Digestibility and nitrogen retention of diets containing different levels of fibre in local (Mong Cai), F1 (Mong Cai x Yorkshire) and exotic (Landrace x Yorkshire) growing pigs in Vietnam

Fiber digestibility in growing pigs fed common fiber-rich ingredients: a systematic review

The application of high-fiber ingredients in the swine feed industry has some limitations considering that high amounts of fiber are resistant to endogenous enzymatic degradation in the pig’s gut. However, there is growing interest in fiber fermentation in the intestine of pigs due to their functional properties and potential health benefits. Many strategies have been applied in feed formulations to improve utilization efficiency of fiber-rich ingredients and stimulate their prebiotic effects in pigs. This manuscript reviews chemical compositions, physical properties, and digestibility of fiber-rich diets formulated with fibrous ingredients for growing pigs. Evidences presented in this review indicate there is a great variation in chemical compositions and physical properties of fibrous ingredients, resulting in the discrepancy of energy and fiber digestibility in pig intestine. In practice, fermentation capacity of fiber components in the pig’s intestine can be improved using strategies, such as biological enzymes supplementation and feed processing technologies. Soluble dietary fiber (SDF) and insoluble dietary fiber (IDF), rather than neutral detergent fiber (NDF) and acid detergent fiber (ADF), are recommended in application of pig production to achieve precise feeding. Limitations of current scientific research on determining fiber digestibility and short chain fatty acids (SCFA) production are discussed. Endogenous losses of fiber components from non-dietary materials that result in underestimation of fiber digestibility and SCFA production are discussed in this review. Overall, the purpose of our review is to provide a reference for feeding the pig by choosing the diets formulated with different high-fiber ingredients.

Effects of various levels of dietary fiber on carcass traits, meat quality and myosin heavy chain I, IIa, IIx and IIb expression in muscles in Erhualian and Large White pigs

This study evaluated the effects of bran fiber levels on carcass traits, meat quality and expression of myosin heavy chain isoform genes in muscles in Erhualian (Er-HL) and Large White pig (LW). Our results showed that fiber level did not affect carcass weight of Er-HL, while carcass weight of LW decreased with the increase of fiber level. Fiber level did not influence meat quality traits of LW, whereas increased fiber level led to an increase in pH_{45 min} of Er-HL, and Er-HL fed 7% bran fiber (BRC) increased redness of meat compared with control diet (CON). We observed a decreased MyHCIIb and MyHCIIx mRNAs and protein levels in Er-HL fed 7% BRC compared with those in other groups, accompanying with a tendency for increased mRNA abundance of MyHCI. The slow-twitch oxidative fiber (MyHCI) is rich in myoglobin and mitochondrial oxidative metabolic enzymes, and the increased expression of MyHCI fiber in pork has resulted in higher redness value. In summary, bran fiber had no adverse effect on the meat quality of LW and appropriate fiber level addition in diets could improve meat quality of Er-HL through regulation the expression of myofiber types.

Increasing levels of rapeseed expeller meal in diets for pigs: effects on protein and energy metabolism

The heavy reliance on imported soybean meal (SBM) as a protein source makes it necessary for the European pig industry to search for alternatives and to develop pigs that perform efficiently when fed such ingredients. Digestion and metabolism are major physiological processes contributing to variation in feed efficiency. Therefore, an experiment was conducted to assess the effects of replacing SBM with increasing levels of rapeseed meal (RSM) in diets for young pigs on apparent total tract digestibility (ATTD) of energy and nutrients, nitrogen (N) balance, energy metabolism and carbohydrate, protein and fat oxidation. Four diets were fed to 32 pigs (22.7±4.1 kg initial BW) for three weeks. The diets consisted of a control cereal grain-SBM basal diet and three test diets where SBM and wheat were partially replaced with 10%, 20%, and 30% of expeller RSM. Increasing level of RSM in the diets linearly reduced ATTD of organic matter, CP, total carbohydrates, dietary fiber and energy. Utilization of digested nitrogen (DN) for N retention and total N excretion were not affected by RSM inclusion, however, RSM inclusion induced a shift in N excretion from urine to feces. Despite a linear increase in liver to metabolic BW ratio, heat production and utilization of metabolizable energy (ME) for retention were not affected by increasing RSM inclusion. In conclusion, replacing SBM with up to 30% of expeller RSM in nutritionally balanced diets for young pigs reduced the ATTD of most nutrients and energy, but did not affect N and energy retention in the body or efficiency of utilization of DN or ME for retention.

