Armsby (1903) coined the term metabolisable energy, ME, for the gross energy of a diet less the energy in the faeces, urine and methane apparently produced from it. He stated an animal's requirement for ME as the sum of its fasting heat production, FHP, its positive energy retention, ER, and the heat increment, HI. In this paper a general method for predicting HI is proposed and tested.

An important constraint to the utilization of forages and roughages by ruminants is the voluntary intake of the feedstuff by the animal. The trial to be reported here was undertaken to study the relationships between in vivo digestibility and voluntary intake of hay by sheep, and the degradation characteristics of the hay as measured by the nylon bag technique.

Studies on the digestion of fresh forages by cattle have indicated that when N content in the forage exceeds approximately 25 g/kg OM, considerable losses of dietary N from the rumen will occur. This finding has been related to the rapid rates of proteolysis and deamination observed on fresh forages, with associated increases in rumen ammonia N concentration due in part to a poor synchronisation of energy and protein availability for microbial synthesis.

Abomasal infusion of casein has been shown to increase the milk yield, fat yield, protein content and protein yield while no clear-cut effects were observed with infusion of glucose (Ørskov, Grubb and Kay, 1977 and confirmed by Oldham, Bines and MacRae, 1983). Little information is available about the changes in blood parameters with abomasal infusion of glucose or casein. The objective of the present experiments was to relate changes in milk production to blood parameters in dairy cows given casein or glucose as an infusion into the abomasum during early or late lactation.

A liveweight-based scale derived from feed intakes of pigs fed twice daily wet (2.5 1 water/kg feed added immediately before feeding) to a daily maximum of 2.95 kg meal/pig, is used in growing pig experiments at Shinfield. The objectives of this 2x2 factorial experiment were to compare the intakes and performance on this method of feeding with ad libitum dry pellet feeding (feed available 24 h/day) with water available ad libitum, and to ascertain the effects of diet energy density under these two feeding methods on performance and carcass composition. The diets fed throughout were based on barley and soyabean meal with wheat and fat being added to the higher energy diets. The moderate and higher energy diets contained approximately (crude protein g/kg and lysine %) 178 & 0.9 and 193 & 1.0, respectively, and were compounded to provide comparable amounts of major nutrients/MJ DE. Diet energy densities calculated from determined gross energies were 12.8 and 13.7 MJ DE/kg feed. Determined digestible energies will be available when the balance data are completed (see later). There were 9 intact male and 9 female LW x Landrace pigs on each treatment on experiment from 15 to 80 kg liveweight. The pigs were housed in individual pens in a building maintained in winter at a temperature of 18°C. Each pig was placed in a metabolic crate, at a liveweight of approximately 50 kg, for 7 days during which it underwent a 5-day total balance. Sample analyses from these 72 balance periods are not yet completed.

Maize gluten feed is a by-product available as an alternative ingredient in pig rations. This trial examined the effects of different inclusion levels of the product to determine the quantity which could be fed without detrimental effects.

Diets containing 0, 10, 20 or 30% of maize gluten feed were formulated to have similar levels of digestible energy (12.9 MJ/kg) and lysine (0.9%).

In some pig herds it is common for 20% or more of pigs born alive to die before weaning, indeed the national average across all herds is approximately 12% (Meat and Livestock Commission, 1983). A large number of these deaths are caused by Esherichia coli, of which up to half are caused by the K88 serotype (Walters and Sellwood, 1982). Several reports (eg. Gibbons, Sellwood, Burrows and Hunter, 1977) have shown that resistance to K88 E. coli is inherited as a simple Mendelian recessive. Of potential practical significance is the evidence that suggests that the sole use of resistant boars within a herd would prevent any K88 scour since the only susceptible progeny produced would be born to susceptible dams which would provide passive maternal protection to their piglets. However, the obvious advantage in using resistant boars in a herd would be nullified if performance of the offspring was significantly lower in important economic traits. Two trials on different farms were set up to investigate this possibility.

