Forty pigs (half each of females and entire males) were used in an ad libitum feeding experiment from weaning to 33 kg live weight (LW). In period 1 to 16 kg LW, the pigs had either food L (134 g crude protein (CP) per kg) or food H (278 g CP per kg) alone. The aim was to delay the growth of pigs on L and create two groups of pigs with different body compositions. At 16 kg LW, eight pigs were killed and their empty bodies chemically analysed. The pigs given L had 1·06 (s.e. 0·08) kg more lipid and a lower protein: ash ratio in their empty body than pigs on H; growth rates, from 9 to 16 kg LW, were 386 (L) and 591 (H) (s.e.d. 17)g/day. Both aims were thus achieved.

In period 2 the pigs previously given L (no. = 16) or H (no. = 16) in period 1, were given L alone (no. = 4), H alone (no. = 4) or a choice between L and H (no. = 8) to 33 kg LW when the choice-fed pigs were killed and their empty bodies chemically analysed. The objective of the experiment was to test the idea that pigs previously given a food deficient in CP, when given a choice between foods, one of high and one of low, protein content will select a diet of a composition that allows them to correct the effects of the previous mis-feeding. The pigs given L alone in period 2 grew more slowly, and ate more per day, than those given H alone, with no effect of the food given in period 1. Of those given H alone in period 2, the pigs previously given L grew faster, and were more efficient, than those previously given H.

The protein contents (g CP per kg food) of the diets selected by the choice-fed pigs were significantly affected by both sex (228 for males v. 181 for females; s.e.d. 15) and the food given in period 1 (233 for L and 175 for H; s.e.d. 15) with no significant interaction between these factors. The pigs from L grew faster (1039 v. 780 (s.e.d. 70) g/day) had a higher daily food intake (1420 v. 1319 (s.e.d. 71) g/day) and were more efficient (0·736 v. 0·595 (s.e.d. 0·034) g gain per g food) than those from H. At 33 kg LW lipid weights were similar for the two period 1 treatments (L had 0·40 (s.e. 0·54) kg more lipid than H); females had 1·79 (s.e. 0·54) kg more lipid than males.

It is concluded that, where pigs are given a choice between foods of low and high protein contents, they will select a diet of a composition such that the effects of previous mis-feeding are corrected. Giving pigs a choice between an appropriate pair of foods allows them to select a diet of a composition suitable for their needs.

Several groups of eight fattening (18 kg to 91 kg) Large White pigs containing both immature female and castrated male animals were established, were fed twice a day on a commercial dry ration, were observed at feeding time and their social orders (linear dominance hierarchy) worked out. Individual pigs were removed, one at a time, from different places in the social order, isolated for varying periods of time, and then replaced in their groups. It was found that the removal of a pig from any rank in the dominance order altered neither the basic social hierarchy nor the amount of aggression within the remainder of the group. The duration of time that an animal could be removed, isolated and returned without being attacked by the rest of its group varied with its social rank. Top-ranking animals could be safely returned even after 25 days' isolation, but lowranking animals were severely attacked after only 3 days' absence.

Ruminant-derived methane (CH4), a potent greenhouse gas, is a consequence of microbial fermentation in the digestive tract of livestock. Development of mitigation strategies to reduce CH4 emissions from farmed animals is currently the subject of both scientific and environmental interest. Methanogens are the sole producers of ruminant CH4, and therefore CH4 abatement strategies can either target the methanogens themselves or target the other members of the rumen microbial community that produce substrates necessary for methanogenesis. Understanding the relationship that methanogens have with other rumen microbes is crucial when considering CH4 mitigation strategies for ruminant livestock. Genome sequencing of rumen microbes is an important tool to improve our knowledge of the processes that underpin those relationships. Currently, several rumen bacterial and archaeal genome projects are either complete or underway. Genome sequencing is providing information directly applicable to CH4 mitigation strategies based on vaccine and small molecule inhibitor approaches. In addition, genome sequencing is contributing information relevant to other CH4 mitigation strategies. These include the selection and breeding of low CH4-emitting animals through the interpretation of large-scale DNA and RNA sequencing studies and the modification of other microbial groups within the rumen, thereby changing the dynamics of microbial fermentation.