Effects of adaptation time and inclusion level of sugar beet pulp on nutrient digestibility and evaluation of ileal amino acid digestibility in pigs

Objective

Two experiments were conducted to determine the effects of adaptation time and inclusion level of sugar beet pulp (SBP) on nutrient digestibility and to evaluate the ileal amino acid digestibility of SBP fed to pigs.

Methods

In Exp. 1, thirty-six crossbred barrows (85.0±2.1 kg) were allotted to 6 diets in a completely randomized design with six replicates per diet. Diets included a corn-soybean meal diet and 5 test diets containing 14.6%, 24.4%, 34.2%, 43.9%, or 53.7% SBP, respectively. The adaptation time consisted 7, 14, 21, or 28 d consecutively for each pig followed by 5 d for fecal collection. Feces were collected from d 8 to 13, d 15 to 20, d 22 to 27, and d 29 to 34, respectively. In Exp. 2, six pigs (35.1±1.7 kg) with T-cannulas at the terminal ileum were fed to 3 diets in a replicated 3×3 Latin square design with 3 periods and 2 replicate pigs per diet. Each period consisted 5 d for diet adaptation followed by 2 d for digesta collection.

Results

The digestible energy (DE) value and the apparent total tract digestibility (ATTD) of gross energy (GE), dry matter (DM), ash, and organic matter in diets linearly decreased (p< 0.05) as the adaptation time increased or as the dietary SBP increased, while the ATTD of neutral detergent fibre and acid detergent fibre in diets linearly increased (p<0.01) as the dietary SBP increased. The DE value and the ATTD of GE and crude protein (CP) in SBP linearly increased (p<0.05) as the adaptation time increased, while the ATTD of CP in SBP linearly decreased (p<0.01) as the inclusion level increased. The standardized ileal digestibility of Lys, Met, Thr, and Trp in SBP was 37.03%, 51.62%, 40.68%, and 46.22%, respectively.

Conclusion

The results of this study indicated that the ATTD of energy and nutrients were decreased as inclusion rate of SBP increased.

Exploratory Analysis of the Microbiological Potential for Efficient Utilization of Fiber Between Lantang and Duroc Pigs

There is growing interest in the use of unconventional feed ingredients containing higher dietary fiber for pig production due to increasing prices of cereal grains and the potential health benefits of dietary fiber on host animals. This study aimed to gain insight into the community-wide microbiome population between the Chinese native Lantang pigs and the commercial Duroc pigs to uncover the microbiological mechanisms for the degradation capacity of fiber in pigs. Utilizing the metagenomics approach, we compared the phylogeny and functional capacity of the fecal microbiome from approximately 150-day-old female Lantang and Duroc pigs fed a similar diet. The structure of the fecal microbial community from the two pig breeds was different at the genus level; the number of genes associated with fiber degradation was higher in Lantang pigs. Further analysis and prediction of their functions from the fecal microbiomes of the two pig breeds revealed that the degradation capacities of fiber, branched chain fatty acids, and oligosaccharides were higher in Lantang pigs. The ability of lignocellulose bonding modules and the transport capacities of xylose, L-arabinose, ribose and methyl galactose were also higher in Lantang pigs. Similarly, the metabolic capacities of xylose, ribose, and fucose and the potential effectiveness of the tricarboxylic acid cycle (TCA) and gene abundance in the hydrogen sink pathway were higher in the fecal microbiome from Lantang pigs. Lantang pigs have a higher capacity to utilize dietary fiber than Duroc pigs, and the differences in the capability to utilize dietary fiber between the indigenous and commercial pigs could be differences in the composition and biological function of the gut microbiota.

Comparative digestibility of nutrients and amino acids in high-fiber diets fed to crossbred barrows of Duroc boars crossed with Berkshire×Jiaxing and Landrace×Yorkshire

OBJECTIVE

This experiment was conducted to determine the differences in the apparent ileal (AID) and total tract digestibility (ATTD) of nutrients and indispensable amino acids (IAA) in high-fiber diets with wheat middlings, rice bran or alfalfa meal fed to Duroc×(Landrace× Yorkshire) (DLY) and Duroc× (Berkshire×Jiaxing) (DBJ) growing barrows.

