology of the Salmon Gill-Maggot Salmincola salmonea (Copepod Crustacean)
Authors: Friend G. F.
Published: June 2019

This study was begun in 1936 primarily as an attempt to work out the life-history of the Salmon gill-maggot Salmincola salmonea (L.), a common and widespread copepod parasite of the Atlantic Salmon (Salmo salar). At that time the adult female stage only was known, although this had been reported in Scotland as early as 1766 on a kelt salmon and had been included by Linnæus among his Vermes. It was not, however, until 1939, after three years of field work, that a complete series of the stages in the life-history of the parasite had been collected and the story began to take shape. During this time not only were parasites collected, but a quantity of statistical and observational data was accumulated bearing both on the parasite. and its host. Much of this referred to conditions in the estuary, a part of the common background of the two animals which was soon recognised to be a critical region for both. Consequently special attention was given to parasitised fish from this region, and this led to a widening of the scope of the investigation to include a consideration of the habitats and interrelations of gill-maggot and fish, indicated by the term “ecology” in the title.
The rôle of the gastrointestinal tract in the control of voluntary food intake
Authors: Rayner D. V. , Gregory P. C.
Published: June 2019

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.
Voluntary food intake of growing pigs
Authors: Cole D. J. A. , Chadd S. A.
Published: June 2019

The amount of food eaten by the pig is a balance between the needs of the animal and the ability of the food to meet those demands. Major factors influencing the needs of the animal are live weight, genotype and sex. Equations have been established to predict the intake of pigs at different live weights but variation exists amongst these equations which reflect a change to genotypes with smaller appetites. Rapid growth may be limited by the appetite of the pig and differences in intake between the sexes are notable, the biggest being castrated males compared with boars and gilts. Intakes of boars and gilts can be similar but often gilts eat slightly more. Dietary energy has a marked effect, with the pig attempting to adjust its daily energy intake by eating less of high-energy diets. The extent to which it can exert this physiological control is limited when a stage is reached where it is unable to compensate by eating more of a low-quality diet because of physical capacity. The influence of protein on intake has received much less attention but there are clear indications that pigs eat less of diets which are very high or very low in crude protein. Intake is also influenced by protein quality and there is evidence from work at the University of Nottingham that quite small variations in lysine level relative to other essential amino acids can markedly affect intake.
The influence of the thermal environment on the voluntary food intake of pigs
Authors: Close W. H.
Published: June 2019

The thermal components of the environment, through their effects on the animals' heat exchange, influence growth, metabolism and voluntary food intake. The environmental components considered include air temperature, either constant or fluctuating, air movement, relative humidity, group size, stocking density and atmospheric concentrations of various gases and dusts. For the growing pig, it has been calculated that each 1°C change in temperature is associated with a 0.65 MJ metabolizable energy (ME) per day change in energy intake; for the other environmental components the variation was between 0.36 and 0.65 MJ ME per day. From the relation between environmental temperatures, food intake and growth, it was shown that for young pigs the optimum temperature range was between 20 and 25°C; for older animals it was between 10 and 20°C. Knowledge of the extent to which food intake changes with the environmental circumstances, both cold and hot, allows feeding and managemental strategies to be developed to ensure optimum growth and efficiency of food utilization.
New approaches to genetic evaluation of beef cattle
Authors: Pollak E. John
Published: June 2019

The beef cattle industry in the United States has undergone dramatic changes over the past decade with the adoption of genetic evaluation programs. The method of choice has been Henderson's mixed model methodology for best linear unbiased prediction (BLUP). The most prevalently used model is the animal model (Henderson and Quaas, 1976) computed by the equivalent reduced animal model (Quaas and Pollak, 1980).

