The dry matter (DM) and water soluble carbohydrate (WSC) concentrations of forage are the main characteristics influencing the course of silage fermentation. Knowledge of these parameters would enable decisions to be made both on the need for additive and the type of additive likely to be most effective. Moreover, the degree of wilt could also be followed in wilted crops. The present study was directed to assessing the relationship between the composition of the crop and the volume and composition of the expressed juice. The ultimate objective was the development of on-farm methodology for predicting the ensiling characteristics of crops.

Whole-crop cereals provide both a concentrated supply of energy and a source of roughage for ruminants, but their nutritive value depends on the digestibility of the grain and straw components (Williams et al., 1983). Preservation with urea provides storage stability, a source of N and may also increase the digestibility of the fibrous components (Wilkinson 1990). The effectiveness of preservation, and intake may be influenced by the physical treatment of the crop, and the scale of this effect may differ between crops. The objective of this experiment was to investigate the effect of choice of crop, and of chopping before and after alkali treatment on the dry matter (DM) intake and digestibility of whole-crop cereals, and on the daily liveweight gain of heifers fed on them.

Sheep and goats are capable of selecting for leaf and leaf sheath, if offered barley straw generously i.e. allowing the animals to refuse about half the amount offered (Wahed et al., 1990). Recent results (M.R. Islam, unpublished results, Reading University) indicate sheep to be capable of selecting when offered oat straw generously. Factors affecting the botanical composition of straws will therefore affect their nutritive value, especially for small ruminants. The increasing use of oat and naked oat grain for humans will mean greater production of oat straw in the future. However, little is known of how agronomic factors affect the botanical fractions of oat straw. In the present study, straw was generated as part of an agronomic experiment sown in autumn 1993 at ADAS High Mowthorpe.

Excessive protein breakdown and ammonia production often lead to inefficient N utilisation in ruminants. Peptides are intermediates in the breakdown process. The aims of this study were to characterize peptidase activities of rumen bacteria and to determine which species of bacteria were responsible for the different steps of peptide breakdown in the rumen.

Four rumen-fistulated adult sheep received a mixed diet (hay, barley, molasses, fishmeal and minerals and vitamins: 500, 99.5, 100, 91 and 9.5 g/kg dry matter respectively) fed in equal meals of 500 g at 0800 and 1600 h. Rumen fluid was removed 3 h after the morning feeding, strained, and mixed bacteria were prepared by differential centrifugation. Bacteria were sonicated and debris was removed by centrifugation. Peptidase activities were determined on the supernatant fluid.

Cellulose and hemicellulose are major components of forages for ruminants, and their partial degradation by chemical (e.g. NaOH, NH4OH) or biological (e.g. enzymes) means prior to feeding may improve both digestibility and feed intake. To identify suitable enzymes for forage treatment, it is necessary to establish their respective pH and temperature optima as well as their stability. In this study Thermoascus aurantiacus, a thermophilic fungus associated with rotting wood and self heated hay, was investigated as a source of stable hemicellulolytic enzymes.

Portal blood flow (PF) is central to the quantitative characterisation of dietary nutrient uptake. Dilution of PAH (p-aminohippurate) is unsuited to rapidly changing flow and visceral studies often use frequent-feeding to encourage “steady-state” digestion and absorption and minimise postprandial PF variation. Such data is of limited value to understanding nutrient flux and visceral responses to conventional feeding (once/twice daily) eg. insulin levels did not differ on similar ME intakes of frequently-fed (12x2h) forage or concentrates (Reynolds and Tyrrell, 1991) whereas in steers fed once daily, insulin was higher (P<0.10) postprandially on a concentrate diet (Thorp et al., 1996). Transit-time ultrasound (TTU) gives real-time, continuous flow but the steer portal vein was regarded as anatomically unsuitable for TTU (Huntington et al., 1990) with PF of less than half those by PAH (20 vs 42ml/min/kg LW). The current study was initiated to monitor temporal PF changes by TTU in steers fed once-daily.

Volatile fatty acids (VFA) constitute the largest fraction of metabolizable energy absorbed from the gastrointestinal tract of dairy cows. The molar proportion of individual VFA is important because individual VFA have a different fate in intermediary metabolism. However, rumen models predict the VFA molar proportions inaccurately from feed characteristics (Dijkstra, 1993). To investigate what model elements are responsible for this inaccuracy, modified descriptions of several elements were tested and sensitivity of VFA predictions was determined. This simulation study aims to identify model elements whose improved description can contribute to a more accurate prediction of VFA molar proportions.

In recent years enzymes have been used in increasing quantities by the animal feed supply industry for the production of both monogastric and ruminant animal feeds. The use of enzymes provides an effective biological way of improving the nutritional quality of cellulose and hemicellulose based feeds (Viikari et al., 1993, Millet et al., 1976). The present study involved the isolation and purification of an endoglucanase produced by Thermoascus aurantiacus with an emphasis on characterising heat stable enzymes which would have an obvious advantage in industrial processes, especially those involving pelleting of the final diet.

