In some pig herds it is common for 20% or more of pigs born alive to die before weaning, indeed the national average across all herds is approximately 12% (Meat and Livestock Commission, 1983). A large number of these deaths are caused by Esherichia coli, of which up to half are caused by the K88 serotype (Walters and Sellwood, 1982). Several reports (eg. Gibbons, Sellwood, Burrows and Hunter, 1977) have shown that resistance to K88 E. coli is inherited as a simple Mendelian recessive. Of potential practical significance is the evidence that suggests that the sole use of resistant boars within a herd would prevent any K88 scour since the only susceptible progeny produced would be born to susceptible dams which would provide passive maternal protection to their piglets. However, the obvious advantage in using resistant boars in a herd would be nullified if performance of the offspring was significantly lower in important economic traits. Two trials on different farms were set up to investigate this possibility.

Urea treated Whole Crop Wheat (WCW) provides a stable, alkaline high DM forage, which is a potential replacement for, or complement to grass silage. Harvesting at about 600 g DM/kg facilitates both optimum crop DM production and energy concentration within the crop. Urea treatment (40 kg/t DM) at harvest prevents fermentation during storage, and may increase the crop digestibility. The nitrogen status of the forage as ammonia is also increased. The aim of these experiments was to investigate the feeding value of WCW for dairy cattle, when offered as the sole basal feed.

A spring wheat crop (var. Axona) was cut at about 600 .g DM/kg (hard dough stage), chopped using a conventional forage harvester and stored in an outdoor clamp silo. Urea was added at 40 kg/t DM during harvesting. After rolling, the clamp was sheeted with polythene for 125 days until feed out.

Livestock food was contaminated with starling excrement by placing caged starlings (Sturnus vulgaris) over livestock food troughs and feeders, and allowing starling excreta to fall on food for periods ranging from 30 to 56 consecutive days. Several levels of contamination were tested by varying the number of caged starlings over troughs, from 1 to 18 birds per m2 of trough area. During the winters of 1979 and 1980, four trials were conducted involving 78 pigs of both sexes, 24 steers and 18 male calves. No significant differences were observed in daily rate of weight gain or efficiency of food conversion (food offered per unit gain), suggesting that neither cattle nor pigs appeared to be adversely affected by exposure to starling excreta in their food. Food rejection observed during these trials appeared to be a negligible problem overall. Although limited disease incidence did occur, it did not appear to be associated with food contamination.

With the increase in the use of wet feeding systems, there has been a controversy over the optimum water to feed ratio to be used in these systems. Braude et al., (1967) showed that the feed conversion ratio was 20% higher for wet fed pigs compared to dry fed pigs. However, Forbes et al., (1968) found no significant difference in daily gain between wet and dry fed pigs.

Gill et al., (1987) conducted an experiment to investigate the effects of different water to feed ratios on the performance of growing pigs provided with an additional water supply. They showed that liveweight gain and feed conversion significantly improved (p < 0.05) as the water to feed ratio of the liquid feed was increased from 2:1 to 3.5:1.

The objective of this experiment was to investigate whether water to feed ratio effects digestibility, digestible energy and nitrogen retention.

An increasing proportion of Agricultural Research funding is being directed to biotechnology and to cell and molecular biology. This shift in funding has two effects on animal production research. First it provides a certain amount of novel information and technology with which to improve current production systems. Second, it leaves less of the research budget for whole animal experiments. It behoves us therefore to keep abreast of the achievements and aspirations of the molecular and cellular biologists. The diverse interests and expertise of the BSAP membership in research, development, advisory work and teaching make the Society a unique forum for conducting the open and on-going debate that is needed to ensure that the results of modern biotechnology are examined critically and applied to the animal production industries in an efficient and acceptable manner.

There is now a considerable volume of evidence to indicate that, with high quality, grass silage-based diets, good animal performance can be achieved by offering supplements of high crude protein content at much lower levels than would be required with conventional supplements. Given the current constraint on milk output at farm level, there is considerable interest in lower cost milk production systems and high protein supplements would appear to have a role to play in this context. However, there is little information available which enables prediction of milk yield responses to increasing levels of supplements of differing protein content. The objective of this study was to determine response curves to supplements of differing protein content, given in addition to grass silage, thereby facilitating a least-cost diet type approach to achieving a given level of milk output.

