Feed preference in pigs: effect of selected protein, fat, and fiber sources at different inclusion rates

Porcine digestible peptides as alternative protein source in weaner diets: effects on performance and systemic cytokine profile in pigs followed from weaning to slaughter

Porcine digestible peptides (PDP) are high-quality hydrolysed proteins obtained from porcine intestinal mucosa as a by-product of the heparin manufacturing process. PDP contain bioactive peptides and are used as alternative protein sources in several animal species, including pigs. We aimed to explore the (carry-over) effects of feeding PDP to weaned piglets on performance and systemic cytokine levels of pigs followed until slaughter. A total of 192 piglets were allocated to one of two dietary treatments: control (CON) or PDP weaner diets. PDP was included at 5.0% until day 13 post-weaning at the expense of skimmed milk powder and partial replacement of soybean meal, and at 2.5% between days 13 and 34 post-weaning at the expense of soy protein concentrate. Grower-finishers were fed commercial diets according to a 3-phase feeding scheme until slaughter, when carcass traits were determined. Six pigs were housed per weaner pen and eight per grower-finisher pen with 16 and 10 pens per treatment, respectively. Pigs were weighed at the start and at the end of each phase, and feed intake was recorded. Faecal consistency was recorded twice a week in the weaner facility. Ten pigs per treatment were sampled for blood at days 13, 34 and 69 post-weaning. We found that PDP-fed piglets had a higher feed intake in the first two weeks post-weaning compared to CON-fed piglets (+32 g/pig per day; P = 0.02). Moreover, piglets in the PDP group showed improved feed conversion between days 13 and 34 versus the CON group (1.36 vs 1.43; P = 0.03). Piglets that were fed with PDP in the weaner diets tended to grow faster in the grower-finisher period (+32 g/pig per day; P = 0.07), tended to reach slaughter age earlier (129.9 vs 131.5 days; P = 0.07) and had a lower dressing percentage at slaughter (76.3 vs 76.7%, P = 0.045) than piglets previously fed with CON. Additionally, PDP-fed piglets showed higher serum levels of pro-inflammatory cytokines interleukin (IL)-12 (P = 0.02), tumour necrosis factor-alpha (P = 0.02), interferon-gamma (P = 0.03) and IL-8 (at day 34 post-weaning, P = 0.06) as well as anti-inflammatory cytokines transforming growth factor-beta (P = 0.02), IL-4 (P = 0.04) and IL-10 (at day 34 post-weaning, P = 0.02). No significant differences among dietary treatments were observed regarding faecal consistency of weaned piglets and carcass weight, lean meat percentage, muscle depth, and back fat thickness at slaughter. We conclude that feeding PDP, as an alternative to conventional milk and soy protein sources, showed positive effects on pig performance, not only during the provisioning period but also thereafter into the grower-finisher phase.

Productive Performance, Physiological Variables, and Carcass Quality of Finishing Pigs Supplemented with Ferulic Acid and Grape Pomace under Heat Stress Conditions

The effect of individual and combined supplementation of FA and GPM on physiological variables, productive performance, and carcass characteristics of finishing pigs under heat stress conditions were investigated. Forty Yorkshire × Duroc pigs (80.23 kg) were individually housed and randomly distributed into 4 groups under a 2 × 2 factorial arrangement (n = 10): Control (basal diet, BD); FA, BD + 25 mg FA; GPM, BD with 2.5% GPM; and MIX, BD with 25 mg FA and 2.5% GPM. Additives were supplemented for 31 days. The inclusion of FA or GPM did not modify rectal temperature and respiratory rate. There was an effect of the interaction on FI, which increased when only GPM was supplemented, with respect to Control and MIX (p < 0.05). Average daily gain (ADG) and feed conversion (FC) were not affected by treatments (p > 0.05). The inclusion of FA improved hot and cold carcass weight, while the addition of GPM decreased the marbling (p < 0.05) and tended to increase loin area (p < 0.10). GPM increased liver weight (p < 0.05). The addition of GPM and FA can improve some carcass characteristics under heat stress conditions. It is necessary to continue investigating different levels of inclusion of GPM and FA in finishing pigs' diets.

Management and Feeding Strategies in Early Life to Increase Piglet Performance and Welfare around Weaning: A Review

The performance of piglets in nurseries may vary depending on body weight, age at weaning, management, and pathogenic load in the pig facilities. The early events in a pig's life are very important and may have long lasting consequences, since growth lag involves a significant cost to the system due to reduced market weights and increased barn occupancy. The present review evidences that there are several strategies that can be used to improve the performance and welfare of pigs at weaning. A complex set of early management and dietary strategies have been explored in sows and suckling piglets for achieving optimum and efficient growth of piglets after weaning. The management strategies studied to improve development and animal welfare include: (1) improving sow housing during gestation, (2) reducing pain during farrowing, (3) facilitating an early and sufficient colostrum intake, (4) promoting an early social interaction between litters, and (5) providing complementary feed during lactation. Dietary strategies for sows and suckling piglets aim to: (1) enhance fetal growth (arginine, folate, betaine, vitamin B12, carnitine, chromium, and zinc), (2) increase colostrum and milk production (DL-methionine, DL-2-hydroxy-4-methylthiobutanoic acid, arginine, L-carnitine, tryptophan, valine, vitamin E, and phytogenic actives), (3) modulate sows' oxidative and inflammation status (polyunsaturated fatty acids, vitamin E, selenium, phytogenic actives, and spray dried plasma), (4) allow early microbial colonization (probiotics), or (5) supply conditionally essential nutrients (nucleotides, glutamate, glutamine, threonine, and tryptophan).

