Genetic improvement of pigs relies heavily on improving feed conversion and controlling feed intake capacity. For this purpose it is vital to measure feed intake of individual pigs. Traditionally this has been achieved by keeping pigs singly or in sib-pairs in small pens. Such facilities are expensive to build and are difficult to design to cater adequately for pigs over a wide range of weights and at low stocking density. Keeping animals in small pens is less than satisfactory from a welfare aspect.

Ammoniation is one method whereby the nutritional value of cereal straws may be increased, It is important if the use of ammonia is to be optimised under a wide range of conditions that the underlying mechanisms of its effect on straw digestion are understood.

Near infra-red reflectance spectroscopy (NIR) is now widely used to predict many nutritional characteristics of forages. However, this predictive approach requires the availability of large calibration sample sets with the parameter to be predicted already determined by traditional means. The technique of mathematically subtracting spectra one from another (difference spectra) to assess changes in straws during digestion and after ammoniation has been reported by Barton et al (1986) and Barnes (1988) respectively. This approach whilst requiring no pre-calibration has so far lacked good definition and has only been used qualitatively.

The purpose of the present work was to assess the ability of new mathematical treatments of the NIR spectra before subtraction to increase definition and yield quantitative data on any observed changes.

Past genetic improvement programmes have concentrated mainly on lean growth. They have relied on a few simple measurements of growth rate, food intake and ultrasonic backfat, which were laborious to record, check and process. Now there is increasing concern to improve, or at least avoid undesirable correlated changes in, eating quality, distribution of lean, and reproduction.

New electronic techniques offer the opportunity to record additional traits, with lower costs and faster data processing. This paper reviews the likely impact of electronics on the rate and nature of genetic improvement in pigs.

Two of the major steps in animal breeding programmes are (i) estimation of breeding values for a defined selection objective (such as milk production or carcass lean content), and (ii) design of optimum breeding programmes, including proportion of animals selected as parents, population size etc. Advances in electronics, and particularly in computer technology, have had a major Impact on these procedures in a number of ways. In this paper we aim to highlight four of these.

The preferred method of estimating breeding values is universally recognised to be BLUP (Best Linear Unbiased Prediction). BLUP is superior to classical procedures, such as contemporary comparison, for several reasons. The most important is that it is more accurate in separating differences between animals which are attributable to genetic rather than environmental factors. BLUP was first proposed by Henderson in 1949 but the first BLUP evaluation was not implemented until 1970 (Henderson, 1987). This delay is almost entirely attributable to inadequate computing facilities and technology at that time, since a BLUP evaluation system requires a large number of equations to be stored and solved.

Manipulation of the bacterial population of the intestine has been shown to result in changes in the structure and function of mucosal tissues. The objective of the present experiment was to investigate the effect of inclusion of a non-therapeutic antibiotic, virginiamycin, in the diet of sheep on the activity of the Na* -dependant transport of glucose and alanine by enterocyte cells. These transport mechanisms can be studied by isolation of brush border membrane vesicles following sub-cellular fractionation of the mucosal tissues.

Tissue was obtained from two separate growth trials in which the effect of inclusion of virginiamycin on lamb growth was being studied. In Trial 1 (glucose studies) the animals had been fed a concentrate diet plus hay ad libitum and virginiamycin was included at 100 ppm in the treatment group. In Trial 2 (alanine studies) the sheep were fed a concentrate diet with virginiamycin included at 50 ppm in the treatment group.

In ruminants duodenal purines,mainly derived from microbial nucleic acids, are catabolised and excreted in the urine as xanthine, hypoxanthine, uric acid and allantoin. The use of purine derivatives as an index of net microbial syntesis in the rumen requires a better understanding of the contribution of endogenus losses to total urinary excretion.

Similar levels of basal excretion of purine derivatives has been determined in ruminants maintained by intragastric nutrition (Giesecke et al. 1984, Fujihara et al. 1987) and preruminants fed on liquid diets (Linberg, 1989). However, lower excretion of allantoin and uric acid were recorded when exogenous supply was reduced by fasting (Rys et al. 1975).

The direct, residual and overall effects of the plane of nutrition of calves in early life were investigated with a factorial arrangement of high, medium and low planes of nutrition (H, M and L respectively) imposed from 2 to 14 weeks of age (Period 1) and high and low planes of nutrition (H and L respectively) from 14 to 26 weeks (Period 2). A common high plane of nutrition was offered from 26 weeks of age until the mean slaughter live weight of 527 kg. The planes of nutrition were based on appropriate fixed allowances of concentrates and good quality silage offered ad libitum apart from the first half of Period 1 where appropriate allowances of milk substitute were offered and the roughage was hay. In addition to the final slaughter point, representative samples of three calves per treatment were also slaughtered at the start of the experiment and at the end of Periods 1 and 2 and crude protein, total lipid and ash were determined. Energy contents of the tissues were also estimated from protein and lipid analyses.

