The effect of weaner diet protein content and diet quality on the long-term performance of pigs to slaughter

Review on Preventive Measures to Reduce Post-Weaning Diarrhoea in Piglets

In many countries, medical levels of zinc (typically as zinc oxide) are added to piglet diets in the first two weeks post-weaning to prevent the development of post-weaning diarrhoea (PWD). However, high levels of zinc constitute an environmental polluting agent, and may contribute to the development and/or maintenance of antimicrobial resistance (AMR) among bacteria. Consequently, the EU banned administering medical levels of zinc in pig diets as of June 2022. However, this may result in an increased use of antibiotic therapeutics to combat PWD and thereby an increased risk of further AMR development. The search for alternative measures against PWD with a minimum use of antibiotics and in the absence of medical levels of zinc has therefore been intensified over recent years, and feed-related measures, including feed ingredients, feed additives, and feeding strategies, are being intensively investigated. Furthermore, management strategies have been developed and are undoubtedly relevant; however, these will not be addressed in this review. Here, feed measures (and vaccines) are addressed, these being probiotics, prebiotics, synbiotics, postbiotics, proteobiotics, plants and plant extracts (in particular essential oils and tannins), macroalgae (particularly macroalgae-derived polysaccharides), dietary fibre, antimicrobial peptides, specific amino acids, dietary fatty acids, milk replacers, milk components, creep feed, vaccines, bacteriophages, and single-domain antibodies (nanobodies). The list covers measures with a rather long history and others that require significant development before their eventual use can be extended. To assess the potential of feed-related measures in combating PWD, the literature reviewed here has focused on studies reporting parameters of PWD (i.e., faeces score and/or faeces dry matter content during the first two weeks post-weaning). Although the impact on PWD (or related parameters) of the investigated measures may often be inconsistent, many studies do report positive effects. However, several studies have shown that control pigs do not suffer from diarrhoea, making it difficult to evaluate the biological and practical relevance of these improvements. From the reviewed literature, it is not possible to rank the efficacy of the various measures, and the efficacy most probably depends on a range of factors related to animal genetics and health status, additive doses used, composition of the feed, etc. We conclude that a combination of various measures is probably most recommendable in most situations. However, in this respect, it should be considered that combining strategies may lead to additive (e.g., synbiotics), synergistic (e.g., plant materials), or antagonistic (e.g., algae compounds) effects, requiring detailed knowledge on the modes of action in order to design effective strategies.

A flexible tool for the assessment of the economic cost of pig disease in growers and finishers at farm level

Pigmeat is the most consumed red meat globally and consumption is expected to continue to increase. The sector is faced by the risk of epidemic and endemic disease impacts and other adverse influences. The aim of this study was to develop a dynamic simulation model of pig growing and finishing that can be used to model the financial and economic impacts of a variety of scenarios both related to disease effects and other influences on production. The model consists of a physical performance module and financial performance module. The core of the physical performance module comprises three stocks to model the flow of pigs from purchase to slaughter. Mortality rates, daily live weight gain and feed conversion ratios influence the dynamics of the physical performance. Since contracts between farmers and slaughterhouses often include large price penalties for over- and underweight pigs, carcase weight distribution is an important determinant of revenues. The physical performance module, therefore, simulates slaughter weight variations. The financial performance module calculates revenue, costs and gross margins. The revenue calculations take into account price penalties for over- and underweight pigs. To demonstrate the capabilities of the model, we apply the model to assess the economic consequences of production impacts associated with respiratory disease. We use estimated production impacts associated with respiratory disease from a study of all-in-all out growing and finishing systems based on pig production data and information from slaughterhouse monitoring in the UK. Our model suggests a reduction in the gross margin of nearly 40 % as a consequence of the estimated production impacts associated with a 10% increase in respiratory disease prevalence. Due to the lack of reliable information on slaughter weight variation, we also simulate the model using different assumptions about the slaughter weight distribution. An increase in the standard deviation of carcase weights from 8 kg to 12 kg, holding average weights constant, more than halves gross margins under our scenarios. We suggest that for all-in-all-out systems, carcase weight variation is likely to be a substantial factor in reducing income in the presence of respiratory disease and the economic impact of respiratory disease may be underestimated if the effects of disease on variation in carcase weights are not included in any analysis.