The aim of this study was to assess the effect of natural light and straw bales on activity levels and leg health in commercial broiler chickens. Houses containing ∼23 000 broiler chickens were assigned to one of four treatments in a 2 × 2 factorial design. Treatments involved two levels of access to natural light (NL) (present ‘+NL’, or absent ‘−NL’) and two levels of access to straw bales (SB) (present (30/house) ‘+SB’, or absent ‘−SB’). All houses were windowed and artificially lit, and windows were shuttered where appropriate. Treatments were applied in one of the two houses on each of the two farms, and were replicated over four production cycles. Behaviour was observed in 2 to 6 weeks of the cycle. This involved observations of general behaviour and activity, gait scores (0 (perfect) to 5 (unable to walk)) and latency to lie (measured in seconds from encouraging a bird to stand). Production performance and environmental parameters were also measured. Average daytime light intensity and UV levels in the +NL treatment were 85.2 lx and 3.37 μW/cm2, respectively, and in the −NL treatment were 11.4 lx and 0 μW/cm2, respectively. Litter moisture levels were lower with NL treatment (P < 0.05), but were not affected by SB (P > 0.05). The percentage of time spent lying was significantly reduced by the provision of NL (P < 0.01), but not by SB (P > 0.05). There were three-way interactions between NL, SB and bird age on the percentage of time spent in locomotion (P < 0.05) and idling (P < 0.05). Both treatment factors had inconsistent effects on these parameters across different weeks. Levels of preening, resting and aggressive behaviour were not affected by treatment (P > 0.05). There was an interaction between treatments in average gait scores, with higher scores in the −NL−SB treatment than in all other treatments, and higher in the −NL+SB treatment than in the +NL treatments (P < 0.001). Average latency to lie was significantly higher with NL (P < 0.001) and SB (P < 0.05). We conclude that environmental modifications have the potential to increase activity levels and improve the leg health of commercial broilers. The light environment appears to be particularly important in this respect.

Soya bean is the main protein source in poultry feed but rising prices make an alternative protein source necessary. Insects, such as the black soldier fly (Hermetia illucens), may be an attractive solution for hens, although little information is available on their effect on egg quality. The present study aims to fill this gap by testing the effect of 100% replacement of soya bean with H. illucens larva meal in the diet of Lohmann Brown Classic laying hens for 21 weeks. At the end of the trial, the eggs were characterized for parameters such as weight, colour, proximate composition of albumen and yolk, and content of carotenoids, tocopherols and cholesterol. The fatty acid profile of yolks was also determined. Hens fed the insect-based diet produced eggs (HIM group) with a higher proportion of yolk than the group fed the soya bean-based diet (SBM group). HIM was associated with redder yolks (red index 5.63 v. 1.36) than SBM. HIM yolks were richer in γ-tocopherol (4.0 against 2.4 mg/kg), lutein (8.6 against 4.9 mg/kg), β-carotene (0.33 against 0.19 mg/kg) and total carotenoids (15 against 10.5 mg/kg) than SBM yolks. The fatty acid composition of HIM yolks was almost identical to that of SBM yolks. Finally, HIM yolks contained 11% less cholesterol than SBM yolks. These results suggest that H. illucens larva meal is a suitable total substitute for soya bean meal in the diet of Lohmann Brown Classic laying hens. A sustainable alternative to the plant protein source therefore seems feasible.

1. One-hundred-and-ten British Friesian, British Friesian × Ayrshire or successive backcrosses to British Friesian heifer calves were allocated to three groups. Groups A and B were rapidly reared and fed a barley-beef diet which resulted in mean body-weight gains exceeding 1 kg/day (13 to 39 weeks) and group C was normally reared on summer grazing and hay plus concentrates in winter at a mean body-weight gain never exceeding 0·74 kg/day. Animals in group A were first mated at an average age of 42·9 weeks (body weight, 302 kg). Groups B and C were mated later at average ages of 78·4 and 78·1 weeks (average body weights, 443 and 353 kg respectively). After the first calving all animals were fed and managed as a single group.

2. There were no significant differences between the proportion of heifers conceiving at first service in groups A (55·5%), B (66·7%) and C (72·4%).

3. There were no differences in the incidence of dystocia at first calving in heifers served by an Aberdeen Angus bull but 12 out of 19 heifers in group A served by a British Friesian bull had dystocia.

4. Average 305-day fat-corrected milk yields in the first four lactations in group A (18 animals) were 1959, 2918, 3545 and 3210 kg and in the first three lactations in group B were2450,3216and3310kgand in group C 3863,4694 and 4813 kg. Thus milk yield was significantly lower in all lactations for rapidly-reared animals irrespective of the age at breeding and was further significantly lowered in the first lactation of animals mated early.

