Zdzislaw Mroz

Organic acids for performance enhancement in pig diets

Organic acids and their salts appear to be potential alternatives to prophylactic in-feed antibiotics and growth promoters in order to improve the performance of weaned piglets, fattening pigs and reproductive sows, although their growth-promoting effects are generally less than that of antibiotics. Based on an analysis of published data, the growth-promoting effect of formates, fumarates and citrates did not differ in weaned piglets. In fattening pigs, formates were the most effective followed by fumarates, whereas propionates did not improve growth performance. These acids improved the feedgain ratio of both weaned piglets and fattening pigs. In weaned piglets, the growth-promoting effects of dietary organic acids appear to depend greatly on their influence on feed intake. In sows, organic acids may have anti-agalactia properties. Successful application of organic acids in the diets for pigs requires an understanding of their modes of action. It is generally considered that dietary organic acids or their salts lower gastric pH, resulting in increased activity of proteolytic enzymes and gastric retention time, and thus improved protein digestion. Reduced gastric pH and increased retention time have been difficult to demonstrate, whereas improved apparent ileal digestibilities of protein and amino acids have been observed with growing pigs, but not in weaned piglets. Organic acids may influence mucosal morphology, as well as stimulate pancreatic secretions, and they also serve as substrates in intermediary metabolism. These may further contribute to improved digestion, absorption and retention of many dietary nutrients. Organic acid supplementation reduces dietary buffering capacity, which is expected to slow down the proliferation and|or colonization of undesirable microbes, e.g. Escherichia coli, in the gastro-ileal region. However, reduced scouring has been observed in only a few studies. As performance responses to dietary organic acids in pigs often varies, more specific studies are necessary to elucidate an explanation.

Digestibility of nutrients in growing-finishing pigs is affected by Aspergillus niger phytase, phytate and lactic acid levels. 2. Apparent total tract digestibility of phosphorus, calcium and magnesium and ileal degradation of phytic acid

In growing–finishing pigs, the effects of supplemental microbial phytase, lactic acid and Na phytate in a maize-soybean meal based diet on the apparent total tract digestibility (ATTD) of ash, total P, Ca and Mg and the ileal degradation (AID) of phytic acid were studied. The experimental design was a 2×2×2 factorial arrangement plus a positive control treatment. Six crossbred castrates of 37 kg initial BW, fitted with steered ileo-caecal valve cannulas were used during six collection periods. The dietary treatments consisted of Aspergillus niger phytase (Natuphos®; 0 or 900 FTU kg−1), sodium phytate (0 or 1.5 g P kg−1) or lactic acid (0 or 30 g kg−1). The positive control diet was supplemented with 1.0 g P kg−1 from monocalcium phosphate monohydrate (MCP). The feeding level was 2.3 times maintenance requirement for energy (418 kJ MEW−0.75). Estimates of AID and ATTD were calculated using Cr2O3 as a marker. The addition of MCP to the diet as the only variable had no effect on the AID of phytic acid and the ATTD of ash, Ca and Mg, but enhanced total P ATTD. Both microbial phytase and lactic acid enhanced the ATTD of ash, Ca and Mg and the AID of phytic acid, but there was no interaction. The ATTD of total P was increased by the combination of microbial phytase and lactic acid to a greater extent than was calculated as the sum of the stimulatory effects of the single additions. It is hypothesized that lactic acid delays gastric emptying, which prolongs the action of phytase in the stomach at its optimum pH. When Na phytate was added to the diets, total P ATTD was enhanced, possibly reflecting efficient phytate hydrolysis by intrinsic phytase.

Digestibility of nutrients in growing-finishing pigs is affected by Aspergillus niger phytase, phytate and lactic acid levels. 1. Apparent ileal digestibility of amino acids

In growing–finishing pigs, the effects of microbial phytase, lactic acid and phytate levels in a maize-soybean meal diet on the apparent ileal digestibility (AID) of N and amino acids were studied. The experimental design was a 2×2×2 factorial arrangement plus a positive control treatment. Six crossbred castrates of 37 kg initial BW, fitted with steered ileo-caecal valve cannulas, were used during six collection periods. The dietary treatments consisted of Aspergillus niger phytase (Natuphos®; 0 or 900 FTU kg−1), Na phytate (0 or 1.5 g P kg−1) and lactic acid (0 or 30 g kg−1). The positive control diet was supplemented with 1.0 g P kg−1 from monocalcium phosphate monohydrate (MCP). Ileal digestible amino acids were supplied at 80% of the Dutch recommended allowances for a 60-kg growing pig. The feeding level was 2.3 times the maintenance requirement for energy (418 kJ ME BW−0.75). Estimates of AID were calculated using Cr2O3 as a marker. Results showed that for almost all amino acids there was a significant interaction between Na phytate and phytase. Supplementing Na phytate to the diets without phytase increased the AID of N and amino acids. In general, phytase alone stimulated the AID of N and amino acids in the diets without Na phytate. Supplementing both Na phytate and phytase slightly decreased AID compared with the diets with only one supplement. Lactic acid stimulated the AID of N and amino acids, but a synergistic effect between phytase and lactic acid was not detected. Adding MCP had no effect on the AID of N and amino acids. It was concluded that when diets are supplemented with either phytase or lactic acid, AID of amino acids is improved. However, supplementing both did not result in a further increase in AID.

