The camel is important in many of the arid zones of the world where its ability to continue to produce and reproduce offers considerable potential. It is able to forage at greater distances from water sources than cattle, goats or sheep; increasing the area which can be grazed and browsed, and thus easing grazing pressure on vegetation close to water sources. These factors commend it as a primary source of transport, power, meat, milk and hides in arid areas. Both the dromedary camel (Camelus dromedarius), and the bactrian camel (Camelus bactrianus) have long been utilised by the peoples of areas where these camels are indigenous, and there has increasingly been a more general awareness of the potential of the species. The United Arab Emirates (UAE) is among countries where camels have considerable cultural importance. Recently attention has focused on the potential of the camel to supply meat, and Wardeh (1992) estimated world annual camel meat production to be 538,000 tons. The number of camels in the UAE increased from 57,000 in 1979 to 100,000 in 1989, and Wilson (1984) reported that camels account for 58% of the domestic herbivore biomass. However little is known about the constraints to camel production (Schwartz et al 1983). A factor limiting production is the availability of feeds. Currently heavily subsidised feed concentrates are imported, and investigations have focused on the better use of local resources. The UAE is one of the largest producers of dates with over 19 million palms. By-products have not been well utilized, but feeding trials with pits (Al-Yousef et al, 1987); and fruits (El-Gasim et al, (1987) and Kohnke and Cluer (1992) have been reported. Dates are low in nitrogen, and no reports on the use of urea in camel diets could be found.

Deer experience a period of reduced appetite and growth in winter which has a major impact on venison supply. Photoperiod manipulation has been shown to modify this. The objective of this experiment was to investigate the effect of extended photoperiod and the modifying effect of dietary energy supply in red deer stag calves

Forty red deer stag calves born in May/June 1992 were weaned in mid-September and put indoors on a grass silage-based ration. On 30 September the stag calves were weighed and randomised to four treatments groups on the basis of liveweight.

Winter inappetance in farmed deer affects the growth and development of carcass tissues and dictates the time of year when stock can be finished to standards of carcass weight and fleshing desired by the meat industry. Artificial winter daylight may be a means of overcoming some of these restrictions, allowing fresh venison to be supplied throughout the year. The objectives of this study, carried out over two consecutive years, were to compare the effects of artificially extended winter daylength with those of normal light on carcass composition and the quality of meat from red deer stags.

Zinc (Zn) is a key nutrient for dogs, playing an important role in many metabolic functions. It has been estimated that 91% of the minimum maintenance requirement for Zn is needed to support hair growth. Coat condition is perceived as being important by pet owners and is thus of fundamental concern when evaluating the adequacy of a diet for dogs.

Zn absorption has been shown to vary as a function of the amount and source of the Zn in the diet and as a function of the presence of elevated calcium and / or phytate levels in the diet.

It has been suggested that when dietary Zn is supplied in the form of a chelate with amino acids, rather than from inorganic sources, a greater proportion of Zn is absorbed an is thus available to the animal. Further, the undesirable effects that dietary antagonists, such as calcium, exert on Zn absorption may be negated

Methanogenesis is the main means of disposal of hydrogen in the rumen. Its formation represents a substantial loss of energy to the animal, and it is also the main source of greenhouse gas emissions from agriculture (Moss, 1993). Inhibition of methane production by ruminants would therefore have significant econimic and environmental benefits.

One possible way to decrease methane formation in the rumen is to promote alternative metabolic pathways to dispose of the reducing power, competing with methanogenesis for the hydrogen uptake. Methane production by mixed rumen bacteria was decreased for short periods in vitro when fumarate was added to the medium (Demeyer & Henderickx, 1967). Fumarate is a metabolic precursor of propionate, and it is reduced to succinate by fumarate reductase. In the present experiment longer-term effects of fumarate supplementation on methane production were investigated by the rumen simulation technique (Rusitec).

Previous studies (El Shaer, Omed and Axford, 1987; Akhter, Owen, Fall, O'Donovan and Theodorou, 1994) with the two-stage in vitro procedure of Tilley and Terry (1963) have shown a high correlation between digestibilities of forages as determined using either sheep rumen liquor, sheep faeces or cow faeces as the microbial inoculum. In the first study of the of the present investigation one objective was to examine the repeatability of these digestibility measurements when made on different occasions. A second objective was to assess whether the correlations between faecal and rumen fluid based inocula could be improved if microorganisms were obtained from pairs rather than individual animals. The objective in the second study using forages of known in vivo digestibility, was to investigate the effect of freezing or freeze-drying of faeces on the repeatability of digestibilities of forages determined in vitro using micro-organisms from cow faeces.

