An experiment was carried out to investigate the proposal that the voluntary food intake of pigs, when given foods based on bulky materials, can be accurately predicted from the water-holding capacity (WHC, g water per g dry food) values of the foods. A basal food (B), with 12·9 MJ digestible energy and 249 g crude protein per kg dry matter, was diluted to two extents by either sugar-beet pulp (S), grass meal (G) or soya hulls (H). The contents of the bulky materials in the total diets were either 320 g/kg (foods BS, BG and BH) or 800 g/kg (foods S, G and H). Each of these six foods was given ad libitum to six pigs in period I, which lasted for 21 days, with a further four given B. In period II, which lasted for 14 days and followed period I immediately, the pigs were also given their food ad libitum. Only the 36 pigs from the six ‘bulky“treatments (i.e. on treatments other than B) continued in a change-over design. Two pigs from each of the six ‘bulky’ treatments were allocated to the three foods of the same level of dilution (e.g. the six pigs from BS were changed to BS, BG and BH). Of the ‘bulk’ characteristics measured (crude fibre, acid-detergent fibre, neutral-detergent fibre, apparent digestibility of the organic matter, density and WHC) only WHC accounted sufficiently for the effects of the foods on the voluntary food intake of the pigs. The two methods of centrifugation and filtration that were used for the WHC determination were very highly correlated (r = 0·978), with food B having the lowest value, 3·86 g water per g dry food, and food S having the highest value, 8·48 g water per g dry food, when measured by centrifugation. In both periods the rate of intake was calculated as g/kg live weight per day, scaled intake (SFI). Live-weight gain and food conversion efficiency both decreased significantly (P < 0·001) as B was diluted with S, G and H. For the six ‘bulky’ feeding treatments SFI in the last 14 days of period I was proportional to the reciprocal of the WHC of the foods: SFI (g/kg per day) = 235 (s.e. 6·3). No effects of previous feeding treatment on site were observed in period II as a whole; however, intake initially increased when the food had lower WHC than the one previously offered and decreased when it had higher WHC. It was concluded that: (a) the WHC of a food is a sufficient descriptor of its ‘bulk’ and that it accounts for the effects on the voluntary food intake of pigs; (b) the detailed methods used for measuring WHC need to be standardized; (c) pigs can adapt more rapidly to bulky foods when they have had prior experience of such foods; (d) the length of time needed to observe an intake, which will be characteristic of the bulky food on offer, depends on the prior experience of the pig.

On termination of a 56-day feeding trial, the effect of dietary oxidized oil and all-rac-α-tocopheryl acetate on fatty acid and α-tocopherol status of juvenile African catfish (Clarias gariepinusj muscle and liver was investigated. Clarias of mean initial weight 15·8 (s.e. 0·29) g were given food at -proportionately 0·03 body weight per day on diets of two oxidative states (fresh or oxidized) at two levels of supplemental α-tocopheryl acetate (20 or 100 mg/kg dry matter).

As well as having a significant detrimental effect on final body weight (P < 0·001), oxidation of the dietary lipid source was responsible for decreasing muscle but not hepatic polyunsaturated fatty acids (PUTAs). Liver tissue was suspected of actively synthesizing longer chain PUT As in response to consumption of oxidized oils, as indicated by decreases in the proportions of linoleate (18:2 n-6) and linolenate (18:3 n-3) and the increased abundance of eicosatetraenoic acid (20:4 n-6, arachidonate) and docosahexaenoic acid (22: 6 n-3, DHA). This phenomenon has not been described in fish nutrition and therefore possible mechanisms are discussed. Additionally, oxidized oils in catfish diets caused significant depletion of a-tocopherol from both muscle and liver (P < 0·05).

Modulation of the effects of oxidized lipids was achieved at the higher dietary tocopherol concentration. Appearance of an unknown aliphatic compound (equivalent chain length (ECL) = 13·1), believed to be a product of lipid peroxidation, demonstrated that catfish given rancid/low-tocopherol diets had been subjected to heightened oxidative nutritional stress. Values obtained for this peak were significantly correlated with dietary regime (P < 0·02), Once more, dietary α-tocopheryl acetate moderated this effect. It was concluded that elevated inclusion of all-rac-α-tocopheryl acetate into diets for African catfish could abrogate the effects of oxidized dietary lipids on muscle and liver fatty acids and α-tocopherol.