Surplus dietary tryptophan reduces plasma cortisol and noradrenaline concentrations and enhances recovery after social stress in pigs

Social stress occurs in intensive pig farming due to aggressive behavior. This stress may be reduced at elevated dietary levels of tryptophan (TRP). In this study, we compared the effects of high (13.2%) vs. normal (3.4%) dietary TRP to large neutral amino acid (LNAA) ratios on behavior and stress hormones in catheterized pigs ( approximately 50 kg BW), which were exposed to social stress by placing them twice into the territory of a dominant pig ( approximately 60 kg) for 15 min. Pre-stress plasma TRP concentrations were 156+/-15 vs. 53+/-6 micromol/l (p<0.01) in pigs on the high vs. normal TRP diets, respectively. Pre-stress plasma cortisol and noradrenaline concentrations were twofold (p<0.01) and 1.4-fold (p<0.05) lower but plasma adrenaline concentration was similar in pigs on the high vs. normal TRP diets, respectively. During the social confrontations, pigs on the high vs. normal TRP diets show a tendency towards reduced active avoidance behavior (3.2+/-1.1 vs. 6.7+/-1.2 min, p<0.1) but their physical activity (8.5+/-0.6 vs. 10.2+/-0.8 min) and aggressive attitude towards the dominant pig (11+/-3 vs. 7+/-2 times biting) were similar. Immediate (+5 min) post-stress plasma cortisol, noradrenaline and adrenaline responses were similar among dietary groups. After the social confrontations, the post-stress plasma cortisol, noradrenaline and adrenaline concentrations and/or curves (from +5 min to 2 h) were lower/steeper (p<0.05) in pigs on the high vs. normal TRP diets. In summary, surplus TRP in diets for pigs (1) does not significantly affect behavior when exposed to social stress, (2) reduces basal plasma cortisol and noradrenaline concentrations, (3) does not affect the immediate hormonal response to stress, and (4) reduces the long-term hormonal response to stress. In general, pigs receiving high dietary TRP were found to be less affected by stress.

Water in pig nutrition: physiology, allowances and environmental implications

C O N T E N T S l N T R O D U C T I O N . . 137 PHYSIOLOGICAL REGULATION OF BODY WATER STATUS . . 138 SPONTANEOUS D R I N K I N G A N D INTESTINAL TRANSPORT OF WATER . . 138 EFFECTIVE CIRCULATING VOLUME I N THE VASCULAR SYSTEM . . 139 CHANGES IN PLASMA OSMOLALITY . . 142 CHANGES OF CATION-ANION EQUILIBRIUM . . 143 WATER CONSUMPTION: C I R C A D I A N RHYTHMICITY . . 146 WATER A L L O W A N C E S . . 147 PIGLETS . . 148 The sucking piglet . . , 148 The weanedpiglet . . . 148 G R O W I N G F I N I S H I N G PIGS . . 149 REPRODUCTIVE SOWS . . , 151 Non-pregnant and pregnant sows . . 151 Lactating sows . . 153 ENVIRONMENTAL lMPLICATIONS , . 154 IMPACT OF DIET O N WATER INTAKE A N D MANURE PRODUCTION B Y PIGS 155 Dietary electrolytes . . 155 Dietary protein . . 157 S U M M A R Y . . 159 REFERENCES . . 160

Diurnal variation in degradation of phytic acid by plant phytase in the pig stomach

The effects of plant phytase on the gastric degradation of phytic acid and digestibilities of DM and P, and their diurnal variation were evaluated in pigs from 90 to 115 kg BW fitted with simple duodenal T-cannulas. Three diets were fed to three pigs in four collection periods according to a cross-over design. The diets were a wheat–barley-based diet (phytase activity 1005 phytase units [FTU] kg−1), a maize-based diet (91 FTU kg−1) and this maize-based diet mixed with 30% wheat (342 FTU kg−1). Digestibility of DM in the duodenal samples was zero in all treatments. Digestibility of P was high (17%) and equal for all treatments. The diurnal disappearance ratios of DM and P were similar for all diets. Their levels were dependent on gastric retention time. The lowest ratios were found 3 h post-feeding; maximal ratios were observed prior to feeding. The gastric degradability of phytic acid was 3% in the maize-based, 31% in the wheat–maize-based and 47% in the wheat–barley-based diets. The diurnal disappearance ratio of phytic acid degradation was similar for all treatments, and dependent on gastric retention time. Marked differences in degradability levels were observed among the diets.

