A total of 64 nine-week-old pigs were used in two experiments to study the influence on feed intake, growth and carcass quality of dietary restriction at various ages or live weights. Two diets of different energy content were given throughout each experiment, which was divided into four periods on either an age or weight basis. Feed was restricted or offered ad libitum during each of the first three periods, all pigs being fed ad libitum during the last period.

Compensatory intake following a period of feed restriction occurred at most stages of growth but was most marked in the early stages. Compensation when it occurred took several weeks to develop fully and persisted for some time, often after an intervening period of ad libitum feeding. Increased gains resulted from increased intake although some of the early compensatory gains could not be fully explained by increased intake.

There were few appreciable differences between the pigs on the highand those on the low-energy diets. However, in the early stages the latter did not show the same response in intake following restriction as did the former (but in experiment I the latter were considerably lighter).

No effects on carcass quality were demonstrated under the conditions of these experiments.

Carcass data for a total of 1385 pigs from years 3 to 6 of the Meat and Livestock Commission's Commercial Pig Evaluation were used to examine the value of different shape assessments as predictors of carcass composition, when used in addition to carcass weight and fat thickness over the m. longissimus at the head of the last rib (P2). The sample comprised pigs from 13 breeding companies and a purebred Large White control.

The standard deviation of carcass lean proportion at equal weight and P2 was 24·5 g/kg. The addition of carcass length or visual conformation assessments (five-point scales) provided a small improvement in precision (minimum residual standard deviation = 24·2 g/kg). This improvement was associated with a reduction in the variation of lean to bone ratio.

The addition of an effect for breeding company to weight and P2 improved the precision substantially (residual standard deviation = 23·1 g/kg). The improvement was due mainly to the identification of differences in carcass fat content, there being a range of 30g/kg in carcass fat content between companies at equal weight and P2.

There was a further small improvement in precision from the addition of conformation assessments to weight, P2 and company (minimum residual standard deviation = 22·9 g/kg).

The study confirms earlier results which indicate that shape assessments are of limited value as predictors in the British pig population, due mainly to limited variation in lean to bone ratio. It also indicates that significant variation exists between companies in fat content at equal P2 and weight which is not explained by shape assessments.

Information available on the role of Mg for growth and cellulose degradation by rumen bacteria is both limited and inconsistent. In this study, the Mg requirements for two strains each of the cellulolytic rumen species Fibrobacter succinogenes (A3c and S85), Ruminococcus albus (7 and 8) and Ruminococcus flavefaciens (B34b and C94) were investigated. Maximum growth, rate of growth and lag time were all measured using a complete factorial design, 2(3)×6; factors were: strains (2), within species (3) and Mg concentrations (6). R. flavefaciens was the only species that did not grow when Mg was singly deleted from the media, and both strains exhibited a linear growth response to increasing Mg concentrations (P<0.001). The requirement for R. flavefaciens B34b was estimated as 0.54 mM; whereas the requirement for R. flavefaciens C94 was >0.82 as there was no plateau in growth. Although not an absolute requirement for growth, strains of the two other species of cellulolytic bacteria all responded to increasing Mg concentrations. For F. succinogenes S85, R. albus 7 and R. albus 8, their requirement estimated from maximum growth was 0.56, 0.52 and 0.51, respectively. A requirement for F. succinogenes A3c could not be calculated because there was no solution for contrasts. Whether R. flavefaciens had a Mg requirement for cellulose degradation was determined in NH3-free cellulose media, using a 2×4 factorial design, 2 strains and 4 treatments. Both strains of R. flavefaciens were found to have an absolute Mg requirement for cellulose degradation. Based on reported concentrations of Mg in the rumen, 1.0 to 10.1 mM, it seems unlikely that an in vivo deficiency of this element would occur.

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.

