Positive effects of protected organic acids on nutrient digestibility and faecal microflora in lactating sows

Among a variety of candidates for the replacement of antibiotics, organic acids have been broadly applied worldwide with a reasonable success rate (Mroz 2005). Organic acids may influence the physiology of the intestinal mucosa by their action on the villi, by maintaining their integrity, promoting an increase in the number of cells, preventing its flattening, as well as serving as a substrate in the intermediary metabolism of the citric acid-cycle (Partanen and Mroz 1999). Organic acids can also reduce the diets buffering capacity, inhibit the proliferation and decrease colonization of undesirable microorganisms, act on the physiology of the gastrointestinal mucosa by improving the availability of nutrients in the diet, and improve their digestion, absorption, and retention (Costa et al. 2011). It was hypothesised that blends of different organic acids with medium chain fatty acids (MCFA) in a matrix coating could play an influential role in improving growth performance, microbial population, nutrient digestibility, blood profiles, and faecal gas emission of lactating sows.

A total of 12 sows with an average initial body weight (BW) of 252 ± 11.7 kg (mean ± SD) were used in a 21-day trial. The protected organic acid consists of MCFA and composite organic acids. The active ingredients were 58.8% stearic acid (palm oil), 17% fumaric acid, 13% citric acid, 10% malic acid, and 1.2% MCFA (capric and caprylic acid). Treatments were: CON, basal diet; POA1, CON + 0.1% protected organic acid; and POA2, CON + 0.2% protected organic acid. The BW and backfat of sows was checked 4 days before farrowing and at weaning day to calculate body weight loss and backfat loss during that period. Chromium oxide was added to diets at 0.2% as an indigestible marker to determinate the coefficient of total tract apparent digestibility (CTTAD) of DM, nitrogen (N) and gross energy (GE). All feed and faecal samples were analysed for DM (method 930.15, AOAC 2007) and crude protein (method 990.03, AOAC 2007). Chromium was analysed via UV absorption spectrophotometry (Shimadzu UV-1201, Shimadzu, Kyoto, Japan). The GE was determined by measuring the heat of combustion in the samples using a Parr 6100 oxygen bomb calorimeter (Parr instrument Co., Moline, IL). A total of 300 g fresh faecal samples were collected from each sow, and they were transferred to a sealed box and fermented for 48 h at 32°C in an incubator. At d 1, 3, 5, and 7, concentrations of ammonia, thiol, hydrogen sulphide, and acetic acid were measured. Blood from sows were collected via vena cava puncture before feeding at farrowing and weaning (d 21). The concentration of white blood cells (WBC) and lymphocytes in the whole blood samples were determined using an automatic blood analyser (ADVIA 120, Bayer, Tarry town, NY, USA). Whole blood samples were subsequently centrifuged for 15 min at 3000×g at 4°C and the harvested serum was used to determine IgG by using nephelometry (Dade Behring, Marburg, Germany). Effects of treatments (Control, POA1, and POA2) were analysed by ANOVA. Results are presented as least square mean and the variability in data was expressed as standard error (SE). Probability values less than α = 0.05 were considered as significant.

Protected organic acid (0.2%) diets increased (P < 0.05) the CTTAD of DM (4.75%), N (4.83%) and GE (5.77%) over those fed CON diets throughout the experimental period. Dietary supplementation with 0.2% protected organic acid led to a higher (P < 0.05) WBC (45.0%) and lymphocyte (6.7%) concentration than the CON treatment at weaning. The IgG concentration was greater (P < 0.05) in protected organic acid groups than CON lactating sows. Faecal Lactobacillus counts were increased (P < 0.05), and E. coli concentration was decreased (P < 0.05) in sows fed with the diets of protected organic acids at both farrowing and weaning. The faecal H₂S contents were decreased (P < 0.05) in protected organic acid groups during farrowing on d 1 compared with CON. It can be concluded from this preliminary study, albeit with a very small number of sows, that dietary supplementation with protected organic acid had some beneficial effects on digestibility and microbial populations in lactating sows.