Steen (1992) demonstrated that grass silage diets sustained lower carcass lean gain per MJ digestible energy (DE) intake than diets of low forage: concentrate ratios (F:CR), at equal levels of DE intake. Jugular concentrations of IGF-1, insulin and glucagon were significantly elevated in animals offered the latter diets while rumen VFA were unaffected (Thorp et al1994). Both IGF-1 and insulin stimulate protein synthesis (Abdul-Razzaq and Bickerstaffe 1989, Douglas et al1991) and it is generally accepted that insulin and glucagon influence carbohydrate metabolism in the ruminant. Plasma propionate and butyrate stimulate insulin and glucagon secretion (Harmon 1991). This experiment was part of a series designed to investigate the control of lean and fat deposition in beef cattle and aimed to determine concentrations of IGF-1, insulin, glucagon and VFA appearing across the splanchnic tissues.

A previous experiment (Sutton, Abdalla, Phipps, Cammell and Humphries, 1995) showed that low digestibility is a major cause of the poor utilisation of urea-treated whole crop wheat (WCW) by lactating cows. The purpose of the present experiment was to examine energy balance in more detail by means of indirect calorimetry.

Four multiparous Holstein-Friesian cows were offered diets based on spring wheat (cv Axona), harvested on 11 August at 603 g dry matter (DM)/kg and preserved with 20 or 40 g urea/kgDM (WCW-20, WCW-40), and first-cut perennial ryegrass silage (GS). For GS, WCW-20 and WCW-40 respectively, DM was 213, 801 and 712 g/kg; crude protein (CP) 124, 163 and 171 g/kg DM; ammonia-N 3.1, 4.6 and 7.6 g/kg DM; pH 3.9, 6.7 and 7.2. The cows were offered four diets in a 4 X 4 latin square with 4-week periods starting 10 weeks after calving. In week 4 of each period urine and faeces were collected for 6 days and gas exchange was measured for 3 days in respiration chambers.

An experiment was carried out to investigate the hypothesis that the diet selection of ruminant animals from two foods of different rapidly rumen degradable protein contents could be affected by the differences in the rate of synchrony between carbohydrate fermentation and degradation of protein in the rumen. The diet selection of the animals was measured both in the 'long-term' (daily) and 'short-term' (2h intervals within the day).

Twelve rumen fistulated mature female sheep (liveweight 59.1 kg) were used. Four foods (A,B,C and D) with the same ME (9.6 MJ/kg fresh food) and similar, high metab/sable protein contents were made into pellets. Two of the foods were based on a rapidly fermentable carbohydrate source (barley, A and B foods) and the other two on a slowly fermentable carbohydrate source (plain sugar beet pulp, C and D foods). Within each source one food (A or C) had a low (70) and the other a high (140 g/kg) concentration of effective rumen degradable content (RDP).

Ewes fed good quality grass silage need low levels (0.4-0.6 kg/d) of concentrate supplement to satisfy energy requirements in late pregnancy. However, the UK Metabolisable Protein (MP) system predicts that using a low level of a typical 180 g/kg crude protein (CP) compound will result in an undersupply of MP and therefore a higher digestible undegradable protein (DUP) content of compounds is required. Although the benefits of supplying additional DUP to lactating ewes are well established there is little or no experimental evidence to support the practice of supplementing silage based diets with supplementary DUP. The objective of the experiment was to evaluate the response to supplementary DUP in silage based diets.

One hundred and twenty five scanned Scotch Mule ewes were synchronised, mated to Texel rams and allocated to 5 treatments balanced for liveweight, condition score, litter size, and parity. Five supplements were formulated to supply varying amounts of DUP and eRDP.

The purpose of this experiment was to quantify the seasonal variations in lamb meat quality and identify the contributory factors associated with the various production systems used in the UK. The approach taken was therefore largely a systems one, with the various production systems used in the project mimicking those typical of the British sheep industry supplying lambs onto the market from April to January.