5. There was a high incidence of laminitis and bloat in heifers reared on the barley-beef diet, but during lactation, there was a lower incidence of mastitis in the lower-yielding, rapidly-reared groups.

An animal model was used to estimate heritabilities of faecal egg count (FEC) and packed cell volume decline (PCVD) in lines of Merinos selected for divergent levels of resistance to Haemonchus contortus. The estimated heritability of FEC was 0·23 (s.e. 0·03) and of PCVD was 0·21 (s.e. 0·03). A cube root transformation was found to be effective in normalizing FEC data and reducing the range of within selection line-birth year variances from 118-fold to 10-fold. Transforming FEC data increased the heritability estimate to 0·29 (s.e. 0·03) and reduced selection bias due to heterogeneity of variance, but the further step of pre-adjusting the transformed data to a common variance had only a trivial effect. Heritability estimates for FEC in years with high means and variances were similar, as were estimates for transformed FEC. The estimated genetic correlations between measurements in years with high and low means and variabilities were 0·77 to 0·91.

PCVD and pre-adjusted transformed FEC had a phenotypic correlation of 0·48. Estimates for the genetic correlation ranged from 0·76 in the decreased resistance line to 1·00 in the increased resistance line and 0·87 with pooled data. Other effects on resistance included birth type and dam age, with twins and progeny of maiden dams being more resistant than their cohorts. Sex effects were unimportant for FEC but males had higher PCVD than females in most, but not all, years. Younger animals had higher FEC and PCVD than older animals. Maternal genetic effects were found to be unimportant, as were the effects of low levels of inbreeding.

Two experiments investigated the welfare of pigs during transport. In experiment 1, 12 groups offour 90-kg pigs were transported to slaughter in a commercial livestock lorry for 1·5 h. Half the animals were transported in their social groups (unmixed condition) and half were transported with groups of previously unfamiliar pigs mixed together (mixed condition). Behaviour was recorded, a general activity index scored and saliva samples taken at different stages of the journey for analysis ofcortisol. Pigs spent most of their time standing in both conditions. The journey was very rough (as revealed by characterization with an accelerometer) and in the unmixed condition the pigs appeared to stand to reduce travel sickness. In contrast, in the mixed condition, this preference for standing seemed to be due to fighting which stressed and exhausted the animals (the general activity index was three times the unmixed condition). Levels of salivary cortisol were higher in the mixed condition at the beginning, middle and end of the journey. In experiment 2, six 35-kg pigs, prepared in advance with jugular vein catheters, were loaded onto a commercial livestock lorry (09.30 h) where they were individually penned. The vehicle remained stationary with the engine off and blood samples were taken at 30-min intervals during the next 8 h (control). Two days later this procedure was repeated while the vehicle was driven for 8 h (on main roads and motorways). Plasma concentrations of cortisol and beta-endorphin increased markedly in both conditions immediately after loading. Cortisol levels were greater (relative to control) at the beginning, in the middle and at the end of the journey. Concentrations of beta-endorphin did not differ between control and experimental conditions except during the final 180 min of the journey when the control levels were higher.

Heart rate (HR) measurements have been used to determine stress in livestock species since the beginning of the 1970s. However, according to the latest studies in veterinary and behaviour–physiological sciences, heart rate variability (HRV) proved to be more precise for studying the activity of the autonomic nervous system. In dairy cattle, HR and HRV indices have been used to detect stress caused by routine management practices, pain or milking. This review provides the significance of HR and HRV measurements in dairy cattle by summarising current knowledge and research results in this area. First, the biological background and the interrelation of the autonomic regulation of cardiovascular function, stress, HR and HRV are discussed. Equipment and methodological approaches developed to measure interbeat intervals and estimate HRV in dairy cattle are described. The methods of HRV analysis in time, frequency and non-linear domains are also explained in detail emphasising their physiological background. Finally, the most important scientific results and potential possibilities for future research are presented.