Degree of Saturation and Free Fatty Acid Content of Fats Determine Dietary Preferences in Laying Hens

Simple Summary

Understanding fat sensing in chickens has the potential to improve least cost feed formulation relevant to poultry feeds. Acid oils (soybean acid oil and palm fatty acid distillate) are economical and sustainable feedstuffs with similar fatty acid composition to crude oils (soybean oil and palm oil) but richer in free fatty acids. However, potential issues relevant to the palatability of these oils have been raised. Four experimental diets were offered in a series of double-choice tests to study the effect of free fatty acid content and the unsaturated:saturated ratio on dietary preferences in hens. Hens showed a feed preference for palm oil added diets over soybean oil diets, with palm oil and palm fatty acid distillate being equally preferred. However, the hens demonstrated a preference for soybean oil when offered in choice with soybean acid oil. In conclusion, free fatty acid content and saturation degree affected feed preferences in hens. The use of oils with greater preference values may give rise to greater feed palatability, enhancing feed intake at critical stages.

Abstract

Behavioural and genetic evidence shows that the taste system is intimately related to the sensing of nutrients with consequences for poultry nutrition practices. A better understanding of how chickens may sense fat could provide the background for selecting feedstuffs used in poultry feeds. Acid oils have the potential to be economical and sustainable feedstuffs. These fat by-products from the edible oil refining industry possess a similar fatty acid composition to the crude oils but are richer in free fatty acids (FFA). An experiment was conducted to study the effect of FFA content and the unsaturated:saturated ratio (U:S) on dietary preferences in hens. Four fat sources were added to a basal diet at an inclusion rate of 6%, determining the experimental diets: soybean oil (SO; high U:S, 5% FFA); soybean acid oil (SA; high U:S, 50% FFA); palm oil (PO; low U:S, 5% FFA); and palm fatty acid distillate (PFAD; low U:S, 50% FFA). The experimental diets were offered in a series of double-choice tests to forty-eight Lohmann Brown laying hens housed individually in cages. Each hen was offered the ten potential binary combinations of the four diets including each diet compared to itself (referred to as four control double-choices). Feed intake was measured for two hours twice a day after one hour of fasting. Consumption was analysed as a standard preference index (% of test diet intake in comparison with the total intake). Preference values were compared to the random choice value of 50% using the Student’s t-test. None of the four control comparisons differ significantly from 50% (p > 0.05), indicating that the changes in preference values observed in the other binary comparisons were related to the dietary changes associated to fat ingredients. Hens showed a feed preference for palm oil added diets over soybean oil diets (p < 0.05), with PO and PFAD being equally preferred (p < 0.05). However, in this trial the hens demonstrated a preference for SO (low %FFA) when offered in choice with SA (high %FFA) (p < 0.05). These results suggest that the degree of saturation plays an important role in dietary fat preferences: hens prefer predominantly saturated oils even when these are rich in FFA. Furthermore, when presented with a choice between predominantly unsaturated oils, hens prefer feed with a low %FFA. In conclusion, %FFA and the U:S ratio affected feed preferences in hens. The use of oils with greater preference values may give rise to greater feed palatability, enhancing feed intake at critical stages.

Porcine Digestible Peptides (PDP) in Weanling Diets Regulates the Expression of Genes Involved in Gut Barrier Function, Immune Response and Nutrient Transport in Nursery Pigs

Simple Summary

Porcine digestive peptides (PDP) are a coproduct of the heparin industry obtained from the enzymatic hydrolysis of porcine intestinal mucosa. They have proven to be a valid substitute for other high quality dietary protein sources for piglets, like spray-dried plasma (SDP), but knowledge about their influence on intestinal function is still scarce. This study found that substituting soybean ingredients with PDP and SDP to the diets of weaned piglets increased growth rate at 14 d post-weaning. In addition, the combination of PDP with SDP increased the expression of certain genes related to intestinal function in the jejunum, which suggests that this combination might have functional properties that contribute to improving the intestinal health of the pigs, although more research is needed to confirm it.

Abstract

This study was conducted to investigate the effects of dietary supplementation of porcine digestible peptides (PDP), spray-dried plasma (SDP), or a combination of both, on growth performance and the expression of genes related to intestinal function of weaned pigs. A total of 180 piglets (trial 1) and 198 piglets (trial 2) were used to evaluate the partial substitution of soybean ingredients with 2% SDP or 2% PDP (trial 1), and with 3% SDP or the combination of 1% SDP and 2% PDP (SDP-PDP; trial 2) during the pre-starter period (0–14 days). The gene expression of 56 genes was quantified in a qPCR platform in jejunum and ileum samples obtained from piglets 14 d after weaning (trial 2). Piglets fed SDP, PDP and SDP-PDP had a higher body weight (BW), average daily gain (ADG) and feed efficiency (G:F) than the soybean control on day 14 (p < 0.05). In addition, the combination of SDP and PDP upregulated ten genes in jejunum samples (p < 0.05) related to intestinal function. More research is needed to confirm that gene expression upregulation by PDP in combination with SDP has an impact on intestinal function and to elucidate its underlying mechanisms.

