Consumers are becoming increasingly aware of dietary issues and are demanding that food is labelled effectively with compositional information. In the past 20 years major changes have taken place in beef production, in particular the greater use of young bulls and the introduction of genes from several continental breeds, which have the potential of producing leaner meat. The current standard reference, McCance and Widdowson's ‘The Composition of Foods’ was last revised over 10 years ago, so this trial was set up in collaboration with the Ministry of Agriculture, Fisheries and Food to provide up-to-date estimates of the chemical composition of beef.

Recently methods based upon the HPLC separation and detection of cytosine (Koenig 1980) and the spectrophotometric analysis of the total purine content of microbes (Zinn and Owens 1986) have been proposed to estimate microbial nitrogen flow at the duodenum. Little work has been undertaken in-vivo to evaluate cytosine as a marker and to compare it with current techniques. The present trial was designed to evaluate this marker and to compare it with diaminopimelic acid (DAPA), [3H]leucine and the total purine technique. In addition, recent reports (Hvelpund and Madsen 1985) have indicated that expressing miaobial efficiency in terms of carbohdrate, as opposed to organic matter degraded in the rumen, reduced the variation in microbial yield. This was also investigated.

The Agricultural Research Council Working Party (ARC, 1980) summarised the predicted energy requirements for cattle growing at different rates of gain. These predictions suggest that feed conversion efficiency will improve with increased energy intake. McCracken and Unsworth (1989) developed an empirical model for growth and carcase composition based on ARC (1980) and concluded that the model over-predicted body fat and did not accord with the effects of plane of nutrition on feed efficiency and body composition observed by Andersen, Ingvartsen and Klastrup (1984). Two problem areas were identified (a) the efficiency of utilisation of energy for growth, (b) the relationship between plane of nutrition and energy content of gain. The study described below was undertaken to provide definitive information on the effects of slaughter weight and plane of nutrition on the body composition and energy retention of Friesian steers as being representative of a medium breed type within the ARC (1980) classification.

The clearance rate of digesta from the reticulo-rumen may limit feed intake and thus production in ruminants. The longer the retention time in the rumen the better the cell wall carbohydrates are digested. However, a fast rate of passage of indigestible feed particles to the lower digestive tract is essential for maximal feed intake. The feeding level, type of diet and the physical characteristics of the feed particles affect the rate of passage from the rumen. The rate of passage has mostly been determined by external marker techniques. Because of physico-chemical characteristics these markers do not always accurately represent the behaviour of feed.particles. An alternative method, the rumen evacuation technique, may describe better the kinetic characteristics of cell walls. In this study marker and rumen evacuation techniques were compared in the determination of the passage rate and retention times.

Potentially digestible fibre leaves the rumen either by enzymatic breakdown or by passage to the lower tract. The digestibility of potentially digestible fibre is a function of the rate at which fibre is digested and its retention time in the rumen. The procedures used for estimating the rate of fibre digestion (kd) and the rate of passage of feed particles (kp) are extremely variable. The estimates for kd and kp derived by using different procedures can have a large effect on the fibre digestibility calculated from kinetic parameters of fibre. The objective of the present study was to evaluate the different methods in estimating the kinetic parameters of mathematical models that will describe cell wall digestion in the rumen.

Fungal probiotics are gaining increasing acceptance as growth promoters that act via the rumen fermentation. Products have been described based on Saccharomyces cerevisiae and Aspergillus oryzac (Williams and Newbold, 1990). However not all species of Aspergillus or strains of S. cerevisiae exhibit probiotic properties (Tapia and llerrera-Saldana, 1989; Newbold, 1990). The selection of fungi with probiotic properties would be greatly facilitated by the development of a rapid method for assessing their efficacy. In the present study the effects of one of these products (Amaferm, based on Aspergillus oryzae; AO) on short term incubations invitro were compared with results obtained previously in longer-term in vitro fermentations (Rusitec) and with in vivo measurements.

