In saline areas livestock are often offered food and water with high sodium contents and there is evidence for major effects of the sodium content of feeds on their palatability, ingestive behaviour and the performance of ruminants (Youssef et al 1993). The aim in this experiment was to examine whether calves could be conditioned to accept high sodium feeds by early experience.

Sixteen dairy Friesian heifer calves, aged 7 days, were allocated to receive their ad libitum concentrate feed with or without 27g added Na/calf/day, up to weaning at 6 weeks. The daily concentrate and water intakes were recorded for each calf until weaning time. The behaviour of calves was also observed for 12 hours per week at 8 min-intervals throughout the weaning period. At 6 months of age, calves were offered silage with added sodium, to give 0.1, 0.3, 0.5, 0.7, 0.8, 1.1, 1.3 and 1.5% sodium content in the DM. The daily silage intake for each calf was recorded for 2 weeks, beside observing the ingestive behaviour of calves for 24 hours at 3 min - intervals.

To obtain more information about rumen fluid composition, levels of different components are determined by a range of techniques which are often slow and cumbersome. This study was established to develop calibration equations for the rapid determination of the composition of rumen fluid with a view to monitoring changes in composition with time.

Forty-three strained rumen fluid samples, taken throughout a 7 h period from three lactating cows offered silage either alone or with fish meal or rapeseed meal/urea twice daily, were used. Immediately upon withdrawal from the rumen each sample was analysed for pH, then acidified using concentrated sulphuric acid before storing at -18°C. Following centrifugation at 11600 G concentrations of volatile fatty acids and ammonia-nitrogen were determined in the supernatant by packed column gas chromatography and enzymatically using glutamic dehydrogenase respectively.

Rumen capacity can constrain the voluntary intake of roughages. Few published experiments have combined manipulation of rumen digesta volumes with measurements of intake, eating behaviour, and rumen volume and outflow. All these measurements were made in the experiment reported here.

Three Holstein steers (680-750kg) with large rumen canulae were used. They were given hay ad libitum (degradation characteristics a = 35.2, b = 45.6, c = 0.0397 when degradation (P) in ‘t’ hours is given by P = a + b(l-e-ct). The hay was ‘chopped’ to lengths of about 40-60mm and supplemented with urea, sodium sulphate, minerals & vitamins. There were seven periods of five days. Periods 1, 3, 5 & 7 were controls, and periods 2, 4 & 6 treatment (3x3 latin square). As treatments the reticulo-rumen was totally emptied once daily, and the digesta weighed, sampled, and A) 1.15 (add), B) 0.75 (remove), or C) 1.00 (replace) returned to the rumen (digesta from B was used to add to A). Daily DM intake and excretion, feeding behaviour, and digesta flow (pulse dose of PEG on the last day of all seven periods) measured. Digesta was manipulated at 11.30h, the process taking less than an hour. Treatment effects were analysed as differences from the means of the controls proceeding and succeeding the appropriate treatment. These differences (‘change’ or ‘Δ’ values) were analysed as 3 x 3 latin squares, with period and animal effects included in the residual variance.

In developing countries, straws, stovers and stubbles provide a large proportion of the nutrient intake of ruminants. Cereal breeders working for these countries need a rapid test to predict the nutritional value of straw. An important component of nutritional value of straw is voluntary intake (Goodchild et al. 1992). Voluntary intake (DMT) is usually measured in samples of straw weighing 100 kg or more: in contrast, only a few plants weighing tens of grams are available for each genotype in the early stages of breeding. Indirect methods of estimating voluntary intake, like in vitro gas production, are available but relatively costly. For these reasons, and because selecting for grain yield and stem stiffness has been a priority in developed countries, breeders have tended to ignore straw quality.

There is increasing government and consumer pressure on agriculture to reduce nitrogen pollution of the environment and EC legislation is now in place to reduce nitrate levels in drinking water. Dairy cows excrete large amounts of nitrogen and use of the Metabolisable Protein (MP) system (AFRC, 1992) which defines the dietary nitrogen characteristics and animal requirements, may reduce environmental pollution by increasing the efficiency of nitrogen capture.

Few data are available to evaluate the Metabolisable Protein (MP) System (AFRC, 1992) as an aid to ration formulation for dairy cows. Responses of lactating dairy cows to MP were evaluated in two experiments.

In Experiment One, groups of 10 Holstein cows were offered grass silage ad libitum and 7kg DM/d of one of six (treatments 1-6) compound foods from 39d after calving, for eight weeks. All rations were isoenergetic, assuming silage intake of 11kg DM/d (typical for the herd). Ratios between MP supply (calculated from in situ protein degradability measurements) and requirement (calculated for a standard cow: 565kg live weight, 281 milk/d, 40g/kg butterfat, 33g/kg milk protein, liveweight change =0kg/d) were 1.00, 1.02, 1.06, 1.06, 1.1 and 1.17 for treatments 1-6, respectively.