Management strategies for increasing ruminant legume consumption and mitigating methane emissions from tropical livestock production systems require further study. The aim of this work was to evaluate the herbage intake, animal performance and enteric methane emissions of cattle grazing dwarf elephant grass (DEG) (Pennisetum purpureum cv. BRS Kurumi) alone or DEG with peanut (Arachis pintoi cv. Amarillo). The experimental treatments were the following: DEG pastures receiving nitrogen fertilization (150 kg N/ha as ammonium nitrate) and DEG intercropped with peanut plus an adjacent area of peanut that was accessible to grazing animals for 5 h/day (from 0700 to 1200 h). The animals grazing legume pastures showed greater average daily gain and herbage intake, and shorter morning and total grazing times. Daily methane emissions were greater from the animals grazing legume pastures, whereas methane emissions per unit of herbage intake did not differ between treatments. Allowing animals access to an exclusive area of legumes in a tropical grass-pasture-based system can improve animal performance without increasing methane production per kg of dry matter intake.

Three groups of four mature boars were housed in individual pens for 3 mo under one of the following social conditions: near ovariectomized female pigs induced into sexual receptivity at 2-week intervals; isolated from female pigs but either with or without visual and physical contact with neighbouring boars. The total number of copulations achieved in six mating tests throughout the period was significantly greater (P<0·01) for the boars housed near sexually receptive females than for those housed in the other two social conditions. For the subsequent 3 mo all boars were housed near sexually receptive females and no significant differences were found between the three groups for total number of copulations.

Prompted by current concerns about energy resources and greenhouse gas emissions, we sought to assess the impact of certain key factors on energy efficiency in sheep-for-meat production and to evaluate the main directions for improvement. We used a modelling approach to simulate the functioning and performances of sheep-for-meat production systems integrating an energy balance calculation module. In the first step of this study, we reconstructed system functions and technical and economic results of four typological groups of farms in plainland areas. This served as a basis for calculating their energy efficiency in order to focus on the main factors of energy efficiency, such as high levels of fodder self-sufficiency (low concentrate consumption) and high ewe productivity. The Graze system presented the highest energy efficiency (EE) for sheep unit (EEs = 0.62) with the lowest consumption of equivalent fuel litres requirements (FuReq) per kilogram of lamb carcass produced (1.47), while the ‘sheep and cash crop’ system had the lowest EEs (0.36) and the highest FuReq per kg carcass (2.54). We then took the ‘mixed-farming system’ (a 130 ha farm, including 610 ewes and 40 ha of cropland) and studied three adaptations designed to increase the EEs: improvement of feed self-sufficiency (increased proportion of concentrate produced on-farm), introduction of legumes into the rotation (removal of bought-in nitrogen fertilisers), and production of fuel-oil (from rapeseed) with the flock using oil cakes. The most effective adaptation was the removal of the nitrogen fertilisers. The successive adaptations make it possible to cut energy consumption from 2.2 FuReq/kg carcass down to 0.98 after the optimisations, thereby increasing EEs from 0.42 to 0.93. Finally, we went on to study the energy impact of four factors influencing flock functioning and farm structure, i.e. ewe productivity, lamb weight, distances between plots, and flock size. Ewe productivity and lamb weight had a strong positive impact on EEs. When ewe productivity switched from 0.80 to 1.70, EEs increased from 0.29 to 0.48 while FuReq per kilogram carcass dropped from 3.39 to 1.88. When flock size was increased to over 1000 ewes, there were little or no energy-related economies of scale, as farm area also increased and most of the systems required more equipment.

Forty-eight individually-penned lambs (mean live weight 31-4 kg) were offered one of four diets, to investigate response to a supplement of fish meal (0 and 100 g dry matter (DM) per kg M) given with diets of either 60: 40 or 40: 60 forage-to-concentrate ratio. Nitrogen (N) degradability in the rumen and fractional outflow rates of protein supplements were determined. The diets were formulated such that the lambs received about 3 or 9 g undegradable rumen N per kg DM. The diets were given daily to provide sufficient metabolizable energy for maintenance and 150 g gain, and were adjusted according to live weight at weekly intervals.