Concentrates containing either 100, 220, 340 or 460 g crude protein (CP)/kg fresh weight were offered to 72 autumn-calving dairy cows from day 14 of lactation, with each concentrate offered at four levels of feeding.

In an integrated group housing system for sows, animals of all stages of production are kept in one group, except around farrowing, and remain there throughout their productive life. Lactating sows have access to the suckling section of the house via an electronic gate. Jostling of piglets from different litters is avoided by keeping the litters in their own suckling pen until weaning. The system allows lactating sows to freely evade their piglets, and move between the suckling section and the communal area. They can maintain their social position and cool off in the relative cool communal area. Earlier observations (Houwers et al., 1992) showed sows decreased sucklings and increased their absence from the farrowing pen towards weaning. It was not clear whether the overall performance of the piglets was depressed by absence of sows before weaning. The relevance for practical farming partly depends on the production results that can be achieved.

Since the cell wall content (CWC) and cell wall digestibility are the main factors influencing the animal's energy supply from forages, the ability to accurately measure CWC is crucial. This is becoming increasingly important as feed evaluation methods move towards a more dynamic approach of assessing nutrient supply from a wide range of substrates in order to reflect the two-stage nature of digestion in ruminants. Originally developed for forages, the neutral detergent fibre (NDF) procedure of Goering and Van Soest (1970) is generally regarded as providing a satisfactory measure of CWC despite the fact that varying amounts of cell wall pectins are soluble in neutral detergent solution (Chesson, 1986). However, previous work (IVVO, 1991) suggests that sample drying temperature and other factors can influence the measurement of CWC. An experiment was undertaken to study the effect of different drying temperatures and method of NDF analysis on the measurement of CWC in different forage types.

Discussion of this topic requires clear definition of terms. For instance, because size can be such an ambiguous word, it is essential at all times to state the units of measurement of size of the animal. The units may referto height, weight, skeletal size, metabolic body weight or to some component of body composition. Most frequently the subject is discussed in terms of body weight, or some function of it representing metabolic body size, and little cognisance is taken of possible differences in body composition. I consider this to be a serious omission, because it seems highly unlikely that weight of the animal will have the same relationship to productivity irrespective of the composition of the weight.

Active immunisation against androstenedione (Fecundin, Coopers Animal Health) increases ovulation and lambing rates. A study undertaken during the 1984-85 breeding season in randomly cycling ewes mated during October and November showed an increase in lambing rate of 24 lambs/100 ewes mated amongst ewes treated with Fecundin (Vipond, Keeling and Hunter, 1986). Fecundin increased the Incidence of triplet and quad births, suggesting that the greater benefit from the product would be derived in a situation where management could ensure the survival of additional lambs. The early lambing flock is such a case. Ovulation rates tend to be lower than later on in the breeding season, so fewer triplets might be expected amongst treated ewes. Management tends to be of a high standard, and the value of the early finished lamb is high.

Pollution problems caused by silage are mainly odour and effluent production.

Odour can be virtually eliminated by ensuring a satisfactory silage fermentation, i.e. a low pH and a low ammonia concentration in the total nitrogen. This can be achieved by following the basic rules of good silage making, including the correct use of an effective acid additive.

Effluent is the major problem, particularly when it enters drains and water courses. This is because a typical effluent will have a pH of approximately 4.0 and a high 5-day biological oxygen demand (BOD5) up to 90 000 mg O2, per 1. This compares with BOD5, values of 5000 and 500 mg O2 per 1 in cow slurry and untreated domestic sewage respectively. Thus silage effluent in water courses removes the dissolved oxygen and will kill fish and other aquatic fauna. Effluent from a silo containing 300 t of low dry matter (DM) silage is equivalent in BOD5 to the daily sewage from a town of 80 000 people.

