A latin square design with three periods of 3 weeks was used to measure the dry-matter intake, live-weight gain and water intake of 12 British Friesian calves offered an all-concentrate diet ad libitumin wet form. The diets contained 30% (B), 20% (C) or 15% (D) dry matter. A further six calves were given the same diet in dry form (A) throughout the experimental period. Digestibility and nitrogen balance were measured on four calves on each treatment at the end of the experimental period. In addition, two Ayrshire calves, each fitted with a permanent abomasal cannula, were used to study the site of digestion of the feed when given in dry or wet form.

The mean dry-matter intakes of the calves given the dry and wet feeds were 75·5 and 80·8 g/kg W0·75 per day respectively and mean daily live-weight gains were 849 g for the calves on both types of feed. The mean dry-matter intakes of the calves given the wet diets were 80·9 (B), 81·2 (C) and 75·5 (D) g/kg W0·75 per day, and the live-weight gains (g/day) were 857 (B), 879 (C) and 812 (D). None of these differences were significant. The intake of water by the calves was significantly increased by reducing the dry-matter content of the diet. The form or dry-matter content of the diet offered had no effect on the digestibility of dry matter (76·1%), organic matter (77·9%), energy (75·8%) or crude protein (75·8%) or on nitrogen retention (32·5% of N intake).

The rumen was the main site of digestion for all Tour diets and an average of only 7% of dietary starch passed undigested through the abomasum.

Glucosinolate levels are thought to be the major factor limiting the use of rapeseed meals in pig diets. The greatest differences In glucoslnolate content between samples of rapeseed appear to be attributable to variety and site of cultivation. A growing pig feeding trial was set up to Investigate varietal and site differences in the nutritive value of different rapeseed meals.

Rapeseed of the double low varieties Tapidor, Cobra, Libravo and Ariana were obtained from each of two sites (High Mowthorpe EHF, North Yorkshire and Bridgets EHF, Hampshire) where agronomic practices at both sites were very similar. These materials were solvent extracted to yield eight rapeseed meals of commercial type.

Four groups of 20 Simmental cross heifers were actively immunized against human serum albumin (control, (C), androstenedione (A), a 30 amino acid synthetic fragment of porcine inhibin alpha (I) or A and I in combination (AI). At the time of the third and final antigen injection and again 2 weeks later, all animals were injected with synthetic prostaglandin F2α (PG) to synchronize oestrus. Concentrations of LH, FSH, insulin-like growth factor-1 (IGF-1) and inhibin (C and A heifers only) in serum samples collected twice daily during 3 days before the second PG injection and at 15-min intervals from 24 to 32 h after PG injection were determined. Two weeks later, all heifers were administered PG and ovariectomized 24 h later. Ovarian follicles were dissected from the stroma, measured and cultured in medium 199 for 2h at 37°C. Numbers of small (3·0 to 7·9 mm diameter) and large (>8·0 mm diameter) follicles were not significantly altered by any of the immunization treatments. Intrafollicular concentrations and secretion rates of oestradiol, testosterone, progesterone and inhibin, determined in vitro, were not affected by immunization. Intrafollicular IGF-1 concentrations were not affected; this hormone was not detectable in the culture medium. Intrafollicular concentrations of oestrogen and testosterone and secretion rates of all three steroids were greater (P < 0·05) in animals which had regressing corpora lutea at the time of ovariectomy. Of the animals that had dominant follicles, one of 17, one of 13, four of 19 and six of 15 in the C, A, I and AI groups, respectively, had two or more. Only the difference between AI and C cows in the incidence of dominant follicles was statistically significant (P < 0·05). Mean circulating concentrations of LH, and inhibin (C and A groups only) and mean LH pulse frequency and pulse amplitude were unaffected by treatment but FSH concentrations were higher in A (P < 0·001) and lower in AI and I heifers (P < 0·001) compared with C animals while IGF-1 concentrations were lower in A heifers (P < 0·001) and higher in AI heifers (P < 0·05) compared with C heifers. It is concluded that immunization against inhibin, either alone or in combination with immunization against androstenedione increased the incidence of multiple dominant follicles in heifers but did not increase their ovulation rate.

Observations of the effect of the immunogen ovandrotone-albumin (Fecundin ® Coopers Animal Health) when used in ewes mated in their breeding season have shown that with a boost-tupping interval (BT) of 21 days for natural oestrus and 28 days for synchronised oestrus there was an increased fecundity but that treated ewes lambed a little later than controls.

While this latter effect was not dramatic it was felt advisable to investigate the use of Fecundin as a means of boosting lamb production in an early lambing flock in conjunction with progestagen and PMSG treatments.

