The use of lower crude protein (CP) diets immediately after weaning has long been associated with reduced post-weaning diarrhoea (PWD). However, failing to maintain an appropriate standardized ileal digestible lysine ratio (SID: Lys) may outweigh the benefits in improving PWD outcomes. In this experiment, 560 weaners were fed either a control diet (CON; 20.6% crude protein 1.34% standardized ileal digestible lysine, SID Lys: CP = 0.06), LH: a low crude protein, higher SID Lys: CP ratio diet (19.0% CP, 1.34% SID Lys, SID Lys: CP = 0.07), or LL: a low crude protein control SID Lys: CP ratio diet (18.7% CP, 1.1% SID Lys, SID Lys: CP = 0.05) for 1 week after weaning. Pigs were scored for the presence or absence of diarrhoea for 12 days after weaning. Blood samples were taken on days 5, 12 and 28 for inflammatory marker analyses and plasma creatinine analyses. Relative to the CON diet, there was a 42% reduction in the diarrhoea index in pigs fed the LH diet and a 63% reduction in those fed the LL diet (p < 0.05), but LH was significantly higher than LL. There tended to be a greater average daily gain in the LH diet in the first week post-wean (p = 0.054). In summary, lower crude protein diets, irrespective of Lys: CP ratio, were found to be effective at reducing PWD. Moreover, increasing the SID Lys: CP ratio by reducing the CP content of diets from 20.6 to 19% appeared to improve post-weaning growth.

Post-weaning diarrhea (PWD) remains a major problem for some pork producers, exacerbated by restrictions or bans on the use of antimicrobial compounds. Acetylated high-amylose maize starch (HAMSA) delivers acetate to the large bowel and may reduce the severity of enteric infections, including those caused by Escherichia coli (E. coli). This study examined the effects of HAMSA and zinc oxide (ZnO) supplementation on PWD and performance in pigs experimentally inoculated with an F4 enterotoxigenic strain of E. coli (F4-ETEC). Seventy-two weaned pigs were divided into three dietary groups: 1) control (no antimicrobial compounds); 2) control plus 3,000 mg ZnO/kg; and 3) control plus 50 g HAMSA/kg. Pigs commenced diets on the day of weaning, were inoculated with an F4-ETEC strain on days 5 and 6, and were fed diets ad libitum for 21 days. The incidence of PWD (χ2 = 0.035) and the diarrhea index (P = 0.032) were both lowest, commensurate with a lower plasma haptoglobin concentration (P = 0.010), in pigs fed ZnO than pigs fed other diets, despite there being a trend for an interaction (P = 0.088) in pigs fed HAMSA to have a lower F4 E. coli:total E. coli ratio on d 11 after weaning. Pigs fed ZnO and HAMSA grew faster (P = 0.009) and ate more (P = 0.048) in week 3 than control pigs. Overall, there was a trend (P = 0.065) for pigs fed the ZnO diet or HAMSA diet to eat ~ 20% more than those fed the control diet that resulted in a trend (P = 0.064) for ZnO- and HAMSA-fed pigs to weigh ~ 10% more than control-fed pigs at the end of the study. The HAMSA-fed pigs had a lower (P = 0.044) FCR in week 3, and overall (P = 0.003). Pigs fed HAMSA did not show any increase (P > 0.05) in their fecal short-chain fatty acid or acetate concentrations. The significant effect of HAMSA on FCR justifies further investigation as this may improve production efficiency in the post-weaning period following an enteric F4-ETEC infection.

This experiment examined whether multiparous sows fed a diet lower in energy and lysine at a reduced feed allowance would still mobilise fat and (or) protein to support piglet growth and negatively impact subsequent reproductive performance. A total of 152 multiparous sows was allocated in a 2 × 2 factorial design with the respective factors being diet type fed in lactation (gestation, 13.0 MJ digestible energy (DE)/kg, 0.42 g standardised ileal digestible (SID) lysine/MJ DE; or lactation, 14.3 MJ DE/kg, 0.62 g SID lysine/MJ DE) and feed allowance (ad libitum or 7.5 kg/d, ~15% reduction on ad libitum intake). Body composition was estimated on the day after farrowing (day 2) and at weaning (day 21). Blood was collected on days 2, 21 and at standing heat, for the analysis of insulin and insulin-like growth factor 1 (IGF-1). Diet type did not alter (p > 0.05) bodyweight or P2 backfat depth change in lactation, estimated body fat and protein changes, litter growth, or subsequent total piglets born. Ad libitum-fed sows showed a significant gain in girth compared to sows offered 7.5 kg/d (2.9 versus −0.4 mm, p = 0.015) and had a tendency for a shorter wean-to-service interval (p < 0.10). Sows fed the lactation diet had higher insulin concentrations at weaning (p < 0.05), but levels were the same (p > 0.10) by heat detection; IGF-1 concentrations remained unaffected. These data indicate that imposing a calculated negative energy and lysine balance on lactating sows had a limited impact on lactation or subsequent reproductive performance, supporting the notion that the modern sow may be more resilient to nutritional impositions than has been historically reported.