The effects of supplementing a tropical, low-quality grass hay (Brachiaria dictyoneura) with legume foliage (Cratylia argentea) or fruits of the multipurpose tree Sapindus saponaria on ruminal fermentation, methane release and nitrogen (N) utilization were evaluated. Six Swiss White Hill lambs were used in a 6 ✕ 6 Latin-square design with a 3 ✕ 2 factorial arrangement of treatments with measurements of energy metabolism being conducted using open-circuit respiratory chambers. Treatments consisted of three basal diets, either grass alone or legume: grass ratios of 1: 2 or 2: 1. These basal diets were supplemented (1: 3) with a control concentrate or with a concentrate containing 250 g/kg dry matter of S. saponaria fruits. The apparent total tract digestibilities of organic matter (OM) and neutral-detergent fibre (NDF) were reduced and the proportionate crude protein (CP) losses through faeces were increased (P 0·01) by supplementation with S. saponaria, and digestibilities of OM and NDF were linearly reduced (P 0·001) with increasing legume proportion. Body energy retention, however, was similar in all diets. Along with CP intake, the proportionate CP losses through faeces decreased (P 0·001) with increasing legume proportion which was associated with improved (P 0·001) body protein retention and reduced (P 0·1) fat retention. Ruminal fluid ammonia concentration was not significantly affected (P > 0·1) by the inclusion of S. saponaria in the concentrate, but increased linearly (P 0·001) as dietary legume proportion was elevated. Supplementation with fruits of S. saponaria increased (P 0·01) total bacteria count, and decreased (P 0·001) total ciliate protozoa count by more than proportionately 0·50. Daily methane release was reduced (P 0·01) by S. saponaria supplementation in all basal diet types. Although being not clearly affected on a daily basis, methane release relative to body protein retention decreased linearly (P 0·05) with increasing legume proportion. The fact that interactions were mostly non-significant (P > 0·05) indicates that supplementation with S. saponaria fruits is a useful means to reduce methane emission from sheep given both tropical grass-based and grass-legume-based diets. Likewise, including legumes in N-limited tropical diets seems to represent an environmentally friendly way to improve animal productivity.

Livestock farming systems provide multiple benefits to humans: protein-rich diets that contribute to food security, employment and rural economies, capital stock and draught power in many developing countries and cultural landscape all around the world. Despite these positive contributions to society, livestock is also the centre of many controversies as regards to its environmental impacts, animal welfare and health outcomes related to excessive meat consumption. Here, we review the potentials of sustainable intensification (SI) and agroecology (AE) in the design of sustainable ruminant farming systems. We analyse the two frameworks in a historical perspective and show that they are underpinned by different values and worldviews about food consumption patterns, the role of technology and our relationship with nature. Proponents of SI see the increase in animal protein demand as inevitable and therefore aim at increasing production from existing farmland to limit further encroachment into remaining natural ecosystems. Sustainable intensification can thus be seen as an efficiency-oriented framework that benefits from all forms of technological development. Proponents of AE appear more open to dietary shifts towards less animal protein consumption to rebalance the whole food system. Agroecology promotes system redesign, benefits from functional diversity and aims at providing regulating and cultural services. We analyse the main criticisms of the two frameworks: Is SI sustainable? How much can AE contribute to feeding the world? Indeed, in SI, social justice has long lacked attention notably with respect to resource allocation within and between generations. It is only recently that some of its proponents have indicated that there is room to include more diversified systems and food-system transformation perspectives and to build socially fair governance systems. As no space is available for agricultural land expansion in many areas, agroecological approaches that emphasise the importance of local production should also focus more on yield increases from agricultural land. Our view is that new technologies and strict certifications offer opportunities for scaling-up agroecological systems. We stress that the key issue for making digital science part of the agroecological transition is that it remains at a low cost and is thus accessible to smallholder farmers. We conclude that SI and AE could converge for a better future by adopting transformative approaches in the search for ecologically benign, socially fair and economically viable ruminant farming systems.

