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Bioefficacy of high enzyme producing Bacillus spp. strains in nursery and grow-finish pigs fed corn-soybean based diets containing high co-products
The potential of Bacillus spp. direct-fed microbial (DFM) in maintaining the intestinal ecosystem and improving animal health and performance is well recognized. However, with the increased usage of cereal by-products (CBP), including corn distillers-dried grains with solubles, little or no information is available on the specific bioefficacy of DFM in nursery and grow-finish pigs fed diets containing high levels of CBP. The current studies evaluated the bioefficacy of Bacillus spp. specifically selected for high enzyme producing capability on the performance and lean accretion in nursery and grow-finish pigs fed corn-soybean meal-based diets (CSBM) containing 40-50% CBP. Ten independent (4 nursery and 6 grow-finish) with 10-30 and 4-10 pigs/pen in the nursery and grow-finish pigs trials, respectively were conducted. Pigs in each trial were blocked by initial BW and sex, and randomly assigned to pens within blocks. Pens were randomly assigned to the two dietary treatments with a total of 48 and 66 pens/treatment in the nursery and grow-finish trials, respectively. The nursery and the grow-finish trials lasted for an average of 6 and 12 weeks, respectively. The diets were: Control (CSBM with 40-50% CBP; CON), and CON plus Bacillus spp. DFM, containing viable spores (3x108 CFU per g, added at 0.5 kg/MT of feed). The diets were formulated to be isocaloric and isonitrogenous, and met nutritional requirements for nursery and grow-finish pigs. Feed and water were offered ad libitum. Pigs and feed were weighed at the start and completion of each feeding phase, and ADG, ADFI and G:F ratio were calculated. In two of the grow-finish trials, back fat depth and loin eye area (LEA) were measured at the end of the experimental period using real-time ultrasound and fat free lean (FFL) was calculated. Data were checked for normality and pooled together for Meta-analysis. In the nursery and grow-finish studies, dietary treatment had no effect (P>0.05) on final BW, ADFI and ADG. However, G:F ratio improved (P<0.05) in pigs fed DFM compared with CON in the nursery (0.662 vs. 0.646; SEM=0.004) and in the grow-finisher (0.360 vs. 0.352; SEM=0.003). Compared with CON, grow-finish pigs fed the DFM diet had improved (P<0.05) LEA (41.0 vs 43.6 cm2; SEM=0.58), FFL (32.5 vs 33.5 kg; SEM=0.33) and daily lean gain (0.348 vs 0.359 kg/d). In conclusion, Bacillus spp. strains specifically selected with high enzymatic activities allowed pigs to more efficiently utilize CSBM containing 40-50% CBP and improve lean accretion in finisher pigs.
Keywords: Bacillus, Pigs, Meta-analysis