Growth Performance, Nutrient Digestibility, Fecal Microbiota and Fecal Noxious Gas Emission in Weaning Pigs Fed High and Low Density Diet with and without Protected Organic Acid Blends

Organic acids possess both bacteriostatic and bactericidal properties depending on the dosage used. Generally, organic acids get dissociated and lose most of their antibacterial capacity before reaching to the distal part of the digestive system. For this reason, a microencapsulation (protection) technology was developed to allow organic acids to reach the distal parts of the gastro-intestinal tract progressively without being totally dissociated and maintaining their efficacy. This study was conducted to evaluate the effects of dietary supplementation of protected organic acid blends including medium chain fatty acids and different nutrient density diets on growth performance, nutrient digestibility, fecal microbiota and fecal noxious gas emission in weaning pigs. A total of 90 crossbred [(Landrace × Yorkshire) × Duroc] weaning pigs with an initial body weight (BW) of 6.54 ± 0.78 kg were used in a 6-wk trial. Pigs were randomly allocated into one of six treatment groups in a 2 × 3 factorial arrangement with two nutrient density diets; high density containing 16.75 and 16.33 MJ/kg digestible energy during phases 1 and 2 respectively (HD) vs low density containing 16.33 and 15.91 MJ/kg digestible energy during phases 1 and 2 respectively (LD) supplemented with or without 0.1 and 0.2% of protected organic acids (OA) according to their sex and BW (3 replicate pens per treatment with 2 gilts and 3 barrows per pen). Feces samples were collected at day 21 and day 42 via rectal massage for microbial counts and gas analysis. For gas analysis, the collected fresh feces (300g) were immediately stored in plastic boxes with a small hole in the middle of one side that was sealed with adhesive plaster and allowed to ferment for 24h after which gas analysis was done. The inclusion of OA (0.1%, 0.2%) improved (P<0.05) the average daily gain (ADG) during week 6. Likewise, during the overall experimental period, the ADG was higher (P<0.05) in pigs fed HD diet than LD diet as well as in OA supplemented diet, but average daily feed intake (ADFI) was significantly improved (P<0.05) only in diet supplemented with OA than non-supplemented diet. The gain: feed (G:F) ratio was higher (P<0.05) in pigs fed HD than LD diet during week 3 and week 6 and overall experimental periods. The supplementation of OA (0.2%) led to a higher (P<0.05) apparent total tract digestibility (ATTD) of energy during week 3 and 6 compared with non-supplemented diet. In week 3, dry matter (DM) digestibility was higher in pigs fed diet supplemented with 0.2% OA but in week 6, DM digestibility was higher in both 0.1% and 0.2% OA treatments compared with control. The ATTD of energy was higher (P<0.05) in pigs fed HD than LD diet during week 6. The supplementation of OA (0.2%) in the diet reduced fecal E.coli during week 3 and increased Lactobacillus counts during week 6. In conclusion, protected OA and different density diets improved growth performance, nutrient digestibility but no interactive effects with different density diets and OA were observed.

Key words: nutrient density, organic acid, weaning pig