The spreading of slurry and other livestock wastes onto grassland is used as a means of recycling nutrients. Often these areas of grassland are subsequently used for silage production and there has been concern that the timing of slurry application may influence the outcome of the silage fermentation (O'Kiely et al. 1993). The application of slurry alters the microbial flora of the herbage and some of those added bacteria are associated with poor silage fermentations (Ostling and Lindgren, 1991).

The objective of the experiment was to examine the effect of the timing of a high level of slurry application to grassland on survival of enterobacteria, lactic acid bacteria and Clostridia on the herbage, and subsequent effects on it's fermentation during ensilage.

Silage fermentation is progressively restricted as the extent of pre-wilting increases (O'Kiely et_al., 1988). The magnitude of the improvement in silage nutritive value in response to a lactic acid bacteria inoculant could be related to the extent of the fermentation in the untreated silage. The objective of this experiment was to determine if the response in silage nutritive value to a Lactobacillus plantarum inoculant was similar at different levels of dry matter (DM) concentration.

Additives based on acids, have been widely used. Rather than encouraging latic acid fermentation, these act by partially, or completely, inhibiting microbial growth. With continuing concern over the safety aspects of these products, many farmers have tried inoculants, which encourage a lactic acid fermentation. However, in good silage making conditions, inoculants like other additives have not shown any consistent benefits in terms of silage fermentation or intakes. In poor silage making conditions, the industry still relies on tried and tested acid products to ensure adequate preservation of silage.

A new granular additive is now being evaluated. Its use is not to supress fermentation, but to supplement the natural fermentation by the addition of 1500 g/kg of sulphuric acid. This study was carried out to compare this additive with an untreated control and a positive control, formic acid.

There are plenty of examples in the literature of silages harvested from the same sward being different due to additive-treatment, digestibility, fermentation quality, etc. and resulting in different dry matter intakes. In these studies the treatments were imposed with the animals having no choice of diet. However, little evidence exists as to which silage or mixture of silages the animal would eat if given free access to a number of treatments. Therefore the present study was designed to evaluate the effects of different silage fermentations firstly on the preference of dairy animals for a particular silage and secondly on the rate of silage intake.

Various studies have reported that the voluntary intake (VFI) of hays (Hovell, Ngambi, Barber & Kyle. 1986, Khazaal, Dentinho, Ribeiro & 0rskov. 1993) and straws (Ørskov, Reid & Kay 1988, Blummel & Ørskov, 1993) is predicted better by rumen degradation characteristics than by whole tract digestibility. Prediction of grass silage VFI is in general poor but is related to both whole tract digestibility and silage fermentation characteristics. However no attempts have been made to relate silage VFI to rumen degradation characteristics. It was the purpose of this study to attempt to predict silage VFI from rumen degradation characteristics measured using either the polyester bag technique or the in vitro Menke gas production technique.

The analysis of grass silage by near-infrared spectroscopy (NIR) of dried samples is established as a valid alternative to wet chemical methods. Analysis of undried samples offers potential advantages in terms of :d of analysis and accuracy of determination of volatile components, provided calibration equations can be validated against independent populations of silage. Accumulation of analyses for a large number of pies allows relationships between silage nutrient value and management factors such as additive use, which are poorly understood, to be examined.

Whole crop fodder beet silage is a highly nutritious feed for both cattle and sheep. It is also considered that the addition of an absorbent further enhances both the feeding value and its palatability. The objective of this experiment was to compare the nutritive value of two types of whole crop fodder beet silage with that of grass silage when fed to ewes in late pregnancy.

Twenty two oestrus synchronised, twin bearing, mature ewes (2-7 yrs) of mixed lowland breeds were selected for the trial. They were housed on December 17th, approximately 10 weeks prior to their expected mean lambing date. Following pregnancy scanning, the ewes were allocated to their respective treatment groups. Each of the three treatment groups were balanced for breed, age and live weight. The ewes were individually penned with peat moss as the bedding material.

The use of fodder beet in diets fed to cattle and sheep has always been valued highly. Recent long-term experiments have shown that the palatability and high feeding value of fodder beet is fully preserved during the ensiling process. The objective of this experiment was to compare the nutritive value of whole crop fodder beet silage with that of grass silage when fed to sheep.

The grass silage was harvested from a primary growth of perennial ryegrass, which had a dry matter (DM),water soluble carbohydrate and crude protein contents of 191,137, and 53 g/kg DM respectively on 30/31 May following a 12 hour wilt and had 2.5 litres of formic acid applied in the field via the forage harvester. The whole crop fodder beet (var. Amigo, DM 155 g/kg; CP. 65 g/kg DM) was harvested on 30 October using a whole crop harvester. Eight cheviot cross castrated male sheep weighing on average 47 kg were randomly allocated to the two silage treatments, and then housed in metabolism cages fitted with urine and faeces separators. The trial consisted of an initial 10 day acclimatisation period and a further 10 days during which feed intake, faeces and urinary output were recorded.