Fish-meal supplementation improved daily growth over a 49-day period (P < 0·001) and enhanced N retention (P < 0·001). Live-weight gain was also marginally improved on the high-forage diets. (P < 0-05), but there was no protein supplement × forage-to-concentrate ratio interaction. Apparent digestibility of acid detergent fibre was improved by the fish-meal supplement on the high-concentrate diet.

The four diets were also given to rumen-fistulated sheep. The high-concentrate diet was associated with a higher molar proportion of propionate (P < 0·05) and a lower proportion of acetate (P < 0·001). Rumen concentrations of ammonia tended to be maintained at higher levels throughout the day by the fish-meal supplement.

In two experiments young British Friesian cattle were allowed restricted access to maize silage on a self-feed system. Restrictions were imposed by either limiting the width of feed face per animal or by reducing the time available for feeding.

The social order of each group of cattle was determined by observing dominance-submission interactions between pairs of individuals. Dominance rank and angular dominance values were calculated for individuals in each group and related to silage intake, feeding time and rate of eating. Silage intake and rate of eating increased significantly with dominance value, and feeding time decreased although not significantly.

Over the past 100 years, the French livestock sector has experienced significant intensification that has occurred in different ways across the country. Specifically, France has changed from a homogeneous state with most of the agricultural area covered by grasslands and a uniform distribution of animals, to a heterogeneous state characterised by an uneven distribution of grasslands, livestock numbers and livestock species. Studying the dynamics of this change is fundamental to the identification of drivers that shaped the various intensification trajectories and led to these different states, as well as to the prediction of future changes. Hence, the objective of this study was to characterise the trajectories undertaken by the French livestock sector to understand the intensification process and the role of socioeconomic, land use and production-related factors. A set of 10 indicators was employed to analyse the main changes between 1938 and 2010, using principal component analysis followed by a clustering of the 88 French departments. Between 1938 and 2010, significant increases in farm size, mechanisation, labour productivity and the stocking rates of monogastrics enabled the French livestock sector to double its production. The most important changes involved mechanisation (with the number of tractors per hectare (ha) rising from 0.0012 to 0.0053), labour productivity (improving from 8.6 to 35.9 ha/worker), livestock production (e.g. milk production increasing from 758 to 1856 l/ha of fodder area) and stocking rates (rising from 0.57 to 0.98 livestock units (LU) per ha). The increased heterogeneity apparent in the patterns of change throughout France’s departments was captured by clustering four trajectories. Two trajectories were formed by departments that experienced strong specialisation towards livestock production, with one type mainly orientated towards high-intensive dairy, poultry and pig landless production systems, and a second type orientated towards extensive beef grazing production systems. Another trajectory corresponded to departments that specialised in crop production with high labour productivity; mixed crop-livestock systems were still maintained at the margins of this group of departments. The fourth trajectory corresponded to the lowest livestock population and productivity levels. The increase in mechanisation during the period was important but uniform, with no significant differences between the trajectories. This typology of intensification trajectories will enable the targeting of specific areas in which the detrimental impacts of livestock intensification require mitigation and provide guidance for future livestock sector developments.

Age and weight at puberty, age at first conception and number of services per conception of 90 females at Santa Monica Experimental Station, Valencia, State of Rio de Janeiro, were studied. The females were of six red and white Holstein-Friesian (HF) × Guzera (G) grades: 1/4, 1/2, 5/8, 3/4, 7/8 and ≥ 31/32.

A model (1) including the effects of grade and season of birth resulted in the following least-squares means for the six grades in the above order (± s.e.): age at puberty, 770 (± 17), 725 (± 18), 799 (± 26), 788 (± 23), 777 (± 17) and 803 (± 24) days; weight at puberty, 309 (± 8), 334 (± 9), 316 (± 13), 311 (± 11), 303 ((± 9) and 298 (± 12) kg; age at conception, 865 (± 19), 773 (± 19), 867 (± 31), 808 (± 25), 852 (± 22) and 837 (± 25) days; number of services per conception, 1·9 (± 0·2), 1·7 (± 0·2), 1·5 (± 0·3), 11 (± 0·2), 1·6 (+ 0·2) and 1·3 (± 0·2).