Acceptability, Preferences, and Palatability of Diets Containing Summer and Winter Brassica Forage in Growing Pigs: A Pilot Study

Simple Summary

The inclusion of fiber in pigs’ commercial diets may represent an opportunity to reduce feeding costs and benefit animals’ health and welfare. However, antinutritional factors that generate a bitter taste may reduce the voluntary intake of animals. The present experiments evaluated growing pigs’ feeding behavior for winter and summer brassicas, when incorporated on commercial diets as a replacement for wheat middlings. Experiment 1 studied the feeding behavior of pigs when summer turnip or forage rape were included into the diets, while experiment 2 studied the inclusion of kale and swede by replacing 15% of wheat middlings. No differences were found between diets that included brassicas and control diet in pigs’ acceptability or palatability. However, during preference tests of experiment 2 (winter brassicas), diet that incorporated swede presented a higher consumption than control diet and a diet that incorporated kale. This suggests that brassica forage may be incorporated in growing pigs’ diets without negative repercussions in animals’ oral perception during short term feeding tests.

Abstract

Brassica forage may be included in pigs’ diet as a dietary fiber ingredient to reduce feeding costs, benefit gut health, immune system, reproductive traits, and welfare. However, they contain antinutritional factors which may affect feeding behavior. This study evaluated feeding behavior of growing pigs offered winter (kale and swede) and summer (turnip and forage rape) brassicas incorporated on their diets as dried ground meal. Two consecutive experiments with six growing castrated male pigs were conducted. Experiment 1 evaluated the inclusion of turnip bulbs and forage rape, while experiment 2 studied inclusion of kale and swede bulbs. Brassica meal was included at 15% of the diet by replacing wheat middlings (control diet). In each experiment, pigs were offered experimental diets over six consecutive days for 10 min to test their acceptability (day 1–3) and preferences (day 4–6). No differences were found between diets that included brassicas and control diet in pigs’ acceptability or palatability (p > 0.05). However, during preference tests of winter brassicas, swede presented a higher consumption than control and kale (p < 0.05). This suggest that brassicas may be incorporated in growing pigs’ diets without negative effects in animals’ oral perception during short term feeding tests. Nevertheless, the long-term effects need to be explored.

Dietary Inclusion of Monosodium Glutamate in Gestating and Lactating Sows Modifies the Preference Thresholds and Sensory-Motivated Intake for Umami and Sweet Solutions in Post-Weaned Pigs

Simple Summary

Umami is an innately hedonic taste in pigs, which has been related to glutamic acid (i.e., monosodium glutamate (MSG)) and other dietary amino acids. We studied the inclusion of 5% MSG in gestating and lactating sow diets, with the objective of altering feeding behavior of the progeny. It was observed that the addition of MSG to maternal diets decreased the preference thresholds for umami and sweet tastants in the progeny, and increased sucrose sensory-motivated intake. In contrast, MSG supplementation decreased MSG-motivated intake and did not modify the total consumption and consumption patterns of pigs for these solutions. We concluded that MSG inclusion in maternal diets modifies feeding behavior in pigs in what appears to be a compensatory mechanism to balance the diet for basic nutrients.

Abstract

Pigs show an innate preference for umami (monosodium glutamate, MSG) taste. Nevertheless, the influence of a pre and postnatal umami exposure remains unclear. An experiment was conducted to test the hypothesis that MSG inclusion into maternal diets would modify the feeding behavior of post-weaning pigs. A total of 22 sows were selected on day 85 of gestation and randomly assigned to one of two gestating and lactating programs (standard commercial diets without or with 50 g/kg of MSG). Later, 208 pigs born from these sows were selected to evaluate their preference thresholds, sensory-motivated intake, total consumption, and consumption patterns for MSG and sucrose solutions. Pigs born from MSG-fed sows showed lower (p < 0.045) preference thresholds for MSG and sucrose than did animals born from control sows, and displayed an increased (p < 0.050) sensory-motivated intake for sucrose and decreased for MSG. Conversely, no differences (p > 0.05) were observed in the total consumption or consumption patterns of MSG or sucrose solutions among pigs born from control and MSG-fed sows. It is concluded that the feeding behavior of nursery pigs can be influenced by pre and postnatal inclusion of a taste active compound into maternal diets. It would appear that a compensatory mechanism to balance dietary nutrients might be in place.