Piglets have a high requirement for iron due to their rapid growth rates and low body iron stores; moreover, intensive production conditions restrict access to environmental sources of iron, such as soil. The low iron content of sow colostrum and milk, combined with the partitioning of limited nutrients among many piglets in a litter, results in inadequate piglet iron intake, predisposing them to iron-deficient anemia (IDA) during lactation and weaning. Prevalent IDA results in reduced post-weaning growth and reduced hemoglobin (Hb) concentrations. To combat this, indoor-reared piglets are given an injectable iron supplement shortly after birth to maintain body iron stores until weaning, when feed containing dietary iron is consumed. Due to continued selection for growth rates and litter sizes, this single injection is now considered inadequate to meet iron requirements. It was hypothesized that an additional iron injection, irrespective of timing, would improve Hb concentrations and growth performance, with a day 7 injection resulting in higher Hb and growth at weaning and a weaning injection increasing Hb and performance in pigs later in the nursery period. A total of 440 mixed sex pigs were used in this experiment in three treatment groups: control: only receiving iron dextran two days after birth; day 7: receiving iron injections at days two and seven after birth; Weaning iron: receiving iron dextran injections on day two and at weaning (20.1 days). Hb concentrations were significantly (P < 0.001) improved in the day 7 treatment for 18 days after weaning. Pigs in the control and weaning iron groups had a treatment mean of 9.9 g/dL ± 0.32 and 9.7 g/dL ± 0.32, respectively, indicating sub-clinical anemia, compared to the day 7 group with a treatment mean of 12.2 g/dL ± 0.32, indicating healthy Hb concentrations. Average daily gain tended (P = 0.08) to be higher in the weaning iron treatment group during the second week of the experiment compared to the control and day 7 groups. Pig removals were also significantly (P < 0.001) reduced in the weaning treatment group. Plasma hepcidin anti-microbial peptide, was elevated in the weaning iron group after injection, possibly impairing enteric iron absorption. An additional injection at weaning showed potential for improved growth in the post-weaning period and has practical advantages for producers.

Progeny born to primiparous sows (gilt progeny; GP) have lower birth, weaning and slaughter weights than sow progeny (SP). GP also have reduced gastrointestinal tract (GIT) development, as evidenced by lower organ weights. Therefore, the aim of this experiment was to quantify changes in GIT barrier function that occur in birth and weaning, representing two major challenges to the young piglet. The effects of parity (GP vs. SP) in GIT barrier integrity function were quantified at four timepoints: birth (~0 h), 24 h after birth (24 h), 1-d preweaning (PrW), and 1-d postweaning (PoW) in commercially reared piglets. Due to inherent differences between newborn and weanling pigs, the results were analyzed in two cohorts, birth (0 vs. 24 h, n = 31) and weaning (PrW vs. PoW, n = 40). Samples of the stomach, jejunum, ileum, and colon were excised after euthanasia and barrier integrity was quantified by measuring transepithelial resistance (TER), macromolecular permeability, the abundance of inflammatory proteins (IL-8, IL-1β, and TNF-α) and tight junction proteins (claudin-2 and -3). Papp was characterized using a dual tracer approach comprising 4 KDa fluorescein isothiocyanate (FD4) and 150 kDa tetramethyl rhodamine isothiocyanate (T150)-labeled dextrans. Characteristic effects of the initiation of feeding and weaning were observed on the GIT with the initiation of feeding, such as increasing TER and reducing Papp at 24 h, consistent with mucosal growth (P = 0.058) This was accompanied by increased cytokine abundance as evidenced by elevations in TNF-α and IL-1β. However, GP had increased IL-8 abundance (P = 0.011 and 0.063 for jejunum and ileum respectively) at birth than 24 h overall. In the weaning cohort, jejunal and ileal permeability to FD4 was higher in GP (P = 0.05 and 0.022, respectively) while only higher ileal T150 was observed in GP (P = 0.032). Ileal claudin-2 abundance tended to be higher in SP overall (P = 0.063), but GP ileal claudin-2 expression was upregulated weaning while no change was observed in SP (P = 0.043). Finally, other than a higher jejunal TNF-α abundance observed in SP (P = 0.016), no other effect of parity was observed on inflammatory markers in the weaning cohort. The results from this study indicate that the GIT of GP have poorer adaptation to early life events, with the response to weaning, being more challenging which is likely to contribute to poorer postweaning growth.