1. A comparison lasting 3 years has been made of 5 types of crossbred ewes produced by mating Border Leicester, Clun Forest, Dorset Horn, Finnish Landrace and Tasmanian Merino rams to Scottish Blackface ewes. Data from a total of 576 ewe years became available.

2. In body weight at mating time when they were 7, 19 or 31 months old, the Border Leicester and Dorset Horn crossbred ewes were heaviest, followed by Cluns. Finnish and Merino crossbreds were about 15–20% lighter than the Border Leicester crossbreds.

3. In fleece weight, Finnish crossbreds were lower by about 1·0—1·5 lb relative to Border Leicester crossbreds.

4. In fertility, Finnish crossbreds were highest with 1·5, 2·0 and 2·3 lambs born per ewe lambing at ages 1, 2 and 3 years respectively. The corresponding averages for the combined Border Leicester, Clun and Dorset Horn crossbreds were 1·1, 1·6 and 1·6 and for Merino crossbreds 1·0, 1·1 and 1·2. Numbers weaned were similarly ranked.

5. Lambs out of crossbred ewes showed a sequence of group differences in weight at birth and at weaning corresponding to those shown by their mothers at mating time. The heaviest lambs were produced by Dorset Horn and Border Leicester crossbreds, and the lightest by Merino crossbreds. As a percentage of ewe weight at mating, lamb weight at weaning was highest for the Finnish group.

6. In terms of litter weight at weaning, fitted values for the Merino group were the lowest while those for the Finnish group were the highest. The other three groups gave similar and intermediate values.

An experiment (complete randomised design) was conducted to investigate the effects of supplementing different molecular weights (MW) of chitooligosaccharide (COS) on intestinal morphology, selected microbial populations, volatile fatty acid (VFA) concentrations and the immune status of the weaned pig. A total of 28 piglets (24 days of age, 9.1 kg (± s.d. 0.80) live weight) were assigned to one of four dietary treatments for 8 days and then sacrificed. The treatments were (1) control diet (0 ppm COS), (2) control diet plus 5 to 10 kDa COS, (3) control diet plus 10 to 50 kDa COS and (4) control diet plus 50 to 100 kDa COS. The COS was included in dietary treatments at a rate of 250 mg/kg. Tissue samples were taken from the duodenum, jejunum and ileum for morphological measurements. Digesta samples were taken from the proximal colon to measure lactobacilli and Escherichia coli populations and digesta samples were taken from the caecum and proximal colon for VFA analysis. Gene expression levels for specific cytokines were investigated in colonic tissue of the pig. Supplementation of different MW of COS had no significant effect on pig performance during the post-weaning period (days 0 to 8; P > 0.05). The inclusion of COS at all MW in the diet significantly reduced faecal scores compared with the control treatment (P < 0.01). Pigs fed the 10 to 50 kDa COS had a higher villous height (P < 0.05) and villous height : crypt depth ratio (P < 0.05) in the duodenum and the jejunum compared with the control treatment. Pigs fed the 5 to 10 kDa COS had a lower lactobacilli population (P < 0.05) and E. coli population (P < 0.05) in the colon compared with the control group. Pigs offered the 5 to 10 kDa COS had significantly lower levels of acetic acid and valeric acid compared with the control group (P < 0.05). The inclusion of different MW of COS had no significant effect on the expression of the cytokines tumour necrosis factor-α, Interleukin (IL)-6, IL-8 and IL-10 in the gastro-intestinal tract of the weaned pig. The current results indicate that a lower MW of 5 to 10 kDa COS possessed an antibacterial activity, while the higher MW of 10 to 50 kDa was optimum for enhancing the intestinal structure.