A second model (2) was fitted, including the effects of season of birth, direct (g1) breed additive effects (HF - G) and heterosis effects (hl). g1 and h1 were estimated by the partial regression coefficient of the traits studied on, respectively, the expected HF gene frequency and the expected heterozygosity of the females. The estimates of g7 were not significantly different from zero except for age at first conception (g7 = -102 (s.e. 46) days) (P < 0·05). Heterosis effects were significant for age at puberty (h1 = -86 (s.e. 34) days), weight at puberty (h1 = 44 (s.e. 17) kg) and age at first conception (h1 = —119 (s.e. 37) days). These three estimates of h1 amounted, respectively to —0106, 0151 and —0·132 of the estimated mean of the parental breeds.

F-tests on the extra variation due to fitting model 1 after model 2 were not significant (P < 0·05) indicating that epistasis or other genetic effects, not included in model 2, were of little importance for the traits studied.

The horse’s hindgut bacterial ecosystem has often been studied using faecal samples. However few studies compared both bacterial ecosystems and the validity of using faecal samples may be questionable. Hence, the present study aimed to compare the structure of the equine bacterial community in the hindgut (caecum, right ventral colon) and faeces using a fingerprint technique known as Automated Ribosomal Intergenic Spacer Analysis (ARISA). Two DNA extraction methods were also assessed. Intestinal contents and faeces were sampled 3 h after the morning meal on four adult fistulated horses fed meadow hay and pelleted concentrate. Irrespective of the intestinal segment, Principal Component Analysis of ARISA profiles showed a strong individual effect (P<0.0001). However, across the study, faecal bacterial community structure significantly (P<0.001) differed from those of the caecum and colon, while there was no difference between the two hindgut communities. The use of a QIAamp® DNA Stool Mini kit increased the quality of DNA extracted irrespective of sample type. The differences observed between faecal and hindgut bacterial communities challenge the use of faeces as a representative for hindgut activity. Further investigations are necessary to compare bacterial activity between the hindgut and faeces in order to understand the validity of using faecal samples.

Genetic selection is well established as a means of improving productivity in pigs, but the effects of continued selection for increased performance on immunity are not well understood, nor are genetic relationships between performance and immunity. This study compared differences in the levels of a range of immune traits between lines of Large White pigs divergently selected for a number of productivity traits. Selection lines compared were high v. low lean growth under restricted feeding (31 high line v. 10 control v. 38 low line pigs), high v. low lean growth under ad libitum feeding (18 high line v. 10 control v. 19 low line pigs), and high v. low food intake (24 high line v. 26 low line pigs). Immune traits measured were total white blood cell numbers (WBC), and the numbers of leukocyte subsets: neutrophils, monocytes, eosinophils, lymphocytes, CD4+ cells, CD8α+ cells, B cells, γδ T cells and CD11R1+ Natural killer (NK) cells. CD4+, γδ T cells and CD11R1+ cells were subdivided into subpopulations that were positive or negative for the CD8α marker, and conventional CD8αhigh+ cytotoxic T cells were also determined. Pigs were tested under ad libitum feeding conditions from 14 to 24 weeks, and immune traits were assessed at ages 18 and 24 weeks. Line differences were estimated using residual maximum likelihood techniques. Consistent differences in immune trait levels were evident between pigs previously selected for high and low lean growth under restricted feeding: at age 24 weeks, high line pigs had higher basal levels of WBC (39·6 v. 27·8×106 cells per ml, s.e.d. 2·09, for high v. low line pigs) mainly explained by higher levels of lymphocytes (25·5 v. 17·3×106 cells per ml, s.e.d. 1·54, for high v. low line pigs) with increased numbers of CD8α+ cells (8·19 v. 5·15×106 cells per ml, s.e.d. 0·14) and CD11R1+ cells (5·23 v. 2·46×106 cells per ml, s.e.d. 0·43), predominantly the CD11R1+ CD8α? subpopulation ((3·20 v. 1·64×106 cells per ml, s.e.d. 0·11). High line pigs also had increased numbers of monocytes (2·64 v. 1·83×106 cells per ml, s.e.d. 0·35). Similar results were obtained at age 18 weeks. There were no consistent differences between divergent lines in pigs selected for lean growth under ad libitum feeding or food intake. This is the first report to demonstrate that selection for some aspects of performance can influence WBC and leukocyte subset numbers in pigs.

