Optimum designs of three-tier open nucleus breeding schemes are evaluated deterministically by maximizing the equilibrium rate of genetic gain for two methods of selection. Methodology is developed for both restricted and unrestricted migration between tiers and incorporates the loss of variance due to selection. A formula is derived for calculating the asymptotic rate of inbreeding. In the extensive livestock industries, proportional improvements in the equilibrium rate of genetic gain of between 0·12 and 0·22 are possible over a closed nucleus if no restrictions are imposed on male and female migration between tiers. The value of the extra tier in an optimized three-tier open nucleus scheme is approximately 0-45 of the maximum proportional improvement of a two-tier open nucleus over a closed nucleus scheme. The optimum structure is to have approximately 1% and 10% of the population in the nucleus and multiplier respectively. With this optimum structure the asymptotic rate of inbreeding will be reduced to one-sixth of that in a closed nucleus. The effects of various factors on the optimum structure, genetic gain and inbreeding are examined. The advantage of a three-tier open nucleus scheme over a closed nucleus scheme can be reduced substantially if thesefactors are operating.

This paper presents the economic perspectives applied when either using or not using opportunity costs of postponed replacement in deriving the economic value of herd life. Results show the equivalence of the rescaling method and the correction for opportunity costs. In economic terms, using rescaling or correction for opportunity costs forces the value of genetic improvement to change from revenues of increased output to reduction of costs per unit of (fixed) ouput. Under the zero profit theory, the economic value of herd life is equal when either using or not using correction for opportunity costs. In deriving economic values to define breeding goals, the choice of a method and price parameters will have to depend on foreseen future production circumstances for the system under study.

Six Holstein-Friesian cows in mid lactation were used to examine the effects of replacing increasing proportions of grass silage (GS) by whole-crop wheat (WCW) in the diet of lactating dairy cows. Grass silage was a first-cut perennial ryegrass. The WCW was harvested at 645 g dry matter (DM) per kg and was preserved with either 20 (WCW-20) or 40 (WCW-40) kg urea per t DM. The diets were 6 kg DM dairy concentrate daily with one of six forage treatments offered ad libitum. The forage treatments were GS alone, GS with either WCW-20 or WCW-40 in a 2:1 DM ratio, GS with either WCW-20 or WCW-40 in a 1:2 DM ratio, or WCW-40 alone. The experiment consisted of an incomplete change-over design with three 4-week periods. DM intakes were highest with the mixtures (P < 0·05) but milk yield was not significantly affected by the treatments although it tended to be highest with the 1:2 ratio. Milk composition responses were generally small and non-significant, but yields of fat and protein were highest with the mixtures (P < 0·05). The apparent digestibility of DM and organic matter (OM) decreased linearly (P · 0·01) with increasing WCW inclusion but digestible DM and OM intakes were not significantly affected. Apparent digestibility of neutral-detergent fibre tended to be lower with the forage mixtures (quadratic P < 0·20). Apparent digestibility of starch was higher with GS than with diets containing WCW and decreased linearly with diets containing increasing proportions of WCW (P < 0·01). Intakes of starch and digestible starch rose with increasing WCW inclusion but so also did faecal starch output such that 0·75 kg starch per day was excreted on WCW-40 alone. Water intake from food and water excretion in urine decreased linearly with increasing WCW inclusion but water excretion in faeces and milk was not significantly affected by diet. The difference between measured water intake and output (water deficit) increased from 38 kg/day on GS alone to 58 kg/day on WCW-40 alone (linear P < 0·001). The only effects of level of urea treatment were to increase milk urea concentration (P < 0·05). It is concluded that the small size of the milk yield response to the increased forage intake obtained when up to two-thirds of the GS is replaced by WCW is due to the reduced digestibility of the OM and particularly of the starch component resulting from the egestion of whole wheat grains in the faeces.