The ability to authenticate the feed given to animals from the animal products has become a major challenge for scientists, monitoring bodies and commercial entities alike. This study compared two methods based on the use of the visible reflectance spectrum of the fat to discriminate pasture-fed (P) from stall concentrate-fed (S) lamb carcasses. A total of 307 (143 P and 164 S) Limousine lambs were used over 2 years. Pasture-fed lambs grazed a permanent pasture that was maintained at a leafy, green vegetative stage, and offered ad libitum; they received no supplementation at pasture. Body weight of P lambs when turning out to pasture and at slaughter averaged 9.2 (standard deviation (s.d.) 2.21) kg and 33.2 (s.d. 2.89) kg, respectively. S lambs were fed indoors on an ad libitum diet of commercial concentrate and hay until slaughter at a mean body weight of 33.7 (s.d. 3.62) kg. The reflectance spectrum of perirenal and subcutaneous caudal fat was measured at slaughter and at 24 h post mortem. Plasma carotenoid concentration was measured at slaughter. In method 1, the fat reflectance spectrum data were used at wavelengths between 450 and 510 nm to calculate an index quantifying light absorption by carotenoid pigments. In method 2, a multivariate analysis was performed over the full set of fat reflectance data at wavelengths between 400 and 700 nm. Method 2 yielded a higher proportion of correctly classified lambs compared with method 1 (P < 0.05 to 0.001), except for measurements made at 24 h post mortem on perirenal fat for S lambs. The proportion of lambs correctly classified using method 2 was 87.4% and 92.9% for measurements made on perirenal and caudal fat at slaughter, and 93.9% and 91.0% for measurements made on perirenal and caudal fat 24 h post mortem. Plasma carotenoid concentrations were higher in P lambs than in S lambs (P < 0.001), which led to correct classification of 90.7% of the lambs.

Wood-chip pads represent a low-cost alternative to housing for cattle during the winter. Considering the negative welfare implications associated with housing indoors on concrete, they may also offer welfare benefits to replacement dairy heifers. However, these animals may not be able to withstand winter weather conditions on a grass silage diet. The aim of this experiment was to evaluate behaviour, limb injuries, dirtiness scores, performance and climatic energy demand (CED) of yearling dairy heifers on two levels of nutrition kept outdoors on a wood-chip pad or indoors in cubicles during the winter. Ninety-six 10-month-old heifers were blocked and assigned in groups of eight, to one of the following four treatments in a 2 × 2 factorial design: (a) indoors, silage only; (b) indoors, silage plus concentrate; (c) outdoors, silage only; and (d) outdoors, silage plus concentrate. There were three replicate groups per treatment. All animals were inspected for skin lesions and were weighed and body condition scored (BCS) at the beginning and end of the trial. Instantaneous scan sampling and continuous all-occurrence behaviour sampling were used to collect behaviour data during two 24-h periods. Animals were also dirtiness scored and group feed intakes were recorded during the trial. Significantly more comfort, social and play behaviours were recorded outdoors (P < 0.05) while trips, slips and falls were only recorded indoors (P < 0.001). Groups outdoors had significantly lower limb lesion scores at the end of the experiment (P < 0.05) and fewer groups outdoors were affected by all categories of limb lesions. However, they were consistently dirtier than animals indoors (P < 0.001). Low-nutrition animals had lower feed intakes, smaller BCS changes and lower average daily weight gains than high-nutrition animals (P < 0.01). Heifers outdoors had significantly lower average daily weight gains and BCS changes (P < 0.05) explained by lower feed intakes (P < 0.01). However, outdoor heifers on both the high- and low-nutrition diets and indoor animals on the low-nutrition diet had lower UFL (feed unit for maintenance and lactation (Irish Republic)) intakes (−0.36, −0.35 and −0.22, respectively) than that required to meet the daily live-weight gains they achieved. Heifers indoors on the high-nutrition diet gained 0.98 kg per day but consumed 0.17 UFL more than what would be recommended to achieve a daily weight gain of 1.0 kg. The CED for outdoor heifers was higher than that of indoor heifers (6.18 v. 5.47 MJ/day per m2 body surface area; P < 0.001, s.e.d. 0.044). However, CED did not exceed heat production in any treatment. Although animal performance was reduced outdoors, the wood-chip pad was associated with welfare benefits compared with cubicle housing.