METHODS

Eighteen DLY and 18 DBJ growing barrows were randomly allotted to a 2×3 factorial arrangement involving 2 crossbreeds and 3 high-fiber diets. The experiment lasted 15 d with 10 d for diets adaptation, 3 d for feces collection and 2 d for digesta collection. Three diets were based on corn and soybean meal with 25% wheat middlings, rice bran and alfalfa meal respectively.

RESULTS

DBJ had a greater (p<0.05) AID of isoleucine, leucine, lysine, phenylalanine and valine and a lower (p<0.05) AID of methionine than DLY. The hindgut disappearance of acid detergent fiber for DBJ was greater (p<0.05) than DLY. The ATTD of gross energy, dry matter, organic matter, neutral detergent fiber and acid detergent fiber in wheat middlings diet were greater (p<0.05) than in rice bran and alfalfa meal diets. The hindgut disappearance of neutral detergent fiber and acid detergent fiber in wheat middlings diet or rice bran diet were the highest or lowest (p<0.05), and those of alfalfa meal diet were the middle. Barrows fed rice bran diet had a greater (p<0.05) hindgut disappearance of gross energy, dry matter and organic matter and lower hindgut disappearance of neutral detergent fiber and acid detergent fiber than barrows fed alfalfa meal diet.

CONCLUSION

DBJ growing barrows showed a significant higher digestibility of fiber in the hindgut and most IAA in the small intestine compared with DLY barrows. The digestibilities of chemical constituents and IAA were affected by the diets formulated with different fiber sources.

Nutrient utilisation in grower pigs fed a protein concentrate blended with sweet potato roots either boiled or ensiled with or without vines

Blending sweet potato (Ipomoea batatas L. (Lam)) with a protein concentrate for pig feed is a common strategy used by small-scale livestock farmers across Africa, Asia and the Pacific. However, high dietary fibre in sweet potato (SP) forage may reduce nutrient utilisation and energy metabolism and reduce the growth rate of young pigs. A 32-day metabolic trial with grower pigs using a 4 × 4 Latin square design tested the hypothesis that there would be no difference in apparent total tract digestibility (ATTD) of nutrients, energy and nitrogen (N) balance in 25 kg grower pigs (Large White × Landrace × Duroc) fed diets based on a blend of 43–40% protein supplement with 57–60% of DM as SP roots either boiled (BR43) or ensiled alone (ER43) or ensiled with vines (ERV40). Blended SP diets provided ~14–15% crude protein (CP), 16.1–16.3 MJ digestible energy (DE)/kg DM and 0.54–0.58 g lysine/MJ DE. The control diet (STD) contained 16.5% CP, 14.8 MJ DE/kg DM, 0.58 g lysine/MJ DE. The major findings were as follows: (1) DM intake was higher (P &lt; 0.05) for BR43 than ER43, ERV40 and STD diets, which were similar; (2) DM ATTD and energy utilisation were higher (P &lt; 0.05) in pigs fed SP diets; (3) carbohydrate (N-free extracts) ATTD was higher (P &lt; 0.05) in pigs fed BR43 and ER43 diets, while CP ATTD of both these diets was similar to that of STD and higher than that of ERV40; (4) ATTD of fats (ether extracts), CP, carbohydrates (N-free extracts) and total phosphorus was lower (P &lt; 0.05) on ERV40, but fibre ATTD was higher; (5) N intake and N retained were similar (P &gt; 0.05) for pigs fed BR43, ER43 and STD diets but lower for ERV40 (P &lt; 0.05). Boiled or ensiled SP roots provided high nutrient and energy utilisation in growing pigs, but the inclusion of SP vines lowered ATTD, energy utilisation and N retained from the mixed diet (ERV40). It is concluded that boiled or ensiled SP root are equally valuable as blended feed for grower pigs. However, at 30%DM, ensiled SP vine in blended feed led to reduced grower-pig performance.