The technology to measure individual feed consumption of pigs in groups using electronic feeders is a recent development. As well as providing information on total feed consumption and consequently feed efficiency it is also possible to examine feeding behaviour under normal social conditions (ad libitum feeding in groups). Changes in feeding behaviour over a performance test are of particular interest to determine if growing pigs increase consumption by larger meals, more frequent feeding or a combination of both.

Selection for high lean growth rate may lead to changes in both feeding behaviour and duration of feeding which could have undesirable side effects in a genetic selection programme. Increased feeding activity may lead to aggression and lost efficiency of feed conversion due to greater activity.

Calculating optimal truncation values for independent culling selection procedures has been difficult. Previously published charts took much of the tedium out of the calculations but the charts are difficult to read with accuracy and are not available for all possible parameter values. Therefore a computer program was written to calculate optimal truncation values for two-trait independent culling, with the option of restricting the genetic change of one or both traits. The program is described and an example of its use is given.

It has been suggested that female broiler chickens, having lower growth potential, are overprovided with dietary protein and that they will benefit more than males from a choice between a commercial standard food and whole wheat. The need for an initial learning period, before animals make ‘correct’ dietary choices has been emphasised (Mastika and Cumming, 1987; Rose and Kyriazakis, 1991; Shariatmadari and Forbes, 1991), but the problem of predicting the amount of necessary sampling, the method of learning and consequently the length of the experience period, or how often it has to be repeated, remained to be considered.

Therefore, the present experiment was designed to study whether birds need a learning period when presented with two foods, a commercial standard food (N) and whole wheat (W) in a choice feeding system.

The relationships between some wool characteristics and blood group genotypes (AaAa, AbAb, AaAC, AAb, AC and AbAc) were studied in Ossimi and Rahmani Egyptian fat-tailed breeds of sheep.

Interrupted medullation and coarse wool percentages and grade of wool were significantly related to blood group genotypes (P < 0·01). Fibre length and diameter and continuous medullation percentage were significantly related to genotype (P < 0·05). Staple length, number of crimps per cm, percentages of kemp, clean wool, impurities, moisture regain and fine wool were not significantly related to blood group genotype (P > 0·05).

In three experiments, four grass silages and four grass hays were offeredad libitum to a total of 164 Finn Dorset ewes rearing twins in the 1st month of lactation. In addition, one of three constant daily levels (300, 650 or 1000 g fresh weight per ewe) of a barley-based concentrate was offered. In the first experiment, replacement rate of silage with in vitro organic matter digestibility (OMD) of 0·65 was less than for hay (OMD 0·59), at –0·09 v. –0·62 g forage OM per g concentrates OM. Consequently, lamb growth rate was greater and ewe weight loss was less with increased concentrate level for the silage than for the hay. In the second experiment, the replacement rates of three silages (OMD 0·56, 0·60 and 0·67) were not significantly different (mean –0·29) and, once again, increased concentrate level gave significantly better ewe and lamb performance. Finally, the replacement rates for three hays (OMD 0·51, 0·59 and 0·72) were also not significantly different (mean –0·30). Equations are presented to predict the intakes of hays and silages by ewes in early lactation.

Neonatal piglets were given three daily injections of dexamethasone at 1 mg/kg body weight to examine if their stress response and carcass fat distribution at a 120-kg market weight could be altered. The daily acute injections tended to increase the amount of muscle and adrenal leptin mRNA expression (P < 0·1) for 1 and 3 days after the end of the treatment but had no effect on the amount of glucocorticoid receptor mRNA. The treated animals had a 19% lower adult stress response to transport than the controls as measured by salivary cortisol levels. There was no significant change in the treated animals’ carcass and meat quality traits at market weight. However, a trend towards more marbling fat and carcass backfat were seen in the dexamethasone treated pigs at market weight.

Economic and production reasons dictate that the breeding stock of domestic pigs are normally fed a food ration less than their ad libitum intake (Whittemore 1987), and commercial levels of food restriction have been shown using operant conditioning to result in sustained feeding motivation (Lawrence et al 1988). However, operant conditioning procedures can be criticised on the basis that they impose artificial conditions on the animal.

The practice of food restriction with dry sows has been directly linked to the performance of stereotypic behaviour (Appleby and Lawrence 1987) which maybe interpreted as an indicator of poor welfare (Mason 1991). Stereotypies in sows have often been associated with physically restrictive housing such as stalls and tethers. However, stereotypies can also develop in loose housed sows if they are also food restricted (Terlouw et al 1991). The performance of stereotypies may then reflect underlying feeding motivation and the subsequent potentiation foraging behaviour (Hughes and Duncan 1988). Stereotypies may arise where restrictive housing in some way interferes with the expression of that foraging behaviour perhaps by modifying or channelling complex and variable foraging behaviour into more simple and often repeated forms (Lawrence and Terlouw, in press.