Forage cell wall content (CWC), accounting for 400 to 600 g kg-1 dry matter (DM) (Van Soest, 1982) and its rumen degradability (CWD) are major factors influencing the animal's energy supply from forages. Therefore, in order to maximise the nutritional potential of forages for ruminants, the ability to accurately and rapidly measure CWD is crucial. This is becoming increasingly important as feed evaluation methods move towards assessing nutrient supply. While the measurement of CWD is largely based on the polyester bag technique an experiment was undertaken to study the potential of measuring CWD in vitro for different forage types.

Three methods of measuring CWD were compared using four samples each of grass (G), grass silage (GS), maize silage (MS) and straw (S) in a factorial design. The methods were; 1) fresh (undried) forage, chopped to 1 cm lengths using an homogeniser, was incubated in the rumens of sheep in polyester bags (pore size 43um) for different lengths of time (0, 3, 8, 16, 24, 45 and 72h).

The pressure transducer technique has been proposed as a method of evaluating feed degradation characteristics (Theodorou, 1993) and it has been shown to predict the in vivo and in sacco degradability of forages (Blummel and Orskov, 1993). However the original technique requires rumen liquor and hence access to surgically prepared animals. Faecal material is generally easier to obtain and this work assessed it's suitability as an alternative source of microbes.

Rumen liquor (R) and faeces (F) were collected simultaneously from a rumenally fistulated lactating dairy cow. R was mixed 1:1 with modified van Soest medium and F 1:2 to obtain similar dry matter contents. Homogenised strained 20 ml aliquats were inoculated into vented 250 ml bottles containing 180 ml of modified van Soest medium and 1.5g DM of a 7:3 mixture of milled air dried grass silage and 180 g CP / kg DM concentrates. The 7:3 ratio of silage and concentrates was chosen to reflect the diet the donor cow was consuming.

An in vitro technique (Theodorou, 1993) to determine the Dry Matter degradation by measuring the amount of gas produced may reduce the need for in situ degradability studies. A strong relationship has been shown for cereal straws (Blummel and Orskov 1993) but little work has used concentrate feeds. Washing a feed contained in a dacron bag will remove a fraction containing soluble material and fine particles. The relative contributions of these components to the gas production in vitro is unknown. This work investigated if removal of this ‘a’ fraction from concentrate feeds used in vitro would improve the relationship with the in situ degradablility.

Samples of four feeds, winter beans (WB), soyabean meal (SBM), rapeseed meal (RSM) and spring barley (SPB) were ground through a 1mm screen. Half was machine washed in a dacron bag of pore size 43 um using a cold water cycle to provide the Washed feed (W) and the remainder left Unwashed (UW).

Tree leaves are important fodders in many less developed countries, particularly in dry seasons when alternative feeds can be scarce. Although many leaves appear to be good quality fodders due to their generally high crude protein content, many contain anti-nutritive factors which reduce their nutritive value. Tannins are the most widespread of the anti-nutritive factors and are to be found in many tree species. An in vitro gas production method has been developed by Theodorou et al (1994) and applied to the ranking of tree leaf fodders (Wood et al, 1993). This paper combines data obtained from three separate pieces of work investigating the nutritive value of tree leaf fodders in Bolivia, West Africa and Colombia. It seeks to investigate relationships between in vitro gas production at various times of incubation and proximate composition, fibre and tannin content in order to identify which components are of particular importance in determining gas production characteristics and whether these relationships are consistent over a wide range of species from different sources.

When forage in vitro digestibilities are determined on different occasions, they can be different and this is generally related to differences in rumen liquor from which the microbial inoculum was obtained. Experiment 1 of the present study, using rumen liquor only, investigated whether fermentation kinetics of forages as determined by in vitro gas production assays (Theodorou et al, 1994) made on different occasions are repeatable. It was argued that kinetics of fermentation were likely to be more sensitive to quality of rumen micro-organisms than digestibility assessment.

In previous experiments (Barbi et al, 1993, 1994a 1994b) to minimize the reliance on fistulated animals in feed evaluation, RUSITEC fluid was used to replace strained rumen liquor as the inoculum for the gas production method (PTT) of Theodorou et al (1994). Experiment 2 investigated whether the day-to-day repeatability of gas production assays using RUSITEC fluid was comparable to that using sheep rumen liquor.

As feed evaluation methods for ruminants move towards a more dynamic approach of assessing nutrient supply, in order to reflect the complex nature and microbial intervention in the digestion process in ruminant animals, it is becoming increasingly important to predict the rate, extent and site of digestion. Presently the main method for measuring feed degradation is the in situ polyester bag technique. However, it is now known that this method is not appropriate for starch rich feeds due to the loss of fine particles. An alternative approach is to measure the rumen fermentation kinetics using the gas production technique as this may also give a better estimate of energy available for microbial growth. An experiment was undertaken to study the influence of feed processing on the fermentation profiles of ruminant feeds using an automated gas production system.