Impact of a dietary challenge with peroxidized oil on the glutathione redox status and integrity of the small intestine in weaned piglets

Glutathione (GSH) is considered to play an important role in maintaining the integrity of the small intestine. In piglets, altered mucosal GSH levels might therefore be involved in weaning-induced changes of the small intestinal morphology and barrier function. To test this hypothesis, we aimed to challenge the mucosal GSH redox status during the first 28 days after weaning, by feeding diets containing 5% fresh linseed oil (CON), or 2.5% (OF1) or 5% (OF2) peroxidized linseed oil (peroxide value 225 mEq O2/kg oil) and exploring the effects on gut integrity. Piglets were pair-fed and had a total daily feed allowance of 32 g/kg BW. A fourth treatment included animals that were fed the control diet ad libitum (ACON). Animals were sampled at days 5 and 28 post-weaning. The malondialdehyde (MDA) concentration and GSH redox status (GSH/GSSG Eh) were determined in blood, liver and small intestinal mucosa. Histomorphology of the duodenal and jejunal mucosa was determined, and Ussing chambers were used to assess fluorescein isothiocyanate dextran (FD4) and horseradish peroxidase (HRP) fluxes across the mucosa. Results show that peroxidized linseed oil imposed an oxidative challenge at day 28, but not at day 5 post-weaning. At day 28, increasing levels of dietary peroxides to pair-fed pigs linearly increased MDA levels in duodenal and jejunal mucosa. Moreover, FD4 fluxes were significantly increased in OF1 (+75%) and OF2 (+64%) in the duodenum, and HRP fluxes tended (P=0.099) to show similar differences, as compared to CON. This co-occurred with a significant 11 mV increase of the hepatic GSH/GSSG Eh, potentiated by a significantly increased GSH peroxidase activity for treatments OF1 (+47%) and OF2 (+63%) in liver as compared to CON. Furthermore; duodenal HRP flux significantly correlated with the hepatic glutathione disulphide (GSSG) level (r=0.650), as also observed in the jejunum for hepatic GSSG (r=0.627) and GSH/GSSG Eh (r=0.547). The jejunal permeability was not affected, but FD4 and HRP fluxes significantly correlated with the local GSH (r=0.619; r=0.733) and GSSG (r=0.635; r=0586) levels. Small intestinal histomorphology was not affected by dietary lipid peroxides, nor were there any correlations found with the GSH redox system. To conclude, under oxidative stress conditions, jejunal barrier function is related to the local and hepatic GSH redox system. It is suggested that the hepatic GSH system participates in the elimination of luminal peroxides, and thereby impacts on duodenal barrier function.

Essential Oils as Feed Additives-Future Perspectives

The inconsistency of phytogenic feed additives' (PFA) effects on the livestock industry poses a risk for their use as a replacement for antibiotic growth promoters. The livestock market is being encouraged to use natural growth promotors, but information is limited about the PFA mode of action. The aim of this paper is to present the complexity of compounds present in essential oils (EOs) and factors that influence biological effects of PFA. In this paper, we highlight various controls and optimization parameters that influence the processes for the standardization of these products. The chemical composition of EOs depends on plant genetics, growth conditions, development stage at harvest, and processes of extracting active compounds. Their biological effects are further influenced by the interaction of phytochemicals and their bioavailability in the gastrointestinal tract of animals. PFA effects on animal health and production are also complex due to various EO antibiotic, antioxidant, anti-quorum sensing, anti-inflammatory, and digestive fluids stimulating activities. Research must focus on reliable methods to identify and control the quality and effects of EOs. In this study, we focused on available microencapsulation techniques of EOs to increase the bioavailability of active compounds, as well as their application in the animal feed additive industry.

Essential oils as alternatives to antibiotics in swine production

This review article summarizes the efficacy, feasibility and potential mechanisms of the application of essential oils as antibiotic alternatives in swine production. Although there are numerous studies demonstrating that essential oils have several properties, such as antimicrobial, antioxidative and anti-inflammatory effects, feed palatability enhancement and improvement in gut growth and health, there is still a need of further investigations to elucidate the mechanisms underlying their functions. In the past, the results has been inconsistent in both laboratory and field studies because of the varied product compositions, dosages, purities and growing stages and conditions of animals. The minimal inhibitory concentration (MIC) of essential oils needed for killing enteric pathogens may not ensure the optimal feed intake and the essential oils inclusion cost may be too high in swine production. With the lipophilic and volatile nature of essential oils, there is a challenge in effective delivery of essential oils within pig gut and this challenge can partially be resolved by microencapsulation and nanotechnology. The effects of essential oils on inflammation, oxidative stress, microbiome, gut chemosensing and bacterial quorum sensing (QS) have led to better production performance of animals fed essential oils in a number of studies. It has been demonstrated that essential oils have good potential as antibiotic alternatives in feeds for swine production. The combination of different essential oils and other compounds (synergistic effect) such as organic acids seems to be a promising approach to improve the efficacy and safety of essential oils in applications. High-throughput systems technologies have been developed recently, which will allow us to dissect the mechanisms underlying the functions of essential oils and facilitate the use of essential oils in swine production.

