With the increasing interest in the use of fibrous feeds as energy sources for pigs, it is important to establish appropriate methods for determining the digestibility of such feedstuffs. In pig nutrient balance studies, a seven-day adaptation period to a new diet is frequently used. However one week may be insufficient for stability of measurements of non-starch polysaccharide (NSP) digestibility to be achieved, for Giusi-Perrier et al (1989) found that fermentation of high-cellulose diets by pigs increased up to 4 weeks after initial exposure to the diet. The aim of this experiment was to measure the development of NSP, nitrogen and energy balance in growing pigs fed contrasting types of NSP at two levels of inclusion over a period of 6 weeks. The two NSP sources chosen for study were wood cellulose (Solka floC) and plain sugar beet pulp (SBP), which are known to be poorly and highly fermentable respectively (Longland and Low 1988).

Peas (Pisum sativum) are a good source of protein for pigs (Saini and Batterham, 1989) and can be substituted for soyabean meal (Gatel and Grosjean, 1990). However, there is relatively little information on the true replacement value of peas in terms of energy and protein. The present study was undertaken to compare extracted, dehulled soyabean meal and a spring variety of peas (Solara) when used as the sole source of supplementary protein or in combination.

It is well recognised that fats and oils utilised in diets for pigs are variable commodities in terms of their dietary energy value. One of the major factors determining this is the degree of saturation. Thus vegetable oils, being unsaturated, are of higher digestible energy (DE) than the more saturated fats of animal origin. This generalisation, however, has not been adequately quantified which was the objective of the current study.

In addition to the degree of saturation, the second major chemical variable that influences the dietary energy value of fats is the free fatty acid (FFA) content. Whilst it is appreciated that the digestible energy (DE) value of a hydrolysed fat (i.e. with a high FFA content) is lower than that of the same fat prior to hydrolysis, quantifying the response remains to be studied. Previous attempts to evaluate the effect of increasing FFA content have often been confounded with variability in degree of saturation. Accordingly it was the objective of the current study to examine the DE value of fats of varying FFA content but of constant degree of saturation.

The greatest loss in litter size occurs prior to farrowing. That loss is the embryonic or fetal death loss; this is normally 25-40% of the number of eggs ovulated in swine. Recently a report from Canada (Fengler et al., 1990) demonstrated an improvement in embryo survival of about 14% with the dietary supplementation of oils in early gestation. The Canadian research supplemented the diet at a rate of 4% with either safflower oil or olive oil. The assumption tested and discussed was related to the role of linoleic acid (C 18:2w6) in swine diets. Linoleic acid is thought to be the only essential fatty acid needed by swine and it can be found in large amounts in many fats and oils.

Interestingly, in the analysis of the fatty acid composition of the embryos, the only significant difference in the embryonic fatty acid content was an increase in the omega-3 fatty acid docosahexanoic acid (C 22:6w3) in embryos from those sows fed diets supplemented with oil. Docosahexanoic acid is not found in plant oils; however, through a series of metabolic reactions swine can manufacture this fatty acid from another fatty acid - linolenic acid (C 18:3w3). There are three good sources of linolenic acid from plant origin; those sources are linseed oil (from flax), canola oil (from rapeseed or canola) and soyabean oil. The positive results which they observed then may have been due to trace amounts of linolenic acid in the oils which they evaluated.

Thirty to forty per cent of sows in Irish herds are culled annually, one third of which are for reproductive problems such as anoestrus, anovulation and small litter size. Causes of reproductive failure include genetic, nutritional, environmental and behavioural factors. Failure to meet the nutritional requirements of sows during lactation and after weaning results in losses of liveweight and body fat (due to mobilization of body reserves) which can subsequently compromise reproductive performance. Although sows normally exhibit oestrus within one week of weaning, Sterning et al. (1990) observed that a large proportion of first parity sows showed a delayed return to oestrus. This results in a longer farrowing interval, fewer litters per sow per year and a reduction in herd output. The effects of malnutrition on reproduction are more severe in first parity than in multiparous sows (Kirkwood and Aherne, 1985). The objective of this study was to investigate the effects of low feed intake during lactation and postweaning on the subsequent reproductive performance of first parity sows.

Mating is one of the most critical processes influencing the success of any breeding pig enterprise since the efficiency of this process establishes the potential output of pigs. A study was conducted on 100 recently weaned sows during the mating process to determine potential sources of inefficiency.