Indigestible markers are important in the determination of digestibility values when only a sample of the material may be collected. This situation arises when collecting ileal digesta for determination of ileal digestibilities via a T-piece cannula. Consequently a comparison of indigestible markers was undertaken.

The trial consisted of five treatments: (a) 0.1% Cr2O3, (b) 0.5% Cr2O3, (c) 0.1% TiO2, (d) 0.5% TiO2 and (e) no external marker. Treatment (e) was used for the determination of lignin. 5 cannulated (Landrace x Large White) x Landrace gilts, initially weighing an average of 35 kg, were arranged in a 5 x 5 Latin square. They were placed in metabolism crates, for the collection periods, and housed in a building with a controlled environment. Each of the five periods was preceded by a 9 day acclimatization period. Before period 1 faecal samples had been taken from the 5th to the 9th day after external markers had been included in the diets. These samples were used to determine the quantity of marker excreted in relation to time after inclusion in the diet. Each period consisted of a 5 day marker-to-marker collection of faeces and collection of ileal digesta on the 1st, 3rd and 5th day after the faecal collection. Ileal digesta was collected every 2 hours for 12 hours. Pooled samples of ileal digesta and faeces for each period were used for the determination of nitrogen digestibility.

An experiment was conducted to evaluate the erythrocyte glutamate-oxaloacetate transaminase activity coefficient (EGOT-Ac) as a biochemical indicator of vitamin B-6 status and to document clinical effects of a B-6 deficiency in mature swine. A 12% crude protein diet, formulated with cornstarch and an isolated soy protein, was analyzed to contain .24 ppm B-6. Sixty-one gilts, initially averaging 111 kg, were individually fed 1.9 kg daily of a diet providing .45, 1.8, or 90 mg B-6/d (treatments (Trt) 1, 2 and 3, respectively). In addition, another group of gilts was fed 90 mg B-6 for the initial 57 d then switched to the diet providing .45 mg B-6 for the remainder of the experiment (Trt 4). On d 0, 57 and 121 animals from each Trt were killed and samples of the semitendinosus (ST) and semimembranosus (SM) were collected. Following a 24-h chill, the entire SM and ST were dissected from the carcass and weighed Blood was sampled on d 0 and monthly thereafter. The EGOTAc was determined by measuring the glutamate-oxaloacetate transaminase (GOT) activity in isolated, hemolized erythrocytes with and without pyridoxal phosphate added to the reaction mixture.

Pig husbandry systems in current use do not equally meet the physiological and behavioural needs of the animals. The aim of the study is to further develop on alternative system of housing/ feeding dry sows, in keeping with the Animal Welfare Codes. The system adopted allows sows housed in groups,individual use of an automatic concentrate dispenser which can be programmed to each sow'individual requirements. Two different feeding frequencies were adopted for the same daily feed allowance: 1 feed/day and 4 feeds/day (ie.1 feed/6 hours). Four groups of six sows in mid-pregnancy were placed on each regime for three weeks. During each trial the animals’ behaviour was observed on seven days, between 0700-1100 GMT, this having been previously established to be a period of high behavioural activity for sows on a number of different systems. Behavioural activity was recorded continuously for each sow with 29 various activities being noted. The behavioural activity associated with the feeder was observed over 24 hours for two further groups of six sows, on the 10th day after establishing the groups.

The use of Automatic Control of Natural Ventilation (ACNV) has been shown to give good temperature control in a range of circumstances [2, 3]. Information on the performance of the system in wide, solid floored, pig finishing houses under extreme climatic conditions is sparse. A study was made of a commercial pig finishing house during the hot summer of 1983. Information collected allows an assessment of the climatic conditions encountered in relation to long term meteorological records.

This study measured the amount of water consumed by dry and lactating sows when available ad libitum and the amount of slurry produced. Limited information was available on both subjects and this required verification.