Previous studies (e.g Rogers et al., 1985; Estell and Gaylean, 1985) have shown that addition of sodium (Na) as NaHCO3 or NaCl to conserved feeds increases rumen pH, fluid dilution rate, digestibility of dietary nutrients and rumen cellulolysis. Little research has involved the effect of Na supplementation on cattle fed fresh herbage.

The objective of the present experiment was to examine the effects of 0 (Nil), 32 (Low), 66 (Medium) and 96 (High) Kg Na ha-1 yr-1 applied as fertilizer to zero-grazed perennial ryegrass pasture, on rumen digestion and feed and water intakes.

There is a clear need to improve financial returns from hill sheep to help maintain rural populations in hill/upland areas while at the same time reducing the reliance of hill sheep farmers on social/production type subsidies. Particular problems with hill sheep are their small carcass size and poor conformation, which result in reduced values for both draft ewes and wether lambs. These poor carcass attributes are also passed down to the lowland producer through the production of poor conformation halfbred ewes out of hill ewes. With the increasing pressures being placed on the lowland sector to improve carcass quality, many producers are beginning to look at the possibility of breeding their own replacement top-cross ewes. Any widespread adaption of this practice will further undermine the profitability of sheep production in the hill and upland sectors.

Recent studies have shown that piglets, growing pigs and sows can perform well on diets containing substantial proportions of plain sugar beet pulp (SBP) (Bulman et al., 1989; Low et al., 1990; Close et al., 1990). SBP contains c. 600 g non-starch polysaccharides (NSP)/kg which, unlike starch, cannot be digested by the hosts’ enzymes but must be fermented by the gut microflora to yield VFA for subsequent use as an energy source by the animal.

The objective of this study was to determine the degree to which 32-day-old piglets, growing pigs of various ages, and mature sows can ferment the NSP content of diets containing varying proportions of SBP.

Milk quotas have resulted in a reduction in dairy cow numbers between 1983 and 1987 which represents a loss of almost 250,000 calves for beef rearing. Increasing slaughter weights is one way to make up for some of the consequent shortfall in beef production. However slaughter weights will not increase unless it is profitable to the producer.

MLC investigations are showing that differences in performance within a group of finishing cattle means that there is extra profit in keeping faster growers longer than average. Table 1 shows slaughter weights of a group of Charolais cross male suckled calves at different ranges of daily gain. Optimised slaughter weights for each sub-group and the extra gross margin after interest which should have accrued if they had been sold at the optimised weights are also given. Within the group the fastest growing bulls should have been kept longest and would have shown the biggest increase in margins.

The gastrointestinal tract is a major organ of the immune system. Gut associated lymphatic tissue (GALT) contains approximately 40% of mature lymphocytes and represents a significant part of gut mass. GALT consists of a complex of immune cells found in discrete organs e.g. Peyer's patches and mesenteric lymph nodes, as well as dispersed within the lamina propria and the epithelium. Both B cells and the two main subsets of T cells, CD4(helper/inducer) and CD8 (suppressor/cytotoxic) are found. This significant involvement of the immune system in the gut should not be a surprise, given that the gut represents a major site of interaction with the ‘outside world’ and therefore represents a major challenge to homeostasis, specifically from infectious disease.

The gut also has a fundamental dilemma, it must respond vigorously with a protective response against any pathogens presented at its mucosal surface, yet sustain digestive and absorptive function of dietary non-harmful antigens. On occasion it gets it wrong, resulting in damaging hypersensitivity reactions e.g. Coeliac Disease, milk intolerance in children, food allergies and diarrhoea in the postweaned pig and the pre-ruminant calf. It is these inappropriate immunological responses that can prove to be a constraint on animal production, specifically on the use of legumous protein sources for animal feeds.

Moving onto silage aftermath is an integral part of the 1.2.3 grazing system. In this system two thirds of the grass area are conserved for first cut silage while the other third is grazed. Between first and second silage cuts the silage aftermath is grazed while the original grazing area is closed for silage. After the second silage cut the whole area is grazed. In this trial the contribution of silage aftermath to the system was investigated by comparing the intake and performance of young cattle moved onto aftermath in raid-season with that of similar animals grazing the same sward continuously.