Genetic (or ‘genomic’) imprinting, a feature of approximately 100 mammalian genes, results in monoallelic expression from one of the two parentally inherited chromosomes. To date, most studies have been directed on imprinted genes in murine or human models; however, there is burgeoning interest in the effects of imprinted genes in domestic livestock species. In particular, attention has focused on imprinted genes that influence foetal growth and development and that are associated with several economically important production traits in cattle, sheep and pigs. We have re-sequenced regions in 20 candidate bovine imprinted genes in order to validate single nucleotide polymorphisms (SNPs) that may influence important production traits in cattle. Putative SNPs detected via re-sequencing were subsequently re-formatted for high-throughput SNP genotyping in 185 cattle samples comprising 138 performance-tested European Bos taurus (all Limousin bulls), 29 African B. taurus and 18 Indian B. indicus samples. Analysis of the resulting genotypic data identified 117 validated SNPs. Preliminary genotype–phenotype association analyses using 83 SNPs that were polymorphic in the Limousin samples with minor allele frequencies ⩾0.05 revealed significant associations between two candidate bovine imprinted genes and a range of important beef production traits: average daily gain, average feed intake, live weight, feed conversion ratio, residual feed intake and residual gain. These genes were the Ras protein-specific guanine nucleotide releasing factor gene (RASGRF1) and the zinc finger, imprinted 2 gene (ZIM2). Despite the relatively small sample size used in these analyses, the observed associations with production traits are supported by the purported biological function of the RASGRF1 and ZIM2 gene products. These results support the hypothesis that imprinted genes contribute significantly to important complex production traits in cattle. Furthermore, these SNPs may be usefully incorporated into future marker-assisted and genomic selection breeding schemes.

The responses of growing pigs to dietary lysine concentration, as influenced by food intake, sex (entire male and female) and live weight were investigated in an experiment involving 128 pigs. The basal barley-soya-bean diet (14·2 MJ digestible energy (DE) per kg) was offered either ad libitum or according t o a restricted feeding scale to both sexes from 20 to 85 kg live weight. The eight dietary lysine concentrations ranged from 8·0 to 12·2 g/kg during the 20 to 50 kg phase and from 6·4 to 9·8 g/kg during the 50 to 85 kg live-weight phase. Performance was assessed by response-surface analysis based on data from successive 10-kg live-weight intervals. Regression analysis was used to assess the response of carcass lean content after slaughter at 85 kg live weight.

Daily gain of females fed ad libitum was curvilinear up to maxima of 0·72 and 0·69 g lysine per MJ DE during the 20 to 50 and 50 to 85 kg growth phases respectively. Daily gain response was small but linear up to the maximum dietary lysine concentration for all other combinations of sex and food intake.

The response of carcass lean for males given food at a restricted level was linear up to the maximum dietary lysine concentration. For males given food ad libitum, carcass lean response was curvilinear with maximum lean content attained with 0·73 and 0·59 g lysine per MJ DE during the 20 to 50 and 50 to 85 kg live-weight phases respectively. Carcass lean content of females was not affected by lysine concentration within the range used.

