Evaluation of direct-fed microbials and xylanase supplementation on performance and nutrient digestibility in pigs fed high fiber diets

Abstract

The main aim of the thesis is to investigate Direct-fed (DFM) Microbial supplementation alone or in combination with xylanase in high fiber diet on performance and nutrient digestibility in pigs. To achieve this main aim, three experiments were conducted.In study I (I chapter 3), Calsporin® biotechnical feed additive based on viable spores of Bacillus subtilis C-3102 was investigated alone. An experiment was conducted to evaluate the effect of Calsporin® on growth performance; microbial population and carcass characteristics of wean to finish pigs. One hundred and ninety-two (Topigs 20 x Compart's Duroc; 18 d, initial BW (6.7±0.27 kg)) crossbred piglets were allocated two treatment groups in a randomized complete block design. The results showed that supplementation of Calsporin® did not affect (P > 0.05) blood urea nitrogen (BUN) concentration. Calsporin® did not influence (P > 0.05) the final body weight, average daily gain but numerically reduced average feed intake (ADFI) which resulted in a potential to improve feed conversion efficiency during the overall period of study at an inclusion rate of 1.5 X 105/g of diet. The measured carcass characteristics, including hot carcass weight, yield percentage, back fat depth, loin depth, and lean percentage, were not affected (P > 0.05) by the dietary treatments. Calsporin® in the diet did not significantly affect (P > 0.05) the total counts of Enterobacteriaceae, Bifidobacteria and total anaerobes in the feces but Lactobacillus count was reduced (P < 0.05).Key words: Pigs, Calsporin, growth performance, carcass traits, microbial enumeration.In studies II and III different DFMs were used. Study II (Chapter 3) was conducted to investigate the effect of supplementing xylanase alone or in combination with either Bacillus species direct-fed microbials (DFM1) or lactobacillus multi-species direct-fed microbials (DFM2) on nutrient digestibility, visceral organ weight and intestinal morphology of nursery pigs fed high fiber diets in a 14 d trial. Thirty-six male pigs (30 d old, 9.0 ± 0.15 kg) of genotype [(Landrace × Yorkshire (Topigs, Winnipeg, Canada)) × Duroc (Compart's, Nicollet, MN) were allocated to 1 of 6 dietary treatments in a randomized complete block design. Six dietary treatments evaluated were T1, basal diet without xylanase or DFM as control; T2, control supplemented with DFM1 at 500g/MT; T3, control supplemented with xylanase 250g/MT; T4, xylanase (250g/MT) and DFM1 (500g/MT); T5, DFM2 (500g/MT) and T6, xylanase 250g/MT and DFM2 (500g/MT). The study reveal that pigs supplemented with DFM2 recorded an improvement (P < 0.05) in ileal crude protein digestibility, decreased water intake and reduced ileal digester viscosity by 13.7%. Supplementation of xylanase alone significantly improved ATTD of fat, NDF, ADF and numerically improved apparent ileal crude protein digestibility by about 10 percentage units. Dietary treatments did not affect pH of ileal digester content (P > 0.05) but pH of stomach chyme was reduced (P < 0.05) with combination of xylanase and DFMs. Addition of xylanase to DFMs led to a reduction in: organ weight, ileal viscosity, tended to improve villus height, significantly improved villus to crypt ratio and improved ATTD of energy. Key words: Xylanase, Direct-fed microbials, fibre diets, nursery pigs, viscosity and digestibility. In Study III, (Chapter 5) the effect of supplementing xylanase alone or in combination with either Bacillus species direct-fed microbials (DFM1) or lactobacillus multi-species direct-fed microbials (DFM2) on effect of blood urea nitrogen (BUN) concentration and growth performance of nursery pigs fed high fiber diets was studied in a 28 d trial. One hundred and forty-four (18 d old) [(Landrace × Yorkshire (Topigs, Winnipeg, Canada)) × Duroc (Compart's, Nicollet, MN) pigs were allocated to 1 of 6 dietary treatments with 6 replicates in a randomized complete block design. The treatments were T1, basal diet without xylanase or DFM as control; T2, control supplemented with DFM1 at 500g/MT; T3, control supplemented with xylanase 250g/MT; T4, xylanase (250g/MT) and DFM1 (500g/MT); T5, DFM2 (500g/MT) and T6, xylanase 250g/MT and DFM2 (500g/MT). The study revealed that xylanase, DFM1 or DFM2 individual supplementation did not influence BUN concentrations (P > 0.05) but addition of xylanase to the DFMs numerically reduced BUN concentration (P > 0.05). Supplementation of xylanase, DFM1 and DFM2 alone did not influence (P > 0.05) final body weight, average daily feed intake, average daily gain and feed efficiency but xylanase synergizes with DFM to numerically reduce feed intake and improve feed efficiency. Comparison between DFM1 and DFM2 did not affect pig performance (P > 0.05) during the study. In summary, supplementation of DFMs alone did not impact carcass traits and feed efficiency but addition of xylanase to the DFMs numerically reduces: BUN concentration, organ weights, ileal digesta viscosity, feed intake and synergizes to improve feed efficiency during the overall period of study (P < 0.05).Key words: Xylanase, Direct-fed microbials, fibre diets, nursery pigs, BUN and performance.