Public aversion to animal experimentation demands the replacement of typically expensive, laborious and lengthy in vivo forage evaluation techniques with non-invasive, laboratory-based techniques. This study aimed to assess the suitability of three less animal-dependent techniques (in vitro digestibility (Tilley and Terry, 1963), in situ degradability (Ørskov and McDonald, 1979) and gas production (Theodorou et al., 1994)) for predicting the in vivo digestibility of whole crop wheat (WCW). The study forms part of an on-going MAFF LINK project that aims to develop equations for the laboratory-based prediction of the nutritive value of WCW.

Mucuna bean (Mucuna sloanei, MB) is widely cultivated as a cover crop in a traditional bush fallow system of tropical regions. Despite its protein value and high yield in Nigeria, its use is limited to grazing animals. Its physical-chemical properties may be responsible for under-utilization. Like other legumes, Mucuna bean may contain antinutrients i.e., phenolic compounds which limit their utilization for man and animals. The utilization may be increased by either modifying or removing these compounds using simple processing methods. The following studies were conducted to test the efficacy of using physical-mechanical methods to improve the nutritive value of MB for rats and by implication for other species including human beings.

Browse legumes are an important source of fodder for ruminants throughout the tropics. However, the presence of certain anti-nutritive factors may reduce intake and hinder the utilisation of these fodders by livestock and more information relating to their nutritional characteristics is required before they can be utilised effectively. NIR has generally been used as a quantitative tool to predict chemical composition but the use of detailed NIR spectra in qualitative analysis may provide some insight into differences between forages or forages which have been chemically treated. The objective of this work was to use NIR difference spectra to examine two tropical forages legumes, Leucaena and Calliandra, which contain different amounts of condensed tannins and to investigate whether in vitro digestion of the legumes may be enhanced by incubating in the presence of PEG, to counteract some of the anti-nutritive properties associated wim polyphenolics.

The carbohydrate portion of dietary fibre is increasingly being measured as non-starch polysaccharides (NSP). Unlike the more traditional, indirect gravimetric methods of measuring dietary fibre such as the crude fibre, acid detergent fibre, or neutral detergent fibre (NDF) techniques, the NSP method is a direct measurement of the monomeric constituents of the carbohydrate portion of the fibre fraction. Neutral NSP monomers are measured by gas chromatography of alditol acetate derivatives of acid hydrolysates of destarched samples, whereas the acidic sugars in the hydrolysates are determined by colorimetry (EnglystandCummings, 1984) or decarboxylation (Theander and Aman, 1979). As it has been shown that mode of drying can affect the values obtained for fibre determined gravimetrically by the NDF technique (Deinum and Maassen, 1994), it is important to know if NSP values are similarly affected. Therefore the effects of oven drying versus freeze drying on the NSP values obtained for various temperate forages was assessed.

The use of Indigestible Dry Matter (IDM) has been proposed to be used as internal marker to estimate digestibility (Milne, 1977, Kotb and Luckey, 1972), but information of reliability of this marker is limited.

The aim of this experiment was to study the effect of sward height and sampling period on Dry-Matter Digestibility of pasture (DMD), using IDM as internal marker.

Enhanced cellulolytic activity in the rumen and improved balance between amino acids and energy have been suggested to increase silage dry matter intake in cows given high quality protein supplements. The objective of this study was to investigate the effects of casein infused continuously into the rumen, duodenum or both on forage intake, milk yield, milk composition and microbial protein production.

The ability to predict microbial protein yield in any feeding situation is important in maximising the utilisation of feed nitrogen since it will guide decisions as to whether to take steps to improve rumen function or provide supplementary undegradable protein (UDP). The UK Metabolisable Protein (MP) system (Agricultural and Food Research Council, 1992) predicts the yield of microbial protein from the rumen according to the supply of Fermentable Metabolisable Energy (FME). This has led to an improved understanding of responses seen on farms, though there remains uncertainty about microbial protein yield. The excretion of purine derivatives (PD), allantoin and uric acid, in urine has been used as a non-invasive index of microbial protein flow to the duodenum (Chen et al, 1990) and might form the basis of an on-farm diagnostic test. In earlier work, with spot sampling of urine (Dewhurst et al, 1994), we have shown a relationship between milk protein yield and urinary PD excretion; the current work extended these studies by utilising 6-day total collections of urine.

The use of either purine bases (PB) in duodenal digesta or the urinary excretion of purine derivatives as an index of the ruminal microbial supply is based on the assumption that only a negligible amount of dietary nucleic acids (NA) reaches the duodenum. Such assumption is based on a rapid degradation of free NA incubated with rumen content and a constant RNA/DNA ratio in rumen digesta similar to values obtained in mixed rumen bacterial samples, indepent of feed ratio (McAllan & Smith, 1973). However it is generally accepted mat NA tend to overestimate rumen microbial synthesis due to dietary contamination of the microbial marker in the duodenum (Smith et al. 1978). This experiment aimed to determine the duodenal contribution of non-microbial NA by using 15N incorporation in PB, and the degradation rate of dietary PB by the “in situ” method.