Salmon oil (16·5 kg /t), a source of long-chain polyunsaturated n-3 fatty acids, was included in diets offered to multiparous sows during pregnancy and lactation to measure responses in pre-weaning mortality and performance of piglets in two studies. The first study, carried out under commercial conditions, included 196 sows which were offered salmon oil and control diets from immediately post service until weaning. The same diets were also offered to 10 sows per treatment from day 58 of pregnancy in a controlled nutritional study which measured the effects of salmon oil on piglet tissue fatty acid composition. Offering salmon oil to the sow significantly increased gestation length and decreased individual piglet birth weight but had no effect on litter size at birth. Overall, salmon oil reduced pre-weaning mortality from 11·7% to 10·2% mainly by reducing the incidence of deaths from crushing by the sow. More detailed analysis of mortality using a general linear mixed model and 2294 piglet records, demonstrated that the incidence of pre-weaning mortality was significantly decreased with increasing individual piglet birth weight and by inclusion of salmon oil in the diet; the incidence of mortality increased with average piglet birth weight in a litter. Salmon oil inclusion had no effect on weight of litter weaned, sow lactation food intake or subsequent reproductive performance. In both studies, dietary salmon oil increased the proportions of long-chain n-3 polyunsaturated fatty acids in colostrum to a similar extent. In the nutritional study, inclusion of salmon oil reduced the proportions of 20: 4 n-6 in piglet liver and brain at birth and increased the proportions of long-chain n-3 polyunsaturated fatty acids. Therefore, despite reducing piglet birth weight, offering sows salmon oil reduced pre-weaning mortality of piglets. The nutritional study showed that the amount and type of marine oil used may not have been optimal.

Sow productivity improvements continue to increase metabolic demands during lactation. During the peripartum period, energy requirements increase by 60%, and amino acid needs increase by 150%. As litter size has increased, research on peripartum sows has focused on increasing birth weight, shortening farrowing duration to reduce stillbirths and improving colostrum composition and yield. Dietary fibre can provide short-chain fatty acids to serve as an energy source for the uterus prior to farrowing; however, fat and glucose appear to be the main energy sources used by the uterus during farrowing. Colostrum immunoglobulin G concentration can be improved by increasing energy and amino acid availability prior to farrowing; however, the influence of nutrient intake on colostrum yield is unequivocal. As sows transition to the lactation period, nutrient requirements increase with milk production demands to support large, fast-growing litters. The adoption of automated feed delivery systems has increased feed supply and intake of lactating sows; however, sows still cannot consume enough feed to meet energy and amino acid requirements during lactation. Thus, sows typically catabolise body fat and protein to meet the needs for milk production. The addition of energy sources to lactation diets increases energy intake and energy output in milk, leading to a reduction in BW loss and an improvement in litter growth rate. The supply of dietary amino acids and CP close to the requirements improves milk protein output and reduces muscle protein mobilisation. The amino acid requirements of lactating sows are variable as a consequence of the dynamic body tissue mobilisation during lactation; however, lysine (Lys) is consistently the first-limiting amino acid. A regression equation using published data on Lys requirement of lactating sows predicted a requirement of 27 g/day of digestible Lys intake for each 1 kg of litter growth, and 13 g/day of Lys mobilisation from body protein reserves. Increases in dietary amino acids reduce protein catabolism, which historically leads to improvements in subsequent reproductive performance. Although the connection between lactation catabolism and subsequent reproduction remains a dogma, recent literature with high-producing sows is not as clear on this response. Many practical aspects of meeting the nutrient requirements of lactating sows have not changed. Sows with large litters should approach farrowing without excess fat reserves (e.g. <18 mm backfat thickness), be fed ad libitum from farrowing to weaning, be housed in a thermoneutral environment and have their skin wetted to remove excess heat when exposed to high temperatures.

Lameness is one of the most costly dairy cow diseases, yet adoption of lameness prevention strategies remains low. Low lameness prevention adoption might be attributable to a lack of understanding regarding total lameness costs. In this review, we evaluated the contribution of different expenditures and losses to total lameness costs. Evaluated expenditures included labor for treatment, therapeutic supplies, lameness detection and lameness control and prevention. Evaluated losses included non-saleable milk, reduced milk production, reduced reproductive performance, increased animal death, increased animal culling, disease interrelationships, lameness recurrence and reduced animal welfare. The previous literature on total lameness cost estimates was also summarized. The reviewed studies indicated that previous estimates of total lameness costs are variable and inconsistent in the expenditures and losses they include. Many of the identified expenditure and loss categories require further research to accurately include in total lameness cost estimates. Future research should focus on identifying costs associated with specific lameness conditions, differing lameness severity levels, and differing stages of lactation at onset of lameness to provide better total lameness cost estimates that can be useful for decision making at both the herd and individual cow level.