Feeding value of hays of tropical forage legumes in pigs: Vigna unguiculata, Psophocarpus scandens, Pueraria phaseoloides and Stylosanthes guianensis

The effects of four tropical forage legume hays (Vigna unguiculata, Psophocarpus scandens, Pueraria phaseoloides and Stylosanthes guianensis) on voluntary feed intake (VFI) and their nutritive value were studied in growing pigs using a corn-soybean meal-based diet containing varying proportions of forage legume hays (0, 10, 20 and 40 % or 0, 12.5 and 25 % for VFI and nutritive value determination, respectively). There was no difference in VFI between species (P > 0.20), but a linear response to forage inclusion level (P < 0.05) was observed decreasing from 126 for 0 % to approximately 84 g/kg of body weight for the 40 % forage diets, except for V. unguiculata, where the response was quadratic (P = 0.01). All four forage species linearly decreased the total tract apparent digestibility (TTAD) from 0.76 to 0.61, 0.80 to 0.68, 0.54 to 0.40 and 0.58 to 0.31 except for S. guianensis (0.44) for DM, N, NDF and N retention, respectively. Differences in digestibility (P < 0.05) between species were also observed. Due to their negative influence on the overall digestibility, the contribution of hays should not exceed 12.5 %, except for S. guianensis, in which N retention remained quite high (0.44) at the highest inclusion level (25 %). P. phaseoloides hay should be avoided in pigs as it combines the lowest VFI with the lowest nutrient digestibility.

Fiber effects in nutrition and gut health in pigs

Dietary fiber is associated with impaired nutrient utilization and reduced net energy values. However, fiber has to be included in the diet to maintain normal physiological functions in the digestive tract. Moreover, the negative impact of dietary fiber will be determined by the fiber properties and may differ considerably between fiber sources. Various techniques can be applied to enhance nutritional value and utilization of available feed resources. In addition, the extent of fiber utilization is affected by the age of the pig and the pig breed. The use of potential prebiotic effects of dietary fiber is an attractive way to stimulate gut health and thereby minimize the use of anti-microbial growth promoters. Inclusion of soluble non-starch polysaccharides (NSP) in the diet can stimulate the growth of commensal gut microbes. Inclusion of NSP from chicory results in changes in gut micro-environment and gut morphology of pigs, while growth performance remains unaffected and digestibility was only marginally reduced. The fermentation products and pH in digesta responded to diet type and were correlated with shifts in the microbiota. Interestingly, fiber intake will have an impact on the expression of intestinal epithelial heat-shock proteins in the pig. Heat-shock proteins have an important physiological role in the gut and carry out crucial housekeeping functions in order to maintain the mucosal barrier integrity. Thus, there are increasing evidence showing that fiber can have prebiotic effects in pigs due to interactions with the gut micro-environment and the gut associated immune system.

Models to quantify excretion of dry matter, nitrogen, phosphorus and carbon in growing pigs fed regional diets

Modern pig production contributes to many environmental problems that relate to manure, especially in areas with highly intensive production systems and in regions like Asia where the regulative control is not effective. Therefore, the objective of this study was to use three different pig diets varying in dietary protein, fibre and fat as representative for Danish (DK), Thai (TH) and Vietnamese (VN) pig production to develop and evaluate different approaches to predict/calculate excretion from growing pigs in comparison with the experimentally determined values.

Nine female growing pigs were used in a digestibility and balance experiment. Excretion of dry matter (DM), nitrogen (N), phosphorus (P) and carbon (C) of the experimental diets were determined.

Due to the highest dietary fibre content, VN had the lowest digestibility of N, P and C (73, 49, and 73%, respectively) compared with the DK and TH pig diets. From the known diet composition using standard table values on chemical and nutrient digestibly, high accuracy (bias) and low variation was found and the results could be used for prediction on chemical composition and excretion in faeces and urine in growing pigs. Calculation based on standard values regarding nutrient retention in the pig body as used in the Danish manure normative system (DMNS) showed likewise to be quite useful for quantifying the total excretion of N and P.

Overall, the results demonstrate that simple models that require cheap and normally available information on dietary nutrients can give useful information on nutrient excretion in growing pigs.