Feed preference of weaned pigs fed diets containing soybean meal, Brassica napus canola meal, or Brassica juncea canola meal

Brassica napus and Brassica juncea canola meal (CM) may replace soybean meal (SBM) in pig diets, but differ in fiber, glucosinolates content and profile. Preference of weaned pigs provided double-choice selections to diets containing 20% SBM, B. napus CM, or B. juncea CM was evaluated in two studies. In experiment 1, 216 pigs (9.4 ± 1.6 kg initial BW) were housed in 27 pens of 8 pigs (four gilts and four barrows). In experiment 2, 144 pigs (8.9 ± 1.1 kg) were housed in 36 pens of 4 pigs (two gilts and two barrows). Pigs were offered three dietary choices: B. napus CM with SBM as reference (B. napus CM [SBM]), B. juncea CM with SBM as reference (B. juncea CM [SBM]), and B. juncea CM with B. napus CM as reference (B. juncea CM [B. napus CM]) in a replicated 3 × 3 Latin square. Diets were formulated to provide 2.4 Mcal NE/kg and 4.5 g standardized ileal digestible Lys/Mcal NE and were balanced using canola oil and crystalline AA. Each pair of diets was offered in two self-feeders per pen as mash (experiment 1) or pellets (experiment 2) during three test-periods of 4-d, followed by a 3-d non-test period when a common diet was offered in both feeders. Feeders with different diets were rotated daily among pens during preference periods for both experiments, and feeder positions (right or left) were switched daily in experiment 2. Prior to the study and between periods, pigs were fed non-test diets containing SBM (experiment 1) or without test feedstuffs (experiment 2). Overall in both experiments, pigs preferred (P < 0.001) SBM over B. napus and B. juncea CM diets, and preferred (P < 0.001) B. napus over B. juncea CM diet. Dietary choice did not affect (P > 0.05) growth performance in both experiments, except for greater G:F (P < 0.05) for pigs fed the B. juncea CM [B. napus CM] diets than pigs fed the B. napus CM [SBM] or B. juncea CM [SBM] diets in experiment 1. In conclusion, weaned pigs preferred SBM over CM diets when given a choice, and preferred B. napus over the B. juncea diet that contained more total glucosinolates especially gluconapin. Weaned pigs fed the B. juncea CM [B. napus CM] diets in the double-choice selection did not reduce feed intake, weight gain, and G:F compared to pigs fed the B. napus CM [SBM] or B. juncea CM [SBM] diets.

Utilisation of a mix of powdered oils as fat supplement in nursery- and growing-pig diets

Two experiments were conducted to challenge nursery and growing pigs to increased levels of dietary fat (5–10% as fed), using a crystallised powdered oil mix (CPOM), produced by a modified freeze-drying process. Growth performance of nursery pigs was determined and a digestibility trial was also conducted with growing pigs (Experiment 2). The CPOM was compared, at similar levels of lipid inclusion (10% total lipids), with other fat sources commonly used in swine diet, namely soybean oil (SBO) and hydrogenated palm oil. For the growth assay (Experiment 1), the CPOM was prepared and added at different levels (0%, 2.6% and 3.8%) commonly used in commercial diets (Phase 1–4 diets). Seventy-five weaning pigs (28 days of age) were housed in 15 pens (5 pigs per pen) and randomly assigned into the three dietary treatments until 70 days of age. Growth performance and feed utilisation were compared weekly among experimental groups. The use of CPOM improved average daily gain (~60%), and increased average daily feed intake by 40% and 50% at the 2.6% and 3.8% CPOM levels respectively. In the digestibility trial (Experiment 2), pigs fed with 5% incorporation of CPOM (10% of total lipid content) had digestibility of energy and ether extract similar to those fed the SBO-supplemented diet, although the SBO diet had a significantly greater polyunsaturated fatty acid concentration. The powdered crystallisation process of the CPOM fat allowed an equivalent digestibility of this fat source with more saturated fatty acids, and the physical-property effect of this processed oil source on apparent total-tract digestibility should be further studied.

Physiological and metabolic control of diet selection

The fact that most farm animals have no dietary choice under commercial practices translates the dietary decisions to the carers. Thus, a lack of understanding of the principles of dietary choices is likely to result in a high toll for the feed industry. In healthy animals, diet selection and, ultimately, feed intake is the result of factoring together the preference for the feed available with the motivation to eat. Both are dynamic states and integrate transient stimulus derived from the nutritional status, environmental and social determinants of the animal with hard-wired genetic mechanisms. Peripheral senses are the primary inputs that determine feed preferences. Some of the sensory aspects of feed, such as taste, are innate and genetically driven, keeping the hedonic value of feed strictly associated with a nutritional frame. Sweet, umami and fat tastes are all highly appetitive. They stimulate reward responses from the brain and reinforce dietary choices related to essential nutrients. In contrast, aroma (smell) recognition is a plastic trait and preferences are driven mostly by learned experience. Maternal transfer through perinatal conditioning and the individual’s own innate behaviour to try or to avoid novel feed (often termed as neophobia) are known mechanisms where the learning process strongly affects preferences. In addtition, the motivation to eat responds to episodic events fluctuating in harmony with the eating patterns. These signals are driven mainly by gastrointestinal hormones (such as cholecystokinin [CCK] and glucagon-like peptide 1 [GLP-1]) and load. In addition, long-term events generate mechanisms for a sustainable nutritional homeostasis managed by tonic signals from tissue stores (i.e. leptin and insulin). Insulin and leptin are known to affect appetite by modulating peripheral sensory inputs. The study of chemosensory mechanisms related to the nutritional status of the animal offers novel tools to understand the dynamic states of feed choices so as to meet nutritional and hedonic needs. Finally, a significant body of literature exists regarding appetite driven by energy and amino acids in farm animals. However, it is surprising that there is scarcity of knowledge regarding what and how specific dietary nutrients may affect satiety. Thus, a better understanding on how bitter compounds and excess dietary nutrients (i.e. amino acids) play a role in no-choice animal feeding is an urgent topic to be addressed so that right choices can be made on the animal’s behalf.