A total of 30 7-week-old pigs were used to evaluate the effects of chicory inclusion on digestibility, digestive organ size and faecal microbiota. Five diets were formulated: a cereal-based control diet and four diets with inclusion of 80 and 160 g/kg chicory forage (CF80 and CF160), 80 g/kg chicory root (CR80) and a mix of 80 g/kg forage and 80 g/kg chicory root (CFR). Generally, the pigs showed a high growth rate and feed intake, and no differences between the different diets were observed. The coefficients of total tract apparent digestibility (CTTAD) of energy, organic matter and CP did not differ between the control and CF80, whereas they were impaired in diet CF160. The CTTAD of non-starch polysaccharides and especially the uronic acids were higher (P < 0.05) with chicory inclusion, with highest (P < 0.05) values for diet CF160. Coliform counts were lower and lactobacilli : coliform ratio was higher (P < 0.05) in diet CFR than in the control. Global microbial composition was investigated by terminal restriction fragment length polymorphism combined with cloning and sequencing. Analysis of gut microbiota pattern revealed two major clusters where diet CF160 differed from the control and CR80 diet. Chicory forage diets were correlated with an increased relative abundance of one species related to Prevotella and decreased abundance of two other species related to Prevotella. For diet CFR, the relative abundance of Lactobacillus johnsonii was higher than in the other diets. This study shows that both chicory forage and root can be used as fibre sources in pig nutrition and that they modulate the composition of the gut microbiota differently.

Milk production data were collected on 8- and 9-year-old Angus × Hereford or Hereford × Angus; Charolais × Angus or Hereford; Jersey × Angus or Hereford; and Simmental × Angus or Hereford cows at days 14, 28, 56, 84, 112, 140, 168 and 196 after parturition. During the study, cows were given diets differing in quantity of brome grass (Bromus inermis) haylage. Lactation curves were estimated by the empirical equation Y(n) = n/aekn. Differences were observed among the breed crosses in 25-week lactation yield and time of peak lactation.

Previously published data from serial slaughter trials on growing pigs of five genotypes were reanalysed. Gompertz curves were fitted to body protein and lipid mass in order to estimate mature protein and lipid mass (P∞, L∞) and the rate parameter (BGomp J that was presumed to be equal for the protein and lipid curves. L∞ was expressed as its ratio to P∞, R L∞P∞. The maximum rate of protein deposition was derived as Pdep,max = P∞ X BGomp/e. The analysed data encompass body weights of 10 to 133 kg, 13 to 217 kg, 18 to 106 kg, 20 to 110 kg and 11 to 145 kg. The Gompertz function fitted all data sets well, as judged by the standard deviations and distribution patterns of the residual terms. Autocorrelations among the residuals were non-significant.

Averaged over sexes (females and entire and castrated males), the P estimates were all close to 31 kg; the RL∞/P∞ estmates ranged from 1·4 to 4·7 kg/kg; the BGomp estimates ranged from 0·009 to 0·017 kg/day per kg. The resulting Pdep,max estimates ranged from 110 to 193 g/day. The genotypes were placed in 1969, 1976, 1984, 1990 and 1993. Plotting the estimates against time (year) showed distinct time trends for all parameters except P∞. RL∞/P∞ seems to gradually reach a plateau around unity, whereas BGomp and Pdep/max increase linearly. These trends were confirmed by an analysis of body weight based on the same data plus data on three other genotypes that spanned the same time period. Analyses of the same protein and lipid data to fit a sigmoid growth function with a flexible point of inflexion did not change the apparently absent time trend of F. The estimates of the inflexion points of the fitted protein accretion curves, expressed as proportions ofF, were indistinguishable from the fixed 0·368 value of the Gompertz function for the earliest three genotypes and then showed a tendency to increase, up to 0·46 for the 1993 population. These time trends must be the consequence of a combination of changes in nutritional and other environmental factors and genetic changes. They cannot be the sole result of within-line selection for growth and body composition traits, since this should increase P∞. It seems as if pig breeders have repeatedly initiated their sire lines from genetic resources with small mature size, to subsequently increase this trait as an indirect result of within-line selection.

Digestibility of dry matter, energy and cell wall was measured in two series of digestibility trials in which sheep were fed on pelleted mixed rations containing either 32·0 or 22·6% cell wall at various levels of intake. There were significant depressions in digestibility of all nutritive components as the level of intake increased. The ration lower in cell wall showed smaller declines in dry matter and energy digestibility but a greater decline in cell wall digestibility. The results indicate that the cell wall fraction of concentrate-supplemented rations for sheep is a primary factor in the decline in digestibility observed with increase in level of intake.