A stochastic bio-economic model has been used to determine the effects of new reproductive technologies over a 15-year period. A strategy of using conventional artificial insemination (AI) or embryo transfer (ET) using two sex-controlled embryos at different conception rates (CRs) and herd sizes resulted in a 24 state model. The genetic means of AI population increased over the years, and the genetic means of milk production for all of the embryo strategies were greater than those of AI. In addition, the genetic means of milk yield using different embryo-based scenarios in the expanding herds were greater than those for the fixed herds. The net profit of using sexed ET in the expanding herds was greater (P < 0.05) than that of fixed size herds. In general, there was a roughly consistent trend in net profit per cow for sexed ET strategies in the expanding herds over the years, but there was an increasing trend in net profit per cow for sexed ET strategies in the fixed herds over the years. Medium to high CRs for ET and the use of sex-controlled embryo systems, especially for induction of twin births to produce dairy replacements, will be critical elements of a system that produces significant numbers of female calves. The greater number of female calves produced in the sex-controlled scenarios allows the farmer to select animals with the best genetic potential as dairy replacement heifers; therefore, the rate of genetic gain increased in the dairy herd. Results of sensitivity analyses showed that a significant decrease in the production costs and increase in the ET performance are essential for embryo-based technologies to be profitable.

The utilization of diets high in fibre (defined here as non-starch polysaccharide - NSP) is dependent on the extent to which the NSP is fermented by the gut microflora, and the subsequent utilization by the animal of the end-products of fermentation - the VFAs. It has frequently been assumed that fermentation of NSP in the pig occurs almost exclusively in the hind-gut. However, a number of studies using pigs fitted with ileal-cannulas have suggested that some fermentation of NSP may occur prior to the hind-gut (e.g. Graham et al., 1985). The aim of this study was to determine the relative roles of the small and large intestine in a) the digestion of feeds containing non-starch polysaccharides, and b) the subsequent utilization of energy by growing pigs. This was achieved by comparing the abilities of intact or ileo-rectomised pigs to digest and grow on cereal-based diets containing 0 or 300 g/kg sugar beet pulp.

There Is considerable evidence that end products of carbohydrate fermentation and distension of the rumen are involved in limiting intake in ruminants. Intraruminal Infusion of acetate or propionate (Montgomery et al., 1963) distension of the rumen (Campling and Balch, 1961) depressed hay Intake in cattle It is unlikely, however, that any single factor is entirely responsible for terminating feeding but that the effects of the changes that occur In the rumen during a meal, such as production of SCFA, changes In pH, osmolality, rumen distension, are Interpreted as a whole to induce satiety.

In a previous study with dairy cows distension of the rumen together with Intraruminal infusions of sodium acetate and sodium propionate had additive effects on hay Intake (Anil et al, 1987) and a similar experiment has now been carried out with silage.

The proportion of Holstein blood for each of 725 bulls progeny tested by the Milk Marketing Board, was obtained from a three generation pedigree. The bulls were grouped according to the proportion of Holstein blood and the means and standard deviations for their progeny tests for Beef Shape Score calculated. Only bulls with Beef Shape Scores based on an effective number of daughters of at least 20 were included. The mean Beef Shape Score decreased from 99·6 in pure Friesian bulls to 88·5 in pure Holsteins. Only four bulls within the pure or three-quarter (0·75) Holstein groups had a Beef Shape Score above the overall mean of 98·6 with the maximum being 102. The range of Beef Shape Scores for all bulls was 76 to 116.

The product moment correlations between Beef Shape Score and milk, fat and protein yields were −0·36, −0·35 and −0·32 respectively. These values were significantly different from zero (P < 0·01).

Pigs are believed to posses a strong motivation to perform exploratory behaviour, which include a range of activities such as walking, orientation towards stimuli and direct investigation. Under free-ranging conditions these activities often occur in connection with foraging (Stolba and Wood-Gush, 1989). In ad libitum fed young growing pigs the provision of straw has been found to stimulate various behaviours involving direct investigation of the straw (e.g. Fraser et al., 1990; McKinnon et at., 1989). As it is assumed that growing pigs under such ad libitum conditions ingest sufficient nutrients, it is often assumed that the straw directed behaviour is unrelated to feeding motivation. However, individual pigs offered single diets may not be able to meet their nutritional requirements (Kyriazakis et al., 1990), and this may have behavioural consequences. For example, the straw directed behaviour observed in growing pigs may be a reflection of unfulfilled nutritional demands and in fact represent appetetive foraging. The aim of the present experiment was to assess the extent to which the exploratory activity of growing pigs is affected by limitations in nutrient intake (specifically the crude protein content of the food).