Sodium can increase feed digestibility if a deficiency is rectified by supplementation (Chiy and Phillips, 1991, 1993; Moseley, 1980), but too much can reduce digestibility by creating toxic conditions for rumen microflora. Such conditions may be more exacerbated by adding sodium to concentrates, which are eaten rapidly compared to forage.

Sodium was added either to concentrate (C) or grass (G) at two levels (high.H or low.L) before being fed to 20 Welsh Mountain ewes in metabolism crates. Treatments were applied in a Latin Square design with two week periods, in order to determine the effects on digestibility in comparison with a Control. Ewes were fed 100 g DM concentrate/d, with +0 (Control), 5 (L) or 10 (H) g Na/kg DM added, and fresh cut perennial ryegrass herbage which was soaked in water with 0 (Control), 10 (L) or 20 (H) g NaCl/litre for 15 minutes and then drained for 10 minutes before feeding. Grass contained 183 g CP/kg DM and 297 g MADF/kg DM and 1.7, 4.1 and 7.7 g Na/kg DM for the Control, GL and GH treatments respectively.

The ewes requirments for energy and protein increase rapidly during the last two months of pregnancy and particularly in the final few weeks. A major limitation to the use of changes in liveweight or condition score as indices of the adequacy of nutrition during late pregnancy is that they provide information only in hindsight. By the time an inadequate weight gain or an excessive loss of condition has been recognised an irreparable production penalty may have been incurred. A more immediate assessment of the adequacy of contemporary nutrition is afforded by the measurement of circulating concentrations of certain blood metabolites. The objective of this experiment was to compare the effects of seven dietary treatments in ewes carrying twins on the pattern of plasma β-hydroxy-butyrate, glucose, albumin and urea levels in the last month of pregnancy and their relationship with energy and crude protein intakes.

Phosphorus deficiencies in tropical pastures, as well as the effects of this mineral deficiencies in ruminant performance are well-known. There is still some controversy on the metabolism, as the influence of Ca:P ratio on P absorption, even though, TCORN (1991) has indicate to be unnecessary and even misleading to establish limits for Ca:P ratio, once that individual mineral requirements have been met. The aim of this experiment was to evaluate the influence of different Ca:P ratio, in diet, on P absorption in sheep commonly raised in Brazil.

Trace element deficiencies have been reported throughout the UK and are known to decrease the productivity and welfare of animals. Selenium deficiency is characterised by muscular myopathy, white muscle disease or stiff lamb disease. Subclinical deficiencies can also cause reduced growth rate and impaired immune function. In ruminant animals, cobalt is required for the synthesis of vitamin B12 and deficiency leads to Pine, characterised by emaciation, anaemia and listlessness. Trace element deficiencies can be due to either a single element or multiple elements. Situations occur particularly in sheep where cobalt and/or selenium are deficient but where copper supplementation can be toxic. To correct these deficiencies, a single long-lasting and effective treatment in the form of a soluble glass bolus has been designed to release cobalt and selenium. This new bolus is similar to the commercial Cosecure® bolus, which is a Co/Se/Cu soluble glass, in which zinc replaces the copper.

Whisky production generates fermentation and distillation residues of considerable nutritive value for livestock but when processing takes place in copper (Cu) vessels, by-products become so enriched with Cu that poisoning can occur in recipient animals. However, absence of Cu toxicity in studies with sheep given pot ale syrup, a distillation by-product, have inferred a low availability of the Cu contained. Since no quantitative estimates of Cu availability in distillery by-products have been published, these were sought and compared with those of cupric sulphate (CuSO45H2O).

Chelated trace elements are increasingly used to supplement livestock feeds despite little evidence that they have a higher nutritive value than simpler and cheaper inorganic salts. Advantages for chelated sources should be most evident for elements such as copper (Cu) in the diet of ruminants which rarely absorb more than 10% of the Cu they ingest because of antagonisms with sulphur and molybdenum initiated in the rumen.

A copper:lysine complex (CuPLEX, 100; ZinPro Animal Health Ltd) was, therefore, compared with cupric sulphate (CuSO4.5H2O) for ability to increase liver Cu stores in sheep. Five groups of five Suffolk cross sheep, 10 months old and weighing 44kg on average, received 4.0kg DM daily of a basal diet of (kg/l00kg) whole oats (90.8), urea (1.8), calcium sulphate (1.4), sodium bicarbonate (1.8), and potassium chloride (0.5), with trace elements and vitamins A, D and E coated onto the grain in a sugar solution. A control group received the unsupplemented diet containing 3.5mg Cu/kg DM while four groups received Cu:lysine or CUSO4 added at a lower (1) and a higher (2) level, giving diets containing 9.8 and 14.6 or 8.4 and 13.2mg Cu/kg DM, respectively.

In tropical areas reliable estimation of feedstuff nutritional value often proves difficult. Recording in vitro gas production from feedstuffs, using caecal digesta as a gut microbial source, is a promising new method for analysing digestion kinetics in equids. However, this demands caecal fistulation. Substituting caecal fluid with faeces provides a potential non-invasive alternative.

Naked Oats (NO) and four forages (Grass Pellets (GP), Alfalfa Hay (AH), Oat Straw (OS) and Millet Stover (MS)), of known in-vivo digestibility, were incubated in vitro with either a faecal or a caecal digesta inoculum.