Genetics affects not only the weight of piglets at birth but also the variability of birth weight within litter. Previous studies on this topic assigned the sample standard deviation of piglet birth weights within litter as an observation to the sow. However, the contribution of the difference in mean birth weight per sex on the within-litter variance has been neglected so far. This work deals with the genetic effect on within-litter variance when different statistical models with different distributional assumptions are used and considers the sex effect and appropriate weights per trait. Traits were formed from the pooled sample variance of male and female birth weights within litter. A linear model approach was fitted to the logarithmized within-litter variance and the sample standard deviation. A generalized linear model with gamma-distributed residuals and log-link function was applied to the untransformed sample variance. Models were compared by analysing data from 9439 litters from Landrace and Large White of a commercial breeding programme. The estimates of heritability for different traits ranged from 7% to 11%. Although the generalized linear mixed model is preferred from a mathematical view, the rank correlations between breeding values of the linear mixed models and the generalized linear mixed model were relatively high, i.e. 94% to 98%. By residual diagnostics, a linear mixed model using the weighted and pooled within-litter standard deviation was identified as most suitable.

Total teat number in a Large White and a British Landrace population had a modal number of 14. The trait was highly leptokurtic, indicated by the fact that 086 of the population falls within one standard deviation of the mean. There was no sex difference in total teat number, although a small but significant breed difference existed. Heritability of the trait was low, of the order of 0·10 to 0·20 based on the sire component of variance. Larger dam terms suggested a maternal effect.

Severely inverted teats (nipple invisible) were observed in 0·17 of gilts. Mean number of inversions was 0·738 in the entire population but 4·01 in affected gilts. The heritability of the trait was of the order of 0·20 and a maternal component was possibly involved.

Inverted teats are not distributed at random. They occur most frequently in the umbilical and anterior regions and diminish sharply in frequency towards the rear. In this study 0·97 of all affected pigs had one or more inverted teats in the umbilical and anterior regions.

Reproductive success is a key component of lifetime efficiency – which is the ratio of energy in milk (MJ) to energy intake (MJ) over the lifespan, of cows. At the animal level, breeding and feeding management can substantially impact milk yield, body condition and energy balance of cows, which are known as major contributors to reproductive failure in dairy cattle. This study extended an existing lifetime performance model to incorporate the impacts that performance changes due to changing breeding and feeding strategies have on the probability of reproducing and thereby on the productive lifespan, and thus allow the prediction of a cow’s lifetime efficiency. The model is dynamic and stochastic, with an individual cow being the unit modelled and one day being the unit of time. To evaluate the model, data from a French study including Holstein and Normande cows fed high-concentrate diets and data from a Scottish study including Holstein cows selected for high and average genetic merit for fat plus protein that were fed high- v. low-concentrate diets were used. Generally, the model consistently simulated productive and reproductive performance of various genotypes of cows across feeding systems. In the French data, the model adequately simulated the reproductive performance of Holsteins but significantly under-predicted that of Normande cows. In the Scottish data, conception to first service was comparably simulated, whereas interval traits were slightly under-predicted. Selection for greater milk production impaired the reproductive performance and lifespan but not lifetime efficiency. The definition of lifetime efficiency used in this model did not include associated costs or herd-level effects. Further works should include such economic indicators to allow more accurate simulation of lifetime profitability in different production scenarios.

Previously, feeding fish oil (FO) and sunflower seeds to dairy cows resulted in the greatest increases in the concentrations of vaccenic acid (VA, t11 C18:1) and conjugated linoleic acid (CLA) in milk fat. The objective of this study was to evaluate the effects of forage level in diets containing FO and sunflower oil (SFO) on the production of trans C18:1 and CLA by mixed ruminal microbes. A dual-flow continuous culture system consisting of three fermenters was used in a 3 × 3 Latin-square design. Treatments consisted of (1) 75:25 forage:concentrate (HF); (2) 50:50 forage:concentrate (MF); and (3) 25:75 forage:concentrate (LF). FO and SFO were added to each diet at 1 and 2 g/100 g dry matter (DM), respectively. The forage source was alfalfa pellets. During 10-day incubations, fermenters were fed treatment diets three times daily (140 g/day, divided equally between three feedings) as TMR diet. Effluents from the last 3 days of incubation were collected and composited for analysis. The concentration of trans C18:1 (17.20, 26.60, and 36.08 mg/g DM overflow for HF, MF, and LF treatments, respectively) increased while CLA (2.53, 2.35, and 0.81 mg/g DM overflow) decreased in a linear manner ( P < 0.05) as dietary forage level decreased. As dietary forage levels decreased, the concentrations of t10 C18:1 (0.0, 10.5, 33.5 mg/g DM) in effluent increased ( P < 0.05) and t10c12 CLA (0.08, 0.12, 0.35 mg/g DM) tended to increases ( P < 0.09) linearly. The concentrations of VA (14.7, 13.9, 0.0 mg/g DM) and c9t11 CLA (1.78, 1.52, 0.03 mg/g DM) in effluent decreased in a linear manner ( P < 0.05) as dietary forage levels decreased. Decreasing dietary forage levels resulted in t10 C18:1 and t10c12 CLA replacing VA and c9t11 CLA, respectively, in fermenters fed FO and SFO.