Neither the methodology or the models being used are particularly new. What is new in this industry is the widespread application of these techniques to the analysis of the data banks maintained by the breed organizations. Today many breed associations publish a national sire evaluation, and most of these have published their first in the last three years. This rapid proliferation of published evaluations has coincided with an attitude in the industry of promoting specification beef and predictable performance. Genetic evaluations provide information not only to achieve goals in selection but as well for merchandizing cattle based on quantifiable potential. The enthusiasm for genetic evaluations right now in the U.S. beef industry is high.
Impact of the new statistical technology on pig improvement
Authors: Webb A. J. , Bampton P. R.
Published: June 2019

Past improvement programmes in pigs have concentrated on lean growth, and have relied on direct comparisons of contemporaries in a common environment. The new mixed model technology now allows comparisons across environments and generations, and, by utilizing all possible genetic relationships, more accurate prediction of genetic merit for traits of low heritability. In addition, breeding programme design will benefit from more precise estimation of genetic parameters. Principal benefits of the new technology are greater flexibility of structure of breeding programmes, and faster improvement of litter size. The consequence will be larger populations under selection with lower costs per unit of genetic improvement. For national improvement schemes using a high proportion of AI matings, central testing stations could become unnecessary. Main research priorities are the optimum family structure to balance selection and inbreeding, more efficient computing strategies for large numbers of traits, and the incorporation of single genes into predictions of merit. The new technology will be important for the exploitation of biological advances in manipulation of both reproduction and the genome.
Long-term selection for meat production in poultry
Authors: Siegel P. B. , Dunnington E. A.
Published: June 2019

Selection for meat production in poultry includes commercial development of meat-type chickens, turkeys and waterfowl and laboratory studies that involve these types of poultry. Heritabilities for growth traits are moderate to high, enabling response to selection for these traits. Changes in growth traits result in correlated responses in feed intake and have a negative relationship with reproductive traits. That is, deviations from intermediate growth rates are deleterious to reproduction. In this paper we discuss genetic aspects of poultry meat production and long-term laboratory selection experiments for growth. Emphasis is given to the species with the most extensive research base, the chicken.
2.1 Data Recording
Authors: Burgess A. D.
Published: June 2019

Computers or computing devices are in use, and will be in use in the future to a greater extent, in the interest of animal production. Data collection, in one form or another, is fundamental to that usage. The ready availability of low cost digital processors, data converters and signal amplifiers, where appropriate, has ensured that this is so. The only constraint is with the difficulty of measurement and, in signal recording, whether suitable instrumentation devices or transducers exist or can be devised.

The important considerations are why the data are needed, how many data, when and in what form they are required.

From the answer to these questions will come as many diverse forms of data recording — albeit based on established techniques — as there are requirements to record, all of which may be realized using the same basic hardware components by virtue of the flexibility introduced by the need to program the processing element. In the manner of pure research, the answers to these questions constitute the design of the experiment, which too easily can be ill-considered, resulting in quantities of data useless to its original intent; where automation is considered, they constitute the design of the digital system required.

The range of requirements for data recording extends from manual keyboard entry to small computers engaged in farm management, through the systems designed to gather data automatically for the management of animal enterprises, to the specialized requirements for data to substantiate mathematical models of particular physiological processes in the animal. Within this range, the variation of requirement is fundamentally that of its dependancy upon the dimension of time.
4.4 A Policy for Encouraging the Effective Use of Computers in Animal Production Development
Authors: Whittemore C. T.
Published: June 2019

In addition to data and record handling and the completion of complex and arduous mathematical calculations, the computer may serve a wide range of purposes for the agricultural industry; these include the provision of day-to-day management information, the mechanical enactment of management decisions, business forecasting, interpretation of real life and prediction of future response by use of simulation models, analysis of cost effectiveness of various tactics and stratagems, the transfer of information, scrutinization of existing knowledge and the formulation of experimental programmes. The computer is seen as a major linking medium between research, development and production practice; being both the preferred route for information flow and an ideal way of packaging dispersed pieces of knowledge into practical, usable, systems advice.