Two experiments were completed with grower-finisher pigs to determine if pigmeat output, as measured by carcass gain per m2 per year, could be increased, by 1: increasing group size or 2: split-marketing pen groups. In experiment 1, 390 pigs (mean initial live weight 36·7 (s.d. 1·99) kg) were assigned to one of three treatments each with 10 replicates: 11, 13 or 15 pigs per single-sex group in pens measuring 11·04 m2. Space allowance was 1·00, 0·85 and 0·74 m2 per pig, respectively. Pelleted food was provided ad libitum. There were no differences (P > 0·05) between group sizes in growth rate, food intake, food conversion ratio, carcass growth and carcass food conversion ratio, backfat and muscle depth or carcass lean content. Pigmeat output per unit area increased with each increase in group size (234, 279 and 314 kg/m2 per year for 11, 13 and 15 pigs: P < 0·001). In experiment 2, 26 groups of 13 pigs (mean initial live weight 38·3 (s.d. 2·15) kg) were assigned to one of three treatments: 1D - group sold on 1 day (no. = 9), 2D - group sold over 2 days (14 days apart, no. = 10), or 3D - group sold over 3 days (each 7 days apart, no. = 7). Pigs were given a standard liquid diet three times daily. No differences (P > 0·05) were observed between treatments for overall growth rate, food intake, food conversion ratio, carcass weight, carcass lean content, backfat and muscle depth, carcass growth and carcass food conversion ratio or killing-out proportion of pigs. Split-marketing increased cycle length (67·7, 75·9 and 76·8 days for 1D, 2D and 3D, respectively; P < 0·001). Live and carcass daily growth rates per pig place decreased with increase in number of sale days (live: 772, 680, 670 g/day and carcass: 658, 575, 571 g/day; P < 0·001). Carcass gain per unit area decreased in split-marketed groups (358, 318, 312 kg/m2 per year for 1D, 2D and 3D, respectively: P < 0·05). Carcass weight variation (s.d.) within pen decreased with each increase in number of sale days (s. d. 5·28, 3·81 and 1·74, respectively; P < 0·001). In conclusion, pigmeat output, as measured by carcass gains per m2 per year, was improved with increase in group size and by marketing all pigs in a group on a single day.

1. A survey of management practices associated with the self-feeding of silage was carried out on a group of 130 farms during the winter of 1958-9.

2. The majority of farmers housed their cows in covered yards and allowed them free access to silage stored in a roofed surface clamp.

3. An average of 56 square feet per cow of covered yard and, under free access, 9·7 inches of face width per cow were allowed.

4. The average estimated consumption of silage over the whole feeding period was 2·12 cubic feet per cow per day. Where the feeding face was lit at night, the estimated silage consumption was 0·27±0·10 cubic feet per cow per day more than on other farms. There was also a suggestion that on farms where hay and/or straw was fed, the consumption of silage was less than on the remainder.

5. Levels of milk production were similar and concentrate feeding were slightly lower than those found in National Milk Recorded and Private Milk Recorded herds.

Methane production by ruminant animals is an important anthropogenic source of methane to the atmosphere and is considered an important source to more accurately estimate and to control. It has been known for some time that, in ruminants, diet type and composition can influence methane production, yet there is little quantitative information for contemporary diets used in the UK. Attempts to predict methane production from either diet chemical composition or digestibility have not been successful (Moss and Givens, 1990; Johnson et al., 1991). In order to estimate more accurately the amount of methane produced by a ruminant on a given diet, it is essential to establish whether there are interactions of various substrates with forage and to relate this to the rumen environment. Previous work showing interactions has used mainly hay-based diets (Blaxter and Wainman, 1964); as grass silage is now the major forage in the UK, work with this forage was undertaken.

The effects of plane of nutrition on the body composition of growing sheep are very apparent when animals are compared at the same age following different nutritional histories. These differences are, however, less obvious when animals of the same breed and sex are compared at the same body weight and at present there is some conjecture whether composition is affected by growth rate. This uncertainty is not limited to fat and protein but includes the bone and ash, fraction and the ash composition.

The primary objective of this trial was to study the effects of different growth rates achieved by feeding different amounts of the same concentrate diet on the composition of empty-body gain and on the retention of minerals by growing lambs. A secondary objective was to examine the effect of adding supplementary calcium carbonate to the basal diet at the fast rate of growth.