The literature suggests that supplementation of fibrous roughages with small amounts of rapidly fermentable carbohydrates can increase intake. A wide range of supplements has been used such as sugar beet pulp, (Silva, 1985), barley (Chimwano et al, 1976), maize starch (Huque, 1991) or sucrose (Campling et al, 1962). It has been suggested that one of the positive effects of rapidly fermentable carbohydrates on poor quality roughages is to provide extra fermentable organic matter, thereby enhancing microbial activity and fermentation of the less readily degradable components of the roughage. Thus Chappel and Fontenot (1968) used an 8 per cent concentrate inclusion with a roughage-based diet, and observed higher cellulose digestibility than without supplementation. We have suggested (Hovell et al 1988) that the outflow from the rumen of undegraded roughage residues is driven by salivary flow, rumen VFA levels stimulating saliva production during rumination. In this case, at least part of the effect of starchy concentrates on stimulating intake would be through a stimulation of rumen outflow. This hypothesis would seem to have been confirmed by the observations of Huque (1991) who supplemented a basal straw diet with maize starch (10, 20 or 30%) and observed an increased intake and rumen outflow with the lower levels of supplementation.

The objective of the experiment described here was to study the effect of the addition of starch to a straw diet on voluntary intake and rumen parameters including the dynamics of water flux.

Hair follicles have been described as dynamic structures in which cell proliferation, migration and synthesis of macromolecules occur. Detailed knowledge is still lacking in areas related to cell proliferation, growth and migration and it has been suggested that our limited understanding of mechanisms regulating hair growth has been partly caused by the lack of reliable in vitro models. In the work desribed here, we have adapted a recent technique developed for the isolation and maintenance of human hair follicles in vitro (Philpott et al. 1990), to the isolation of intact anagen follicles from the Angora goat and report on their growth over 4 days and aspects of metabolic activity over 5 days in culture.

Circulating concentrations of insulin-like growth factor-1 (IGF-1) are closely related to the nutrition of animals and their rates of growth. The major site of IGF-1 production is thought to be the liver. Whilst growth hormone (GH) is thought to be the main regulator of IGF-1 production in farm animals, in laboratory rats, altering the GH status of the animal (without hyperphysectomy) has little influence on circulating IGF-1 levels. A series of studies have been conducted with primary cultured rat and sheep hepatocytes to investigate the influence of GH and nutrient availability on the production of IGF-1 by liver cells.

Inadequate uptake of macro-mineral elements in cattle frequently causes economic losses, mainly through clinical disease in the case of Ca and Mg and reduced performance in the case of P and Na. Uptake is a function of mineral intake, solubilization in the digestive tract and absorption of the solubilized fraction. Inadequate Mg uptake is known to be partly caused by fertilizer K, which elevates herbage Ko content and prevents Mg absorption in the rumen. Fertilizer Na, by restricting herbage K uptake offers a means to increase Mg uptake in cattle and could potentially increase the uptake of other minerals.

Choice-feeding has the potential to replace the conventional practice of formulating and manufacturing a series of complete diets for growing pigs. One option is to allow the pig to select a diet from a cereal mixture and a protein rich mixture. However differences in feed ingredient composition, for example amino acid imbalances may influence selection, nutrient intake and performance. The aim was to determine if young growing pigs could select a diet to meet energy and ideal protein requirements, from cereal and protein rich feed ingredients, both of which were supplemented with synthetic amino acids to idealise for apparent ileal digestible (AID) protein.

The aim of these trials was to discover if growing pigs can select an appropriate mixture of two feeds differing only in the level of one amino acid.

A trial was conducted with 40 male pigs, with an initial mean weight of 13.1 kg. A basal low lysine feed was formulated with 172 g digestible protein (DP)/kg feed which was supplemented with synthetic lysine. The resulting feeds were similar in all respects except digestible lysine (DL) level, which was 25 (L), 50 (ML), 109 (MH) and 141 (H) g/kg DP.

A second trial was carried out with threonine, using 48 male pigs with an initial mean weight of 11.94 kg. The same basal feed was supplemented with synthetic lysine to 70 g DL/kg DP and then supplemented with varying amounts of synthetic threonine to form four feeds with digestible threonine (DT) levels of 29 (L), 35 (ML), 55 (MH) and 68 (H) g/kg DP.

Cropper (1987) considered the influence of the ‘bulkiness’ of foods upon the diet selections made by growing lambs. The food pairs offered differed in both crude protein (CP) concentration and digestibility. The lambs offered such choices did not completely avoid the more bulky food, which would have been expected from an optimal foraging point of view (Krebs & McCleery, 1984). This led to the suggestion that the consumption of small quantities of the more bulky food was beneficial to the lamb, perhaps to maintain rumen function. The foods used in Cropper's (1987) experiment had different metabolisable energy concentrations and so the ratio of protein:energy would have varied between foods, thus these lambs may have attempted to select diets in order to achieve a specific ratio of such nutrients.