Impact of fibre intake and fibre source on digestibility, gut development, retention time and growth performance of indigenous and exotic pigs

The impact of fibre level and fibre source on digestibility, gastrointestinal tract (GIT) development, total tract mean retention time (MRT) and growth performance was studied in indigenous Mong Cai (MC) and exotic Landrace × Yorkshire (LY) pigs. The diets were based on maize, rice bran, soyabean meal, fish meal and soyabean oil, and cassava residue (CR) or brewer's grain (BG) as fibrous ingredient sources in the high-fibre diets (HF) and were fed ad libitum. A low-fibre diet (LF), containing around 200 g NDF/kg dry matter (DM), was formulated without CR and BG as feed ingredients. The HF diets (HF-CR and HF-BG) were formulated to contain around 270 g NDF/kg DM. The experiment was arranged as a 2 × 3 factorial completely randomized design with six replications, and lasted 27 days. Increased dietary fibre level resulted in a reduction (P < 0.05) in average daily gain, digestibility of organic matter (OM), CP and gross energy (GE) at the ileum and in the total tract, and in MRT, and an increase (P < 0.05) in the feed conversion ratio and in the weight of the GIT (except for small intestine and caecum). The coefficients of total tract digestibility of fibre fractions were higher in HF diets than in the LF diet, with highest values for diet HF-CR, which had a high proportion of soluble non-starch polysaccharides. MC pigs had longer MRT of digesta than LY pigs (P < 0.05), resulting in higher digestibility at the ileum and in the total tract. Across diets and breeds, the total tract apparent digestibility of OM, CP and GE was positively related (R 2 = 0.80 to 0.84) to the MRT of solids, whereas the MRT was negatively related to the DM intake (R 2 = 0.60).

Comparison of total tract digestibility, development of visceral organs and digestive tract of Mong cai and Yorkshire x Landrace piglets fed diets with different fibre sources

The aim of the study was to evaluate the effects of piglet age and dietary fibre source on the development of visceral organs and the gastrointestinal tract (GIT), and on growth performance and total tract apparent digestibility (TTAD) in local [pure-breed Mong cai (MC)] and exotic [Landrace x Yorkshire (LY)] piglets. The experimental diets contained different fibre sources: C (basal diet), RB (basal diet + rice bran), SPVM (basal diet + sweet potato vine meal) and CReM (basal diet + cassava residue meal). The neutral detergent fibre (NDF) content in diet C and the fibrous diets was 8.8% and 17.1%-17.7% respectively (dry matter basis). Collection of faecal samples to determine TTAD was carried out for five consecutive days before the experiment was finished (63 days). The piglets were killed at the age of 10 days (before being given the same solid feed), 30 days (weaning, 20 days after solid feed introduced) and 63 days (33 days after being given the different fibrous diets) when the length of intestinal segments, weight of organs (liver, heart, kidneys) and empty weight of the GIT (stomach, small intestine, caecum and colon + rectum) were measured. As the age of animals increased, the relative weight of organs and the length of intestines (expressed on a mass-specific basis) decreased (p < 0.05), and the weight of GIT increased (p < 0.001). The piglets fed fibrous diets had heavier GIT than those fed diet C with the highest values in CReM (p < 0.05). The colon + rectum length was not significantly different among C, RB and SPVM, but was shorter than in CReM (p < 0.05). Coefficient of total tract apparent digestibility (CTTAD) of nutrients in the fibrous diets was lower than in C (p < 0.01). Average daily gain (ADG) and feed conversion ratio (FCR) in C, RB and CReM were not different and were better than in SPVM (p < 0.01). There were no significant differences in the weights of organs between the two breeds at day 10, 30 and 63 (p > 0.05). The weight and length of GIT were not significantly different between the two breeds at day 10 and day 30, but were greater for MC at day 63. The caecum and colon + rectum at 10 and 30 days were longer in MC than in LY (p < 0.001). The relative development of GIT post-weaning was higher than pre-weaning, the difference being most apparent in MC. As a result at 63 days, MC had heavier visceral organs and GIT, and longer intestines on fibrous diets than LY (p < 0.05). The MC at 63 days had higher CTTAD of organic matter, gross energy, crude fibre and NDF (p < 0.001) and ether extract and crude protein (p < 0.05), but lower ADG and poorer FCR than LY (p < 0.001). It can be concluded that the GIT of the MC piglets developed more rapidly than LY when they were introduced to solid feed, and that the difference was more marked on the fibrous diets and after weaning, which resulted in higher total tract digestibility of nutrients in MC compared with LY. Cassava residue meal was better digested than RB and SPVM, and supported higher live weight gains.