A dynamic model of beef cattle growth and composition was developed based upon concepts validated in detailed modelling analyses of the growth of individual organs. Concepts that cell number (DNA) and cell size are primary determinants of organ (animal) size are included. Initial body weight (BW) and composition (percentage body fat), mature body weight, feed intake and feed net energy values for maintenance (NEM) and growth (NEG) are inputs to the model. Alternative inputs descriptive of feed can be metabolizable energy (ME) concentration and efficiencies of ME use for maintenance and fattening. Current body DNA and protein content and ME intake are primary determinants of rates of protein accretion. Net synthesis of body fat is calculated after accounting costs of maintenance and protein synthesis. Rate constants defining DNA synthesis, and protein degradation and synthesis, and effects of feed additives and implants upon these were deduced using data from comparative slaughter (energy balance) trials with over 1,000 cattle (mainly Hereford) fed mixed diets. No systematic errors in prediction of body weight or composition due to mature body weight, ration or feed intake (FI) were evident within this data set.

The beef industry has become increasingly concerned about the eating quality of beef, and the effect this may be having on consumer demand. Much research has been carried out on beef eating quality using expert taste panels. However, it was felt that a clearer understanding of the variation in beef as prepared commercially and those factors affecting eating quality which are important in the market place, could be achieved by using consumer taste panels preparing and eating beef under normal domestic conditions.

In the absence of information on the value of treated straw as a component of the diets of finishing cattle a series of experiments was started in January 1982 to compare diets containing differing proportions of rolled mineralised barley (B) and treated spring barley straw (T) with a control ration of 75% mineralised barley (with extracted soya bean meal supplement (s)) and 25% untreated spring barley straw (U). Two treatments remained common throughout but the others were changed to widen the scope of the investigation. Fishmeal supplementation (F) was introduced as an additional factor in the third trial.

The price difference between milk products and concentrates is resulting in less milk/milk products being fed to calves in the rearing stage. It may be that lower milk intakes at least in some systems of calf rearing are resulting in low performance in early life which in turn could be affecting lifetime performance of animals, particularly those kept for beef production.

The objective of the trial was to examine the effect on live-weight (LW) gain and its components of increasing the supply of nutrients either through an increase in the digestibility of silage or by increasing the proportion of rolled barley given with a low-digestibility silage made from late-cut herbage.

This study was designed to obtain data on the digestion and nutrient supply of the four silage-based diets used in the comparative slaughter experiment described in the previous paper, with a view to providing a better understanding of some of the production response differences noted by Thomas et al.

Cereals are the most important ingredients of diets for pigs in Europe. They supply most of the feed energy and typically half to three quarters of the feed protein, and their nutritive value is correspondingly important to the economy of pig feeding. The purpose of the present work was to examine the interrelationships of yield, nitrogen content and nutritive value in wheat and barley including a number of new varieties.

The physical form of the diet has been shown to be a factor causing the development of oesophagogastric abnormalities and ulcers in the growing pig. A series of growth trials was made to investigate this. The particle size of the diet was varied by grinding through 4.68 mm and 1.56 mm screens and by pelleting. Fibre, in the form of bran or oatfeed, was added to the fine diet. The effect of bran and oatfeed on digestibility and rate of passage through the gut was studied in metabolism experiments.

Coconut meal is a by-product of oil extraction from dried coconut kernel or copra. It is a highly variable material which, in practice, may contain from almost 0% ether extract (EE) when the oil has been solvent extracted to around 20% EE when the least efficient mechanical extraction methods are used. The trial reported here examined the effect of processing which produced meals of varying levels of residual oil, on subsequent dietary energy values.

Five coconut meals (A-E) and one sample of unprocessed copra (F) were used as a basis of the dietary treatments. Sample A was a solvent extracted meal and samples B-E were all extracted by mechanical means. Analysis of the samples is shown in Table 1.