The study was conducted in a large commercial herd with Large White (LW) x Landrace (LR) first cross sows. 4 genotypes of boar were in use, these being LW, LR, LW x LR and Duroc. The parity of the 100 sows involved in the study ranged from 1 to 9. Sows were housed in small groups of 5 to 6 following weaning at a mean of 18 days post partum and were taken daily to an oestrus detection area to test for standing oestrus (SO). Boars were housed around this area and SO was detected using the back pressure test Within 5 minutes of SO being confirmed, each sow was paired with a boar in a specialist 2.9 v 2.65 m mating pen. This pen had a 15 cm floor covering of sawdust-based deep litter which provided good foothold and comfort Boar-sow behavioural interactions, general behaviour of the mating partners and sow vocalisations were recorded from the first pairing in the pen to the dismounting of the boar following mating.

The move towards high welfare systems as an alternative to sow stalls for pregnant female pigs makes the system of once bred gilts very attractive. Increased flexibility of curing procedures also allows many more options for the large joints and cuts. One of the critical factors in efficiency is to have a predictable throughput of relatively young gilts which are mated on at least their second observed heat. To optimise reproductive efficiency in lighter, younger animals and to facilitate the use of artificial insemination (AI) stimulation and synchronization of oestrus is desirable. The object of this study was to investigate the potential of using exogenous gonadotrophin (PG600) to synchronise prepubertal gilts on three group-housed feeding regimes.

There are now many ultrasonic techniques, some capable of measuring fat depth, muscle depth and muscle area, which could be used to improve selection for breeding. An evaluation of seven techniques was conducted by the Meat and Livestock Commission to enable users to select the most appropriate technique based on accuracy, practicality and cost.

Interest in conserving whole-crop cereals as a complementary forage for feeding with grass silage has increased sharply in recent years. In many areas of the UK conserving whole-crop cereals is a viable alternative to forage maize, providing extra forage when the available stocks of grass silage are either low or of moderate quality. Although winter wheat is the main cereal used for forage conservation little information is available on the differences between varieties in either yield or quality.

The aims of the present trial were to determine the changes in the yield and quality of winter wheat varieties harvested at different stages of maturity.

In recent years the quantity of grass silage as big bales has increased substantially, both in the UK and elsewhere. Eyers (1989) reported that about 16% of the grass silage dry matter (DM) conserved in England and Wales was in the form of big bales.

Whilst there is now considerable information on the composition, nutritive value and laboratory procedures for predicting the digestibility and energy value of clamp silage, there are few comparable data for big bale silages. The objectives of the present work were to examine the composition, digestibility and energy value of a population of big bale silages and to compare relationships between laboratory measurements and digestibility in vivo with those derived earlier for clamp silages (Givens et al., 1989).

Feeding pregnant ewes on silage-based rations during housing is widely practised. However, silage making is a capital intensive procedure and the cost is likely to increase due to pollution legislation. Feeding ewes on a cereal-based ration may be a cost effective alternative. This is especially relevant due to the ban on straw burning and the possibility of CAP reform forcing cereal prices down. This experiment compares the effect of silage- and wheat-based rations during the winter housing period on ewe and lamb performance.

Approximately 260 mule (Bluefaced Leicester x Swaledale) ewes were selected from the breeding flock at the time of winter housing in January 1989, 1990 and 1991. They had previously been at grass and had run with Suffolk rams between mid-October and mid-December.

Grass silage provides more than 80% of winter forage for livestock but, despite significant advances in ensilage methods, there remain significant problems of low intake, poor nutrient utilization and high effluent losses. The use of complementary concentrate supplements formulated to match silage composition, and the addition of absorbent feed compounds to grass during ensilage were examined as a means of addressing these problems.

Two contrasting silages were made from the same grass crop, either by applying Add Safe (3.51/T) or by adding an absorbent silage enhancing feed compound (kg/T) during ensilage. These were fed to groups of wether sheep either alone or with a complementary supplement and dry matter intake, digestibility and nutrient balances were estimated.

Since the cell wall content (CWC) and cell wall digestibility are the main factors influencing the animal's energy supply from forages, the ability to accurately measure CWC is crucial. This is becoming increasingly important as feed evaluation methods move towards a more dynamic approach of assessing nutrient supply from a wide range of substrates in order to reflect the two-stage nature of digestion in ruminants. Originally developed for forages, the neutral detergent fibre (NDF) procedure of Goering and Van Soest (1970) is generally regarded as providing a satisfactory measure of CWC despite the fact that varying amounts of cell wall pectins are soluble in neutral detergent solution (Chesson, 1986). However, previous work (IVVO, 1991) suggests that sample drying temperature and other factors can influence the measurement of CWC. An experiment was undertaken to study the effect of different drying temperatures and method of NDF analysis on the measurement of CWC in different forage types.