Thirty-two Hereford x Friesian and thirty-two Limousin x Friesian steers (mean liveweight 193 ± 16.8 kg) were allocated to either Treatment C, grazed continuously on the same sward throughout the experiment or Treatment S where the animals were turned onto silage aftermath in mid-season. Treatments were replicated twice and balanced for breed and liveweight of animals.

A large variety of processes - physical, chemical and/or biotechnological - is currently applied to cereals (Table 1).

Among physical treatments, grinding is the most comnon ; it does not modify the chemical characteristics of the grains but improves the accessibility of the enzymes of the gut to their substrates by disrupting endosperm and aleuron cell walls. Thus, milling exposes the interior parts of the grain to the digestive enzymes. Some physical processing of barley grain, such as rolling, is necessary to give optimum digestion of the nutrients by cattle (ORSKOV, 1976). This treatment, applied to barley, appears to be beneficial for young species (KREFT and BOYLES, 1989). Pigs eat whole or very coarsely milled grain reluctantly (MAXWELL et al., 1970) and utilize whole barley poorly (LAWRENCE, 1970). For this reason, barley grain is commonly milled before feeding. Grinding of maize using a roller mill does not modify average daily gain, feed intake, feed conversion and fattening time of pigs. However, sensory evaluation tests, meat from control pigs fed untreated maize is preferred to meat from pigs given rolled maize (ITOH et al., 1986). However, finely ground barley causes a strong increase in the frequency of oesophagogastric lesions whereas diets countaining coarsely ground barley or crushed oats caused few lesions. Balance trials on lamb indicate that whole maize have more digestible, metabolizable and net energy than ground maize (BONSEMBIANTEE et al., 1988).

The fact that laying hens prefer to lay in a nest is not evidence in itself that a suitable nest-site is necessary for the hens’ well-being. Stronger evidence would be found if hens were prepared to pay some cost to use a nest-site. The objective of this study is to quantify the strength of individual hens’ nesting motivation in terms of meaningful measures such as overcoming aversive obstacles, work or time.

To investigate the motivation to gain access to a nestbox, hens were floor housed in groups of four in a pen containing food and water. Access to a nesting pen containing two nestboxes, could be restricted using a number of obstacles such as a narrow gap, a water bath and a swing door. Between trials hens were singly housed in wire-floored cages containing a perch and a nestbox. Results indicate that hens made less entries of longer duration to the nesting pen (Means + s.e in Figures 1 and 3) on treatment days with an obstacle than on control days without an obstacle. There was little disruption of use of the nest box (Figures 2 and 4). Hens that were due to lay made more visits on both control (C Egg) and treatment (T Egg) days (Figure 1), which may indicate greater motivation to explore the whole pen before oviposition.

The proposed Agricultural Research Council (ARC 1984) protein evaluation system for ruminants provides lower nitrogen allowances than any other. (National Research Council 1985; Alderman 1987). A U.K. Interdepartmental Working Party (IDWP) was set up to consider the ARC (1980) proposals and recommend a practical protein evaluation system for ruminants for use by the advisory services. Its provisional proposals have been reported by Webster (1987). This trial was set up to provide a practical evaluation of the two systems in a commercial dairy herd.

Animals. Thirty-three Friesian cows (mean livewewight 590kg, mean previous milk yield 6120 kg), in early lactation were blocked according to (a) previous treatment, (b) number of previous lactations and (c) previous milk yield. The cows were randomly allocated within blocks to one of three dietary treatments.

Treatments. Dietary nitrogen allowances were calculated, according to (1) ARC(1984) and (2) IDWP (Webster, 1987) except that the ARC (1984) concept of essential amino acid nitrogen was included in the IDWP calculations. The difference in nitrogen allowances between the two systems was so great as to warrant a third intermediate treatment (INT), calculated to provide allowances mid-way between the other two.