Material and methods 504 spring-born lambs [equal numbers of entire male (E), castrated male (C) and female (F)] which were the twin-reared progeny of Mule ewes (Bluefaced Leicester x Swaledale) and Suffolk rams were allocated to one of 7 finishing systems (n=72 per system). These were combinations of 4 diets and 4 slaughter periods (at 2 monthly intervals between June 1992 and January 1993) in an incomplete factorial design: concentrates (CS1), grass (GRI, GR2), silage (SL2, SL3) and roots (RT3, RT4); all but the grass diet were fed indoors.

Herbage intake by beef cows is highly correlated with sward height and therefore intake can be managed in a predictable manner by controlling sward height. For beef cows this requires adjustment of the grazing area and conservation of herbage which is not grazed, with the silage aftermath subsequently grazed later in the summer. Year-to-year variation in herbage growth rate will result in variation in the amounts of silage produced. Most grazing experiments do not consider this year-to-year variation, but it constitutes one of the major features which has to be accommodated in the operational management of beef cow systems which are based on pastoral resources.

During three consecutive summers, 40 spring-calving Hereford x Friesian beef cows and their Charolais-cross calves grazed perennial ryegrass-dominated swards receiving 200 kg N/ha at one of two annual stocking rates (2.0 or 2.5 cows/ha) at one of two sward heights (4 to 5 (short) or 7 to 8 cm (tall)) in a 2x2 factorial experiment, replicated twice.

Naturally occurring genetic variation is the basis for differences in performance and appearance between and within different breeds and lines of livestock. In a few instances (e.g. coat colour, polling) the genes (or loci) which control the variation between animals and breeds have a large enough effect to be individually recognisable. For many traits, however, the combined effects of many different genes act together to control quantitative differences between breeds and individuals within breeds (hence such genes are often referred to as quantitative trait loci or QTLs). Thus the dramatic successes of modern breeding result from generations of selection which has produced accumulated changes at a number of different loci. The genome contains up to 100,000 different genes and identifying those which contribute to variation in traits of interest is a difficult task. One first step is to identify regions of the genome containing loci of potential interest through their linkage to genetic markers.

In 1983, the occurrence of a ram exhibiting an exceptional muscular development was reported in a flock of Dorset sheep. This unusual phenotype was transmitted to some of the offspring, and subsequent matings involving hypermuscled male descendents of the founder ram and normal ewes clearly demonstrated a 50%-50%, sex-independent segregation ratio of the trait. It was therefore postulated that a dominant mutation (CLPG versus the normal clpg allele) at the autosomal “callipyge“ locus was responsible for this hypertrophy. Using the same family material, the callipyge locus was unambiguously mapped to the distal part of ovine chromosome 18 (Cockett et al., 1994).

In this paper, we present very strong evidence that the callipyge locus is subjected to a previously undescribed form of parental imprinting. It is indeed demonstrated that animals only express the callipyge phenotype if they have inherited the CLPG mutation from their sire, not if it is transmitted by the dam.

With the rapid development of genome maps of livestock, many genetic markers are becoming available. These markers usually have no affect on animals in their own right, their value is that they allow the inheritance of sections of chromosome to be followed in suitable pedigrees. How then may genetic markers be used in livestock breeding? It is useful to distinguish the use of markers in selection programmes within breeds and crossbreeding programmes. Furthermore, for both types of breeding programmes there are different kinds of information that can be provided by markers. Genetic markers may be linked to major genes, or in some cases we may have a direct test for a mutation which causes a major difference in animal performance or phenotype. Alternatively, we may have markers which are linked to (unknown) quantitative trait loci (QTLs), i.e. loci which influence traits such as growth, milk yield, carcass quality and litter size.

The pig is a curious ungulate. It is the only one which builds a nest prior to parturition, gives birth to large litters of altricial young, and does not lick the young after birth, just to mention some oddities. I studied the maternal behaviour of pigs in semi-natural enclosures for seven years (Jensen, 1988; Jensen et al 1993) and the results provide some insights into the specific welfare requirements of the sow and its offspring.