Effect of dietary net energy concentrations on growth performance and net energy intake of growing gilts

Objective

This experiment investigated the effect of dietary net energy (NE) concentrations on growth performance and NE intake of growing gilts.

Methods

Five diets were formulated to contain 9.6, 10.1, 10.6, 11.1, and 11.6 MJ NE/kg, respectively. A metabolism trial with 10 growing pigs (average body weight [BW] = 15.9±0.24 kg) was conducted to determine NE concentrations of 5 diets based on French and Dutch NE systems in a 5×5 replicated Latin square design. A growth trial also was performed with five dietary treatments and 12 replicates per treatment using 60 growing gilts (average BW = 15.9±0.55 kg) for 28 days. A regression analysis was performed to predict daily NE intake from the BW of growing gilts.

Results

Increasing NE concentrations of diets did not influence average daily gain and average daily feed intake of growing gilts. There was a quadratic relationship (p = 0.01) between dietary NE concentrations and feed efficiency (G:F), although the difference in G:F among treatment means was relatively small. Regression analysis revealed that daily NE intake was linearly associated with the BW of growing gilts. The prediction equations for NE intake with the BW of growing gilts were: NE intake (MJ/d) = 1.442+(0.562×BW, kg), R² = 0.796 when French NE system was used, whereas NE intake (MJ/d) = 1.533+(0.614×BW, kg), R² = 0.810 when Dutch NE system was used.

Conclusion

Increasing NE concentrations of diets from 9.6 to 11.6 MJ NE/kg have little impacts on growth performance of growing gilts. Daily NE intake can be predicted from the BW between 15 and 40 kg in growing gilts.

Anethol, cinnamaldehyde, and eugenol inclusion in feed affects postweaning performance and feeding behavior of piglets

The early exposure of the fetus to certain volatiles may result in a further preference for these compounds later in life and could positively affect the acceptance of feed containing a similar flavor and the zootechnical responses. The study consisted of 2 trials to determine if including Fluidarom 1003 (a commercially flavored feed additive containing >25% anethol and cinnamaldehyde and >10% eugenol; Norel S.A., Madrid, Spain, Spain) in sow and postweaning piglet diets 1) provokes the presence or absence of 3 major volatile compounds (anethol, cinnamaldehyde, and eugenol) in amniotic fluid and milk, affecting piglet performance (BW, ADG, ADFI, and feed conversion ratio) after weaning, and 2) modifies creep feed consumption and feed preference in a 2-choice test. The major compounds, anethol, cinnamaldehyde, and eugenol, were detected in amniotic fluid; however, only traces were observed in milk. The inclusion of flavor in the sow diets improved piglet consumption and growth after weaning ( = 0.001). Furthermore, the positive reward associated with the flavor included in the sow diet was stronger when piglets were offered a nonflavored creep feed ( < 0.05). Therefore, early exposure of pigs' fetuses to maternal dietary clues at the end of gestation might allow for conditioning pigs after weaning.

Valorization of Proteins from Co- and By-Products from the Fish and Meat Industry

Large volumes of protein-rich residual raw materials, such as heads, bones, carcasses, blood, skin, viscera, hooves and feathers, are created as a result of processing of animals from fisheries, aquaculture, livestock and poultry sectors. These residuals contain proteins and other essential nutrients with potentially bioactive properties, eligible for recycling and upgrading for higher-value products, e.g. for human, pet food and feed purposes. Here, we aim to cover all the important aspects of achieving optimal utilization of proteins in such residual raw materials, identifying those eligible for human consumption as co-products and for feed applications as by-products. Strict legislation regulates the utilization of various animal-based co- and by-products, representing a major hurdle if not addressed properly. Thorough understanding and optimization of all parts of the production chain, including conservation and processing, are important prerequisites for successful upgrading and industrial implementation of such products. This review includes industrially applied technologies such as freezing/cooling, acid preservation, salting, rendering and protein hydrolysis. In this regard, it is important to achieve stable production and quality through all the steps in the manufacturing chain, preferably supported by at- or online quality control points in the actual processing step. If aiming for the human market, knowledge of consumer trends and awareness are important for production and successful introduction of new products and ingredients.

Dietary fat preference and effects on performance of piglets at weaning

Objective

An experiment was to evaluate the interplay of dietary lipid sources and feeding regime in the transition from sow milk to solid food of abruptly weaned piglets.

Methods

Soon after weaning, 144 piglets were selected and were trained over a 15 day period to experience gradually reducing dietary fat content from 12% to 6% for lard (L), soybean oil (S), and coconut oil (C) and their feeding behavior and diet preference then tested in a behavior observation experiment. Another 324 weaned piglets were used in three consecutive feeding experiments to measure the effect of different dietary fats on performance and feed choice in the four weeks after abrupt weaning. The lipid sources were used as supplements in a 3% crude fat corn/soya basal diet, with 6% of each being included to form diets 9C, 9S, and 9L respectively, and their effects on performance measured. Combinations of these diets were then further compared in fixed blends or free choice selection experiments.