Monensin, an ionophore, and AO, a fungal feed additive, are growth promoters which modify rumen fermentation. Previous studies have shown that monensin increased propionate, the efficiency of bacterial growth and the flow of protein from the rumen and decreased methane production and fibre digestion (Schelling, 1984), whereas AO increased bacterial numbers and fibre digestion and lowered methane production (Frumholtz et al., 1989; Fondevila et al., 1990). The aim of the present study was to determine, using Rusitec, the effects on rumen fermentation of combining these additives.

Efficient utilization of silage diets depends upon the nutritional value of the forage and the amount eaten by the animals. However, even good quality silage is usually supplemented with energy concentrates (principally cereal based) to provide sufficient dietary energy for a high producing dairy cow. This experiment was therefore designed to examine two concentrate energy sources (starch and sugar) at two levels of crude protein on animal production, using the sugar based concentrate (molaferm 20) as a true silage supplement.

A 3 x 4 week changeover design based on Latin squares, the experiment was conducted with 18 individually fed Autumn calving dairy cows, on average 77 days calved. The animals were second lactation or more and commenced their experimental period at least six weeks postpartum, with the preceding 2 weeks being used as a covariance period. Cows were blocked according to current milk yield, liveweight and lactation number and from these randomly assigned to 6 treatment groups.

In Bangladesh, locally produced fishmeal is available as a protein source for lactating cows but sometimes it is scarce and expensive. There is a need to find an alternative concentrate such as a legume which can be grown by the roadside, embankment and home. An experiment has been carried out to assess the effect on performance of partly replacing fishmeal with fresh foliage from Leucaena leucocephala.

In Kuwait there is a high demand for forage and roughage to meet the livestock needs for the production of milk and meat. Kuwait dairymen are obliged to feed their animals a diet with high concentrate and low roughage content for economic reasons, i.e. the unit cost of roughage is greater than that of concentrates due to a government policy of subsidising imported concentrates, but not roughages. There is a need to find a locally produced source of roughage to encourage higher levels of inclusion and to reduce feed costs.

This experiment was designed to compare the effects of feeding locally produced date palm leaves rather than imported barley straw to Friesian and Holstein cows given a high concentrate diet.

The investigation was designed to examine the use of draff ensiled with molassed sugar beet nuts (MSBN) as a concentrate replacer in silage based diets for dairy cows.

Twenty four British Friesian cows in early lactation were used in a changeover design experiment consisting of 3 x 3 week periods. The cows were allocated to the treatments listed below in such a way that one cow from each of the 12 pairs was allocated to proprietary concentrate treatments and the other to draff treatments for the duration of the experiment.

In Great Britain the use of animal-derived protein in animal feeds has recently been subject to restrictions (The Bovine Spongiform Encephalopathy Order 1988 and subsequent orders), including a prohibition on the use of animal protein produced from ruminant carcases in feed given to ruminants. More generally, livestock producers are increasingly demanding more detailed information about the ingredients included in the compound feeds they purchase, and may stipulate that meat and bone meal derived from particular animal species is not used in their feed. In order that compliance with these legal and commercial requirements can be monitored and enforced, it is important that feed manufacturers, their customers and the regulatory authorities should have recourse to a means of identifying the species from which animal protein, when present in a feed, is derived.

The neonatal calf is especially prone to enteric and respiratory infections during the first two to three months of life. The mortality rate and disease incidence are of enormous economic importance in the production of calves. The innovation of embryo transfer techniques has made it possible to produce twin calves from both dairy and suckler cattle, therefore the health and survival of these calves is of prime importance to the viability of twin calf production. The neonatal calf relies upon three mechanisms for protection against pathogens; the barrier provided by mucus secreting epithelial cells; the non-specific engulfing of foreign antigenic material by phagocytic cells and the immunoglobulins received via the colostrum. Neonatal calves are born with low levels of β-carotene and essential fatty acids (Noble, 1984) which have both been shown to be important for the health and performance of a number of animal species (Bendich and Shapiro, 1986) and may enhance the immune response in newborn animals.