In 30 Swedish Landrace sows, more than 100 farrowings and subsequent mother-young interactions were observed in three enclosures measuring 7,12 and 13 hectares. The animals were fed daily full rations of concentrate and had access to shelters. In addition, series of experiments have been carried out under controlled laboratory conditions to test and validate some of the findings (for example Jensen, 1993).

Following on from the previous paper, this paper could be subtitled 'The welfare of the sow, her litter, the stockperson, the farmer and the bank manager'. There are many different considerations involved in assessing a farrowing system and, in some cases, these can lead to conflicting conclusions.

As reviewed in the previous paper, the animals have a set of requirements for optimal welfare. For the sow, these include the ability to exhibit certain hormonally regulated behaviour patterns including pre-farrowing ambulation and nest building. For the piglet, although longer term issues of behavioural development exist, the immediate welfare challenge is to stay alive and healthy in a situation fraught with dangers (Fraser, 1990). This requires environmental measures which reduce the likelihood of crushing, hypothermia, starvation and infection. Increasingly, as sow prolificacy has become a goal of genetic selection, it is also dependant on inputs of skilled stockpeople (English, 1993).

In the UK, farm animal effluents have been identified as a major potential source of nitrate pollution of the water system and it would be beneficial if nitrogen excretion from animals could be kept to a minimum. Recent work (Kay and Lee, 1995 and Lee et al., 1995), has shown that nitrogen excretion by pigs can be reduced by approximately 40 per cent by supplying amino acids in the diet in better agreement with the pigs requirement than currently available commercial diets. However, such diets will only be acceptable to the pig industry if they also maintain pig performance.

One hundred and ninety two pigs housed in 16 groups of 12 were given either a commercially available diet (G-com) or a diet (G-lc) low in crude protein (CP) during the growing phase (35-55kg). During the finishing phase (65-90kg), these pigs were then given either a commercially available diet (F-com) or a low CP diet (F-lc).

Increasingly emissions from livestock production has caused problems for the industry. If the problem can be reduced at source by a change of diet this could be the simplest solution, requiring the minimum of effort.

Reducing nitrogen excretion by pigs offered low crude protein (CP) diets may not only reduce nitrogen polluting potential of slurry, but also change gaseous and odorous emission characteristics.

Slurry was collected from beneath slatted pens at the end of the fmishing period (65 to 90 kg live weight) of groups of pigs offered either a commercially available finisher diet (F-com), slurry A, or a low CP diet (F-lc) formulated using a commercial least cost database which has been shown to reduce the nitrogen concentration of the slurry, slurry B. Slurry samples were placed in a closed odour emission chamber and air samples taken after 0, 15, 40, 65, 95, 155 and 225 minutes. Odour concentration (OC) was determined by dynamic dilution olfactometry.

Cooked cereals in weaner diets are considered to enhance digestion, gut health and intake. However, studies (McCone et al., 1991; Lynch et al., 1992) have shown adverse effects of cooked wheat on performance. The nutritional significance of cooking may include: (1) increased antinutritive effects of non-starch polysacharrides (NSP), (2) formation of retrograded starch (RS) which is resistant to α-amylase but is available for microbial fermentation (Englyst and Cummings, 1987) and (3) reduced protein quality due to heat damage. In this study, the aim was to obtain further understanding of this response to cooked wheat by evaluating the effects of different processing methods and feed enzyme supplementation on performance and indicators of gut health.

The energy requirement for maintenance in pigs has been suggested to be a function of liveweight (W), using equations such as 0.46 MJ digestible energy (DE)/g W0.75 (ARC, 1981). For a 60 kg pig, the predicted energy required for maintenance can proportionately account for 0.30 of the daily energy intake. Therefore, substantial reductions in pig production costs could be achieved, if the energy required for maintenance was reduced. The present study estimated the energy required to maintain liveweight, rather than the energy required for maintenance, as the latter assumes no change in protein or lipid content of the animal. Genotypes from the Edinburgh lean growth selection experiment provided the experimental resource to determine if selection for lean food conversion ratio over seven generations had changed the DE required to maintain liveweight.