In one room containing 12 farrowing crates the water supply to 6 crates was metered separately to washing down water. Sows used a nose operated drinker to dispense water into the feed rough so water usage recorded was consumed and not wasted.

The rear third of each farrowing pen was perforated metal and the slurry produced was contained in a channel within the building and periodically pumped out for measuring.

Previous work at this centre has indicated that the roles of mature boar contact, transportation and mixing in the stimulation of puberty in the gilt need further investigation. An experiment was therefore conducted to determine the relative potency of each of these components both alone and in combination following rearing of gilts with either contemporary boars or contemporary gilts.

Courtship behaviour in pigs has been extensively studied in recent years, and it is now clear that boar-originating cues are important in eliciting both proceptive and receptive behaviour in the female. What is less clearly understood is the pattern of development of the ‘boar-component’ stimuli in the young male. There are suggestions in the literature that both olfactory and auditory cues may be sub-optimal or even absent in the early post-pubertal boar, these possibly influencing his stimulatory value and hence mating efficiency. Thus, the present study was designed to evaluate the stimulatory value of young boars and to relate this to their mating performance.

Puberty can be stimulated from about 160 days of age by the introduction of a mature boar usually in accomodation which is novel to the gilt. The interval between stimulation and response is not always predictable and therefore does not facilitate the synchronisation of gilt matings with the mating pattern in an established sow herd. It has been reported previously that a single injection of pregnant mares’ serum gonadotrophin (PMSG) pits human chorionic gonadotrophin (HCG)* will initiate puberty. The investigations reported here concern the use of these exogenous hormones as an additional or alternative stimulus to those described above.

The most important factor affecting the overall efficiency and profitability of pig production is the accurate timing of insemination in the breeding herd. Low conception rates and litter sizes result from pigs inseminated during the ‘incorrect’ period of oestrus in relation to ovulation. The average time at which ovulation takes place is between 38 and 42 hours after the onset of oestrus (Du Mesnil du Buisson, Mauleon, Locatelli and Mariana, 1970) with highest fertility achieved for matings carried out approximately 12 hours prior to ovulation (Dziuk, 1970). The back pressure test in the presence of a boar is generally used to indicate oestrus but does not indicate the time of onset or the stage of oestrus.

Efficient reproductive performance in the pig breeding herd depends on many different factors including the behaviour and semen production characteristics of the boar. The latter are difficult to measure under on-farm conditions but results are accumulating from experimental and A.I. units (e.g. Du Mesnil du Buisson, Paquignon and Courot,1978; Fent, Wettermann and Johnson, 1983). The preliminary results presented here investigated semen production traits in a large commercial A. I. stud.

Fat thickness measurements taken laterally over the M. longissimus in the caudal rib region normally provide a more precise prediction of carcass lean content than other measurements suitable for use in classification and grading schemes. Such measurements are currently taken using the Danish optical probe (intrascope) in the national pig carcass classification scheme operated by MLC.

The MLC has just completed a review of its beef breeding services,

1. 1) To evaluate the design of a selection index in which all records of performance could be combined into a single overall estimate of breeding values,

2. 2) To consider the organisational structure of breeding herds within which beef breeding services could be utilised most effectively.

It is well documented for cattle that there are distinct differences between breed types in the partitioning of carcass fat, the dairy breeds having relatively more intermuscular (IF) and kidney knob and channel fat (KKCF), and less subcutaneous fat (SF) than the British beef breeds at the same level of total fatness. Many of the simpler methods for predicting the fat content of an animal or carcass are based on measurement of the subcutaneous fat depot only (some ultrasonic techniques; carcass classification and fat depth probes) and would be expected to suffer from breed bias because of these different relations. This study examines a second aspect of the effect of breed type on fat deposition, namely the relative variability within the different depots among beef and dairy breeds. If the variability within the subcutaneous depot differs between types, this would lead to differences in the stability of prediction methods.