One classical theory of food intake control suggests that, within limits, food intake is regulated to ensure that requirements for energy are just met. Two of the prime objectives of the calf rearer are to achieve rapid growth and early intake of solid food (to allow early weaning). The optimum concentration of energy, therefore, will be sufficiently low to maximise intake of solid food, yet high enough to maximise total intake of energy. A complication is introduced by the fact that the pre-ruminant calf receives two foods simultaneously; a daily allowance (usually fixed) of milk replacer supplemented by ad libitum access to solid starter feed. Theory predicts that intake of starter will be determined by concentrations of energy in both starter and milk replacer (assuming other nutrients supplied in excess of requirements). If the calf is able to select a level of intake of starter which allows requirements for energy to be met, rate of growth will be independent of concentrations of energy in both starter and milk replacer. Our objective was to test these predictions in a conventional calf rearing system.

It is generally recognised that the nutritional and metabolic status of the sow during lactation can influence its subsequent reproductive capacity. Thus sows which mobilise large quantities of body weight during lactation have extended weaning to oestrus intervals and reduced litter sizes. However, it is not known how nutrition during lactation may influence metabolic efficiency in the post-weaning period, especially in relation to the accumulation of body reserves. The present experiment was therefore designed to investigate the effect of feeding level during lactation on nutrient partitioning and metabolic efficiency in the weaned sow.

Current strategies for sow feeding are based on maintenance of a constant body condition throughout the reproductive cycle by feeding at levels only slightly above maintenance in pregnancy and feeding generously for milk production in lactation. Recent evidence suggests that feeding at a low level during pregnancy, whilst meeting nutritional requirements, may be detrimental to sow welfare. The large intake capacity of the sow also offers opportunities for utilising cheaper, alternative feeds at this stage. If bulky feeds are available at low cost, it might be economically attractive to feed for fat deposition by the sow in pregnancy and utilise this during the subsequent lactation. This experiment was designed to investigate whether sows with increased body fat reserves at farrowing could be encouraged to utilise these efficiently during lactation by the provision of a high protein diet.

The choice-feeding method has been suggested as an effective way of estimating nutritional requirements and it may be helpful from a practical point of view for meeting the nutrient requirements of animals with great variability in nutrient intake and requirements, for example sows in lactation. Friend (1971) reported high variability in protein intake in lactating sows on choice feeding. Growing rats (Leshner et al.,1971) respond to temperature changes by modifying the proportion of protein selected in order to maintain their protein intake. The main objective of this experiment was to investigate the ability of sows offered diets of different nutrient content to select the combination that best fits their requirement, particularly in relation to problems of reduced food intake routinely encountered in high summer temperatures.

There has been an increasing interest in recent years in the feeding of bulky, high fibre diets to sows for both economic and animal welfare reasons. The potential of the pregnant sow to utilise sugar beet pulp, a highly digestible, high fibre by-product has previously been investigated (Close et al 1990, Edwards et al 1990). However, in both these investigations, the feeding of the high fibre diet was restricted to the pregnant sow and conventional diets were fed throughout lactation. The main objective of this trial was to assess the effect of substituting cereal and cereal by-products with molassed sugar beet feed (SBF) throughout pregnancy and lactation, on the condition and performance of both gilts and adult sows.

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.

Piglets which are heavier at weaning generally show a lower incidence of post weaning disease and mortality, superior growth rates and convert feed to gain with greater efficiency than smaller piglets. Weaning weight is largely determined by the yield and quality of milk available to the suckling piglet, and these parameters are becoming increasingly important with the large litter sizes produced by modern prolific sows.This experiment was designed to quantify milk production by sows of a modern commercial genotype and investigate possibilities for dietary manipulation of milk yield and composition as a means of increasing piglet performance.