Tail biting (TB) in pigs is a complex issue that can be caused by multiple factors, making it difficult to determine the exact etiology on a case-by-case basis. As such, it is often difficult to pinpoint the reason, or set of reasons, for TB events, Decision Support Tools (DSTs) can be used to identify possible risk factors of TB on farms and provide suitable courses of action. The aim of this review was to identify DSTs that could be used to predict the risk of TB behavior. Additionally, technologies that can be used to support DSTs, with monitoring and tracking the prevalence of TB behaviors, are reviewed. Using the PRISMA methodology to identify sources, the applied selection process found nine DSTs related to TB in pigs. All support tools relied on secondary information, either by way of the scientific literature or expert opinions, to determine risk factors for TB predictions. Only one DST was validated by external sources, seven were self-assessed by original developers, and one presented no evidence of validation. This analysis better understands the limitations of DSTs and highlights an opportunity for the development of DSTs that rely on objective data derived from the environment, animals, and humans simultaneously to predict TB risks. Moreover, an opportunity exists for the incorporation of monitoring technologies for TB detection into a DST.

Forty LW × L pigs (20 boars and 20 gilts) (51.1 ± 0.41 kg) were allocated to a 2 × 2 × 2 factorial design with the respective factors being supplemental organic iron (Fe, 0 and 500 mg/kg), inulin (In, 0 and 50 g/kg) and sex (boars and gilts). After 5 weeks the animals were transported to an abattoir before slaughter and collection of samples. Serum iron was increased by supplemental Fe (28.4 v. 30.9 μmol/L, P = 0.05), although there was an interaction (P = 0.03) such that pigs fed diets with In had lower serum Fe concentrations than those without In (26.8 v. 32.3 μmol/L). Boars had lower (P < 0.01) haemoglobin (116 vs 125), haematocrit (36.7 v. 39.7%) and erythrocyte (6.6 v. 7.1 × 106/mL) concentrations than gilts. Dietary In increased liveweight gain (795 v. 869 g/d, P < 0.02) and carcass weight (62.9 v. 65.2 kg, P < 0.02). Dietary Fe or In supplementation did not improve muscle Longissimus thoracis et lumborum (LTL) total Fe concentration (P > 0.05). Muscle non-heme Fe concentration was higher in Fe-supplemented pigs (P < 0.04) and gilts (P < 0.05) than their counterparts. Muscle heme Fe concentration was greater (3.04 vs 2.51, P < 0.05) in boars than in gilts. The LTL marbling score was greater (P < 0.01) for In-supplemented pigs, and the response was more notable when Fe and In were fed together. These data show that dietary supplementation of Fe increased serum Fe and muscle non-heme Fe concentrations. Supplementation of In at 5% in the diet of finisher pigs improved liveweight gain and the marbling score of pork.

Different cereal types, in combination with different protein sources, are fed to pigs after weaning, but their interactions and possible implications are not well researched. In this study, 84 male weaned piglets were used in a 21-day feeding trial to investigate the effects of feeding either medium-grain or long-grain extruded rice or wheat, in a factorial combination with protein sources of either vegetable or animal origin, on postweaning performance, shedding of β-haemolytic Escherichia coli, and the coefficient of total tract apparent digestibility (CTTAD). Pigs fed either rice type performed the same (p > 0.05) as wheat-fed pigs after weaning. The use of vegetable protein sources reduced growth rate (p < 0.001) and feed intake (p = 0.007) and deteriorated the feed conversion ratio (p = 0.028) in weeks two and three compared to pigs fed animal protein sources. The number of antibiotic treatments given for clinical diarrhoea was similar (p > 0.05). However, the faecal E. coli score showed a trend for the main effect of protein source, with pigs fed animal proteins showing a higher E. coli score than pigs fed vegetable proteins (0.63 vs. 0.43, p = 0.057). There was also a tendency for an interaction (p = 0.069) between cereal type and protein source (p = 0.069), with this difference being associated with a greater faecal score in pigs fed diets with long-grain rice plus animal proteins and wheat plus animal proteins. Significant interactions occurred for the CTTAD when assessed in week three. In general, pigs fed diets with medium-grain rice or long-grain rice with animal proteins had a higher (p < 0.001) CTTAD for dietary components than pigs fed all other diets, and vegetable proteins depressed (p < 0.001) CTTAD compared to animal proteins (main effect of protein: p < 0.001). In summary, pigs tolerated the extruded rice-based diets well and performed equivalently to pigs fed wheat as the sole cereal, and the use of vegetable proteins decreased the E. coli score.