The purpose of this study was to estimate genetic parameters for measures offertility and several health disorders in dairy cows. Data consisted of 33732 records, of which 9163 were on heifers, on 305-day milk yield, health disorders and inseminations. Measures offertility were calculated from calving and insemination dates and included calving interval, days to first service and conception to first service. Health disorders included milk fever, mastitis and lameness. Genetic and phenotypic (co)variances were estimated using restricted maximum likelihood. Heritability estimates for both health disorders and fertility traits were low, ranging from 0·003 to 0·080. All genetic correlations between 305-day milk yield and health and fertility traits, in cows and heifers together, were antagonistic implying that selection for milk yield may have caused a deterioration in health and fertility. The unfavourable correlation between milk yield and health and fertility traits, plus the economic importance of the latter, suggests that future breeding goals should be expanded to include some health disorders and fertility.

Charolais cows were individually given hay ad libitum around calving for two successive winters (no. = 40 and no. = 43). Profiles of hay intake are defined for each cow as the evolution of individual daily intake level around calving.

The aim of this work was to build a typology of these profiles, using multivariate analysis. Four and three groups of cows were distinguished respectively for a 2-month and a 4-month period around calving (PI and PI). These groups corresponded to different kinetics of intake level around calving which were defined as follows: group 1 — plane profiles, with a low difference of intake level between pregnancy and lactation; group 2 — profiles characterized by a marked decrease in intake level just before calving followed by a long and regular increase after calving; group 3 — profiles with no decrease before calving but an early break in the increase in intake after calving; group 4 — intake profiles with a large difference in intake level between pregnancy and lactation. Groups 2 and 3 were pooled for P2.

Cows from groups 2 and 4 increased intake after calving fast enough to prevent the use of their body reserves even with a high milk-production level. Their calculated energy balance became positive very quickly, only 1 week after calving. At the other extreme, a decrease in body reserves was observed for cows which needed at least 1 month after calving to reach their maximum intake capacity and then recover a positive energy balance.

The purpose of this work was to investigate the relationship between individual animal performance and production per unit area of land of steers of different potential growth rate under different grazing stocking rates (SR). The analysis involved 160 steers divided equally between two breeds, over 2 years at four SRfor each breed and two replicates for each SR. Thus there werefive steers per replicate. The breeds were purebred Aberdeen Angus (Angus) and 4 Limousin (Limousin). After weaning steers were grazed for 251 days on a pasture dominated by Festuca arundinacea. Given that equal SR does not equate to equal treament for breeds characterized to be of different size and rate of growth at a given age, the analysis was undertaken on the basis of three categories of metabolic body size per ha (S). The variables analysed were individual live-weight gain (final minus initial weight, kg), relative individual live-weight gain (logefinal weight - loge initial weight) and production (kg/ha). A mixed model was used to examine effects of breed, S, year and the interactions between these variables. In general significant (P < 0·05) differences were found for all factors of classification and interactions. Independent linear regressions were calculated for each breed between absolute live-weight gain, relative live-weight gain, and production on S. It was concluded that there was a genotype × environment interaction, with the Angus breed tending to show a higher production per unit area than the Limousin, especially at high levels of S when scarcity of forage was apparent. Nevertheless Limousin steers had higher absolute individual performance than the Angus. The higher production of the smaller breed may be explained by a higher SR at a given S level and also by its higher relative individual live-weight gain in relation to that of the larger breed. The data were coded to use Mott's model to study the relationship between absolute performance (kg) and production (kg/ha). However this model ignores the existing interaction involving breeds.

The effect of post-ruminal fermentation on faecal output of purine bases (PB) and urinary excretion of their derivatives (PD) was studied by the infusion of yeast RNA (2·9 g/day), corn starch (100 g/day), cellulose (200 g/day) and saline solutions into the gastro-intestinal tract offour sheep (35·4 kg live weight) fitted with caecal and duodenal catheters and given 0-80 kg/day alfalfa hay. All substrates were infused into the caecum except cellulose that was infused into the proximal duodenum.

The infusion of RNA did not affect either the faecal excretion of PB or the urinary excretion of allantoin or total PD, although xanthine excretion increased significantly from <0·01 to 0·12 mmol/day.

Starch and cellulose infusions promoted a significant increase in the faecal excretion of diaminopimelic acid (206 and 159 v. 131 mg/day) and PB (4·55 and 3·62 v. 2·29 mmol/day) and modified the partitioning of total nitrogen losses between faeces and urine. The urinary excretion of allantoin and total PD were not affected by the caecal infusion of starch (6·60 and 22·9 v. 7·02 and 22·8 mmol/day) but both tended to increase with the duodenal infusion of cellulose (7·75 and 26·4 mmol/day).