Low Protein Diet Improves Meat Quality and Modulates the Composition of Gut Microbiota in Finishing Pigs

This study investigated the effect of a low protein (LP) diet on growth performance, nitrogen emission, carcass traits, meat quality, and gut microbiota in finishing pigs. Fifty-four barrows (Duroc × Landrace × Yorkshire) were randomly assigned to three treatments with six replicates (pens) of three pigs each. The pigs were fed with either high protein (HP, 16% CP), medium protein (MP, 12% CP), and LP diets (10% CP), respectively. The LP diets did not influence the growth performance, but significantly decreased the plasma urea nitrogen contents and fecal nitrogen emission (P < 0.05). The LP diet significantly decreased the plasma contents of malondialdehyde (MDA) and increased the plasma glutathione (GSH) contents (P < 0.05). The LP diets significantly increased the backfat thickness at the first and last ribs, L^* (lightness) value of meat color, and muscle fiber density in the longissimus dorsi (P < 0.05). The messenger RNA (mRNA) expression of fatty acid synthetase (FAS), peroxisome proliferator-activated receptor-gamma (PPARγ), leptin, and acetyl-CoA carboxylase (ACC) was significantly downregulated, while that of carnitine palmitoyltransferase 1 (CPT1) and myosin heavy chain (MYHC) IIx in the longissimus Dorsi muscle was significantly upregulated by LP diets (P < 0.05). The 16S sequencing analysis showed that the abundance of unidentified Bacteria at the phylum level, and Halanaerobium and Butyricicoccusat at the genus level in the colonic digesta were significantly decreased by LP diet (P < 0.05). The LP diet significantly decreased the observed species of α-diversity in both ileal and colonic microbiota (P < 0.05). Spearman correlation analysis identified a significant positive correlation between the abundance of the ileal genera Streptococcus and L^* value at 24 and 48 h, and a significant negative correlation between unidentified_Ruminococcasceae in both ileum and colon with L^* value at 24 h (P < 0.05). Collectively, the LP diet supplemented with lysine, methionine, threonine, and tryptophan could reduce the fecal nitrogen emission without affecting growth performance and improve meat quality by regulating the antioxidant capacity and gene expression involved in fat metabolism as well as modulating the gut microbiota composition in finishing pigs.

Temporary lysine restriction in newly weaned pigs does not affect carcass and loin quality at slaughter

Two hundred and forty weaned pigs [initial body weight (BW) 7.2 ± 0.07 kg] were allocated to three diets (eight pens per treatment, 10 pigs per pen) to determine the effects of a temporary lysine (Lys) restriction on subsequent growth, body composition, as well as carcass and loin quality at slaughter. For a 3 wk restriction period, pigs were fed diets that were 110% (control), 20% (Lys20), or 40% (Lys40) below estimated Lys requirements. Thereafter, all pigs were fed a common grower diet containing 120% of the estimated Lys requirement for 6 wk (recovery period) and commercial diets until slaughter at ∼125 kg BW. During the restriction period, average daily gain, gain-to-feed ratio, and whole body protein deposition decreased (linear; P < 0.01), while whole body lipid deposition increased (linear; P < 0.001) with decreased dietary Lys concentrations. At the end of the recovery period, there were no differences in BW, although whole body protein concentration tended to decrease and lipid concentration tended to increase (linear; P = 0.07 and 0.06, respectively) with decreased dietary Lys concentrations. At ∼125 kg, there were no differences in BW, chemical composition, or carcass and loin quality. Compensatory growth was achieved by ∼125 kg BW after a 3 wk Lys restriction for newly weaned pigs without negatively impacting carcass and loin quality.