Rumen capacity together with speed of rumen emptying limit voluntary intake of low quality well balanced forages (Ellis et al., 1983). Chemical composition and physical processing have important effect on both digestion plus absorption and passage through the reticulo-omasal orifice. Feeding chopped forage generate a large rumen pool of coarse particles which must be broken down by chewing and ruminating before to have a chance to escape from the compartment (Grovum, 1983). Grinding, by contrast, greatly reduce this rumen pool increasing likelihood of particles to leave the foregut (Rodrigue and Allen, 1960). This paper aims to study the effect of physical processing of roughage on feeding behaviour and digestive kinetics together with voluntary intake and digestibility.

Urea treated Whole Crop Wheat (WCW) provides a stable, alkaline high DM forage, which is a potential replacement for, or complement to grass silage. Harvesting at about 600 g DM/kg facilitates both optimum crop DM production and energy concentration within the crop. Urea treatment (40 kg/t DM) at harvest prevents fermentation during storage, and may increase the crop digestibility. The nitrogen status of the forage as ammonia is also increased. The aim of these experiments was to investigate the feeding value of WCW for dairy cattle, when offered as the sole basal feed.

A spring wheat crop (var. Axona) was cut at about 600 .g DM/kg (hard dough stage), chopped using a conventional forage harvester and stored in an outdoor clamp silo. Urea was added at 40 kg/t DM during harvesting. After rolling, the clamp was sheeted with polythene for 125 days until feed out.

Treatment of poor quality roughages with ammonia or sodium hydroxide (NaOH) has been demonstrated in numerous studies to improve the nutritive value of these materials. Ammonia is usually applied in anhydrous or aqueous forms in stacks at ambient temperature or anhydrous in high temperature ovens (e.g. Mason et al., 1989) while NaOH is usually applied as an aqueous solution either as a spray or by immersion of the test material (e.g. Wanapat et al., 1985). The objective of this study was to determine the effects on composition and subsequent rumen fermentation when low digestibility grass hay was treated with ammonia and/or NaOH by a procedure which might be readily used at farm level.

Faecal recoveries of herbage n-alkanes (odd-chains) as well as dosed alkanes (C28, C30, and C32) have been shown to be incomplete (Mayes & Lamb, 1984; Mayes et al. 1986). The purpose of this experiment was to identify both the extent and the site or sites of losses of natural and dosed (C32 and C36) alkanes along the digestive tract of sheep and to assess their use as indigestible markers in studies on intestinal digestion. The recovery of both natural and dosed alkanes was compared with that of the conventional marker Cr2O3 at the duodenum, the ileum and in the faeces.

Four mature sheep fitted with re-entrant cannulae placed in the proximal duodenum and ileum (Brown et al, 1968) were used. The sheep were fed twice daily and the diet consisted of 700 g hay and 350 g of a stock ration containing; barley 60%, lucerne 30%, fishmeal 5% and molasses 5% (Table 1). Cr2O3 impregnated paper onto which C32 and C36 alkanes had been absorbed was shredded and introduced into the rumen in form of a 2 g pellet twice daily at feeding time.

Supplementation with Yea-sacc - yeast (Saccharomyces cerivisiae ‘1026’) and its growth medium - has been found by several workers to alter rumen fermentation patterns, increase milk yield and growth rate in dairy cows and calves. This experiment investigated the effect of inclusion in the diet of intensively fed bulls on rumen fermentation and animal performance.

Twenty-six Limousin x Friesian bulls reared to 3 months of age on a common diet were allocated to treatment on the basis of liveweight and previous growth rate at an average liveweight of 133 kg.

The Treatments were Control ‘C” and Yea-sacc ‘YC’ - the control diet supplemented with Yea-sacc. (Alltech Inc. USA) at 1.5 kg/tonne of fresh feed. The diet was a mixture of barley and soyabean meal (Tables 1 & 2) with the inclusions of the latter reduced at 159 days. Mineral and vitamin supplements were included together with molasses to bind the ingredients.

Two trials were carried out to examine the effects of crude protein level in rations for intensively-finished suckled bulls. In 1987/88 (Year 1) high levels were tested as a possible means of delaying finishing and in 1988/89 (Year 2) low levels were tested.

In both years 54 Charolais x (Hereford x Friesian) bulls born in May-June were weaned in November, following paddock-grazing of cows and calves on permanent grassland. Following weaning, the bulls were housed in straw-bedded yards and offered wilted grass silage, with concentrate feed gradually increased. After 14 days the silage was removed and concentrates offered ad libitum. The bulls were allocated to 1 of 3 treatments with 2 replicates per treatment to provide 6 groups of 9 bulls. The experimental diets consisted of rolled barley with a pelleted protein concentrate and extra mineral supplement when appropriate, as described in Table 1. This resulted in diets with a range of protein but similar major mineral contents.