It is concluded that the urinary excretion ofPD is independent of either the supply of nucleic acids to the caecum or the extent of hind gut fermentation although it may be affected by variations in the flow of undigested fibre along the small intestine.

The effects on the behavioural and physiological responses of sheep of providing rest, food and water (lairage) during 24 h of either road transport or stationary confinement (treatment) were investigated. Twenty-four hours of continuous treatment was compared with 12 h of treatment followed by either 12 h of lairage, 3 h of lairage or 3 h of food and water on the vehicle, followed by a second 12 h of treatment. A further group of sheep was kept as controls. The plasma cortisol concentration was increased at the start of the journey and after 24 h of continuous transport it was still greater than that in controls (P < 0·05). Apart from a mobilization of body energy reserves as indicated by raised plasma concentrations offree fatty acids after 12 h and β-hydroxybutyrate after 24 h there was no evidence that the welfare of the sheep during the journey was compromised after a particular time. During the lairage and immediately after the second 12-h transport period, the sheep appeared to be hungry. Although sheep transported for 24 h without lairage drank more post transport than controls, there was no biochemical evidence of dehydration during the journey. The sheep lay down during the journey and there was no apparent difference between lairage treatments in the proportion of scans spent lying down during either the second 12-h treatment period or during the first 12 h post treatment. There were fewer potentially traumatic events during the second 22 h of the 24-h journey than during the first 12 h of the journey and no apparent effect of lairage during the journey on the frequency of potentially traumatic events during the second 12-h period of transport.

There was evidence to suggest that a period of lairage during a 24-h journey can be beneficial in providing sheep with an opportunity to eat, drink and avoid the stressors associated with transport. However, providing hay and water on the vehicle during a 3-h stationary period as compared with unloading into a lairage cannot be recommended. Although sheep readily ate hay on the vehicle, they did not drink sufficient water. This resulted in dehydration and a greater plasma cortisol concentration during the remainder of the journey than in those that had been lairaged for 12 h and a greater water intake post transport than in those given either no lairage or 12 h of lairage.

It has been suggested that the induction of maternal behaviour in non-pregnant ewes by treatment with oestrogen and progesterone followed by artificial, mechanical vaginocervical stimulation (VCS), could be used to produce foster mothers for orphan or triplet lambs. To investigate the reliability of the technique, 46 non-pregnant sheep of two breeds (Suffolk (S) and Scottish Blackface (BF)) and two levels of experience (nulliparous (N) and multiparous (M)) were used. All ewes were given 6 weeks of treatment with vaginal sponges containing oestradiol and progesterone, followed by 2 min of VCS and exposure to a neonatal (< 2 days old) foster lamb. Plasma oestrogen and prolactin concentrations were significantly elevated by the hormonal treatment; prolactin was significantly higher in M ewes compared with N ewes (BFN = 91, SN = 107, BFM = 301, SM = 687 μg/l, P < 0·005). Significant udder development was seen in most ewes (proportionately 1·0 M v. 0·62 N, P = 0·01) and more M ewes produced milk than N ewes (0·67 v. 0·19, P < 0·005). No ewes showed maternal behaviour to the lamb from hormone treatment alone. After VCS, one of 26 N ewes and five of 12 M ewes expressed maternal behaviour. In the M ewes, significantly more S ewes were maternal than BF ewes (proportionately 0·75 SM v. 0·25 BFM, P < 0·05). It is concluded that the technique alone is not sufficiently reliable to be a useful fostering aid. It is suggested, however, that previous exposure to neonatal lambs, handling of ewes before testing and using newborn lambs, may be fruitful areas of investigation to improve the technique.