Diurnal rhythms in plasma cortisol, insulin, glucose, lactate and urea in pigs fed identical meals at 12-hourly intervals.

Diurnal rhythms in plasma cortisol, insulin, glucose, lactate and urea concentrations were investigated in eight catheterized pigs of approximately 35 kg BW. Pigs were fed isoenergetic/isoproteinic diets at a restricted level (2.5 x maintenance requirement for energy) in two daily rations (06:00 and 18:00 hours) in order to obtain equal intervals between feed intake. Preprandial plasma cortisol concentration was 22+/-3 ng/mL in the morning and 14+/-2 ng/mL in the evening (p<0.025), whereas the concentrations of insulin, glucose, lactate, and urea were similar. In the postprandial period in the morning (06:00-09:00 hours) plasma cortisol, insulin and lactate concentrations (expressed as the total area under the curve) were greater (p<0.001) compared to the evening (18:00-21:00 hours) by 100%, 42%, and 24%, respectively, while postprandial plasma glucose and urea concentrations were not affected by time of the meal. When postprandial plasma concentrations were expressed as a response over preprandial concentrations (decremental or incremental area under the curve), the diurnal rhythm was not observed for cortisol and glucose, persisted for insulin and lactate, and appeared for urea with a smaller postprandial urea response (p<0.05) in the morning compared to the evening. We conclude that the diurnal rhythm in plasma cortisol is independent of feeding whereas the diurnal rhythms in plasma insulin, lactate and urea are unveiled by the morning/evening meals in pigs. At equal 12-h intervals between meals, the postprandial responses of lactate and urea show diurnal variations, each in a specific manner, which suggest decreased postprandial efficiency of carbohydrate metabolism and increased postprandial efficiency of protein metabolism in the morning compared to the evening.

Chapter 4 Carboxylic acids as bioregulators and gut growth promoters in nonruminants

Publisher Summary The chapter discusses carboxylic acids as bioregulators and gut growth promoters in nonruminants. The chapter presents a review of current literature relating the modes of action and effectiveness of both short and medium chain carboxylic acids relative to gut health and performance of nonruminant animals, with an emphasis on pigs. Over the past 50 years numerous studies have been addressed worldwide to evaluate four major benefits because of carboxylic acids: (1) improved health and resistance to disease, (2) faster growth, (3) increased efficiency of diet utilization, (4) better carcass quality. Secondary effects, concerning environmental pollution (less total N, volatilized ammonia, P) and/or reduced production costs have also received considerable attention. The chapter discusses the intraluminal and post-absorptive bioactivity of short-chain fatty acids (SCFA) and medium-chain fatty acids (MCFA) in nonruminants, and particularly in pigs. The chapter discusses: (1) Some essentials on the physicochemical properties of SCFA and MCFA, (2) intraluminal production rates and concentrations in particular sections of the gut, (3) direct and/or indirect effects of SCFA and MCFA on gut functionality, (4) transepithelial transport and absorptive mechanisms of SCFA, and (5) post-absorptive roles in metabolic and regulatory processes of the body.

Physiology, regulation and multifunctional activity of the gut wall: a rationale for multicompartmental modelling.

A rationale is given for a modelling approach to identify the mechanisms involved in the functioning and metabolic activity of tissues in the wall of the gastrointestinal tract. Maintenance and productive functions are discussed and related to the distinct compartments of the gastrointestinal tract and the metabolic costs involved. Functions identified are: tissue turnover; tissue proliferation; ion transport; nutrient transport; secretions of digestive enzymes, mucus and immunoglobulins; production of immune cells. The major nutrients involved include glucose, amino acids and volatile fatty acids. In vivo measurements of net portal fluxes of these nutrients in pigs and ruminants are evaluated to illustrate the complexity of physiology and metabolic activity of the gastrointestinal tract. Experimental evidence indicates that high, but variable and specific, nutrient costs are involved in the functioning of the gastrointestinal tract.