Models of pig growth seek to predict the rates of retention of protein and lipid from a knowledge of the pig and the diet fed. The first, and crucial, part of the problem is to predict the rate of protein retention. A simple rule, which we have advocated, is that the marginal efficiency of retention of dietary ideal protein, ep, is the same at all liveweights for a given kind of pig, providing only that protein retention is below the potential of the pig. The objective of the experiment was to test this proposed rule by measuring ep in genetically similar pigs of different liveweights.

An important factor in the production of waste Nitrogen (N) and Phosphorus (P) by cows is the amount of these elements supplied in the diet. Supplying N and P at levels higher than the requirement for maintenance and production will result in the excess being excreted in faeces and urine causing an increased load of environmental pollutants, with ensuing problems for nitrate concentrations in ground water or P concentrations in surface run off water. Appropriate diet formulation should allow a higher level of nutrient capture as milk or tissue, whilst minimising losses in urine and faeces.

Considerable progress has been made recently at this Institute in improving the accuracy of prediction of silage intake when offered as the sole diet. However in most farm situations, silage is usually supplemented with varying levels and types of concentrate when offered to dairy cattle. The aim of the present study was to examine the effects of concentrate energy source on the voluntary food intake and milk yield and composition of lactating dairy cattle when offered a diverse range of grass silages.

A total of five grass silages were used in the study, silages A, B and D were produced from primary regrowths, while silages C and E were produced from second regrowths of perennial ryegrass swards. Silages A, B, C, D and E were ensiled after 48, 24, 0, 0 and 24 hour wilting periods. Silages A and C were ensiled untreated, B and D treated with an inoculant, and silage E treated with a formic acid based additive.

An experiment was carried out to determine the ability of lactating cows to select a diet from two similar feeds differing in the ratio of metabolisable protein to energy (MP/ME) content and to investigate the effect of training through previous access to feeds separately on diet choice.

Holstein-Friesian cows (n=36), 1-5 months in lactation, yielding 37 (s.d.=5) kg of milk were housed in a cubicle shed equipped with 28 computer linked Hokofarm feeders which can be programmed to give or deny specific animals access and record intake, meal size and meal duration. All feeds were mixtures of grass silage and pelleted concentrates. Approximately 75 % of daily offer was given in the morning and topping up occurred during afternoon milking. After adapting to feeders and feed for at least two weeks, intake was recorded in week 1 when all feeders contained a standard mixed feed calculated to contain 8.3 g MP/MJ ME. In weeks 2-7 a low protein (lp) and a high protein (hp) feed were offered in 14 feeders each (in the order 7 lp, 7 hp, 7 lp, 7 hp).

Recent studies have shown that the use of an effective bacterial inoculant as a silage additive results in improvements in animal performance of dairy and beef cattle. Treatment with an inoculant based on a single strain of L. plantarum has increased silage digestibility and altered the composition of rumen fluid in beef cattle (Keady and Steen, 1994 and 1995). Inoculant products vary in composition, containing different bacteria species and numbers, possibly with the addition of enzymes, clostridiaphages and rumen enhancers. The present study was designed to evaluate an inoculant containing mixed strains of bacteria, enzymes, bacteriophages and a rumen enhancer through lactating dairy cattle and to study its effects on diet digestibility and rumen fermentation patterns.

Herbage was harvested from the primary regrowth of a predominantly perennial ryegrass sward, which had received 99 kg nitrogen (N) per ha after the previous harvest, after a fifty-one day regrowth interval. Herbage was mown down using a mower conditioner and picked up immediately, unwilled, using a precision chop harvester.