The objective of this study was to assess the growth and development of carcass composition of entire male and female lambs of three British hill breeds (Scottish Blackface, Welsh Mountain, and Shetland), from weaning to approaching maturity, when kept under conditions designed to be nutritionally non-limiting. Lambs were weaned at 8 weeks of age and given a high-quality pelleted diet ad libitum until slaughter at one offive different degrees of maturity. The Gompertz growth function was used to characterize, for each genotype, the growth curve and to provide estimates of mature weight. As expected, there were significant effects of breed and sex on both food intake and growth rate. Growth rate was depressed, relative to the Gompertz fit, during the months of October to January, and intake was similarly depressed. The estimates of mature weight for the females of each breed were: Scottish Blackface, 69; Welsh Mountain, 61; Shetland, 46 kg. The mature weights of the males were found to be not significantly different from 1-3 times the mature weight offemales. Relationships between carcass composition and live weight were derived by allometric regression. This study provides the first full description of the growth and meat production potential of the three breeds.

The objective of this study was to assess the growth and development of carcass composition of entire male and female lambs of three Greek dairy breeds (Boutsko, Serres and Karagouniko), from weaning to live weights approaching maturity, when kept under conditions designed to be nutritionally non-limiting. Lambs were weaned at 6 weeks of age and given a high quality pelleted food ad libitum until slaughter at one offive different degrees of maturity. As expected, there were significant effects of breed and sex on both food intake and growth rate. The Gompertz growth function was used to characterize, for each genotype, the growth curve and to provide estimates of mature weight and appeared to describe adequately growth rate. For two breeds (Serres and Karagouniko) food intake (g/day) increased in a linear fashion with time up to approximately 24 weeks of age and then remained static for the last 10 to 22 weeks of the experiment; this coincided with the increased environmental temperatures during summer. No such plateau in food intake was seen for the Boutsko sheep. The estimates of mature weight (kg) for the females of each breed were: Boutsko, 60; Serres, 66; Karagouniko, 77. These were substantially in excess (1·4 times on average) of the pre-trial calculations of mature weight. The mature weights of the males were found to be not significantly different from 1·3 times the mature weights of the females. Relationships between carcass composition and weight were derived by allometric regressions. This study provides the first full description of the growth and meat production potential of the three Greek breeds; as such it is part of an overall study that aimed to characterize (for thefirst time as far as the authors are aware) nine sheep breeds from diverse regions of the European Union.

The aim of this study was to determine whether the decrease in plasma growth hormone (GH) levels during a lamb's first autumn is a function of photoperiodic or developmental changes. Wether lambs (no. = 30) from Coopworth sheep selected for low (lean) or high (fat) backfat plus a randomly selected line (control) were subjected to long (16 h light: 8 h dark) or short (8 h light: 16 h dark) photoperiod over a 5-month period after the summer solstice. The animals were regularly blood sampled to determine plasma hormone concentrations. Daily food intake and weekly live weights were measured and the animals were slaughtered at the end of the trial to determine body composition.

Food intake and growth rate were greater for sheep on long than on short photoperiod but photoperiod had no major effect on carcass composition. Mean and basal plasma GH, as well as the number and amplitude of pulses, were not affected by photoperiod, however GH secretion decreased from January to May. Plasma levels ofprolactin, insulin-like growth factor 1 (IGF-1), insulin and glucose were greater in animals under long than short photoperiod, while non-esterified fatty acids (NEFA) were unaffected by photoperiod.

Lean animals had greater mean and basal plasma GH and increased number and amplitude of pulses compared with fat animals. Prolactin concentrations were also greater in the lean than in the fat sheep, while there were no differences in insulin, glucose and NEFA levels. IGF-1 levels were higher in lean than in fat sheep under long photoperiod but lower under short photoperiod.

These results suggest that the decline in plasma GH with increasing age is not affected by photoperiod. While long photoperiod stimulates plasma prolactin and IGF-1 levels as well as intake and growth, the relationship between these parameters is unknown. Hormonal differences between lean and fat genotype sheep are found within the GH axis and prolactin but not within the gonadotropin or insulin axes.