Weaning age and post-weaning nursery feeding regime are important in improving the performance of lightweight pigs

The aim was to investigate the effect of weaning age, weaning weight, and nursery feeding regime on post-weaning performance. The focus was on pigs weaned light, as they may be better off when weaned at a later age and/or offered a specialist nursery feeding regime. Piglets (n = 1,448) from one farrowing batch of 110 sows that farrowed over 2 wk were individually weighed and their morphometric measurements were taken at birth. Pigs were weaned on the same day, but variation in birth date resulted in variable weaning ages (mean age day 34.1, SD = 2.5). The youngest 50% at weaning were classified Y and the oldest 50% as O; within an age class, the lightest 50% were classified L, the heaviest 50% as H, and housed accordingly. Pigs were individually weighed at weaning, 7 and 15 wk post-weaning. At weaning, Y were 6 d younger and 1.4 kg lighter than O pigs, whereas L were 3.2 kg lighter than H pigs. Pigs were randomly allocated to a 3-stage superior (SUP) or control (CON) nursery feeding regime, with SUP pigs having a 65% greater allowance (on a kg/pig basis) of the first and second stage feeds than the CON. Pigs weaned Y had a higher mortality rate from weaning to 7 wk post-weaning than pigs weaned O (9.14% vs. 4.98%; P = 0.046). As expected, age and weight significantly (P < 0.001) affected performance to both 7 and 15 wk post-weaning: at 15-wk pigs weaned Y were 5.5 kg lighter than pigs weaned O; pigs weaned L were 9.0 kg lighter than H pigs. It was estimated that pigs weaned YL needed ~4 d more (P = 0.018) to reach 60 kg BW than pigs weaned OL. Feed intake was not affected by feeding regime, age and weight, or their interactions. Performance was not affected by feeding regime (P > 0.05), but was affected by the weight × feeding regime interaction (P = 0.044) to 7 wk post-weaning: L pigs on SUP were 1.2 kg heavier than L pigs on the CON regime; this was not the case for the H pigs. Performance up to 7 wk post-weaning was positively associated with birth weight to cranial circumference ratio and weaning weight (P < 0.05) for both YL and OL pigs; for the latter, additional performance predictors were weaning age (P = 0.044) and feeding (P = 0.027). Improved growth for L pigs up to 7 wk post-weaning could be obtained by a greater allowance of the nursery diets. However, weaning at a later age benefitted the performance of L pigs to a common BW, suggesting that this might be a strategy with longer term benefits.

Changes in the Ileal, but Not Fecal, Microbiome in Response to Increased Dietary Protein Level and Enterotoxigenic Escherichia coli Exposure in Pigs

Gut bacterial communities have been shown to play a key role in pig health and development and are strongly influenced by host diet, but studies highlighting the complex interactions between nutrition, gut infections and the microbiome tend to focus on bacterial populations in the feces and not other important gut locations. We found that alteration of dietary protein level and exposure to a pathogenic microorganism, enterotoxigenic Escherichia coli (ETEC), changed bacterial populations in the distal small intestine (i.e., the ileum). We found that the most profound changes occurred in pigs fed a high-protein diet in combination with exposure to ETEC, showing a clear interaction between dietary composition and exposure to a key pathogen. These changes were not observed in the fecal samples, revealing the importance of studying biologically pertinent sites in the gut, and so the data will help to inform the development of alternative management strategies for enteric disorders.

The relationship between porcine gut microbiota composition and health is an important area of research, especially due to the need to find alternatives to antimicrobial use to manage disease in livestock production systems. Previous work has indicated that lower crude dietary protein levels can reduce the impacts of postweaning colibacillosis, which is a porcine diarrheal disease caused by enterotoxigenic Escherichia coli (ETEC). Here, to explore the complex interactions between the gut microbiota, protein nutrition, and ETEC exposure, the microbial compositions of both ileal digesta and feces were analyzed with or without ETEC exposure from pigs fed a low- or high-protein diet. Since ETEC colonization is mostly localized to the ileum, changes in the small intestinal microbiota were expected in response to ETEC exposure. This was supported by the study findings, which identified significant microbiota changes in ileal samples but not in fecal samples. Both increased dietary protein and ETEC exposure impacted on ileal microbiota alpha diversity (richness and diversity indices) and beta diversity (structure, stability, and relative taxon abundances) at certain sampling points, although the combination of a high-protein diet and ETEC exposure had the most profound impact on ileal microbiota composition. An understanding of how infection and nutrition lead to microbiota changes is likely to be required if dietary strategies are to be developed for the management of enteric diseases.