Current interventions targeting antimicrobial resistance (AMR), a major impact on commercial pork production, focus on reducing the emergence of AMR by minimising antimicrobial usage through antimicrobial stewardship and a range of alternative control methods. Although these strategies require continued advancement, strategies that directly aim to reduce or eliminate existing antimicrobial resistant bacteria, specifically bacteria resistant to critically important antimicrobials (CIAs), need to be investigated and established. This study established an in vivo model for examining the effects of postbiotics, in the form of Lactobacillus acidophilus fermentation products (LFP) and Saccharomyces cerevisiae fermentation products (SFP), on the shedding of extended-spectrum cephalosporin (ESC)-resistant E. coli. The model was successful in demonstrating the presence of ESC-resistant E. coli as evidenced by its detection in 62 of 64 pigs. There was a strong trend (p = 0.065) for the SFP postbiotics to reduce the shedding of ESC-resistant E. coli, indicating positive impacts of this additive on reducing the carriage of bacteria resistant to CIAs. Overall, this in vivo model enables future evaluation of strategies targeting ESC-resistant E. coli while increasing our knowledge on the carriage of ESC-resistant E. coli in pigs.

The weaning of pigs in most commercial pork production systems is an abrupt event performed at a fairly young age, i.e., mostly between 2.5 and 5 weeks of age. This practice induces a stress response, and its impact on behavior, performance and the gastrointestinal tract has been well described. Historically, there has been a focus on pre- and post-weaning nutritional strategies and post-weaning housing conditions and medication to improve production and reduce mortality after weaning. However, alternative pre-weaning housing and management systems that promote the development of natural social behaviors of piglets before weaning have recently received more attention. Co-mingling of non-littermates before weaning is a strategy that aims to initiate social interactions prior to weaning. The separation of the litter from the sow in the period leading up to weaning, termed intermittent suckling, aims to enhance the gradual separation from the sow. In addition, these practices encourage the young pig to learn explorative nutrient sourcing. Altogether, they may reduce weaning-associated stress. In this review, these strategies are defined, and their effects on behavior, performance, mortality, gastrointestinal function and immunocompetence are described. Though these strategies may be adapted to a commercial setting, it also becomes clear that many factors can contribute to the success of these strategies.

A major priority for the swine industry is the need to successfully transition and then manage the young pig in the period after weaning. Antimicrobial compounds have traditionally been used to assist with this transition. However, bans and restrictions on some antimicrobial compounds and antimicrobial resistance have required different strategies to ensure that the gastrointestinal tract (GIT) can function as effectively and efficiently as possible after weaning. It is well recognized that the protein content and composition of diets offered to pigs following weaning affects GIT structure and function, with the feeding of crude protein diets generally related to looser stools, an increased incidence of post-weaning diarrhea, and more antibiotic treatments. Feeding lower protein diets generally show opposing effects. There are numerous proteinaceous dietary raw materials available for use in post-weaning diets to assist with overcoming post-weaning GIT dysfunction. In this context, feeding highly digestible protein supplements reduces the availability of protein for microbial fermentation in the distal regions of the GIT, which in turn can modulate the microbiota. Blood plasma, e.g., spray-dried porcine plasma, positively influences GIT structure and function, as do spray-dried intestinal hydrolysates. Soy protein hydrolysates from fermentation or enzyme treatment that reduce the contents of anti-nutritional factors also confer production and GIT benefits in the nursery. Some peptides are known to have biological functions beyond their nutritional value and possess antimicrobial, antioxidant, and immunomodulatory activities. The use of such compounds in diets in the nursery warrants further investigation. Practically, the incorporation and use of protein supplements is just one facet in dealing with post-weaning challenges, and needs to be considered holistically with other targeted nutritional and health measures.

Sow body composition largely reflects the amount of lean and fat tissue stores in the body, and is measured, managed and reported because traditionally when sows mobilise body tissues in lactation to support piglet growth, adverse consequences in subsequent reproduction may be observed. These consequences are largely driven by metabolic changes exerting negative influences on the reproductive axes through luteinising hormone and follicle stimulating hormone and direct impact on the ovary. This results in sows that take longer to ovulate, have lower ovulation rates and shed poorer-quality oocytes, translating to delayed wean to service intervals, higher pregnancy failure and lower litter sizes. Sow management needs to meet both the needs of the piglet (adequate colostrum and milk intake for survival and growth) and the needs of the sow (successful re-breeding). The way pork producers tackle this is through diets designed to match sow requirements at different production stages. We have recently observed, despite efforts (nutritional challenges), that we are unable to induce fat or lean tissue mobilisation in lactating sows, which is a novel finding, although pig populations such as in the EU, UK and USA would appear to be experiencing similar outcomes. Despite our lower reproductive performance than in much of the rest of the world as a consequence of having a closed genetic herd, the specific genetic selection programs that exist within Australia, and the resultant leaner, more efficient sows, may be a potential explanation. This, coupled with the high lactation feed intakes now commonly reported, means that sows are less likely to become catabolic and so suffer from poor re-breeding outcomes. A conclusion from these findings may mean that we now have an opportunity to feed the lactating sow to better meet the growth and survival needs of piglets, with the knowledge that we will not compromise subsequent reproduction.