In addition to acting as a source of the amino acid itself, methionine can act as a source of methyl groups. The requirement for sulphur amino acids is therefore influenced by the inclusion level of alternative methyl donors in the diet e.g. choline. An initial experiment was designed to ensure an adequate supply of choline so that in subsequent studies the need for methionine per se could be established. Blood metabolites were used to study the requirements. Three diets with different levels of methionine plus cystine (3.5, 4.5 and 5.5 g/kg) were formulated and randomly assigned to 36 pigs. To a basal diet, containing 660 mg/kg choline, choline chloride was added producing diets with choline levels of 660, 860, 1060, 1260, 1460 and 1660 mg/kg. The pigs were randomly allocated three levels of choline, each for a period of three days; this ensured that each treatment was repeated six times. Blood samples were taken by jugular venepuncture 4 hours after feeding at the end of each 3 day period and repeated at 3 liveweights (35, 55 and 75 kg). Blood parameters (urea and plasma amino acids) were used to measure the response.

Proteins which escape digestion and absorption in the small intestine of the pig are extensively metabolized by the microbial flora of the large intestine. It is known that bacterial enzymes are potentially capable of catabolizing all amino acids (Michel, 1966). Furthermore, it has been shown that virtually all soluble protein or amino acids introduced into the caecum are rapidly metabolized, absorbed (presumably as ammonia, amines etc.) and the nitrogen (N) derived from them is rapidly excreted as urea (Zebrowska, 1973). This has led to the general recognition that the amino acid composition is not a reliable measure of undigested dietary amino acids in pigs. It has been estimated that only 6% of faecal N is of undigested dietary origin, while the remainder is of bacterial or endogenous origin (Low, Sambrook & Yoshimoto, 1978). It was therefore of interest to estimate which proportions of faecal N derived from a barley-soya diet, are of either bacterial, endogenous or undigested dietary origin. We have used germ-free or conventional miniature pigs for this work because they are small enough to be kept in our isolators for periods of up to 20 weeks. It is emphasised that this is a preliminary report on our first efforts at raising miniature pigs under germ-free conditions.

The nature of compensatory growth in pigs remains unclear. But should pigs have undergone a period of growth retardation after weaning be capable of enhanced utilisation of food fed at the same level as their unretarded contemporaries, then exploiting the phenomenon would appear attractive to producers. Compensatory growth defined in this way is illustrated in Fig. 1.

A trial was conducted to measure the voluntary feed intake of pigs drawn from two genetic sources when fed diets of different digestible energy concentrations. The genetic sources were Large White x Landrace commercial hybrids (CH) and Landrace (Landrace x Large White) pigs from the Sutton Bonington herd (SB). Two sexes were used (boars and gilts) and four diets were formulated with energy densities of 8.6, 10.7, 12.9 and 15 MJ DE/kg feed. All nutrients were adjusted to maintain a constant ratio with energy. Pigs were offered these diets ad libitum from 25 - 55kg liveweight in individual pens. After slaughter, backfat and eye muscle measurements were taken and hams dissected into component tissues. Meat quality was also evaluated : pH of ham and loin were taken at 45 minutes and 24 hours post mortem. The ‘Grau Hamm Paper Press’ method was used to evaluate water holding capacity. Depth of colour was determined by reflectance spectrophotometry.

In mature boars the skin and subcutaneous tissues in the region of the scapula form Into a hard pad known as the shield. It is not known whether this is present less obviously in young boars used for meat production and, if so, whether it lowers carcass quality. The aim of this study was to characterise the shield and study Its development in young male pigs.

Characterisation study

Histological examination of tissue samples from the m1d-scapula region in mature boars (ie. >2.5 years of age) showed a high concentration of connective tissue. The tissue had a ‘rubbery’ texture and was difficult to cut. Outer and inner backfat layers were not discernible although approximately 0.80 of the depth of the tissue had the appearance of dermis and the composition of skin (Table 1) and the innermost 0.20 had the composition of adipose tissue (normal backfat). In boar No 1 the dissected shield weighed 3.7 kg, 0.26 of the weight of subcutaneous fat in the half carcass.