Oxalic acid is found in high concentrations in some plants consumed by ruminants and may cause renal toxicity. To determine whether exposure to oxalic acid affects the capacity of the rumen of sheep and goats to degrade the compound, 20 animals (10 sheep and 10 goats) were dosed with free oxalic acid by gelatin capsule twice daily for 3 weeks at one of five levels (0·0, 0·3, 0·6, 0·9 and 1·2 mmol/kg live weight (M) per day). Rumen samples were collected by stomach tube in the week prior to the start of dosing and in each week of the 3-week experiment. Oxalic acid degradation capacity was measured by adding uC-labelled oxalic acid to rumen fluid in vitro and capturing evolved 14CO2. Rates of degradation increased with increasing level of administration (2·30, 4·71, 6·74, 9·83 and 13·90 mmol of oxalic acid degraded per I rumen fluid per day for doses 0·0, 0·3, 0·6, 0·9 and 1·2 mmol/kg M per day, respectively; P < 0·001). Rates of degradation increased during the dosing period (P < 0·001) with the largest increases occurring in the 1st week of dosing. Goats showed a greater response than sheep, with a higher mean oxalic acid degradation capacity (9·04 v. 5·95 mmol of oxalic acid degraded per I rumen fluid, P < 0·05). Oxalic acid administration did not influence plasma calcium concentration or cause renal function impairment as measured by plasma creatinine concentrations. The experiment demonstrated adaptation in the rumen to potential toxins in the host diet and suggests that the rumen micro-organisms of goats may have been more adapted to degrading oxalic acid than sheep.

Six adult and six juvenile goats were used to estimate their feeding preferences when three grasses (ryegrass, barley and brome) and two legumes (clover and alfalfa) were tested. Each grass was separately tested with both clover and alfalfa. A comparison between alfalfa and clover was also performed. The plants were harvested just before their utilization, chopped into 4- to 6-cm pieces and offered to the animals in plastic baskets. Preferences were evaluated by means of a series of seven short-term trials. Each short-term trial consisted of two single-food presentations and one choice-presentation. In the first single-food presentation animals received one of the two plants to be tested. In the second single-food presentation they were offered the alternative plant species. In the choice presentation they received the two species simultaneously. During each presentation animals were allowed to eat for 20 min or take a maximum of 50 bites. In the single-food presentations bite rate, bite mass and intake rate of both juvenile and adult animals were influenced by the plant species offered. Indeed, all goats tended to display a higher intake rate and bite mass for grasses than for legumes. A grass/legume ratio of the intake rates was also computed for each grass-legume comparison. These ratios tended to be higher for juvenile than for adult goats. The results of the choice presentations indicated that food preferences were not affected by age as all goats preferred grasses to legumes and clover over alfalfa. This experiment showed that age may not play an important role in the development of food preferences.

This study examined the temporal relationships between behavioural activity and hormones associated with stress in gilts farrowing in two environments. Thirty-one Large White × Landrace gilts with indwelling jugular catheters were blood sampled daily (08.00 and 16.00 h) from 10 days before their expected parturition date (EPD). Five days before EPD they were moved to either a farrowing crate (C) with no bedding, or a pen (P) (2·5 m × 3·0 m) with straw provided and were blood sampled daily at 08.00, 12.00 and 16.00 h. Around 12 h before the onset of farrowing an extension was fitted to the catheter and blood samples were taken remotely at 30-min intervals. The posture of the gilts was recorded using 5-min scan samples over the 24 h pre-farrowing. The proportion of scans standing (an index of activity) was strongly affected by time (P < 0·001) with peak levels at approximately 8 h pre-farrowing in both treatments, and by treatment (0·25 v. 0·33 (s.e.d. 0·03) for C and P gilts respectively; P < 0·05). Plasma cortisol concentrations also increased before farrowing (P < 0·001) reaching a peak at 12 to 6 h pre-farrowing. Crated gilts had higher cortisol concentrations than, penned gilts (overall mean 41·5 v. 30·7 (s.e.d. 3·8) [μg/l for C and P gilts respectively; P < 0·05) at 24 to 12 (P < 0·05), 12 to 6 (P < 0·01) and 6 to 2 (P < 0·05) h pre-farrowing. Plasma ACTH concentration showed a similar pattern to cortisol over the pre-parturient period, peaking at 12 h pre-farrowing in both treatments (time: P < 0·001); crated gilts had significantly higher concentrations of ACTH at 6h pre-farrowing only (P < 0·05). Plasma β-endorphin concentrations also showed a gradual rise (P < 0·001) towards parturition; however no treatment differences were seen. These results suggest that the pituitary-adrenal (PA) axis is stimulated during pre-farrowing activity irrespective of farrowing environment. Crates, without bedding, further stimulate the PA axis over the pre-farrowing period perhaps by preventing nest-building. The rise in Q-endorphin may be involved in an endogenous defence against parturition pain.

