Impact of bioactive substances on the gastrointestinal tract and performance of weaned piglets: a review

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

The multivariate approach identifies relationships between pre-slaughter factors, body lesions, ham defects and carcass traits in pigs

Abattoir meat inspection has been proposed for the collection of welfare outcomes. The identification of suitable animal-based measures (ABM) is still a critical point that needs to be implemented to avoid collinearity among measures. The present study aims to benchmark the presence of ABM such as skin and tail lesions and ham defects in carcasses from 79 batches of Italian Heavy pigs and to identify possible relationships between the assessed ABM and pre-slaughter factors such as the season and the overnight lairage. Furthermore, the study also considers the effect of pre-slaughter conditions and ABM on carcass traits parameters (cold carcass weight and lean meat percentage). Skin and tail lesions were recorded at the slaughter line. The presence of abscesses, muscle tears and veining defects were assessed in the hams at trimming, according to the Parma Ham Consortium. A multivariate analysis was performed to identify relationships between ABM and pre-slaughter factor; therefore, a linear model was built to assess the effect on carcass weight and lean meat percentage. Main welfare issues were represented by skin and tail lesions and muscle tears (prevalence above 10%). Multivariate analysis evidenced that skin lesions and veining defects were mostly associated with the warm season. Abscesses and muscle tears in the hams were more likely related to overnight lairage, while tail lesions contributed equally to both season and lairage. Moreover, lairage related factors showed to affect lean meat percentage. The findings of the present study suggest that ham defects might be useful indicators of pre-slaughter stress. The validation of these findings with physiological parameters could be of interest for further studies

A meta-analytical approach for evaluating the effect of arginine supplementation on the productive performance of sows during gestation

Arginine (Arg) supplementation for gestating and lactating sows seems to play a primary role in litter development by promoting placental vascularization and improving colostrum and milk quality. The aim of this study was to investigate the effects of the supplementation of dietary standardized ileal digestible Arg (SID Arg) on the productive performance of gestating sows using a meta-analytical approach. A total of 19 studies conducted between 2007 and 2020 which tested the effect of additional SID Arg supplementation in diets for sows were chosen using a systematic literature search. Data regarding backfat thickness, number of piglets born and live born, litter birthweight and weaning weight were extrapolated from each experimental group and expressed as a percentage of the value of the control group within the studies. The SID Arg supplementation was expressed as the percentage of SID Arg in the treated group compared to the control group (Additional SID Arg). Linear and quadratic models were built using a mixed procedure utilizing Minitab® software including Additional SID Arg, parity and feed intake classes and the period of SID Arg supplementation as fixed factors, and the study as the random factor. The SID Arg in control groups was higher than the doses suggested by the National Research Council (NRC; 2012) (4.20–8.90 g/kg of feed vs 3.2–7.9 g/kg, respectively). A quadratic response of Additional SID Arg was observed for placental efficiency (PE; P = 0.003; a=0.0019), the number of total piglets born (P = 0.027; a=−0.0003), the number of live born piglets (P = 0.005; a=−0.0006) and backfat thickness loss (P = 0.057; a=0.0029). A linear increase in the plasma concentration of Pro (P = 0.004; b=0.120), Orn (P = 0.002; b=0.284) and Arg (P = 0.001; b=0.425), and a decrease in the concentration of urea (P = 0.037; b=−0.063) was observed with an increasing level of SID Arg. There was no effect on placenta weight, live litter birthweight, individual piglet weight at birth and weaning, litter size and weight at weaning, and average daily gain during lactation. The estimated requirements of SID Arg for improving PE, reducing backfat thickness loss, increasing the number of piglets born and live born were 11.17 g/kg, 13.03 g/kg, 14.83 g/kg and 15.71 g/kg of feed, respectively. This meta-analysis highlighted the importance of redefining the Arg requirements of gestating sows and suggested a dosage ranging from 11.17 to 15.71 g/kg of feed to improve reproductive performance

Dietary Nitrate: Effects on the health of weaning pigs and Antimicrobial activity on seven probiotic Bifidobacterium spp. strains

The potential role of nitrite as an antimicrobial substance in the stomach may be of some importance in the ecology of the gastrointestinal tract and in host physiology. It has been shown that nitrite, under the acidic conditions of the stomach, may kill gut pathogens like Salmonella enteritidis, Escherichia coli, Salmonella typhimurium, and Yersinia enterocolitica, whereas acid alone has only a bacteriostatic effect. An in vivo study was conducted in order to assess the effects of dietary nitrate on microbiota and on the health of the gut (particularly in the stomach and small intestine). 96 weaning pigs were fed a diet containing high nitrate levels (15 mg and 150 mg) and then challenged with Salmonella enterica serovar typhimurium. Differences in composition of the gut microbiota were assessed by analysing samples from the pigs: To date analysis of 48 pigs has been completed.. Preliminary results demonstrated no effect on the population densities of microbial groups either from the challenge or from nitrate intake. However, increasing the time from challenge decreased either the counts of LAB in the stomach and jejunum or of clostridia in the stomach. Bifidobacteria also decreased in the stomach contents as nitrate supplementation increased. Supplementing the feedstuff with high dietary nitrate intake and then challenging with Salmonella did not affect the gastric pH or the degree of ulceration in the pigs. The synergistic bactericidal effects of pH, nitrite and thiocyanate on seven probiotic Bifidobacterium spp. strains were also investigated in an in vitro study. The results of the in vitro study demonstrated that an inhibitory effect exists on the seven probiotic bifidobacteria investigated with an exposure longer than 2 hours and pH values < 5.0. Addition of thiocyanate also increased the susceptibility of the tested strains. In this in vitro study, the most resistant strains at all conditions were B. animalis subsp. lactis Ra 18 and P32 and B. choerinum Su 877, Su 837 and Su 891