In dairy cattle, diet supplementation with oils affects the lipid metabolism in body tissues via changes in the partitioning and deposition of fatty acids (FAs) and lipogenic gene expression; however, limited data are available in goats. Eight Alpine goats were fed a grassland hay diet supplemented with 90 g/day of sunflower-seed oil or 90 g/day of sunflower-seed oil and fish oil (2 : 1) plus additional starch. The goats were slaughtered on day 21 of the treatments and samples of the mammary secretory tissue, liver, omental and perirenal adipose tissues (ATs) were collected to characterise their FA composition and the mRNA abundance of lipogenic genes and transcription factors involved in their regulation, and to examine the impact of the diet composition on the same parameters. The results are in agreement with the specific physiological adaptation in the lipid metabolism of body tissues that is likely to occur during late lactation because of the coexistence of an active lipogenesis in the mammary secretory tissue and a significant anabolic activity in the ATs. These latter tissues were characterised by high concentrations of saturated FA and very low polyunsaturated FA (PUFA) levels. The content of PUFA was relatively higher in the mammary secretory tissue, in particular in the case of polyunsaturated C18. The highest PUFA contents were found in the liver, in accordance with the greater mRNA abundances of the genes that encode the necessary enzymes for very long-chain n-3 and n-6 PUFA synthesis. However, substantial differences between n-3 and n-6 pathways would most likely exist in the goat liver. Overall, differences in diet composition induced limited changes in the mRNA abundance of genes involved in lipid metabolism, and these were not associated with the few variations observed in tissue FA composition.

Infectious atrophic rhinitis is a disease of the upper respiratory tract of pigs, characterized in the live animal by deformation of the snout and conchal atrophy. However, the severity of the disease in pigs on commercial units is highly variable and air quality may be implicated as a significant factor in addition to the recognized pathogens. In this study the aerial environment was monitored in 49 pig buildings on 12 commercial farrowing-finishing units. A total of 1117 pigs from the 12 farms were examined individually at commercial slaughter weight to quantify the severity of conchal atrophy, using snout scoring and morphometric techniques.

A number of significant relationships were shown between environmental variables in the farrowing house and the severity of conchal atrophy. Mean snout score (MSS) and the percentage of snouts from each herd sample with a score of three or more (SS3) were correlated with total bacterial counts (r = 0·78 (P < 0·01) and 0-83 (P < 0·01) respectively), counts of 10 [mi to >15 urn particles (r = 0·67 (P <0·05), 0·73 (P <0·05)) and concentrations of gravimetric dust (r = 0·65 (P <0·05), 0·64 (P <0·05)). Concentrations of ammonia were correlated with SS3 (r = 0·68 (P <0·05)).

Dust in the first-stage weaner houses was again a significant component of the aerial environment associated with the severity of the disease. MSS and SS3 were correlated with counts of 10 urn to >15 μm particles (r = 0·66 (P <0·05), 0·68 (P <0·05)), concentrations of respirable dust (r = 0·67 (P <0·05), 0·63 (P <0·05)), total dust (r = 0·75 (P <0·05), 0·87 (P <0·001)), and gravimetric dust (r = 0·83 (P <0·01), 0·88 (P <0·001)). The results support the theory that the mass or number of particles present as inspirable aerosols, and the presence of large numbers of viable bacteria may compromise the local defence mechanism of the upper respiratory tract in the pig and facilitate colonization by Bordetella bronchiseptica and Pasteurella multocida. Saturation deficit in the second-stage weaner houses was correlated with both mean morphometric index and SS3 (r = 0·860 (P <0·01) and 0·683 (P <0·05) respectively), and volumetric stocking density in the finishing houses was correlated with both MSS and SS3 (r = -0·84 (P <0·01), -0·64 (P <0·05)). It is hypothesized that the severity of the disease may be lessened by reducing the concentrations of dust, microbes and ammonia which may play a significant role in the development of the disease.