The concern of practical producers is not with discrete little problems but with systems. To help, the extension worker must bring forward systems solutions. Often research and development workers try to get across to producers potential benefits in small bits (3 times daily milking gives a yield lift of 15%; flat rate feeding gives better margins over concentrates; high density diets improve feed efficiency), whereas producer benefits come from the cost effectiveness of whole integrated systems.
Perspectives of animal nutrition with efficient use of by-products and wastes
Authors: Raymond W. F.
Published: June 2019

The preparation of the introductory paper to this Conference has presented two particular problems. First, as always, there was the risk that it would contain too many references to aspects which would be dealt with in greater detail — and possibly contradicted subsequently. Secondly, the title of the Conference, ‘By-Products and Wastes in Animal Feeding’, seemed to be at variance with a definition of waste, ‘a resource arising (in agriculture) where the cost and complexity of using that resource is greater than the returns from using it’, which I had used at a similar Conference a year ago (Raymond, 1977) and which might imply that ‘waste’, once utilized, is no longer ‘waste’. But this is really semantics; the aim of this Conference is to bring together the latest information on whether resources which have conventionally been considered ‘wastes’ can effectively and economically be utilized in new animal feeding systems. The concept of economic use is vital. I strongly believe that we must reject the idea that there is some sort of moral imperative to use wastes; if this is not economic then their use must involve the misuse of some other resource within the total production system.

The situation is of course dynamic; effective research and development (R and D) can transform yesterday's waste resource into a new productive asset. Further, the economic environment is not static; for example, changes in relative costs of feedstuffs mean that farmers will this winter feed large quantities of straw which in 1972 they would have burnt in the field, while high cereal prices mean that more non-tariff components, including by-products, are now being included in least-cost livestock rations. Thus it is worth examining some of the factors that have led to the current interest in the role of by-products and waste materials in animal feeding setting aside any marginal objection to this use of ‘waste’.
Use of straw and cellulosic wastes and methods of improving their value
Authors: Greenhalgh J. F. D.
Published: June 2019

The most widely-quoted estimates of straw supplies and usage in England and Wales are those of a working party of the National Farmers Union (1973). They assumed the yield of straw to be 2.8 t/ha, and hence 9.3 Mt from 3.4 M ha of cereals in 1972. (The same yield from 3.7 M ha of cereals in the UK would give 10.4 Mt.) Of the 9.3 Mt, 37% was estimated to be burned in the field or ploughed in, 36% used for bedding, 15% used for feed, and 12% used for other purposes. The figure of 2.4 t/ha (1 t/acre) may well be too low. Short (1974) found straw yields at four Experimental Husbandry Farms over several years to be as follows (t/ha): winter wheat 3.71, spring wheat 4.68, spring barley 2.71, and spring oats 4.54. Wood (1974) surveyed wheat crops in Oxfordshire in 1973 and found yields of 3.7 t/ha. The total quantity of straw available is therefore likely to be considerably in excess of 9.3 Mt and could if necessary be increased further by cutting at a lower level. The accuracy of the National Farmers Union estimate of 0.15 × 10.4 = 1.6 Mt used for animal feeding is also questionable, but this amount would — if it contained 6.5 MJ metabolizable energy (ME)/kg dry matter (DM) — be sufficient to provide only about 7% of the maintenance requirements of all cattle in Britain. On a larger scale, Balch (1977) has calculated that if all the straw grown in Europe were improved by chemical treatment it could provide 80 to 90% of the maintenance requirements of Europe's ruminant livestock. World estimates for the production of straw and other fibrous wastes are given by Owen (1976).
By-products from the food and dairy industries
Authors: Singer D. D.
Published: June 2019

For the purpose of this paper I intend to include within the term ‘by-products’ all those materials that arise from the food industries which are not consumed by the human population of the United Kingdom. Some of these materials are not acceptable as part of the human diet, or, if acceptable, find no ready market. Other materials are inedible, perhaps by humans and other animals, but can be converted into acceptable food or feed whilst yet others which are edible and acceptable are wasted in processing, storage, transport, distribution and in the kitchen and dining room. It is impossible to give a figure for the annual amount of by-products and waste available but statistical evidence points to approximately 6 million tonnes of food, all of which is edible but not consumed. This figure does not include by-products which are not intended for human consumption such as abattoir wastes, whey and brewery wastes and cereal offals. The total figure is therefore larger and represents a considerable potential economic resource. (It must be observed however, that only a small fraction of these wastes and by-products can be economically utilized. Other speakers are dealing with animal slaughter, fish and cereal wastes and I will therefore give only passing attention to these materials.)