Previous studies (Chaudhry and Miller,1990) have shown the effectiveness of CaO, NaOH and alkaline hydrogen peroxide (AHP) in improving the in vitro dry matter digestibility (IVDMD) of wheat straw (WS). Based on those results, therefore, an experiment was planned to test the effectiveness of some of the selected treatments in improving ruminal and total tract digestibilities by sheep of WS (Norman), treated on a large scale. Rumen conditions were also characterised to see if there was any relationship between digestion and the rumen conditions.

That alkali treatments can improve the nutritional quality of poor quality roughages has long been established (Sundstol and Owen, 1984). However, their effectiveness is limited by their potential hazards to the animals and mankind. Alkaline hydrogen peroxide (AHP) has recently emerged as a possible substitute (Gould, 1985) but its farm scale application is limited by the need for high amounts of chemicals and water. Lack of any information regarding its effectiveness over NaOH alone is another factor which requires further investigation. The present study was, therefore, planned to assess the effectiveness of pH-regulated (11.5±0.2) H2O2 (AHP) in improving the in vitro dry matter digestibility (IVDMD) of wheat straw (WS, Avalon) under different laboratory conditions. The possibility of using CaO on its own or to regulate pH for AHP was also tested.

Growing fattening bulls in Belgium require diets high in concentrate and low in roughages in order to achieve large live weight gains and high quality carcasses. Sugar beet pulp is usually incorporated at a high inclusion rate in fattening diets. It is supplemented with cereals, by-products like wheat bran or glutenfeed and protein supplements very often of vegetable origin. The fat content of such diet is low. Over the recent years, there has been an increasing pressure from the industry to incorporate fat in fattening diets. Each company produces its own fat concentrate. They are blends of various origins. The present experiments were carried out to assess the effects, on animal performances, of soya oil and linseed, two fat concentrates of vegetable origin incorporated in fattening diets.

Since in ruminants urinary excretion of purine derivatives is related to duodenal absorption of purines (Fujihara et al.1987;Giesecke et al.1984), it may be a valuable index to identify nutritive constraints limiting rumen fermentation and microbial synthesis.

In the present experiment, the response in the urinary excretion of purine derivatives to urea supplementation of a N deficient diet was studied to test the validity of the above assumption.

Five Rasa Aragonesa ewes rumen cannulated and 38, 9±2, 52 Kg mean live weight, were offered “ad libitum” OHNa treated barley straw (50 g/Kg DM) ground and pelleted.

Five experimental treatments including four levels of urea supplementation(6.5, 13, 19.5 and 26 g/d) plus a negative control were arranged in a 5x5 latin square design,allowing 14 days of adaptation between experimental periods.The urea was given by continuous infusion to the rumen at a flow rate of 0.92 ml/mn during 18 h per day starting after feeding.

The sharp fall in dairy cow numbers which has occurred since the introduction of milk quotas in 1983 has seen a resurgence of interest in the suckler cow. As a result the June 1989 census revealed that the number of heifers under two years old destined for breeding was 6.1 percent up on the previous year. It therefore seems clear that over the next few years as the beef herd expands more emphasis is going to be placed on the young breeding heifer. Problems with breeding from young heifers are well known. However, current knowledge of the effects of pre partum nutrition on heifer and calf performance is incomplete. The purpose of this study was therefore to monitor the effects, of differing patterns of energy intake in mid and late pregnancy in maiden heifers.

Previous work reported at last years' conference (Hyslop, Offer and Barber, 1989) has demonstrated that the inclusion of molassed sugar beet shreds (MSBS) with malt distillers grains (draff) at ensiling; greatly reduces dry matter loss and enhances animal performance compared with ensiling draff alone. It has also been observed that draff may comprise up to 30% of dietary DM in silage based complete diets for dairy cows; without loss of performance (Hyslop and Roberts, 1989). This experiment examines the long term technical and economic consequences of replacing barley and soya with draff plus additional minerals in dairy cow diets. In addition; a comparison is made between draff ensiled alone, or in conjunction with MSBS.

Interest in milk production from home grown forage has increased in recent years, resulting in a reduction in the amount of compound feed offered. With autumn calving cows there has been a limited amount of work investigating high forage, low compound feeding throughout the winter period. Encouraging results from Trawsgoed over the past 5 years have shown the potential for high forage diets, however reductions in compound feed has consistently resulted in poorer milk quality, particularly milk protein. Experiments conducted by ICI and research workers at Hillsborough, N Ireland have shown favourable responses in milk protein from increasing the compound's protein content. In addition milk butterfat was improved at Hillsborough when the energy content of the compound was increased from 10.8 to 12.9 MJ ME/kg. Unfortunately these trials involved only short feeding periods and were unable to determine long term effects or effects at varying stages of lactation. This experiment examined the effects of both protein and energy concentrations of dairy compound feeds on silage intake and cow performance, when compounds were fed at a flat rate of 3 kg per day to October calving dairy cows throughout a 197 day winter feeding period.