The delivery of certain living microorganisms in food has long been suggested as having positive health effects in humans. This practice has extended into food animal production, with a variety of microorganisms being used; lactic acid bacteria, various Bacillus species and the yeast Saccharomyces cerevisiae have been particularly used in the pig industry. The increased interest in probiotics is essentially due to the problem of microbial resistance to antibiotics and following the ban of the use of antibiotics in animal production, probiotics being considered an alternative means to reduce pathogen infection and improve animal health especially around the time of weaning. However, there is still a need to clarify the probiotic effectiveness in pigs, and the underlying mechanisms. When assessing the efficacy of probiotics one must consider the particular strain of organism being used and the production stage of the pigs being treated. The reproducible delivery of probiotics in industrial pig production is problematic as maintenance of viability is key to their beneficial activity, but difficult to achieve with commonly used feed processing technologies. One specific context where probiotics organisms may be reliably delivered is in systems utilising fermented liquid feeds. Liquid feed may be fermented by the activity of wild lactic acid bacteria or may be stimulated using specific isolates as ‘starters’; the latter system has advantages in terms of reproducibility and speed of fermentation. The farm context in which the organism is used is likely to be critical; the use of probiotics is more likely to result in measurable economic gains in animals living in sub-optimal conditions rather than in those reared in the highest welfare and husbandry conditions. The establishment of a beneficial lactic acid bacteria population at birth may lead to healthier animals, this may be most effectively achieved by treating sows, which provide an amplification step and flood the neonatal pigs’ environment with desirable bacterial strains. In contrast, it may be sufficient to provide a supportive, protective microbiota around the time of weaning as this is a time of major crisis with instability and loss of certain bacterial populations.

The association between transportation and the occurrence of the bovine respiratory disease complex (BRDC) has long been recognised. Many hypotheses regarding this association have been declared through the past decades, and it is agreed upon by most researchers that the multiple stressors that calves experience during transportation result in an overall immunosuppression that allows the respiratory tract to be invaded by numerous opportunistic pathogens. Furthermore, the innate immune cells, neutrophils, may be trapped in a paradox whereby their crucial defence and pathogen-killing activities are counteracted by excessive inflammation and tissue damage that may exacerbate disease, including the BRDC. Neutrophilia in response to glucocorticoids has been attributed to an influx of immature neutrophils newly released from the bone marrow, a decrease in neutrophil margination along endothelial walls, and a decrease in neutrophil apoptosis. Several of these explanations have been confirmed by altered expression of genes and proteins important for neutrophil margination and apoptosis.

The effects of environmental factors in the pre-weaning period on the subsequent growth of mice were studied. The variance caused by maternal effects, i.e. by environmental factors common to litter-mates, increased from birth to 4 weeks of age (1 week after weaning) and then decreased by about 60% between 4 and 8 weeks. Furthermore, a high litter weight at 4 weeks was followed by low subsequent growth and vice versa. The occurrence of compensatory growth from 4 weeks onwards was thus established. In contrast, the genetically determined variation of body weight did not show any reduction during the period of compensation, but increased up to 8 weeks of age.

The modification of the growth curve, by which compensation was achieved, was then studied. It was found that the inflexion point separating the initial phase of exponential growth from the subsequent phase of asymptotic growth corresponded closely with the attainment of sexual maturity in females, as judged by the opening of the vagina. Sexual maturity was reached at approximately the same weight in all litters, but at widely different ages. Thus, litters with rapid early growth as a result of a good maternal environment reached sexual maturity and consequently entered the asymptotic phase early, while litters with slow early growth entered the asymptotic phase late. Compensatory growth was therefore achieved through curtailment or prolongation of the exponential phase of growth.

A number of behavioural problems are associated with weaning piglets including belly nosing, ear and tail biting, and low intake of solid food. These appear to be less pronounced in piglets reared on outdoor systems, which initially consume more solid food and show less belly nosing and aggression than comparable indoor-reared piglets. The objective of this study was to investigate how these differences in post-weaning behaviour relate to the piglets’ pre-weaning behaviour in the two rearing environments. The study was carried out at a commercial pig unit, where piglets of the same genotype are born into conventional indoor or outdoor farrowing systems. In the intensive system, sows were singly housed prior to farrowing in crates and their piglets received a solid ‘creep’ food prior to weaning. On the outdoor system, sows were allowed to build straw nests in arks for farrowing and both sow and piglets had access to pasture. Indoor and outdoor piglets were weaned at 24 (±3) days of age and mixed in straw-yard housing with access to a solid food. Prior to weaning, teat-directed activity was more common in indoor piglets than outdoor piglets. Outdoor piglets performed more rooting, standing and locomotion and were seen chewing the sows’ roll-nuts. Following weaning, outdoor-reared piglets performed more feeding and rooting, and less fighting than indoor-reared piglets. This study supports previous findings that undesirable activities such as fighting are less common in piglets weaned from outdoor systems, even when mixed with indoor piglets. In addition, outdoor-reared piglets were more likely to exploit solid food even though they did not have access to creep food prior to weaning.