About 40 million gallons of cheese whey are produced in the UK each year on the farm. Of this, about 12 million gallons are fed directly to pigs. Although it appears that heavy hog production and cheese making are often associated, disposal of whey on farm remains a problem, since the price fetched by whey may be only a quarter or less than the cost of transport. Disposal on land, where it can be useful as a fertilizer, can lead to pollution problems. Trials carried out by ADAS (Wolverhampton) on both beef and dairy cattle are promising. It has been shown that every kg of barley previously fed to dairy cattle can be replaced by 10 litres of whey at half the cost, making barley feed unnecessary. In diets for steers, calculations have shown that a litre of whey at 6% solids can replace 90g of compound for energy (Peacock, 1977).
The composition and nutritional value of some tropical and sub-tropical by-products
Authors: Morgan D. E. , Trinder H.
Published: June 2019

This paper discusses the composition and nutritional values of a limited number of materials of tropical or sub-tropical origin encountered in advisory work. These products have emerged in recent years chiefly as minor components of compounds and to a lesser extent as ‘straights’. These by-products are olive pulp, grape pulp pellets, grape seed meal, dried coffee residues, citrus pulp pellets, cocoa shell meal, extracted cocoa meal, shea-nut pellets and shea expeller meal, guar meal, illipe meal and cassava meal. Other foods such as cereal by-products and sugar cane molasses are discussed elsewhere, whilst materials that may originally have been by-products of oil extraction such as soya, ground nut and palm kernel, etc., are now such significant parts of the modern sophisticated feed compounding industry that it may be unfair to classify them as by-products in the usually accepted sense. In any case information on them is well documented and readily available and hence they will not be discussed here.

The by-products listed above form only a small proportion of the imported feeding stuffs bill but nevertheless can be of economic and nutritional significance in isolated circumstances. Some idea of their overall monetary significance is as follows. The total quantity of imported feeding stuffs other than cereals in 1977 was 1 495 973 tonnes. Of the above list of by-products, only olive pulp and grape residues are listed separately on official lists and each account for less than 1% of the total. Olive pulp imports were 33 457 tonnes and grape residues 11 276 tonnes. Undefined residues from oil extraction, which presumably includes some of the above listed products, amounted to 58 791 tonnes, whilst ‘Other products of vegetable origin’ would account for some other imported products totalling 45 013 tonnes.
The use of by-products in animal feeds
Authors: Wilson P. N.
Published: June 2019

Over the last 30 years there has been spectacular growth in the UK broiler industry (Richardson, 1976), intensification in the UK pig industry and a move to larger herds and higher yields in the cattle industry. These trends have meant that farmers have bought more livestock feed both as compounds and as straights. Parallel to these changes, the move from ‘target’ to ‘least cost’ formulation by the compounder and computerized home mixer has increased the ability to deal with different raw materials and to utilize these successfully in compounded diets (Wilson, 1975).

In spite of all these technical advances, livestock still depend on large quantities of cereals and other raw materials which are potential food for man (Wilson, 1977) as illustrated in Table 1. This is in spite of the fact that, over the past 15 years, the general trend-line in the ‘carry over’ stocks of world grain has been downwards (Brown, 1977). It follows that, in considering future feeding policies for livestock, there are good reasons why prudent steps should be taken to find and utilize alternative sources of both energy and protein for animal feeds. Holland has been more successful in this respect than the UK (De Boer, 1978) as instanced by the increasing imports of cassava which in part replaces European-grown barley and wheat (Walters, 1978).
Thermoregulation in neonatal ruminants
Authors: Rowan T. G.
Published: June 2019