There is increasing interest in the addition of dry feed materials to grass at ensiling, primarily as a means of reducing effluent production although other benefits claimed include improvements in silage fermentation and animal performance. The objective of the present study was to examine the possible use of molassed sugar beet pulp fed either separately or ensiled with grass at the time of silage making on ewe and lamb performance, and with or without protein supplementation.

Grass from a primary growth of perennial ryegrass with dry matter, water soluble carbohydrate and crude protein contents of 13.2%, 24 g/kg and 106 g/kg DM respectively was mowed on June 2nd and was picked up using a precision chop harvester on the 4th and 5th of June. The weather during this period was extremely unfavourable for good silage making. There were 7.5, 1.5 and 2.8 mm of rainfall on the 3rd, 4th and 5th of June. The temperatures (0 C) on these days were: 2nd June - 12.9: 3rd -10.6: 4th - 10.7. There was no bright sunshine hours on either the 3rd or 5th of June and only 2.1 hours on June 4th. Two treatments were imposed (i) formic acid (2.5 litres/t) applied in the field via the forage harvester (GS) (ii) molassed sugar beet pulp (MSBP)(50 kg/t) applied by hand in the silo on top of each load of grass(GSP).The two silos were filled .consolidated and sealed within 24 hours.

In recent years there has been increasing interest in adding concentrate feedstuffs at ensiling for a number of reasons. Firstly, from a management point of view, it can be an easy method of feeding a concentrate supplement and secondly feedstuffs may have some absorbent capacity and thus reduce effluent production. However, it is important that the feeding value of the material added is retained during the ensiling process and that the silage preserves well. The objective of this experiment was to assess the nutritive value of silage made by adding dried molassed sugar beet pulp to grass at ensiling, when fed to castrated sheep.

Crop by-products are used as ruminants feeds in many parts of the world, but their high content of lignocellulose and low content of protein limits their use in productive farming systems. The nutritive value and utilization of low quality roughage can be improved by treatment with alkali. Urea is a safe and more readily available chemical than caustic soda in many countries. The objective of this experiment was to investigate the effect of level of urea treated wheat straw in combination with grass silage offered to dairy cattle.

Many feeding , economic and managemental problems have been observed to be associated with the silage feeding (Wilkinson, 1990) e.g.;

• 1) The high cost of production, losses during storage and damage to the walls and floors of silos.

• 2) Variation in feed characteristics due to multicut.

• 3) Effluent and pollution problems.

• 4) The unpredictable feeding value and tendency to enhance milk fat but not milk protein in lactating animals.

All these factors have forced animal scientists to look for suitable alternatives to grass silage . Whole crop cereals have drawn the attention of workers as a substitute for grass silage due to the following advantages ;

• 1) The number of cuts and the harvesting cost can be reduced .

• 2) A high dry matter yield of crop can be obtained with modest application of fertiliser and no effluent problem.

• 3) The early harvesting of the crop gives more time for the entry of the following crop.

• 4) More predictable nutritive value , high grain content ( approaching 50 % ) of the total crop yield .

Increasing concern over the role of greenhouse gases in global warming has lead to a renewed interest in the production of methane by ruminants. Sheep are routinely used to study digestibility, however their use as a model to study methane production by cattle has received only limited attention (Blaxter and Wainman, 1964). The objective of the current study was to establish whether differences in methane production exist between sheep and cattle and to measure the magnitude of these differences under various dietary situations.

The response of dairy cows offered grass silage to increases in the level of concentrate supplementation is well documented. However little information exists for dairy sheep. The aim of this trial was to assess the impact of concentrate level on silage dry matter intake, milk production and quality and daily liveweight change in milking ewes.

After weaning at 8 weeks, 24 mature Friesland ewes were individually penned. Ewes were offered precision chopped grass silage: (dry matter (DM) 203 g/kg; ph 3.4; ammonia nitrogen 58 g/kg total N; crude protein (CP) 164 g/kg DM; metabolisable energy (ME) 10.9 MJ/kg DM) ad-libitum and concentrate DM (CP 194) g/kg DM; ME 12.8 MJ/kg DM) at daily rates of 0; 0.7, 1.4 and 2.1 kg/day with no more than 0.6 kg per feed. Water was available ad libitum. All animals were milked twice daily through a Fullwood parlour and weighed weekly. Silage was fed daily and refusals removed twice weekly. The experiment lasted 6 weeks and was analysed as a random block design.