The origin of myristic acid in mammalian cells and the regulation of its endogenous cellular low concentration are not known. Another intriguing question is the potential metabolic properties of endogenous myristic acid as compared with exogenous myristic acid. In the present paper, we hypothesised and demonstrated that, in liver cells, in addition to the usual fatty acid synthase (FAS) pathway that produces predominantly palmitic acid and minor amounts of myristic acid, part of endogenous cellular myristic acid also comes from a shortening of palmitic acid, likely by peroxisomal β-oxidation and from lauric acid by elongation. From a nutritional point of view, C16:0 is universally found in natural fats and its shortening to myristic acid could contribute to a non-negligible source of this fatty acid (FA) in the organism. Then, we measured the distribution of endogenously synthesised myristic acid in lipid species and compared it with that of exogenous myristic acid. Our results do not support the hypothesis of different metabolic fates of endogenous and exogenous myristic acid and suggest that whatever the origin of myristic acid, its cellular concentration and lipid distribution are highly regulated.

The implications of genetic variation in maternal performance for the relative merits of common selection strategies have been investigated. If the accuracy of progeny testing is computed without taking maternal effects into account, the estimate is biased upward. This bias increases as the correlation between direct and maternal genetic effects decreases from positive to negative values. The relative efficiency of progeny and performance test selection is a function of the heritability of direct and maternal genetic effects and the correlation between them. In terms of genetic gain per unit time, progeny testing is almost always less efficient than performance testing. For sire line improvement progeny testing is relatively more useful but is still likely to be less efficient than performance test selection unless there is a negative correlation between direct and maternal genetic effects or the correlation between purebred and crossbred direct genetic effects is very low or negative.

Analysis of body weight at 6 and 14 weeks of age in Galway sheep has shown that maternal genetic effects are an important source of variation in this population.

1. Twelve gilts, six pregnant and six non-pregnant, were each given a daily ration of 2.2 kg. for a 110-day period.

2. Live-weight gain during this period was 53 kg. for the pregnant animals compared with 23 kg. for the non-pregnant animals.

3. Apparent digestibility of nitrogen and dry matter and the energy of digested feed did not differ significantly between the pregnant and non-pregnant animals.

4. Daily nitrogen retention was on average 9·2% higher for the pregnant animals, the difference between the two groups becoming progressively greater during the trial.

5. Highly significant differences were found in pre-slaughter live-weight, weight of reproductive tract and weight of mammary region. The difference in the weight of free draining blood was also significant. No difference was found in the weight of alimentary tract, visceral organs, head or decapitated carcass.

6. The carcasses of the pregnant animals contained less subcutaneous fat plus skin and more intermuscular fat plus muscle than those of the non-pregnant animals. The weights of bone did not differ.

The objective of this study was to identify possible risk factors for poor cow hind limb cleanliness in Danish loose-housed, lactating dairy cows. The study was conducted as a cross-sectional study of 1315 cows in 42 commercial Danish dairy herds with primarily Danish Holstein cows. The effect of four cow-level factors (parity, days in milk, daily lying time and lameness) and eight herd-level factors (herd size, milk production, milking system, floor type, access to pasture grazing, floor scraping frequency, hoof bathing frequency and hoof washing frequency) on the risk of having dirtier hind limbs were analysed using ordinal logistic regression fitting a proportional odds model. Cow hind limb cleanliness was scored using an ordinal score from 1 to 4: 1 being clean and 4 being covered in dirt. The odds ratios (ORs) estimated from the proportional odds model depict the effect of a risk factor on the odds of having a higher rather than a lower cleanliness score. First parity cows had an increased risk of being dirtier compared with third parity or older cows (OR = 1.70). Compared with late lactation, early and mid lactation were associated with an increased risk of being dirtier (OR = 2.07 and 1.33, respectively). Decreasing the daily time lying by 30 min was associated with an increased risk of being dirtier (OR = 1.05). Furthermore, an increased risk of being dirtier was found in herds with no pasture access (OR = 3.75).

We investigated in vitro inhibitory effects of ketoconazole (KTZ) on cytochrome P450 activity in microsomes from pigs and Atlantic salmon. The following enzymatic reactions were studied: 7-benzyloxyresorufin and 7-ethoxyresorufin O-dealkylation (BROD and EROD, respectively), 7-benzyloxy-4-trifluoromethylcoumarin O-debenzylation (BFCOD) and 7-benzyloxyquinoline O-debenzylation (BQOD). KTZ was a potent non-competitive inhibitor of BROD and BQOD in the microsomes from pigs, whereas in the microsomes from Atlantic salmon, these reactions were competitively inhibited by KTZ. BFCOD activity was inhibited by KTZ in a non-competitive manner in both species. KTZ non-competitively inhibited EROD in Atlantic salmon, but not in porcine microsomes. The activity of BROD and BQOD was higher in male than that in female pigs, but the activity of BFCOD showed no sex-related differences.