Results

Piglets pre-trained to experience reducing lipid inclusion showed different subsequent preferences according to lipid source, with a preference for lard at 9%, soybean oil at 3%, and coconut oil at 6% inclusion rate (p<0.001). Following abrupt weaning, whilst after 4 weeks those fed 9C had the heaviest body weights (18.13 kg, p = 0.006). Piglets fed a fixed 1:1 blend of 9C+9S had a poorer feed conversion ratio (FCR = 1.80) than those fed a blend of 9C+9L (FCR = 1.4). The 9C and 9L combination groups showed better performance in both fixed blend and free choice feeding regimes.

Conclusion

After abrupt weaning, they still have dependence on high oleic acid lipids as found in sow milk. A feeding regime offering free choice combination of lipids might give the possibility for piglets to cope better with the transition at weaning, but further research is needed.

Comparison of growth and efficiency of dietary energy utilization by growing pigs offered feeding programs based on the metabolizable energy or the net energy system

The NE system describes the useful energy available for growth better than the ME system. The use of NE in diet formulation should maintain growth performance and carcass parameters when diets contain a diversity of ingredients. This study compared the growth performance of pigs on diets formulated using either the ME or the NE system. A total of 944 gilts and 1,110 castrates (40.8 ± 2.0 kg initial BW) were allotted to group pens and assigned to 1 of 5 different feeding programs according to a randomized complete block design. The 5 treatments included: a corn-soybean meal control diet (CTL), a corn-soybean meal diet plus corn distiller's dried grains with solubles (DDGS), formulated to be equal in ME to the CTL diet (ME-D), a corn-soybean meal diet plus corn DDGS, formulated to be equal in NE to the CTL diet (NE-D), a corn-soybean meal diet plus corn DDGS and corn germ meal, to be equal in ME to the CTL diet (ME-DC) and a corn-soybean meal diet plus corn DDGS and corn germ meal, formulated to be equal in NE to the CTL diet (NE-DC). When required, fat was added as an energy source. Pigs were harvested at an average BW of 130.3 ± 4.0 kg. Growth performance was not affected by treatment ( = 0.581, = 0. 177, and = 0.187 for ADG, ADFI, and G:F, respectively). However, carcass growth decreased with the addition of coproducts except for the NE-D treatment ( = 0.016, = 0.001, = 0.018, = 0.010, and = 0.010 for dressing percentage, HCW, carcass ADG, back fat, and loin depth, respectively). Carcass G:F and lean percentage did not differ among treatments ( = 0.109 and = 0.433, respectively). On the other hand, NE intake decreased ( = 0.035) similarly to that of carcass gain, suggesting a relationship between NE intake and energy retention. Calculations of NE per kilogram of BW gain differed among treatments ( = 0.010), but NE per kilogram of carcass was similar among treatments ( = 0.640). This suggests that NE may be better than ME at explaining the carcass results. Finally, ME intake and ME per kilogram of BW gain were not different among treatments ( = 0.112), but ME per kilogram of carcass gain was different among treatments ( = 0.048). In conclusion, the sequential addition of coproducts in diets formulated on an NE or ME basis can result in similar growth performance, but carcass parameters may be affected independently of the energy system used. However, formulating diets based on NE tended to improve predictability of growth, especially carcass parameters.

Phytogenic compounds as alternatives to in-feed antibiotics: potentials and challenges in application

This article summarizes current experimental knowledge on the efficacy, possible mechanisms and feasibility in the application of phytogenic products as feed additives for food-producing animals. Phytogenic compounds comprise a wide range of plant-derived natural bioactive compounds and essential oils are a major group. Numerous studies have demonstrated that phytogenic compounds have a variety of functions, including antimicrobial/antiviral, antioxidative and anti-inflammation effects and improvement in the palatability of feed and gut development/health. However, the mechanisms underlying their functions are still largely unclear. In the past, there has been a lack of consistency in the results from both laboratory and field studies, largely due to the varied composition of products, dosages, purities and growing conditions of animals used. The minimal inhibitory concentration (MIC) of phytogenic compounds required for controlling enteric pathogens may not guarantee the best feed intake, balanced immunity of animals and cost-effectiveness in animal production. The lipophilic nature of photogenic compounds also presents a challenge in effective delivery to the animal gut and this can partially be resolved by microencapsulation and combination with other compounds (synergistic effect). Interestingly, the effects of photogenic compounds on anti-inflammation, gut chemosensing and possible disruption of bacterial quorum sensing could explain a certain number of studies with different animal species for the better production performance of animals that have received phytogenic feed additives. It is obvious that phytogenic compounds have good potential as an alternative to antibiotics in feed for food animal production and the combination of different phytogenic compounds appears to be an approach to improve the efficacy and safety of phytogenic compounds in the application. It is our expectation that the recent development of high-throughput and "omics" technologies can significantly advance the studies on the mechanisms underlying phytogenic compounds' functions and, therefore, guide the effective use of the compounds.