The objective of this experiment was to test whether nutrient density (concentrations of protein and energy) has an influence upon diet selection. This was achieved by offering pairs of foods with different nutrient densities but a constant ratio of metabolisable protein (MP): metabolisable energy.

Previous studies of diet selection, in a controlled environment (Hou et al, 1991; Kyriazakis & Oldham, 1992) have demonstrated that growing lambs are able to select, from foods differing in crude protein content, a diet which meets their requirements for protein. Little consideration has been given to the effect of other physiological states upon diet selection. The ewe in the last eight weeks before lambing has been chosen as further model; during this period ewes have an increasing requirement for metabolisable energy and protein in order to supply the growth and development of the foetus and maternal tissues. In addition the foetus has an increasing absolute requirement for glucose, which must be supplied by the ewe herself via gluconeogenesis.

The objective of this experiment was determine whether ewes are able to select a diet, from a pair of foods, which enables them to supply these requirements for metabolisable energy and protein. Secondly it was hoped that the size of the pool of non amino precursors could be altered and so it would be possible to test whether the availability of such precursors would have an influence upon the selection for protein.

Different wheat samples can cause variation of up to 15% in the growth rate of broilers (March and Biely 1973). There is a poor relationship between the chemical composition, or the determined ME of the wheat, and it's subsequent feeding value. The diet selections of cockerels change when they are given a choice between a different wheat sample and a balancer feed (Rose and Parker 1990). An objective of this study was to determine whether wheat variety changed diet selections. A second objective was to examine any relationship between selection of wheat by cockerels and it's feeding value for broiler chickens.

Six wheat varieties were grown in 1990 at sites in Yorkshire and Humberside. The samples were produced from randomized block experiments at each site. Diets that contained 70% of each of the 12 wheat samples were fed to 7-day old broilers for 14 days (Rose et al 1992). Excreta were collected for the last 4 days of the feeding trial.

In situ grazing is the most common method of feeding crop residues in semi-arid tropical Africa. The prevailing method of storing is to leave the crop residues standing in the field until grazing. Although such field storage would be expected to result in reduced nutritive value (eg loss of leaf), costs of residue harvesting (eg baling) and storing using conventional forage conservation methods would probably be prohibitive to small-scale farmers (Mlay, 1987).

There is a dearth of information on quantitative and qualitative changes in crop residues left standing in fields after grain harvesting. A study was therefore carried out at Mpwapwa, Tanzania to measure the effects of varying the duration of field storage upon the quantity and quality of sorghum stover and lablab bean haulm.

Previous experiments (Osafo, Owen, Said, Gill & McAllan, 1992), investigated the possibility of using low-input technology to improve intake of sorghum stover in sheep and cattle. Physical form of stover influenced intake differently in sheep and cattle; chopping stover increased intake in sheep but decreased intake in cattle.

In an earlier experiment in the same research project, Aboud, Owen, Reed, & McAllan (1990) offered sheep, chopped stovers from bird-resistant (BR) and non bird-resistant (NBR) sorghum. It was hypothesised that intake of BR stover would be lower on account of its higher content of anti-nutritional, polyphenolic compounds. The results were contrary to expectation. The higher leaf:stem in the BR stover was thought to counteract the anti-nutritional factors and account for the higher intake and growth with BR stover. In view of the differences in leaf-plus-sheath:stem ratios between the BR and NBR stovers, the experiment was considered inconclusive. Also the fact that the stovers were supplemented with cottonseed meal may have alleviated any detrimental effect of feeding NBR stover.

Chemical components of plants vary between species and with maturity. As a result the nutritive value could be affected. Antinutritive factors such as tannins are common in browse. Little is known about mediterranean browse. This paper aimed to study chemical composition and to determine the nutritive value using the in vitrogas production and the in sacco DM degradation techniques of 8 Greek browse at different stages of growth.

Rice polishings (RP) which are produced as a by-product during the pearling of hulled rice have been successfully used as a supplementary food for ruminants. However, information on the effects of feeding RP on rumen fermentation is contradictory. Valdez et al. (1977) found RP had little effect on rumen fermentation in bulls and suggested that the stimulation in growth rate observed, with RP may be mediated by the provision of nutrients postruminally. In contrast, Cardenas et al. (1992) reported that RP stimulated volatile fatty acid concentrations and microbial numbers when added to a rumen simulating fermentor (Rusitec). One reason for these differences might be that changes in the milling process, used to produce RP, have resulted in a by-product with different physical characteristics to that used in earlier studies. The experiment described here was designed to investigate the particle size distribution in Colombian rice polishings and the effect of these fractions on the rumen fermentation in vitro.

Legumes are a very diverse source of food for humans and animals. Generally pulse legumes are used as human foodstuffs while pasture, shrub and tree legumes are more suitable and frequently used as a supplement to low quality feedstuffs for ruminant animals. The importance and potential of forage legumes is due to their diversity, compositional, agronomic and nutritional attributes.