The UK metabolisable protein system (AFRC, 1992) requires the measurement of fermentable metabolisable energy (FME) to determine the potential yield of microbial crude protein in the rumen. FME is defined as:

The objective of this work was to measure the ME , ether extract and volatile fatty acid components of first cut grass silages to assess the range of FME and non-fermentable fractions and hence the range of fermentabilities (FME:ME).

Eighty-four clamp grass silages, predominantly first-cut rye grass, were analysed for modified acid detergent fibre (MADF), individual volatile fatty acids, oil (ether extract) and oven dry matter. ME was predicted from the MADF after correction for oven dry matter. The gross energy of the lactic, acetic, propanoic, butyric and valeric acid were taken to be 15.2, 14.6, 20.8, 24.9, and 28.0 MJ/kg DM, and for the Ether Extract fraction of grass 38.5 MJ/kg DM. The energy content of the volatile fatty acids in the silage were summed and FME was calculated as described above. The fermentability of the silage was the expressed as the proportion of FME to ME.

Cattle exhibit preferences not only for certain sward species but for the same species at different stages of growth, and the various parts of an individual plant and for individual plant of preferred composition. This tendency is termed selective grazing (Fontenot and Blaser, 1965). For example ruminants will select a high Sodium diet. Calves tend to be more selective than adult cattle, muzzling herbage before eating.

The aim of the present experiment was to investigate the effect of sward complexity, species and sodium fertilizer on the grazing behaviour of calves.

Sixteen dairy Friesian calves, aged 5 to 6 months, with no previous grazing experience, were allocated to groups of 4 similar calves, and then at random to four pasture treatments of 3480m2 each with one (Perennial Ryegrass, P), two (P and Timothy, T), three (P, T and Cocksfoot, C) and four (P, T.C and Red Fescue, R) grass species in a balanced change over design. Each species was sown in plots of 290m2 and one half of each plot received 48Kg/ha. nacl.

Stubble grazing is the main source of nutrients for small ruminants in the Middle East for 3-5 months after cereal harvesting in late May or June. As the flocks are usually mated at this time, poor nutrition may affect the prolificacy of the flocks. However, there have been very few studies of the process of grazing stubble that have defined nutrient intakes and the need for supplementation to sustain particular levels of weight change at mating. An experiment was designed to describe the patterns of removal of different fractions of stubble during grazing at different stocking rates.

Many trials at Reading have shown store lambs to be reluctant to eat straw when first housed after grazing. This is especially so if penned individually, as is often the case in feeding trials. Such isolation may induce stress, including depressed intake (Crampton, 1959; Kidwell, Bohman and Hunter, 1954). Farm animals are generally stimulated to eat more when in a group than when isolated (Curtis, 1983), yet most intake studies, particularly with sheep and cattle, are conducted with individually-penned animals. Concern for the welfare of animals being used for trials calls for systems of housing that minimise stress.

The present experiment tested the hypothesis that straw intake, by store lambs first-housed after grazing, would increase if lambs were penned in pairs rather than individually, or confined in pens allowing pen to pen vision rather than prohibiting pen to pen vision.

A previous study with sheep and goats (Muhikambele, Owen & Owen, 1992), measured horizontal reach for food offered through barriers on platforms at 0, 25, 50 or 75 cm above ground. At 75 cm, some animals were unable to reach the food, and in the other animals, reach length was reduced compared to reach at lower platform-heights.

The present study measured reach in a vertical plane. The information, together with that from the previous study, is aimed at modelling ‘reach’ in sheep and goats, with the overall objective of designing mangers for small-ruminant, stall-feeding systems.

Huckle, Rook and Wilkins (1993) have reported elsewhere in this meeting the production responses of cows grazing grass-clover swards maintained at different heights with or without concentrate supplementation. In order to understand these responses more fully the ingestive behaviour of the animals was studied in detail.

Multlparous Holstein-Friesian cows with a mean calving date of 21 March were continuously stocked on mixed grass-clover swards. The cows were blocked by calving date, parity and milk yield in week two of lactation and randomly allocated to one of six treatments, 0 (U) or 4 kg (3.44 kg DM) (S) concentrate supplementation (180 g CP/kg DM, 12.8 MJ ME/kg DM) with swards maintained at 4, 6 or 8 cm compressed (rising plate) sward height by adjusting the grazed area. In order to avoid the possibility of social facilitation occurring between supplemented and unsupplemented animals, two paddocks were maintained at each sward height with the concentrate treatments alternating daily between the paddocks at each height. Jaw movements were recorded automatically over a 24 hour period for a different cow on each treatment for each of 6 days between 15 and 25 June 1992, using the apparatus described by Huckle, Clements and Penning (1989).