Growth performance and preference studies to evaluate solvent-extracted Brassica napus or Brassica juncea canola meal fed to weaned pigs

Inclusion of conventional dark-seeded (Brassica napus) and novel yellow-seeded (Brassica juncea) canola meal (CM) can potentially replace soybean (Glycine max) meal (SBM) in pig diets. Our objective was to examine the preference of weaned pigs fed diets containing SBM or B. napus or B. juncea CM and to compare it against previously reported growth performance data (Exp. 1 and 2). In Exp. 1 and 2, growth performance was evaluated using 220 and 240 weaned pigs, respectively, by replacing dietary SBM with up to 20% B. napus (Exp. 1) or 24% B. juncea CM (Exp. 2). Feeding up to 20% B. napus CM to pigs did not affect growth performance, but increasing inclusion of B. juncea CM linearly reduced (P < 0.001) ADFI, ADG, and G:F most likely due to the higher content of glucosinolates, particularly gluconapin in B. juncea CM as confirmed by principle component analysis. In Exp. 3 and 4, SBM and B. napus and B. juncea CM fed at 20% dietary inclusion were evaluated in 2 preference studies using 216 and 144 pigs of 35 d of age, respectively. Pens equipped with 2 feeders housed 8 or 4 pigs per pen, in Exp. 3 and 4, respectively. Diets formulated to equal NE and standardized ileal digestible AA were offered in a paired choice as mash (Exp. 3) or pellets (Exp. 4) for 3 consecutive 7-d periods (3 d nontest and 4 d preference test). The 3 treatments offered were (i) SBM vs. B. napus CM, (ii) SBM vs. B. juncea CM, and (iii) B. napus vs. B. juncea CM. Pigs preferred SBM (P < 0.001) over B. napus and B. juncea CM diets, and pigs preferred B. napus (P < 0.001) over B. juncea CM diet. High content of the glucosinolate gluconapin likely reduced feed preference in B. juncea more than in B. napus CM. In conclusion, the contrast between preference and performance studies feeding CM to pigs indicates that preference studies should be interpreted cautiously until validated by growth performance data.

Influence of source and micronization of soybean meal on nutrient digestibility and growth performance of weanling pigs

A total of 288 piglets weaned at 28 d and weighing 7.6 ± 0.2 kg were used in a 35-d experiment to evaluate the effect of CP content (44% vs. 49% CP) of soybean meal (SBM), micronization (fine grinding) of the 49% CP SBM (HP-SBM), and soy protein concentrate (SPC; 65% CP) on total tract apparent digestibility (TTAD) and growth performance. In phase I (d 0 to 21 of experiment), there was a positive control diet that included 6.5% of CP from a SPC with 65% CP and a negative control diet that supplied the same amount of CP as regular SBM (R-SBM) with 44% CP. The other 4 diets included the same amount of dietary CP from 2 different sources of HP-SBM that were either ground (990 μm) or micronized (60 μm). All diets were isonutritive, and the main difference was the source of SBM used. Each treatment was replicated 8 times (6 pigs per pen). In phase II (d 21 to 35), all pigs were fed a common commercial starter diet. For the entire phase I, the type of soy product did not affect growth performance of the pigs. However, from 0 to 7 d of experiment, pigs fed the micronized HP-SBM had better G:F (1.11 vs. 0.98; P<0.05) than piglets fed the ground HP-SBM. Also, from 7 to 14 d of experiment, ADFI tended to be greater (P=0.08) for pigs fed the micronized HP-SBM than for piglets fed the ground HP-SBM. During phase II (all the pigs received the same diet), no differences among treatments were observed. In general, TTAD of nutrients at 7 d of experiment was greater for the SPC than the R-SBM diet, with the HP-SBM diets being intermediate. The TTAD of CP was greater (83.8% vs. 81.9%; P≤0.01) for the SPC diet than the average of the SBM diets. Also, the digestibility of OM and DM was greater (P<0.01) for the HP-SBM either ground or micronized than the R-SBM diet. Micronization of the HP-SBM did not affect nutrient digestibility. It is concluded that when the R-SBM is substituted by SPC, CP digestibility is improved, but no effects are observed on growth performance. The use of the HP-SBM in substitution of the R-SBM in the diet improved nutrient digestibility but did not affect piglet performance. The inclusion of micronized HP-SBM in the diet improved G:F during the first week postweaning but did not affect TTAD of nutrients. In general, the inclusion of added-value soy products (SPC or micronized SBM) in the diet presents little advantage in terms of growth performance over the use of HP-SBM in pigs weaned at 28 d of age.

Dissimilar sweet proteins from plants: oddities or normal components?

The fruits of a few tropical plants contain intensely sweet proteins. Their common property points to a protein family. Generally, proteins belonging to the same family share similar folds, similar sequences and, at least in part, similar function but sweet proteins constitute an exception to this rule. Apart from sharing the rather unusual taste function, they show no obvious similarities either in their sequences or in three-dimensional structures. In this review we describe the nature, structure and mechanism of action of the best known sweet tasting proteins, including two taste modifying proteins. Sweet proteins stand out among sweet molecules because their volume is not compatible with an interaction with orthosteric active sites of the sweet taste receptor. The best explanation of their mechanism of action is the interaction with the external surface of the sweet taste receptor, according to a model that has been named "wedge model". It is hypothesized that this mode of action may be related to the ability of other members of their protein families to inhibit different enzymes.