IMPORTANCE Gut bacterial communities have been shown to play a key role in pig health and development and are strongly influenced by host diet, but studies highlighting the complex interactions between nutrition, gut infections and the microbiome tend to focus on bacterial populations in the feces and not other important gut locations. We found that alteration of dietary protein level and exposure to a pathogenic microorganism, enterotoxigenic Escherichia coli (ETEC), changed bacterial populations in the distal small intestine (i.e., the ileum). We found that the most profound changes occurred in pigs fed a high-protein diet in combination with exposure to ETEC, showing a clear interaction between dietary composition and exposure to a key pathogen. These changes were not observed in the fecal samples, revealing the importance of studying biologically pertinent sites in the gut, and so the data will help to inform the development of alternative management strategies for enteric disorders.

Gut Health of Pigs: Challenge Models and Response Criteria with a Critical Analysis of the Effectiveness of Selected Feed Additives - A Review

The gut is the largest organ that helps with the immune function. Gut health, especially in young pigs has a significant benefit to health and performance. In an attempt to maintain and enhance intestinal health in pigs and improve productivity in the absence of in-feed antibiotics, researchers have evaluated a wide range of feed additives. Some of these additives such as zinc oxide, copper sulphate, egg yolk antibodies, mannan-oligosaccharides and spray dried porcine plasma and their effectiveness are discussed in this review. One approach to evaluate the effectiveness of these additives in vivo is to use an appropriate disease challenge model. Over the years, researchers have used a number of challenge models which include the use of specific strains of enterotoxigenic Escherichia coli, bacteria lipopolysaccharide challenge, oral challenge with Salmonella enteric serotype Typhimurium, sanitation challenge, and Lawsonia intercellularis challenge. These challenge models together with the criteria used to evaluate the responses of the animals to them are also discussed in this review.

Animal and management factors influencing grower and finisher pig performance and efficiency in European systems: a meta-analysis

A meta-analysis on the effects of management and animal-based factors on the performance and feed efficiency of growing pigs can provide information on single factor and interaction effects absent in individual studies. This study analysed the effects of such factors on average daily gain (ADG), feed intake (FI) and feed conversion ratio (FCR) of grower and finisher pigs. The multivariate models identified significant effects of: (1) bedding (P<0.01), stage of growth (P<0.001) and the interaction bedding×lysine (P<0.001) on ADG. ADG was higher on straw compared with no bedding (710 v. 605 g/day). (2) FI was significantly affected by stage of growth (P<0.01), bedding (P<0.01), group composition (P<0.05), group size (P<0.01), feed CP content (P<0.01), ambient temperature (P<0.01) and the interaction between floor space and feed energy content (P<0.001). Pigs housed on straw had a lower FI in comparison with those without (1.44 v. 2.04 kg/day); a higher FI was seen for pigs separated by gender in comparison with mixed groups (2.05 v. 1.65 kg/day); FI had a negative linear relationship with group size, the CP content of the feed and ambient temperature. (3) Stage of growth (P<0.001), feed CP (P<0.001) and lysine content (P<0.001), ambient temperature (P<0.001) and feed crude fibre (CF) content (P<0.01) significantly affected FCR; there were no significant interactions between any factors on this trait. There was an improvement in FCR at higher ambient temperatures, increased feed CP and lysine content, but a deterioration of FCR at higher CF contents. For ADG, the interaction of bedding×lysine was caused by pigs housed without bedding (straw) having higher ADG when on a feed lower in lysine, whereas those with bedding had a higher ADG when on a feed higher in lysine. Interaction effects on FI were caused by animals with the least amount of floor space having a higher FI when given a feed with a low metabolisable energy (ME) content, in contrast to all other pigs, which showed a higher FI with increased ME content. The meta-analysis confirmed the significant effect of several well-known factors on the performance and efficiency of grower and finisher pigs, the effects of some less established ones and, importantly, the interactions between such factors.