In many of the ruminant production systems of the developing world, native or naturalised grass pastures make up the bulk of the feed. The low quality and seasonal nature of the forage supply, together with the low intake by animals and the poor digestibility of the forage are major factors which contribute to low productivity of ruminant animals. There is thus substantial scope for the utilisation of the large array of forage legumes as a supplement for ruminant diets, especially in the arid and semi-arid tropics. Although the potential of forage legumes is high there is relatively little information on the vast array of materials available. There is some evidence, however, that some forage legumes have low digestibilities and contain a considerable variety of antinutrients and toxins which influence their nutritive value (Mueller-Harvey and Reed, 1992; D’Mello & Acamovic, 1989, Acamovic et al, 1992; Baintner et al, 1992; Jones et al, 1992; Topps, 1992).

The most important crop residues in Northern Nigeria are sorghum, millet, groundnut and cowpea straws. The cereal straws especially sorghum is the most important for cattle feeding during the dry season when grass and fodder is limiting, but cereal straw has a poor nutritive value due to low nitrogen and extensive lignification. The use of chemical methods (acids, alkalis or urea) to improve the nutritive value of crop residues has not found acceptance among pastoralists. These chemicals are expensive and not readily available. The leguminous straws of groundnut and cowpea have a higher nitrogen content. Their use as supplements to improve the feeding value of cereal straws is a cheaper and more practical approach. jThis experiment examine the potential of groundnut hay as a supplement to cattle fed basal diet of sorghum stover in Northern Nigeria.

Sesbania sesban var. nubica is a tropical tree legume. Tree legumes have a number of uses which make them of interest to smallholder farming systems in the tropics. When incorporated into land use systems such as alley farming they provide a source of fuel wood for the household and forage for ruminant animals, as well as providing shade and pumping mineral nutrients from lower soil profiles to the surface where they can be used by more shallow-rooting companion crops. Sesbanias have considerable potential as providers of forage. The leaves are generally considered to be excellent sources of protein to supplement protein-deficient roughages such as straws and stovas in ruminant diets. Palatability of Sesbania foliage does not seem to be a problem and phenolic concentrations are low.

Sesbania is a rapidly growing leguminous shrub mainly used for improving soil fertility in Bangladesh. Recently farmers have shown growing interest in the use this plant as an animal feed. The main variety of Sesbania grown in Bangladesh is Sesbania aculeata(SA), however, recently a new variety has been introduced, Sesbania rostrata(SR) which has become popular with farmers due to its high production characteristics, the robust nature of the plants and the fact that it can be propagated vegetatively. A recent study has shown that the use of Sesbania leaf as a supplement to lactating cows given a urea treated straw based diet has a beneficial effect on performance (Khan et al.1989). When used as a suitable protein supplement, particularly for straws, browse legume must have a high protein content to supply both fermentable and undegradable protein and also should contain other critical nutrients & micronutrients (Preston, 1986). Since the new variety shows improved production and growth characteristics compared to SA, a comparative study was undertaken to assess their nutrient contents and the effect of time of cutting and drying method on digestibility in vitro.

Previous experiments (Muinga et al. 1992 a, b) have demonstrated that giving protein supplements such as copra cake or the legume Leucaena to cows fed Napier grass ad libitum did not depress Napier grass intake and increased milk production. However little additional response in milk production was obtained when 2 rather than 1 kg Leucaena dry matter (DM) was fed as a supplement. The experiment described here aimed to establish the effects of feeding an energy supplement, maize bran in addition to Leucaena on Napier grass intake and milk production and to measure the effects of the diets on rumen digestion.

Cross-bred cattle (Ayrshire x Sahiwal) were fed Napier grass ad libitum as the sole feed (N) or with the following feeds, 1 kg DM Leucaena (LL), 2 kg DM Leucaena (LH) or 2 kg DM Leucaena and 1 kg DM maize bran (LM). The composition of the feedingstuffs is given in Table 1. Feeds were offered twice daily at 06.00 and 18.00h to the cattle housed in roofed, open-sided stalls. Napier grass was chopped to 20mm lengths and Leucaena was offered after removal of stems thicker than 5mm.

There is a demand for organically produced meat from consumers concerned about environmental protection, food quality and animal welfare. Premium prices are claimed for most organic foods, but offset against these must be the possibility of reduced output. In order to quantify the reduction in physical output and the potential for improved sale prices, a beef systems comparison was carried out at Craibstone, Aberdeen, centred on two grassland farmlets; a conventional fertiliser-based system (C) and an organic system based on clover (O) each of which supported an 18-month beef unit. This paper describes the results from three full production cycles covering the period from autumn 1988 to spring 1992.

The primary aim of the calf rearer is to ensure a successful transition from non ruminant to ruminant status while achieving rapid growth and an early intake of solid food. Newbold, Blake and Hagges (1991), found that increasing the concentration of ME in either the starter or milk replacer will not promote more rapid growth, but will simply reduce the rate of starter consumption. This present study investigated the extent to which the energy density of a calf starter ration affected starter intake and liveweight gain in calves receiving a fixed allowance of a high energy milk replacer with ad libitum access to solid calf starter rations.