The effect of Bacillus probiotic on growth performance and fecal The effect of Bacillus probiotic on growth performance and fecal consistency of growing-finishing pigs consistency of growing-finishing pigs

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Introduction
Probiotic bacteria have been promoted to improve growth performance and as an alternative method of preventing gastrointestinal disease in several species.One theory to explain the mechanism of action is that nonpathogenic Bacillus supplements compete for pathogenic bacterial binding sites, which leads to a reduction in the incidence of diarrhea.Supplemental feeding of Bacillus spp.bacteria also has been hypothesized to alter fecal consistency, which may reduce manure buildup and facility wash time.
Diet composition has changed dramatically for most swine farms in the United States in the last few years.Alternative ingredients such as DDGS or bakery meal have increased in the diet, which may alter the response to products such as Bacillus.Reports also indicate that including these by-products in diets leads to increased manure volume and increased barn wash times.Thus, the objective of this experiment was to investigate the effect of a Bacillus product on growth performance and carcass composition of finishing pigs fed corn-soy or by-product (DDGS and bakery meal) diets and the resulting effects on fecal consistency and pen wash time.

Procedures
The Kansas State University Institutional Animal Care and Use Committee approved the protocol used in this experiment.The study was conducted at a commercial research-finishing barn in southwestern Minnesota.The barns were naturally ventilated and double-curtain-sided. Pens had completely slatted flooring and deep pits for manure storage.Each pen was equipped with a 5-hole stainless steel dry self-feeder and a cup waterer for ad libitum access to feed and water.Daily feed additions to each pen were accomplished through a robotic feeding system (FeedPro; Feedlogic Corp., Willmar, MN) capable of providing and measuring feed amounts for individual pens.
A total of 1,099 pigs (PIC 1050 × 337) with an initial body weight of 75 lb were used in a 104-d study.A similar number of barrows and gilts were placed in each pen with 26 to 27 pigs per pen, with 7 pens per treatment.Pens of pigs were allotted to 1 of 6 treatments in a completely randomized design while balancing for body weight.Treatments were arranged in a 3 × 2 factorial with main effects of Bacillus product dose (0, 1x, or 10x; Sporzyme, Direct Biologicals, Inc., Crofton, NE) and diet formulation strategy (corn-soybean meal or by-product diet).The dietary Bacillus dose was approximately 200 million cfu/g feed for the 1x level and 2 billion cfu/g feed for the 10x level.The diets contained 30% DDGS until the last phase before market, when they contained 20%, and these diets used 20% bakery only in the first phase of the study (from 75 to 120 lb).Diets were fed in 5 phases with phases from 75 to 120 lb, 120 to 160 lb, 160 to 200 lb, 200 to 240 lb, and 240 lb to market (Tables 1 and 2).
Pens of pigs were weighed and feed disappearance was recorded at d 14, 29, 43, 65, 77, and 104 to determine ADG, ADFI, and F/G.At the end of the experiment, pigs were individually tattooed by pen number to allow for carcass data collection at the packing plant and data retrieval by pen.Pigs were transported to JBS Swift and Company (Worthington, MN) for processing.Standard carcass criteria of loin and backfat depth, HCW, percentage lean, and percentage yield were collected.
To measure fecal consistency, each pen was scored for manure texture and manure buildup at the end of the trial by 3 observers.The 3 scores were averaged to determine a mean score, which was used for analysis.Manure textures were categorized in 3 categories as firm, medium, and loose with the score of 1, 0, and -1, respectively.Manure buildup was given a value of 1 for visual manure buildup and -1 for no visual manure buildup.The time required to wash each individual pen was measured to determine whether the diet or supplement influenced wash time.
The experimental data were analyzed using the MIXED procedure of SAS (SAS institute, Inc., Cary, NC).Treatments were arranged in a 2 × 3 factorial and data were analyzed for the main effects of diet type, linear and quadratic effect of Bacillus, and any interactions between linear and quadratic effects of Bacillus level and diet type.Pen was the experimental unit for all data analysis, and significance and tendencies were set at P < 0.05 and P < 0.10, respectively.

Results and Discussion
No linear or quadratic interactions were detected between increasing Bacillus dosage and diet type (P > 0.13; Table 3), so the main effects of Bacillus dosage and diet type are presented (Table 4).Overall (d 0 to 104), no differences were measured in growth performance or carcass composition for pigs fed different levels of Bacillus product; however, pigs fed the 1x level of Bacillus tended (quadratic, P = 0.10) to have the lowest ADG.Due to this tendency, carcass value was affected in a quadratic manner, with pigs fed the 1x Bacillus having the highest price and premium and lowest sort loss.Manure texture score tended to increase (linear, P = 0.07) as Bacillus increased, suggesting that pigs fed the Bacillus product had firmer stools.Wash time was numerically reduced (linear, P = 0.16) as Bacillus level increased in the diet.The 50-sec difference in wash time per pen would equate to a 40-min reduction in wash time on a 48-pen barn for pigs fed the 10x level of the Bacillus product compared with the control.
For diet formulation, pigs fed the by-product diet had increased (P = 0.01) ADFI compared with pigs fed the corn-soy diet, but with no difference in ADG, feed efficiency was poorer (P < 0.01) for pigs fed the by-product diets.Pigs fed the by-product diets tended (P = 0.06) to have decreased backfat than pigs fed corn-soybean meal diets, which led to a tendency (P = 0.09) for greater carcass premium.No differences occurred in any other carcass criteria.Manure texture tended to be looser (P = 0.09) with more manure buildup (P = 0.08) in pens where pigs were fed by-product diets compared with pens with corn/soybean meal diets.Pens where by-product diets were fed required longer wash time (P < 0.01).Wash time was 2.4 min longer per pen where pigs were fed the by-product diets compared with pens where pigs were fed cornsoybean meal diets.When extrapolated over a 48-pen barn, feeding the high-by-product diets would increase wash time per barn by just less than 2 h (1 h and 53 min) compared with a barn where corn-soybean meal diets were fed.  2 By-product diets contained 30% dried distillers grains with solubles (DDGS) until the last phase before market, when they contained 20%, and these diets used 20% bakery only in the first phase of trial. 3The Bacillus that was used for this trial was approximately 200 million cfu/g feed (1 lb/ton) for the 1x level and 2 billion cfu/g feed (3.5 lb/ton) for the 10x level. 4Manure textures were categorized in 3 categories as firm, medium, and loose with the score of 1, 0, and -1. 5 Manure buildup was given value of 1 for visual manure buildup and -1 for no visual manure buildup.

Table 1 .
Composition of Phase 1, Phase 2, and Phase 3 diets 1 3,4Bacillus (Sporzyme, Direct Biologicals, Inc., Crofton, NE) was added to the diet in place of corn to provide approximately 200 million cfu/g feed for the 1x level and 2 billion cfu/g feed for the 10x level.

Table 3 .
Interactive effects of probiotic (Bacillus product) on growth performance and fecal consistency of growing-finishing pigs 1

Table 4 .
Main effect of probiotic (Bacillus product) on growth performance and fecal consistency of growing-finishing pigs 1