The clearance rate of digesta from the reticulo-rumen may limit feed intake and thus production in ruminants. The longer the retention time in the rumen the better the cell wall carbohydrates are digested. However, a fast rate of passage of indigestible feed particles to the lower digestive tract is essential for maximal feed intake. The feeding level, type of diet and the physical characteristics of the feed particles affect the rate of passage from the rumen. The rate of passage has mostly been determined by external marker techniques. Because of physico-chemical characteristics these markers do not always accurately represent the behaviour of feed.particles. An alternative method, the rumen evacuation technique, may describe better the kinetic characteristics of cell walls. In this study marker and rumen evacuation techniques were compared in the determination of the passage rate and retention times.

The incidence of human coronary heart disease has been correlated with the serum cholesterol level and a high consumption of saturated fat. Furthermore the cholesterol level can be raised by shorter chain fatty acids (Rose, 1990). It was therefore interesting to compare breeds extreme in terms of fatness. The adipose tissue proportion of the Belgian Blue double muscled type (BBDM) is low while that in Holstein is high, the Belgian Blue dual purpose (BBDP) type being intermediate. The present experiment was designed to investigate how large difference in degree of fatness can be associated with differences in fatty acid composition.

Four bulls of the 3 breeds were used in a fattening trial. Their initial weight was 340 kg. Biopsy samples were taken from the Longitimus Dorsi (LD) at weeks 5 and 16 of the fattening period. They were slaughtered after 145 days. The 7-8-9 ribs and perirenal fat (PR) were removed at slaughter. Intramuscular (M) and intermuscular (IM) fats of the LD were obtained after dissection of the 7-8-9 ribs.

When grass with an adequate content of fermentable substrate and epiphytic lactic acid bacteria is ensiled properly, the fermentation which follows is normally considered satisfactory. This fermentation can be altered by various categories of additive such as acids, sugars and inoculants, each of which can influence the fermentation differently. The experiment reported compared the fermentation products, aerobic stability and animal performance for silages made using formic acid or a Lactobacillus plantarum inoculant with well preserved silage made without additive treatment.

A 42 day regrowth of Lolium multiflorum (cv. Lemtal) was harvested without wilting using two precision - chop harvesters. Alternate loads of grass were ensiled with (a) no additive, (b) formic acid (850g/kg) at 3.0 1/t or (c)inoculant (Ecosyl - ICI plc) at 3 1/t (separate harvester). The inoculant was constituted immediately before use and was applied in accordance with the manufacturers instructions. Harvesting was completed and the silos sealed within 26 hours of mowing. The silos were opened after 113 days.

Slaughter weights for pigs in the United Kingdom have traditionally been much lower than those in most other European countries and in North America. For example, in 1988 average carcass weights in the UK were around 64 kg compared to 72 kg in Denmark, 80 kg in Holland and over 105 kg in Italy. Currently, there is considerable interest within the BritisTi pig industry in heavier slaughter weights for pigs to exploit potential advantages in reducing fixed costs of production per unit of output. A research programme is currently being undertaken at this centre to investigate the potential for increasing slaughter weight and results from the first two studies undertaken are reported here.

Sesbania, a tropical legume browse, provides green foliage high in crude protein and low in crude fibre (Sen, Ray and Ranjhan, 1978). In Bangladesh two varieties of sesbania, Sesbania aculeata and a recently introduced African Sesbania rostrata are largely cultivated for green manuring in agricultural fields during kharif season. The leaves of sesbania may be used as good source of protein to supplement protein-poor roughages in ruminants diets. However, there is an extreme paucity of information on its nutritional value for goats. An attempt was therefore made to study the effect of feeding sesbania leaves as sole feed on growth performance and nutrient utilization in growing Black Bengal goats.

Nine Black Bengal male castrated goats aged about 5 months and weighing 9.0 kg on average initially were used in a 56 day study.The goats were housed individually in a slatted floor and were introduced to the experimental feed over a period of 2 weeks.The animals were allocated at random to one of three dietary treatments in a randomised block design according to live weight.The control group A given road-side grass and the groups B and C offered green leaves of Sesbania aculeata and Sesbania rostrata, respectively.

Normal reproductive function in female animals can be drastically impaired by a variety of stressful stimuli. For example, undernutrition and hypoglycaemia in sheep have been shown to suppress pulsatile LH secretion and to reduce the number of ewes showing pre-ovulatory LH peaks (Crump and Rodway 1986, Clarke et al. 1990). Similar stresses are also known to cause release of the opioid peptide β-endorphin into the circulation. Opioids are well-known to have a central inhibitory effect on LH release, although whether the elevated plasma concentrations of these peptides have any effect on LH secretion is unclear. The present study investigated the affect of insulin-induced hypoglycaemia on plasma concentrations of β-endorphin and LH.