This review is directed to thermoregulation in ruminants relative to weather and husbandry conditions of the United Kingdom in which the principal ruminant species are cattle and sheep. The main thermoregulatory demands for neonates, but not necessarily for older animals, are posed by cold rather than heat. Thermoregulation is critical to the survival of neonatal ruminants. On many farms, neonatal deaths are, for example, 20% of lambs born. Neonatal ruminants are precocial compared with many altrical neonatal mammals and have well developed thermoregulation which allows them to maintain homeothermy in many environments. However, at birth the neonatal ruminant moves from a very stable thermal environment, of similar temperature to its core body temperature, to a variable thermal environment which is 10 to 50°C colder than its core temperature. At birth the coat is wet and energy losses can be very high. To maintain homeothermy, heat production can usually be increased 3- to 5-fold above resting heat production. However, there are only limited quantities of tissue substrates available for this and the early intake of sufficient colostrum by the newborn is essential to continued heat production and survival. Nutrition in early and late pregnancy also affects the viability of, at least, young lambs: placental insufficiency may cause chronic prenatal hypoglycaemia and hypoxaemia which, postnatally, inhibits spontaneous respiration and restricts heat production. In calves, dystocia may cause acidosis and decreased heat production.

The principal thermoregulatory mechanisms and some factors which affect their efficiency in newborn calves and lambs are presented, with consideration of the limitations of lower critical temperatures.
Behavioural aspects of neonate survival
Authors: Lawrence A. B. , O'Connor C. E.
Published: June 2019

The postnatal period is the most dangerous phase of life and survival depends on the neonate behaving appropriately from birth. Consequently, many aspects of neonate behaviour are often near to being fully formed at birth. However, experience will often be required to shape the expression of the behaviour and improve its effectiveness. The immediate problems facing the neonate will be related to the overall reproductive strategy of the species. In pigs, sibling rivalry will be critical in establishing and maintaining fidelity to a teat, and this early conflict is probably most important for survival. The teat order that succeeds this early rivalry is probably not, however, the result of competition over the most productive teats but because of certain intrinsic advantages of teat fidelity that maximize growth. In sheep the need to quickly follow and solicit sucking only from the dam makes learning to recognise the mother a priority. Recent results suggest that the ability of the neonate lamb to recognize its mother has been under-estimated and that failure of lambs to recognise their mothers can make a significant contribution to mortality rates. Survival in any species is, however, not simply a matter of appropriate neonate behaviour but may depend critically on the quality of the interaction between the mother and offspring. It is difficult to determine the end of the neonate period given the often protracted nature of weaning. As weaning progresses there is a shift to bonding with siblings and peers and to an extent these relationships take over some of the social functions of the mother-infant relationship such as avoidance of predators. Lastly, experiences gained during the neonate period can have long-term effects on behaviour such as diet selection, social preferences and responses to fear with important implications for farmed livestock.
Diets for young pigs
Authors: Hardy B.
Published: June 2019

In the United Kingdom, the majority of pigs are weaned at 3 to 4 weeks of age. Prior to weaning the main source of nutrients is milk produced by the sow. After weaning, suitable complete diets need to be given that are compatible with the physiological state of the digestive system and supply adequate nutrient inputs to achieve maximal growth with minimum digestive upset. The weaning process, however, imposes considerable stress on the piglet which frequently results in a retardation of growth, often accompanied by problems associated with diarrhoea.

The challenge to the commercial nutritionist and the pig producer is to achieve sufficiently high nutrient intakes to reach the maximum growth potential. Improved understanding of the digestive physiology of the weaned pig and better estimations of the nutrient requirements of genetically improved stock has led to the development of appropriate diet specifications. There is a perpetual need to reconsider the most suitable food ingredients to use in diet formulations to meet these nutrient specifications, due to economic circumstances. The food ingredients need to be highly digestible, extremely palatable and to contain no anti-nutritive factor or antagonist to the digestive process. The food form and method of feeding can greatly influence food intake post weaning. The piglet weaning weight to age relationship can also affect the subsequent food intake, growth rate and incidence of problems associated with diarrhoea.