Over 95% of laying fowls in the UK are now housed in conventional battery cages. In recent years the general public and more specifically an Agricultural Committee on Animal Welfare in Poultry (1981) have raised doubts concerning the welfare of hens maintained this way and have called for further studies on alternative systems.

Consequently investigations into three alternatives to battery cages have been initiated: a range and covered strawyard system at The West of Scotland Agricultural College and a modified deep litter system at The East of Scotland College of Agriculture. The main objective of these investigations is to determine the practical feasibility and welfare consequences of the respective systems as alternatives to cages for keeping laying fowls. As well as recording productivity, the behavioural activities and distribution of wing-tagged birds have been monitored within the flocks of both the strawyard and deep litter systems. In all three studies ISA Brown layers were used and compared with sister stock housed in cages.

Puberty attainment in the gilt has been shown to be stimulated both by contact with a mature boar and by exposure to stressful situations such as relocation and transportation. It is not clear whether the pen housing the boar represents a puberty-inducing stimulus or whether the stimulus of movement enhances the pubertal response to boar contact. This experiment was therefore designed to examine the influence of boar exposure environment and movement on the efficacy of boar-induced precocious puberty attainment in the gilt.

To evaluate the accuracy of various techniques for determining the sexual state of sows, four multi-parous Landrace sows were housed in stalls in the Veterinary Hospital, Zurich University, 2-5 weeks after weaning. Catheters were inserted under anaesthesia into a prominent ear vein, and four days later blood and urine sampling commenced for 25 days, along with physiological and behavioural measurements (length, width and depth of the vulva, vulval colour, vaginal pH, presence and elasticity of vaginal mucus, rectal temperature, backpressure test, score for interest in each other, in their own or each others’ urine, the occurence of flehmen and the characteristic oestrous ear position. Blood serum was analysed by radioimmuno assay for oestradiol-17ß and progesterone. Urines were analysed for oestrone, oestradiol-17 ß, progesterone derivatives, creatinine and optical density.

Observations in Edinburgh on Large White domestic pigs kept in groups outside or in family pens have indicated that sows regularly exhibit lactational oestrus in rich social and physical environments. In the pig park enclosure oestrus occured in 20 of 25 lactations and in all 21 lactations in the enriched family pen system. To further assess the stimulatory importance of selected factors of these environments, lactating sows were housed on three treatment levels differing in environmental complexity: i) conventional farrowing crates, ii) larger pens with optional outside yards, iii) enriched family pens. On each housing level additional treatment factors were applied: locomotory or manipulative possibilities, partial or full social contact with other sows and boars, restriction of suckling or piglet contact.

Present Welfare Codes recommend systems of dry sow housing which do not involve close confinement. The ‘Pig-code’ system permits automatic individual rationing of group housed sows without the necessity for individual feeding stalls.

The computer controlled feed station has a gating system enabling it to be used by two separately housed groups of sows. On entering, each sow is identified by its collar mounted responder and given any feed remaining from the preset amount for that time period.

It is important to have a quantitative knowledge of the energy value of body-weight change (EV MJ/kg) when designing nutritional strategies for dairy and beef cows. Published values for EV vary widely. For example Chigaru and Topps (1981) give values for cows from 3.7 MJ/kg to 26.9 MJ/kg and Alderman, Broster, Strickland and Johnson (1982) give a mean value as high as 89.1 MJ/kg in mid-lactation. A wide range of values are also calculated for lactating ewes by Cowan, Robinson, Greenhaigh and McHattie (1979). The current ARC (1980) recommendation for cows is to use a constant value of 26.0 MJ/kg. Using mean values can be useful to make practical progress but we cannot avoid facing the fact that averaging, even on a selective basis, tends to obscure real and high variation in reported values. This paper will present a mathematical development which will define what is meant by the energy value of body-weight change and discuss some implications which follow. A final solution to the basic problem is not proposed.