The EU ban on in-feed antibiotics has stimulated research on weaning diets as a way of reducing post-weaning gut disorders and growth check in pigs. Many bioactive components have been investigated but only few have shown to be effective. Amongst these, organic acids (OA) have been shown to exert a bactericidal action mediated by non-dissociated OA, by lowering gastric pH, increasing gut and pancreas enzyme secretion and improving gut wall morphology. It has been postulated that they may also enhance non-specific immune responses and improve disease resistance. In contrast, relatively little attention has been paid to the impact of OA on the stomach but recent data show they can differently affect gastric histology, acid secretion and gastric emptying. Butyrate and precursors of butyric acid have received special attention and although promising results have been obtained, their effects are dependent upon the dose, treatment duration, initial age of piglets, gastrointestinal site and other factors. The amino acids (AA) like glutamine, tryptophan and arginine are supportive in improving digestion, absorption and retention of nutrients by affecting tissue anabolism, stress and (or) immunity. Glutamine, cysteine and threonine are important for maintaining mucin and permeability of intestinal barrier function. Spray-dried plasma (SDP) positively affects gut morphology, inflammation and reduces acquired specific immune responses via specific and a-specific influences of immunoglobulins and other bioactive components. Effects are more pronounced in early-weaned piglets and under poorer health conditions. Little interaction between plasma protein and antibiotics has been found, suggesting distinct modes of action and additive effects. Bovine colostrum may act more or less similarly to SDP. The composition of essential oils is highly variable, depending on environmental and climatic conditions and distillation methods. These oils differ widely in their antimicrobial activity in vitro and some components of weaning diets may decrease their activity. Results in young pigs are highly variable depending upon the product and doses used. These studies suggest that relatively high concentrations of essential oils are needed for beneficial effects to be observed and it has been assumed that these plant extracts mimic most of the effects of antibiotics active on gut physiology, microbiology and immunology. Often, bioactive substances protective to the gut also stimulate feed intake and growth performance. New insights on the effects of selected OA and AA, protein sources (especially SDP, bovine colostrum) and plant extracts with anti-bacterial activities on the gut are reported in this review.

In the post-antibiotics era, prebiotics are proposed as alternatives to antibiotic growth promoters in poultry production. The goal of this study was to compare in ovo method of prebiotic delivery with in-water supplementation and with both methods combined (in ovo+in-water) in broiler chickens. Two trials were conducted. Trial 1 was carried out to optimize the doses of two prebiotics, DN (DiNovo®, extract of beta-glucans) and BI (Bi2tos, trans-galactooligosaccharides), for in ovo delivery. The estimated parameters were hatchability and bacteriological status of the newly hatched chicks. Prebiotics were dissolved in 0.2 ml of physiological saline, at the doses: 0.18, 0.88, 3.5 and 7.0 mg/embryo; control group (C) was injected in ovo with 0.2 ml of physiological saline. Trial 2 was conducted to evaluate effects of different prebiotics (DN, BI and raffinose family oligosaccharides (RFO)) delivered in ovo, in-water and in a combined way (in ovo+in-water) on broiler chickens performance. The results of the Trial 1 indicated that the optimal dose of DN and BI prebiotics delivered in ovo, that did not reduce chicks’ hatchability, was 0.88 mg/embryo (DN) and 3.5 mg/embryo (BI). Both prebiotics numerically increased number of lactobacilli and bifidobacteria in chicken feces (P>0.05). In Trial 2, all prebiotics (DN, BI and RFO) significantly increased BW gain compared with the C group (P<0.05), especially during the first 21 days of life. However, feed intake and feed conversion ratio were increased upon prebiotics delivery irrespective of method used. Injection of prebiotics in ovo combined with in-water supplementation did not express synergistic effects on broilers performance compared with in ovo injection only. Taken together, those results confirm that single in ovo prebiotics injection into the chicken embryo can successfully replace prolonged in-water supplementation post hatching.