This experiment investigated the effects of feeding graded levels of a soya-bean protein product (HP300, Hamlet Protein A/S Company, Denmark) on endogenous ileal lysine loss, apparent ileal amino acid digestibility, standardized true ileal amino acid digestibility determined using the protein-free (PF) method, and real ileal amino acid digestibility determined using the homoarginine (HA) method. The soya-bean protein product was obtained by purifying and defattening soya bean via a proprietary microbial process that decreased the level of trypsin inhibitors and other anti-nutritional factors in soya bean. Six barrows, with an initial body weight of 37·4 ± 1·3 kg, were surgically fitted with simple T-cannulae at the distal ileum and offered six maize-starch-based diets according to a 6 × 6 Latin-square design. The six diets were formulated to provide 0, 50, 100, 150, 200, or 250 g crude protein (CP) per kg by dietary inclusion of 0, 90, 182, 274, 367 or 460 g/kg of soya-bean protein. Five kg of soya-bean protein product was guanidinated in order to estimate endogenous amino acid flow and real ileal amino acid digestibility. Chromium III oxide (5 g/kg) was included in the non-guanidinated diets while dysprosium chloride (0·1 g/kg) was included in the guanidinated diets as an indigestible marker. The experimental periods lasted 8 days. On day 6 of each period, ileal digesta was collected for 24 h to determine apparent and standardized true ileal amino acid digestibility of the non-guanidinated diets. At 08:00 h on day 8, the pigs were given a single meal of the diets containing guanidinated protein and their ileal digesta was collected for 24 h in order to determine the total HA flow and the real ileal digestibility of lysine. Endogenous ileal lysine flow appeared to follow a sigmoid curve starting at about 370 mg/kg dry matter (DM) intake for pigs given the PF diet and continuing asymptotically to about 750 mg/kg DM intake when the inclusion level of the soya-bean protein product was increased to 182 g/kg (100 g/kg of CP). The endogenous ileal lysine flow for pigs given the PF diet was similar (P > 0·05) to that of pigs given 90 g/kg soya-bean protein (50 g/kg of CP) and it increased sharply (P < 0·05) as the level of soya-bean protein increased from 90 to 182 g/kg (50 to 100 g/kg of CP). Thereafter, it was relatively constant (P > 0·05). With an increase in soya-bean protein, there was a quadratic increase (P < 0·01) in the apparent ileal digestibilities for all amino acids except valine and phenylalanine. Standardized true ileal amino acid digestibility decreased (P < 0·05) with an increase in soya-bean protein level. However, real ileal amino acid digestibilities were not influenced (P > 0·05) by soya-bean protein in the diet at levels between 90 and 367 g/kg (50 and 200 g/kg of CP). In conclusion, endogenous ileal lysine flow was not constant and was significantly affected by soya-bean protein level. The results of this study suggest that standardized true ileal amino acid digestibility should be measured between 100 and 200 g/kg of CP (182 and 367 g/kg soya-bean protein) while real ileal amino acid digestibility is unaffected by protein levels between 50 and 200 g/kg of CP (90 and 367 g/kg soya-bean protein).