Evidence from studies of group-housed sows in unbedded systems indicates that hunger may be a cause of increased aggression between animals. The present study aimed to investigate the effects of food level on performance, aggression and skin damage in a deep-straw system. Sixteen groups offive gilts were introduced over 8 months to one of two dynamic groups in a deep-straw yard (2·35 m2 per sow) receiving different food levels from an electronic sow-feeding system: high (H: 3·0 kg and 38 MJ/day) and low (L: 1·6 kg and 20 MJ/day). Seventy second-parity sows were returned to the same treatments in the same subgroups. The behaviour of the animals was recorded throughout both pregnancies using a time sampling technique. Severity of skin damage was recorded as a number from 0 to 4 for each of nine areas, the average of which being the ‘damage score’. The total number of animals in each dynamic group was maintained at around 30, through the use of additional sows. As expected, H sows were heavier than L sows but no effect offood treatment was found on litter size or performance. L sows were more active (L v. H; standing: 41 v. 31% of total observation time respectively, F114 = 7·65, P < 0·05) and showed more straw manipulation than H sows (L v. H: 17 v. 10% respectively, F 3 34 = 18·4, P < 0·001). No differences between treatments were found either in number of aggressive interactions (L v. H: 3·6 v. 3·8 interactions per sow per observation day, F, u = 0·82, P > 0·05), or in damage score (L v. H: 0·24 v. 0·28; Flu = 0·27; P > 0·05).

However, introduction of new animals did influence aggression, with sows being more involved in aggressive interactions on the day they were introduced, than on other sow's introduction days and on no introduction days (Tukey, P < 0·05). Average skin lesions per experimental sow were also higher in the days immediately following introduction. It can be concluded that in a sequential feeding system with plentiful straw, aggression is not influenced by the level offeeding. In these systems, the major factor giving rise to aggression is the introduction of new sows to the resident group.

The present study was undertaken to determine the Heal and total tract apparent digestibility and hindgut disappearance of dietary components and energy in a barley-based diet which included either lucerne or white-clover meal (proportionately 0·10 and 0·20). The experiment was conducted as a 5 × 5 change-over design with growing pigs fitted with simple t-shaped cannulas posterior to the ileo-caecal valve. The Heal and total tract apparent digestibilities of organic matter (OM), crude protein, crude fat, nitrogen-free extractives and energy were significantly reduced ivith increasing inclusion of lucerne and white-clover meal in the diet (P < 0·05). The total tract apparent digestibility of total fibre (TF) was significantly reduced with lucerne meal inclusion (P < 0·05), while the Heal apparent digestibility of TF was unaffected by lucerne and white-clover meal inclusion. Hindgut apparent digestibility (proportion of total tract apparent digestibility) of OM and energy was approximately 0·10, 0·70 and 0·70 for barley, lucerne and white-clover meal, respectively.

Both the Heal and total tract apparent digestibility of OM and energy were significantly higher for the control diet compared with lucerne and white-clover meal (P < 0·05). There was also a significantly higher apparent digestibility of OM, TF, crude fibre and energy in the total tract for white-clover meal compared with lucerne meal (P < 0·05). For neutral- and acid-detergent fibre a similar pattern was observed, however the effect was not significant.

The dietary digestible energy content was significantly reduced (F < 0·05), both at the ileum and over the total tract, with increasing inclusion offorage meal.

Growing pigs fitted with simple t-shaped cannulas posterior to the ileal-caecal valve were used in a change-over design experiment (5 × 5) to determine the Heal and total tract apparent digestibility and hindgut disappearance of dietary components and energy in a barley-based diet with increasing inclusion of either red-clover or perennial ryegrass meal (proportionately 0·10 and 0·20). The total tract and Heal apparent digestibilities of organic matter (OM), crude protein (CP), nitrogen-free extractives (NFE) and energy were significantly reduced with increasing inclusion of red-clover and perennial ryegrass meal in the diet (P < 0·05). For all fibrous components (total fibre (TF), neutral-detergent fibre (NDF), acid-detergent fibre (ADF) and crude fibre (CF)), the ileal apparent digestibility was unaffected by level offibre inclusion in the diet. Also the total tract apparent digestibility of TF, NDF and CF were unaffected by red-clover meal inclusion, while in contrast the total tract apparent digestibility of TF, NDF and CF were significantly reduced with perennial ryegrass meal inclusion (P < 0·05). The hindgut disappearance of crude fat, NDF, ADF and CF was not affected by forage meal inclusion, whereas the hindgut disappearance of OM, NFE, TF and energy were significantly lower in the perennial ryegrass meal diets than in both the control diet and the red-clover meal diets (P < 0·05).