There are continual changes and developments within the animal food and pig production industries that affect nutrition of the young pig. These include genetic selection for prolificacy, development of outdoor pig breeding systems, ‘green issues’ including welfare and use of food additives, use of enzymes and probiotics and improvements in food production technology. In the development of diets for young pigs all these aspects need to be considered in achieving an optimal solution in terms of nutrition, management and economics.
Probiotics and other prophylactic agents
Authors: Andrews A. H.
Published: June 2019

There are many agents which can assist in ensuring neonatal survival and growth. The most important is still colostrum and although there are many substitutes available, the best of which will be prepared from colostrum of the same species (cattle, sheep and goats), or where this is impracticable, from plasma or serum (horses, pigs). Other agents which can enhance viability include antibiotics, probiotics, vitamins, minerals, the lactoperoxidase system, lactoferrin, lysozyme, hyperimmune sera, vaccines, acidifiers, enzymes and oligosaccharides. Many probiotic products are available containing different organisms which may be live or dead. Probiotics have been available for many years as nutritional supplements. However, results obtained with them have been variable and often of dubious validity. There is at present a trend to suggest such products have therapeutic or prophylactic activity. Thus it would appear that they are developing along the reverse route to that of antibiotics which initially were used for therapy or prevention, only later to be used as food additives and growth promoters. It is likely that any successful probiotic will need to meet criteria laid down by proponents of their use in human beings 50 years ago. These include that they contain live organisms capable of multiplication in the alimentary tract and of a strain indigenous to the species. A large number of organisms will be required daily and the diet of the animal will need to be defined. It would appear that treatment should commence as soon as possible after birth.

As therapeutic claims are often directly or indirectly implied it would seem justified that probiotics should be registered and criteria for their evaluation discussed. Results of recent trials with oral colostrum substitute and injection of hyperimmune serum are used to illustrate the type of trials likely to be required for probiotics.

Other methods of enhancing survival are discussed.
An information system to manage hypothermia in newborn lambs
Authors: Stott A. W.
Published: June 2019

Management information can be used as a substitute for other business resources. Sheep farmers may find such substitution provides a means to maintain incomes as the price of information falls relative to other scarce resources during the severe cost price squeeze they are currently experiencing.

To illustrate how management information may be obtained and used, a multivariate regression technique is described. This is applied to data on the physiological responses of newborn lambs to cold exposure. It shows that an increase of one standard deviation in total body insulation provides a significantly greater direct response in cold resistance in lambs bred for high cold resistance (HCR) compared with lambs bred for low cold resistance (LCR). The countervailing correlated drop in peak metabolic response to cold exposure did not show a significant between-line difference. This information suggests that HCR lambs give a metabolically more efficient response to cold exposure than LCR lambs. Subsequent research has provided physiological evidence to corroborate these findings.

The cold resistance of lambs has been shown to be related to lamb survival in the field. Information obtained about the response of individuals or groups of lambs to cold exposure by methods such as those described here may suggest more cost-effective steps that managers should take in order to exploit to the full the varying abilities to resist cold. This in turn should improve enterprise gross output by reducing lamb mortality. It should also reduce costs by ensuring that steps to control cold exposure or alleviate its symptoms are provided only when necessary.
Reducing lamb mortality in hill sheep
Authors: Waterhouse A. , Roger L. C. , Ashworth S. W.
Published: June 2019

Lamb mortality is high in hill farming systems. This is not a new phenomenon. Orr and Fraser (1932) reported losses of lambs between birth and weaning of over 30% and indeed an annual ewe death rate of up to 24%.

Poor nutrition, of both macro- and micro-nutrients, is a prime cause of this problem exaggerated by difficult environmental conditions at the time of birth. Improved nutrition during late pregnancy was believed to be the most important (Wallace, 1948) and nutrition during mid pregnancy received scant attention. However, applied experiments with mid-pregnancy feeding of hill ewes (Milne, 1984; Waterhouse and McClelland, 1987) showed very significant effects of better nutrition during this period. The present paper summarizes the implementation of improved mid-pregnancy nutrition in a monitored systems study, associated with changes in management in late pregnancy made possible by assessment of foetal numbers from ultrasound pregnancy scanning.
5.1 The ARC System for Assessing the Nitrogen Value of Feeds for Ruminants
Authors: Smith R. H.
Published: June 2019

The system put forward by a working party of the Agricultural Research Council is fully described in a recent publication (ARC, 1980) and will be outlined only briefly here. Most attention will be given to considering the usefulness of the system, some of its limitations and probable ways of future development.

