In a 2 x 2 x 2 experiment, 296 Scottish Blackface ewes were fed to achieve one of 2 levels of body condition (high : C.S. ⩾ 2.75; low : C.S. ⩽ 2.50). Half of the ewes of each condition group were then fed dried grass pellets ad libitum with 300 g hay/ head/day (high intake); the remainder were fed a liveweight maintenance ration of 750 g pellets and 400 g hay/head/day (low intake) between 14 days before and 8 days after joining. Thereafter, feed levels for both groups were gradually adjusted to 1250 g pellets and 400 g hay/head/day which was fed until mid pregnancy after which they were fed according to foetal load. Mean daily inatkes of dried grass pellets for ewes fed ad libitum were 2.45 and 2.27 kg fresh weight/head/day for ewes in the low and high condition groups respectively. The patterns of liveweight and condition score changes associated with these feeding regimes are summarised in Table 1.

Evaluation was made of the extent to which amino acids in maize, wheat and barley meals were digested by pigs.

Apparent Digestibility (AD) of an individual amino acid was determined as the difference between amino acid intake and amino acid in the ileal digesta, expressed as a percentage of the intake. AD was adjusted to True Digestibility (TD) by correcting for the endogenous amino acid in the digesta, measured after feeding protein-free diets. An attempt was made to account for the possible influence of dietary fibre on digestility determinations by using protein-free diets which provided similar intakes of crude fibre as that achieved with the cereals.

4 littermate male pigs (22 kg live weight) were each surgically modified to create an ileo-rectal anastomosis. The large intestine was sealed at both ends and a cannula exteriorized from its lumen to enable fermenting residues to escape. Pigs were housed in individual metabolism crates. Digesta by-passed the large intestine, were expelled via the anus and collected in trays. The spurious influence of bacteria in the large intestine, on digestibility measurement, was thus avoided.

An animal's rate of protein accretion (or nitrogen retention) is determined by the most deficient (or first limiting) amino acid in the diet, in a perfectly balanced (or ideal) protein all essential amino acids and the sum of the non-essential amino acids are equally limiting. If a dietary protein had any amino acids in excess of the ideal pattern, then the removal of any of the excess should not affect nitrogen retention. This principle was used to determine the ideal dietary amino acid pattern for growing pigs.

Three nitrogen balance trials were carried out with a total of 64 gilts of weight from 30 to 55 kg. Casein and a mixture of amino acids were used in the semi-purified diets. The animals were given the diets at the rate of 93 g/kg BW0.75/d in three equal meals mixed with 0.3 L water. The feeding times were 08.30, 12.30 and 17.30. All pigs received their experimental diets for 7 days, made up of 3 days preliminary and a 4-day collection, except that the preliminary period before the first collection in the first period was 7 days. Before the first collection bladder catheters were introduced.

In general apparent ileal digestibility values of amino acids are lower than apparent faecal digestibility values (Just, 1980) and since nitrogen entering the large intestine may not be utilised by the pig (Zebrowska, 1973) apparent ileal digestibility values should offer a better estimation of the nutritive value of dietary protein. However, for this to be confirmed it must be demonstrated that such values when used in diet formulation are more accurate predictors of pig performance. Therefore, a trial was conducted to examine whether the detrimental effect of heat treated fish meal on pig performance could be reduced by formulating diets based upon either apparent faecal or ileal amino acid digestibility values.

Commercially produced grower diets for the period 10 to 30 kg liveweight normally contain 13.7 to 14.0 MJ digestible energy per kg. To achieve this level of energy, high energy ingredients such as fats or the higher energy cereals are necessary. These sources of energy normally cost more per unit of energy supplied than lower energy ingredients such as barley or wheat offal. Two experiments were conducted to examine the response of growing pigs to lower energy diets over the liveweight range 10 to 30 kg liveweight. In both studies the diets were given ad libitum as wet meal.

There is considerable concern about the true net energy value that should be assigned to apparently digested energy in diets where a substantial proportion of the substrates are fermented in the gut. Experiments involving both digestibility and growth trials were undertaken to compare the growth supporting properties of apparently digested energy, arising either from fermentation or enzymic hydrolysis. Dried unmolassed sugar beet pulp (SBP) and maize starch (MS) were used as models for fermentation and enzymic hydrolysis respectively.