The major portal of entry for most pathogenic microorganisms is the mucosal surface. It seems reasonable therefore that the host in its turn should possess substantial immune defences at the mucosae to provide protection against these insults. Enteric infections usually result in at least some degree of specific protection against a subsequent infection with the same organism. However artificial induction of mucosal immunity has proved difficult. Clearly, as yet, we do not have a full understanding of the inductive events involved in the generation of mucosal immune responses or the immune mechanisms operating at mucosal surfaces. In this paper I will attempt to briefly review the main aspects of mucosal immunity concentrating on the gut as the model mucosal surface.

At a recent conference on marginal land (Jenkins, Oxley and Gething, 1974) a conclusion was reached that hill land must ultimately contribute more to the growing requirements of food production. Setting aside the economic and sociological constraints, which at present are large, it is clear that increased animal production from the hills is basically a problem of providing sufficient feed. Improved pasture production is therefore a primary prerequisite for this aim.

An experiment was carried out at Terrington to investigate the effect of pre-weaning solid feed or no pre-weaning feed for suckling piglets using diets of either high or low protein levels. Previous work at Terrington with 3 week weaned pigs showed that post-weaning performance had a big effect on subsequent performance so the trial pigs were monitored through to slaughter. Research at Bristol University showed that “abrupt weaning”, i.e. no pre-weaning feed can reduce post-weaning diarrhoea.

In a market where high levels of fat on lamb carcases are not favoured, the supposition that a lamb, given adequate feeding, will grow protein preferentially to gaining lipid, holds interest. However, this idea runs counter to the evidence that body composition is not manipulable in sheep. Therefore, an experiment was undertaken to implement extreme treatments of protein and energy supply to determine to what extent the contrasting views on body composition changes in growing lambs are justified.

Seventy-two Coopworth ram lambs (mean liveweight, (LW) 30.4, s.d. 1.1 kg) were given one of the three feeds of different digestible crude protein (DCP) content at one of three allowances (ad libitum (AL), 1.2 (H) or 0.8 (L) kg/day). The feeds (H, M and L) were formulated as shown in Table 1. Feed M was a mixture of 0.55 Feed H and 0.45 Feed M. The proximate composition, measured DCP and estimated metabolisable energy (ME) content of the feeds is given in Table 1. ALH and ALM lambs were also choice-fed with ad libitum access to feed L. 8 lambs at the start of the experiment and 4 lambs per treatment at 6 and 12 weeks were slaughtered for analysis of body protein (PR), lipid (LP) and wool protein (WP).

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 objective of the paper is to assess the overall structural and competitive implications for the UK pig industry of the EC Single Market; colloquially known as “1992”.

Particular attention is paid both to the effect of those changes in the commercial environment which 1992 will introduce and, secondly, to those aspects which differentiate the UK pig industry from its continental competitors. Analysis of these aspects will assist in drawing conclusions as to the likely effect of the Single Market and in determining an appropriate strategy for addressing the new situation.

A body of admittedly largely circumstantial evidence suggests that the UK pig producer believes the advent of the Single Market will have little relevance to the way in which he conducts his business. This view is buttressed by his perception of the agricultural world as governed by the workings of the Common Agricultural Policy which is regarded as the principle influence upon agriculture and its commercial fortunes.

Your Committee invited me to talk to you and confirm that the era of animal breeding was over. Ten years ago that subject might have been mildly interesting, but meanwhile nutrition, pathology and even physiology have also lost their independent existence in the field of animal production. This, I assume, you will take for granted. On a superficial view, therefore, one might say that the era during which all these subjects made their separate approaches to animal production problems was over. But there is a wider sense in which our traditional thinking has become obsolete.

In the UK feed accounts for 0.80 to 0.90 of the variable costs of dairy production. In recent years the imposition of milk quotas has served to emphasise the importance of efficient milk and milk solids production. In field progeny testing schemes, sires’ transmitting ability or breeding value can be predicted for milk production traits, but not for feed Intake or for efficiency of milk production. As breeders continue to select on production traits, using sires of high genetic merit for production, the important question then is, ‘what correlated response occurs in gross efficiency and in feed consumption?’.

A review of recent trends in animal science is used to provide a flavour of how, from a purely technical viewpoint, evolving biotechnology may influence animal production systems in the foreseeable future. The areas considered are: the nutritive value of foods and forages, animal health and welfare, the temporary alteration of production traits to meet an immediate goal, and the permanent alteration of traits to meet an immediate goal, and the permanent alteration of traits by genetic selection or by the production of transgenic animals. In improving the nutritive value of foods, modern biotechnology has produced food grade enzymes and amino acid supplements. Genetically engineered cereals, grasses and legumes, rich in essential amino acids, are on the horizon. In disease prevention, genetically engineered vaccines may be preferable to conventional ones in that they have a defined composition, with a degree of control during manufacture which allows amino acid substitution within the peptide to confer specificity to a particular serotype.