It is proposed in the scheme that a diet should be formulated in terms of metabolizable energy needed for the required performance. This energy intake largely determines the maximum amount of microbial growth possible in the rumen per day and therefore the amount of N that has to be made available to the microorganisms to achieve this growth. This is referred to as the rumen degradable nitrogen (RDN) in the diet (the crude protein equivalent (RDP) = RDN x 6.25) and its utilization forms the first in a chain of events relating the N compounds eaten with the compounds deposited in the animal's body or products. All the events in the chain are affected by a variety of factors and some of these will be discussed later but, in order to demonstrate the principle of the scheme, average values derived from the literature and given in ARC (1980) will be assigned to them.
6.2 Assessment of Protein Degradability of Forage
Authors: Filmer D. G.
Published: June 2019

A new system for calculating the protein requirements of ruminants has been proposed by the Agricultural Research Council's sub-group on protein evaluation (Roy, Balch, Miller, Ørskov and Smith, 1977; ARC, 1980) to replace the now largely discredited Digestible Crude Protein (DCP) and Available Protein system.

There is little need to discuss the theory of the new system here as a number of excellent publications are now available outlining the new approach (e.g. Miller, Balch, Ørskov, Roy and Smith, 1977; Wilson and Strachan, 1981). Suffice to say that the new system requires the description of dietary crude protein in terms of rumen degradable protein (RDP) and undegradable protein (UDP) requirement for a specific energy input necessary for a particular level of production. Therefore, one of the important aspects of implementation of the new system is a description of the degradable/undegradable protein contents of feedstuffs. This not only applies to cereals, cereal by-products and protein concentrates used in the animal feed trade but also to the on-farm forages which may make up a considerable proportion of the diet of the dairy cow. It is this latter dietary component that is under consideration here but, in the first instance, it is worthwhile examining the importance of degradability overall, before considering the various aspects of forage protein degradability in particular.
7.2 The Effect of Forage Species and Stocking Rate on Protein Supply to the Duodenum of Cattle
Authors: Losada H. R. , Cammell S. B. , Beever D. E. , Austin A. R.
Published: June 2019

Whilst the quantity and nature of the forage available to grazing ruminants is known to vary quite dramatically throughout the growing season, there are still surprisingly few data on the energy and protein value of such materials and, consequently, supplementation of such diets to maintain high levels of animal performance remains empirical.

The recent development of portable equipment for the continuous intraruminal infusion of digesta markers (Corbett, Furnival, Inskip, Perez and Pickering, 1976; Evans, Hayes and Beever, 1981) and the automatic collection of duodenal digesta from T-piece cannulated cattle (Evans, Skelton and Beever, 1981) have, however, provided reliable means by which the flow of nutrients to the small intestine can be measured in grazing sheep (Corbett, Furnival, Inskip and Pickering, 1982) and cattle (Ulyatt, Beever, Thomson, Evans and Haines, 1980). The work reported in this paper is a continuation of the study commenced by Ulyatt et al. (1980), with the objective of this experiment being to examine the digestion of pure swards of perennial ryegrass and of white clover throughout the season when offered at two allowances to young growing cattle.
7.5 Urea and Poultry Manure as Protein Supplement to Low Grade Grass for Sheep in the Accra Plains
Authors: Fianu F. K. , Assoku R. K. G.
Published: June 2019

The low protein content of dry season forage and its growth retarding effect on livestock has long been recognised as one of the main technical bottlenecks in ruminant livestock production in the tropics (Oyenuga, 1957; Lansbury, 1958; Rose-Innes, 1960). Such nutrient deficiency results in as much as 15% live-weight loss in grazing animals during the dry season, this delaying their maturity (Rose-Innes, 1960; Otchere, Dadzie, Erbynn and Abyebo, 1977). To help solve this problem, nitrogenous feedstuffs such as urea, poultry manure, groundnut cake and copra cake have been examined. Reported here is work on urea and poultry manure tested on West African Forest Type lambs at Legon, Ghana.
8.6 A Comparison of the Milk Yield and Composition of Dairy Cows Fed Diets Containing Either Protected or Unprotected Soya
Authors: Hunter E. J. , Rowlinson P. , Brett P. , Armstrong D. G.
Published: June 2019