The total tract apparent digestibility of OM was higher for the control diet compared with the red-clover and perennial ryegrass meal diets. There was also a significantly higher apparent digestibility of OM in the total tract for red-clover meal compared with perennial ryegrass meal (P < 0·05). The Heal apparent digestibility of energy in a barley-based diet with forage meal inclusion decreased proportionately by about 0·014, 0·023 and 0·030 units per unit increase ofTF, NDF and CF in dry matter, respectively. Correspondingly, for the total tract energy apparent digestibility, there was a decrease proportionately by about 0·010, 0·016 and 0·022 units per unit increase of TF, NDF and CF in dry matter, respectively. Digestible energy content was significantly reduced, as measured at the ileum or over the total tract, with increasing inclusion offorage meal (P < 0·05).

Thirty-two male pigs were used to investigate the effects of nine levels of dietary lysine ranging from 0·41 to 1·30 g lysine per MJ gross energy (GE) on the performance of pigs weaned at 1 to 2 days of age and growing between 2 and 7 kg live weight. The nine dietary lysine treatments, which contained similar levels of GE and balance of essential amino acids, were offered to the pigs at a common feeding level of 2·0 MJ GE per kg metabolic live weight (M075) per day. Growth performance and protein deposition rates increased linearly with increasing dietary lysine content up to about 0·97 g lysine per MJ GE and remained relatively constant thereafter. The response of protein deposition (PD, g/day) in the whole body of pigs to dietary lysine (L, g lysine per MJ GE) was described by three models. The respective regression equation for the quadratic function was PD = -14·23 + 87·66 L – 36·00 L2 and maximum protein deposition occurred at 1·22 g lysine per MJ GE. The rectilinear model, which had an ascending linear phase (PD = 1·49 + 40·10 L, R2 = 0·98, P < 0·001) and a horizontal component representing a mean protein deposition rate of 39·7g/day revealed that maximum protein deposition occurred at 0·95g lysine per MJ GE. Finally, application of the asymptotic model also revealed a highly significant equation: PD = 43·40 — 79·99 × 0·07111, R2 = 0·94, P < 0·001; which indicates a dietary requirement of 1·07 g lysine per MJ GE assuming that the dietary requirement was estimated at 0·90 of the asymptote maximal value. The results indicate that the dietary lysine requirement for pigs during the first 3 weeks of life appears to have changed little over the past 20 years despite substantial changes in genotype.

The effect of energy supply between 45 and 100 kg body weight (BW) on the contribution of lean tissue (muscle plus intermuscular adipose tissue) to total protein mass was studied in Large White castrated males (cLW), crossbred Piétrain × Large White castrated males (cPPx) and boars (bPPx). The pigs were allocated to four energy levels (0·70, 0·80, 0·90 or 1·00 ad libitum) and kept in metabolism cages in experiment 1 or given food ad libitum and kept in individual pens in experiment 2. Daily protein supplies were calculated to be non-limiting for growth and identical for all pigs in experiment 1. Temperature was 23°C in both experiments. The pigs were slaughtered at 100 kg BW and physically dissected; the body tissues were chemically analysed. Taking into account housing conditions, the food intake of pigs in experiment 2 corresponded to 1·20 of ad libitum intake of pigs in experiment 1; data of both experiments were combined. The energy supply and the type of pig influenced significantly the protein content of empty BW (eBW) (170 g/kg on average), of lean (184g/kg on average) and non-lean compartment (eBW minus lean, 152 g/kg on average), the proportion of total protein deposited in lean (604 g/kg of total protein, on average) but not the protein content in fat-free eBW (209 g/kg on average). The fat-free eBW can be predicted as 4·8 times the body protein mass.