In the first phase, sixty estimates of digestibility were made with 10 female and 20 castrated male growing pigs. There were five diets, a control (C), and two concentrations of maize starch (100 and 200 g/kg) and two of sugar beet pulp (150 and 300 g/kg). The composition and chemical analysis of the five diets are presented in Table 1 . The pigs were housed in metabolic cages during the trials and female pigs had catheters in the urinary bladder. Collections were made over 10 days following a 7-day preliminary period. In the growth studies, 40 pigs (20 female and 20 male castrates) were allocated randomly to the same five diets.

The recent renewed interest in the feeding of fibrous feedstuffs to pigs has been precipitated by a number of economic and welfare issues. To reduce the costs of pig meat production, farmers have increased the use of cheaper ingredients which tend to contain a high proportion of fibre. The feeding of finely ground cereals in intensive systems has been linked with high rates of mortality resultant from gastric lesions. Adding materials rich in fibre can be beneficial in this respect through its effects on the gut environment.

The addition of fibrous feeds to a diet will however have the effect of diluting the energy concentration of the diet and it is likely that counterbalancing levels of high energy materials will need to be added in order to maintain energy levels.

Fibre digestion in the ruminant is known to be depressed by the addition of lipid to a diet and it may be that fermentation in the hind gut of the pig is similarly affected. Tallow, a saturated fat, and maize oil, an unsaturated oil, were used to investigate the effect of saturation of lipid on the digestibility of fibre from wheat bran. The effect of level of wheat bran on fibre digestibility was also examined.

The Welsh Plant Breeding Station at Aberystwyth has bred varieties of oats which do not retain their husk (Lemma and Palea) when threshed. These “naked” oats (Avenu nuda) are of a relatively high nutritional value, and at Trawsgoed EHF a spring sown variety, Rhiannon, has been used to evaluate their suitability as an alternative to expensive cereal products, such as oat flakes, presently used in piglet rations. Chemical analyses showed Rhiannon to contain in each kg 15.5 MJ of digestibile energy, 132 g of crude protein, 5.5 g of lysine and 8.2 g of lipid. Crude fibre content was low as expected (21 g/kg).

Copra meal is a by-product of the coconut oil industry and is a potential source of protein and energy in the diets of pigs and poultry in the tropics. However, previous studies with pigs have suggested that its use may be limited because of poor growth performance associated with levels of inclusion above 300 g/kg (Creswell and Brooks, 1971). The experiment reported here and conducted under tropical conditions at the University of the Philippines at Los Banos was designed to study possible ways of feeding copra meal at levels of inclusion greater than 300 g/kg in the diets of pigs while maintaining acceptable animal performance.

There has been much recent interest 1n the Duroc as a possible ‘third breed’ in the UK. In particular, claims have been made that meat obtained from Durocs has high eating quality because of raised levels of intramuscular (marbling) fat. In practice, the Duroc 1s likely to be used 1n crosses involving the ‘white’ breeds. Therefore, in this study, carcass and meat quality were examined 1n Duroc, Landrace and Duroc x Landrace pigs produced contemporaneously.

Twenty-one entire males from each of the breed types were used. Landrace pigs were from a long-established Nucleus population of British Landrace. The Durocs were from a selected Nucleus line, originally established from an importation from Canada 1n 1968, expanded and improved by subsequent North American importations and then extensively upgraded by frozen semen from the USA over the period 1980-85 using a wide range of sires. The D x L progeny were produced alongside the purebreds in the Nucleus. All pigs were fed ad libitum on a ration containing 13.8 MJ DE, 200g crude protein and lOg lysine per kg and slaughtered at approximately 80 kg live weight at the IFR abattoir following a standard pre-slaughter procedure.

The efficiency of pig production can theoretically be increased by combining the two productive functions, growth and reproduction in the same animal. This is the underlying principle of the once-bred gilt. The production of once-bred gilts also serves to solve another problem, which is the difficulty of providing adequate welfare for the sow over several parities. These problems arise because the Increasingly diverse size of sows as they mature, results in fighting, particularly when sows are mixed after completing the lactation. Similar reasons also virtually necessitate individual feeding.throughout pregnancy To overcome these problems, it is widespread practice to confine sows very closely in individual stalls or farrowing pens for several years, a practice which has rightly attracted some criticism.