High specification starter diets improve the performance of low birth weight pigs to 10 weeks of age

Piglets born with low birth weights (LBiW) are likely to be lighter at weaning. Starter regimes tailored for pigs of average BW therefore may not be optimal for LBiW nursery performance. The objective was to determine if LBiW pigs benefit from a high specification starter regime and the provision of extra feed (additional allowance of last phase diet of the starter regime) in comparison to a standard commercial regime. Additionally, the effect of starter regime on performance of normal birth weight (NBiW) pigs at weaning was determined and compared to that of LBiW pigs. Finally, the cost effectiveness of the treatments was determined. The experiment was therefore an incomplete 2 × 2 × 2 factorial design, as the provision of extra feed was given only to LBiW pigs (n = 6 replicates per treatment; 5 pigs per replicate). Treatments comprised birth weight (LBiW or NBiW), starter regime (high specification [HS] or standard starter [SS]), and extra feed 3 quantity (yes [YF] or no [NF], for LBiW pigs only; feed 3 corresponded to the last phase diet of the starter regime). At weaning (d 28), pigs were randomly assigned within each birth weight category to treatment groups. Nutritional treatments were fed ad libitum on a kilogram/head basis for approximately 3 wk followed by a common weaner diet fed ad libitum until d 70. Starter regime (P = 0.019), feed 3 amount (P = 0.010), and their interaction (P = 0.029) had an effect on ADG of LBiW pigs from d 28 to 49, with pigs on HS followed by YF (HY) performing best. An improvement in feed conversion ratio (FCR) was noted between d 28 and 49 for pigs fed the additional feed 3 (P = 0.030); between d 49 and 70, the only residual effect seen was of starter regime (P = 0.017) on ADG. In contrast, there was no significant effect of starter regime from d 28 to 70 on ADG, ADFI, or FCR of NBiW pigs. By d 49 and 70, LBiW pigs on regime HY weighed the same as NBiW pigs (d 70 BW; 30.0 vs. 30.6 kg; P = 0.413), with similar growth rates from d 28 to 70 (0.570 vs. 0.533 kg/d; P = 0.137). Despite highest feed cost for regime HY at US$12.30 per pig, its margin over feed was greatest ($23.40). Conversely, regime SS gave the best margin over feed for NBiW pigs at $22.70 per pig. In conclusion, a postweaning feeding regime formulated for LBiW pigs improved the ADG and FCR to the end of the nursery phase enabling them to achieve the same weight as NBiW. Targeting the provision of the high quality expensive regime only to light pigs will ensure maximum growth and increased profitability.

Management strategies to improve the performance of low birth weight pigs to weaning and their long-term consequences

Performance of pigs from birth to slaughter is a result of a complex interaction of factors, with the early stages of a pig's life likely to affect lifetime performance. During the preweaning stage, piglets are reliant on the sow for nutrition, and sibling competition is likely to affect growth, in particular for low birth weight (LBiW) piglets. The objective of the experiment was to determine the effect of litter composition (littermate weight) and milk supplementation during lactation on the performance of LBiW pigs to weaning and the long-term consequences of treatment to slaughter. The experiment was a 2 × 2 factorial with littermate weight (normal or LBiW) and provision of supplementary milk from d 1 to 28 (yes or no) as factors. A total of 265 piglets were selected within 24 h of birth and cross-fostered to create 2 litter types (LOW = LBiW pigs [≤ 1.25 kg] only and MX = both LBiW and normal birth weight pigs [1.6 to 2.0 kg]); half of the litters within a type were supplemented with milk and the other half were not. The behavior of litters given milk was recorded to identify milk consumption patterns. Piglets were weaned at d 28 and kept in their litters until d 70 and then subsequently housed in mixed groups until slaughter. No difference was observed at any stage in the ADG of pigs given access to supplementary milk or not (P > 0.05) nor was there any significant interaction between milk provision and litter composition (P > 0.05). However, LOW litters drank significantly more supplementary milk than MX litters (P < 0.001). There was a significant effect of litter type on ADG from d 14 to 28, with LBiW pigs in LOW litters performing better than those in MX litters (0.252 versus 0.217 kg/d; P < 0.05). At weaning, LBiW piglets in LOW litters weighed over 500 g more than those in MX litters (P < 0.05). In MX litters there was a significant interaction between birth weight and supplementary milk on the CV of BW from d 14 to slaughter (P < 0.05). In conclusion, grouping LBiW piglets with similar sized littermates preweaning can improve preweaning performance by reducing competition from heavier littermates; however, this advantage does not persist after weaning. Although supplementary milk does not improve LBiW pig performance before or after weaning, it affects their drinking behavior and can reduce the variation in the BW of LBiW piglets in mixed litters to slaughter.