During early lactation, when requirements for energy and protein are high, tissue protein requirements cannot be fulfilled by microbial protein alone and the opportunity arises to feed protected protein as a supplement to provide UDP which will compensate for the deficit between tissue protein requirements and microbial protein supplied by RDP.
9.8 The Role of Forbs and Shrubs in the Nitrogen Intake of Grazing Livestock in the Accra Plains
Authors: Fianu F. K.
Published: June 2019

Free ranging cattle in the Accra Plains of Ghana have an almost all grass diet during the rainy season when lush grass abounds (Fianu, 1966). Depending on the ecological status of the grassland, the prominent species include Andropogon gayanus, Brachiaria falcifera, Panicum maximum, Schizachyrium schweinfurthii and Vetiveria fulvibarbis. On bush fallows, grasses of lower successional status, e.g. Chloris and Digitaria spp., are grazed.

At the start of the rainy season (March-April), the young herbage may contain as much as 2.8% N. As the plant matures, however, the N content declines rapidly below critical levels, e.g. 0.95-1.3% at 18 weeks (Fianu and Winch, 1980) and 0.6-0.8% at 38 weeks (Lansbury, Rose Innes and Mabey, 1965).

Such mature grass is burnt in the dry season to induce a more nutritious flush but hard grazing and slashing also induce equally nutritious regrowth (Fianu and Winch, 1980).
Energy requirements and responses: a UK perspective
Authors: Reynolds C. K. , Beever D. E.
Published: June 2019

Ongoing improvements in the genetic merit of United Kingdom (UK) dairy cows as well as changes in the national milk market will increase awareness of and provide focus on the importance of balanced nutrition, particularly with respect to energy and protein. Within the UK, energy is rationed according to the metabolizable energy (ME) scheme, proposed in the 1960s and implemented in the late 1970s. Whilst a significant improvement over previous rationing systems, deficiencies in the scheme have been identified. These relate to an inability to predict animal response including the importance of nutritionally induced changes in milk composition, and to represent adequately body tissue mobilization in early lactation and the control of nutrient partitioning during the phase of tissue repletion. Some of these issues are addressed in this paper. These include the problems likely to occur in formulating rations for dairy cows producing in excess of 50 kg milk per day during significant parts of the lactation, which leads to an appraisal of some of the concepts embodied in the current ME system. By reference to appropriate experimentation, the importance of recognizing the nutrient composition of ME as well as the significance of nutrient metabolism in the portal drained viscera and the liver is established. The rôle of added fat within the diet is discussed, whilst the quantitative importance of mobilized body tissue to whole body energy metabolism and the interaction between specific nutrients is recognized. Finally, it is concluded that a complete revision of the ME system is unlikely at this stage and therefore it will be prudent to deploy available resource to modify the existing ME model in line with some of the inconsistencies and weaknesses that have been identified.
Protein and energy requirements and responses : a United States perspective
Authors: Satter L. D. , Dhiman T. R.
Published: June 2019

A comparison of UK (Agricultural Research Council; ARC) and USA (National Research Council; NRC) feeding standards for dairy cows is made. The two standards appear similar in terms of food energy required for milk production, even though the ARC uses metabolizable energy and the NRC uses net energy. The two systems have the same basic approach to calculating protein supply, although ARC incorporates information on level of food intake in calculating rumen microbial protein synthesis and in estimating undegraded food protein. The maintenance requirement for protein is much less with the ARC system because NRC assigns a large maintenance charge to metabolic faecal nitrogen. The result is that ARC has lower dietary protein recommendations than NRC. Milk production response to incremental additions of energy (grain) or protein diminishes as the point of maximum response is approached. The most profitable level of energy and/or protein supplementation is often below the supplementation level required for maximum milk production. More emphasis must be given to lactation studies for information to improve accuracy of the feeding standards and for construction of milk response curves to incremental additions of supplements.