A recent survey of the handling of commercial slaughter pigs suggested that many animals could experience long periods without food before they were killed. Because prolonged food deprivation is detrimental to carcass yield, meat quality and possibly the animals’ welfare, fasting times in pigs killed in four slaughter plants were assessed. Length of fast was estimated indirectly from the concentration of glycogen in the animals’ livers. The relationship between time of food withdrawal and liver glycogen was determined in laboratory experiments using 341 pigs killed after defined fasting periods ranging from 0 to 48h.

Practical use is made of an increase in the ovulation rate of gilts over the first few oestrous cycles. In large herds it may well be easier to increase the interval between entry into the herd and first service in order to improve the size of the first litter. The present study considers existing herd records, taken from the Easicare management system, in which the relationship between age at first litter and reproductive parameters in the first parity are examined. A total of 3778 gilt litters were involved, mostly Large White or Landrace, from 14 nucleus or multiplication herds. Average age at first litter ranged from 342 to 376 days across herds and total numbers born per litter from 9.03 to 11.27. Within herd variation in age at first service ranged from a standard deviation of 19 days to 40 days, that of litter size being more consistent, ranging from 2.45 to 3.21. The within herd regressions between these traits were generally small, averaging 0.007 piglets per day, and insignificant (p>0.05).

In previous experiments in this series, giving dry meal through a hopper with ad libitum feeding resulted in a poorer carcass feed conversion ratio than giving meal as porridge in a conventional trough (D. C. Patterson, unpublished data). In a further experiment a novel feed hopper was assessed with meal feeding. This hopper was designed to give a form of wet feeding and had nipple drinkers positioned within the trough so that pigs could not drink directly from the nipples, instead water was spilled directly onto the meal in the bottom of the trough. No other water was available to pigs on this treatment.

Rules for feeding pigs have been derived from nutritional and economic considerations with little if any awareness of their behavioural consequences. Pregnant sows generally receive sufficient of a standard sow diet to allow medium growth during pregnancy. This quantity of food is, however, in the order of 0.5 of their (preferred) ad libitum intake (Whittemore et al., 1977). Recent results at Edinburgh have suggested a strong relationship between the food level and the development of stress-related activities, such as repetitive chain chewing, in tethered pregnant gilts (Appleby and Lawrence, 1987). Gilts on low feed levels performed significantly more repetitive behaviour than those on higher levels. These results suggest a link between the motivation to feed (hunger) and stress. There is, however, no information available regarding the hunger of pigs maintained on restricted food levels.

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.

An experiment at Terrington compared restricted floor feeding with ad libitum hopper feeding of group housed pigs over a weight range of about 35-90 kg. A prototype micro-processor controlled feed dispensing system, developed from the “Pig Code” electronic sow feeder, was used to automatically record ad libitum feed intake. Two dispensers were used to investigate the effect of feeder siting on pig performance and pen cleanliness.

Crowding of pigs can adversely affect both performance and welfare of the individual animal, but high costs of buildings encourage increasing stocking rates in commercial practice. Current welfare codes (MAFF, 1983) recommend minimum lying space allowances for pigs but do not specify the total area which should be given. Conflicting experimental and commercial recommendations exist for the optimum space allowances for growing pigs in housing with fully slatted floors, when separation of lying and dunging areas is less important for hygiene and thermoregulation. This experiment was carried out to examine the effects of different space allowances in such housing on pig performance and carcass quality.

The objective of the experiment reported here was to provide the UK farmer with sufficient information to allow economic utilisation of space in flat-deck accommodation without a reduction in performance of the weaned pig.

Two experiments at separate sites were used to compare different methods of achieving the same stocking density. At site 1 pen size was altered by means of a moveable partition while at site 2 it was the number of pigs per pen which was altered.

Consumer demands for food are determined by a wide variety of factors including: taste acceptability, whether the product is easily available, perceptions of quality and the price. Over time demands change as the determining factors (above) alter. Milk is a perishable food which is purchased daily and therefore is particularly susceptible to changes in demand. Furthermore, because of the large size of the milk industry in Britain, any relatively small percentage change in consumer demand can result in substantial alterations to the volume consumed.