Modern techniques with the potential to promote a transitory alteration in a production trait involve either immunization against an inhibitory biochemical pathway or active promotion of a stimulatory pathway by the administration of recombinant-derived hormones and proteins. Strategies for permanent alteration of traits by gene transfer, initially directed to enhancing growth, are now shifting in emphasis towards the transfer of genes for enhanced nutrient digestion, disease resistance, and improved product quality. The role of recombinant DNA technology in the development of diagnostic probes for use in genetic selection programmes and in the monitoring of disease is also expanding rapidly.

In all areas of animal science, molecular biology is promoting a better understanding of the underlying mechanisms that control production. By so doing it should ensure that science fulfils its primary rôle of providing animal production industries with a range of options from which to choose the most acceptable way forward.

Groups of Dorper lambs were castrated at three ages: shortly after birth, and at two and four months of age. All were slaughtered at an age of six months and the carcasses subsequently weighed, graded, measured and scored. The results indicate no marked differences in either weight or quality of carcass between the treatments. It is concluded that the operation can safely be carried out, depending upon circumstances, at any stage between birth and four months.

Previous reports have suggested the presence of a major gene influencing prolificacy in the Cambridge sheep breed. To estimate the effect of such a gene, high and low prolificacy groups were established in a Cambridge sheep flock between lambing years 1990 and 1993. In 1990-1991 ovulation rate (OR) was used as the basis for allocating ewes into groups but for 1992-1993 litter size was used also as a secondary selection criterion. In 1990 and 1991 small groups (each with one ram) of extreme phenotype were formed. In 1992 and 1993, six high and six low groups were formed using all available ewes, increasing the number of observations but with less selection pressure for high and low prolificacy. Results from the groups were interpreted on the basis of a major gene with additive effect resulting in three distinct genotypes (CC, Cc and cc). It was assumed, because of the selection method adopted, that CC ewes were exclusively in the high groups, heterozygotes (Cc) were distributed between the high and low groups and that cc ewes were exclusively in the low groups. In 1990-1991 there was a difference in OR of 4·0 between ewes allocated to the high and low groups. In 1992-1993 the difference was 1·9. Litter size differences between groups averaged 0·73. Whilst the high group progeny had higher OR, the differences between groups were less than differences observed between groups based on selected dam records, possibly a reflexion of the young age at which progeny records were collected. Differences between the high and low groups suggest a gene effect for adult ewes of approximately 2·0, with expected OR, above a basal level of 2·0, of 4·0 and 6·0 for heterozygous and homozygous carriers respectively. The effect of the gene in young ewes (predominantly 1 to 2 years) was approximately 0·8.

One of the causes of culling dairy cows is low milk yield and to the extent that this has any genetic basis one might expect the daughters of old cows to outyield their contemporaries from younger and hence less selected mothers. This is quite apart from any confounding effects resulting from the non-genetic influences of dams' parity. The rate of genetic improvement derived from the culling process will be modified within a population by the extent to which farmers choose to retain the progeny of older rather than younger cows. Milk yields for recorded cows in Scotland, available to the Livestock Records Bureau, have been used to obtain some information on these points.

Mixtures (1: 1) of whole-crop dried wheat or barley, with peas or beans as a nitrogen supplement, were fed ad libitum to four groups of 16 6-mo-old male castrate sheep for a period of 42 days in 1971. The mean dry-matter consumptions (kg/day) and live-weight gains (g/day) were: wheat+peas 1·69, 264; wheat+beans 2·05, 288; barley+peas 1·80, 282; and barley+beans 1·81, 229. This experiment was repeated in 1972. The differences between treatments were non-significant.

Dried pelleted whole-crop maize was fed ad libitum to British Friesian steers for 90 days, in conjunction with molasses and one of three protein sources, soya bean meal, urea or whole crop beans. The dry-matter intakes (kg/day) and live-weight gains (kg) were: maize+soya 9·68, 1·26; maize+urea 9·38, 10·4; and maize+beans 9·72, 1·15.

Dried maize in conjunction with urea, whole crop beans and dried grass to supply crude protein levels between 9 and 11% was fed to 48 Hereford × British Friesian steers. The dry-matter intakes (kg/day) and live-weight gains (kg/day) were: whole crop maize, 8·35, 0·87; whole crop maize+urea, 9·55, 1·0; whole crop maize+whole crop beans, 7·44, 0·70; whole crop maize+dried grass, 8·94, 1·15; whole crop maize+rolled barley, 9·30, 1·23; and dried grass + rolled barley, 9·24, 1·21. Although there was no significant difference in live-weight gain between the treatments, two levels of performance were apparent.