Energy digestibility in the growing pig increases with BW increase and may differ between breeds of pigs or between lines selected on criteria other than digestion. However, little is known about the variability in energy digestibility within a line or a breed of pigs, especially when fibrous diets are fed. For this purpose, 20 Large White castrated male growing pigs originating from four boars (five per boar), and three to four sows per boar, were fed a high dietary fibre (DF) diet (18% NDF) and measured over 10 consecutive weeks (30 to 95 kg BW range) for their apparent faecal energy, nitrogen and organic matter digestibility. Each week, faeces were totally collected over 5 days and the feed dry matter intake over the same days was recorded. All digestibility coefficients increased regularly (P < 0.001) over the experimental periods or with BW increase (+0.6 point/10 kg BW increase for energy); this rate of increase was not affected by boar origin (no interaction; P > 0.05). The digestibility coefficients were affected by boar origin (P < 0.005 for energy), with about 2 points for energy between the extremes (81.7% v. 79.5%), and there was no marked interaction between boar origin and period. These preliminary results suggest the possibility of selecting growing pigs for an increased digestive efficiency when fed high DF diets.

Effects of creep food presentation on feeding behaviour and intake were studied with eight litters of eight to 10 Yorkshire × Landrace piglets in the 3rd and 4th weeks after birth, before weaning at 4 weeks of age. In each week, four treatments were applied, each for 24 h: a single two-space feeder unchanged from the previous day; a clean feeder with fresh food supplied at 09.00 h; a clean feeder with fresh food supplied at three times during the day; and three feeders (six feeding spaces) providing increased access to food throughout the day. There were no significant differences between the first three treatments in time spent at the feeder (recorded by video over 24 h) or food intake of piglets. However, the fourth treatment increased average intake in week 3 to 2·1 times the average of the other treatments, and in week four to 1·4 times. In week 3, most piglets spent more time at the feeder when access was increased, while in week 4 the effect was restricted to piglets which ate very little. This suggested that imitative learning was important in the initiation of feeding. Analysis of both litter means and within-Utter variation showed that piglets which ate more solid food before weaning gained more weight in the 2 weeks after weaning. However, this correlation was confounded by correlations of both measures with birth weight and other variables. Causal links between creep feeding and post-weaning weight gain remain to be demonstrated.

The mammalian target of rapamycin (mTOR) has been shown to be involved in lipopolysaccharide (LPS)-induced immune responses in many mammal cells. Here, we suggest that the mTOR pathway is involved in the intestinal inflammatory responses evoked by LPS treatment in chicken embryos. The intestinal tissue from Specific pathogen free chick embryos was cultured in the presence of LPS for 2 h. Secretory immunoglobulin A (sIgA) concentrations, messenger RNA (mRNA) expression of cytokines, and protein levels of nuclear factor-κB (NF-κB), mitogen-activated protein kinase (MAPK), mTOR and p70 ribosomal S6 kinase (p70S6K) were determined. The results showed that LPS treatment increased sIgA concentrations in a dose-dependent manner. The mRNA levels of interleukine (IL)-6, IL-8, IL-10, tumor necrosis factor-α and Toll-like receptor (TLR) 4 were upregulated by LPS treatment (P<0.05). Lipopolysaccharide increased the phosphorylation of Jun N-terminal kinase (JNK), p38 MAPK and NF-κB (P<0.05) while decreasing the phosphorylation level of mTOR (P<0.05). Supplementation of leucine at doses of 10, 20 and 40 mM dose-dependently decreased sIgA production. Leucine supplementation at 40 mM restored the phosphorylation level of mTOR and p70S6K while suppressing the phosphorylation levels of NF-κB (P<0.05) and partially down-regulating the phosphorylation of p38 MAPK and JNK. The transcription of IL-6 was significantly decreased by leucine supplementation. These results suggested that leucine could alleviate LPS-induced inflammatory responses by down-regulating NF-κB signaling pathway and evoking mTOR/p70S6K signaling pathway, which may involve in the regulation of the intestinal immune system in chicken embryos.