Growth performance, bone mineralization, nutrient digestibility, and fecal microbial composition of multi-enzyme-supplemented low-nutrient diets for growing-finishing pigs.

A study evaluated the effects of adding multi-enzyme mixture to diets deficient in net energy (NE), standardized ileal digestible (SID) amino acids (AA), standardized total tract digestible (STTD) P, and Ca on growth performance, bone mineralization, nutrient digestibility, and fecal microbial composition of grow-finish pigs. A total of 300 pigs (initial body weight [BW] = 29.2 kg) were housed by sex and BW in 45 pens of 7 or 6 pigs and fed 5 diets in a randomized complete block design. Diets were positive control (PC), and negative control 1 (NC1) or negative control 2 (NC2) without or with multi-enzyme mixture. The multi-enzyme mixture supplied at least 1,800, 1,244, 6,600, and 1,000 units of xylanase, ß -glucanase, arabinofuranosidase, and phytase per kilogram of diet, respectively. The PC was adequate in all nutrients. The NC1 diet had lower content NE, SID AA, STTD P, and Ca than PC diet by about 7%, 7%, 32%, and 13%, respectively. The NC2 diet had lower NE, SID AA, STTD P, and Ca than PC diet by 7%, 7%, 50%, and 22%, respectively. The diets were fed in four phases based on BW: Phase 1: 29-45 kg, Phase 2: 45-70 kg, Phase 3: 70-90 kg, and Phase 4: 90-120 kg. Nutrient digestibility, bone mineralization, and fecal microbial composition were determined at the end of Phase 1. Pigs fed PC diet had greater (P < 0.05) overall G:F than those fed NC1 diet or NC2 diet. Multi-enzyme mixture increased (P < 0.05) overall G:F, but the G:F of the multi-enzyme mixture-supplemented diets did not reach (P < 0.05) that of PC diet. Multi-enzyme mixture tended to increase (P = 0.08) femur breaking strength. Multi-enzyme mixture increased (P < 0.05) the ATTD of GE for the NC2 diet, but unaffected the ATTD of GE for the NC1 diet. Multi-enzyme mixture decreased (P < 0.05) the relative abundance of the Cyanobacteria and increased (P < 0.05) relative abundance of Butyricicoccus in feces. Thus, the NE, SID AA, STTD P, and Ca could be lowered by about 7%, 7%, 49%, and 22%, respectively, in multi-enzyme mixture-supplemented diets without negative effects on bone mineralization of grow-finish pigs. However, multi-enzyme mixture supplementation may not fully restore G:F of the grow-finish pigs fed diets that have lower NE and SID AA contents than recommended by 7%. Since an increase in content of Butyricicoccus in intestine is associated with improved gut health, addition of the multi-enzyme mixture in diets for pigs can additionally improve their gut health.

A study evaluated the effects of supplementing a multi-enzyme mixture that contain fiber degrading enzymes and phytase on the growth performance, bone strength, and fecal microbial composition of grow-finish pigs fed corn-wheat-wheat bran-based diets. Five diets fed were a positive control (PC) diet, and two negative control (NC1 and NC2) diets without or with the multi-enzyme mixture. The PC diet was adequate in all nutrients and had greater available (net) energy and digestible amino content than NC1 diet or NC2 diet by 7%, and greater digestible P content than the NC1 diet (by 32%) and NC2 diet (by 50%). The diets were fed from 30 to 120 kg body weight. Feed efficiency for PC diet was greater than that for NC1 diet or NC2 diet. Multi-enzyme mixture improved feed efficiency, bone strength, and fecal concentration of beneficial micro-organisms (known as Butyricicoccus) for NC1 and NC2 diets. However, feed efficiency for the NC1 and NC2 diets did not reach that for the PC diet. Thus, multi-enzyme mixture can fully restore bone strength (but not feed efficiency) and improve health of grow-finish pigs fed corn-wheat-wheat bran-based diets in which available energy, amino acids, and P contents have been reduced by the afore-mentioned margins.

Growth performance, visceral organ weights, and gut health of weaned pigs fed diets with different dietary fiber solubility and lipid sources.

The objective of this study was to determine the interactive effects of dietary fiber solubility and lipid source on growth performance, visceral organ weights, gut histology, and gut microbiota composition of weaned pigs. A total of 280 nursery pigs [initial body weight (BW) = 6.84 kg] weaned at 21 d were housed in 40 pens (7 pigs/pen). The pigs were fed four diets (10 pens/diet) in a randomized complete block design in two phases: Phase 1 from 0 to 2 wk and Phase 2 from 2 to 5 wk. The diets were corn-soybean meal-based with either sugar beet pulp (SBP) or soybean hulls (SBH) as a fiber source and either soybean oil (SBO) or choice white grease (CWG) as a lipid source in a 2 × 2 factorial arrangement. The BW and feed intake were determined by phase, whereas visceral organ weights, intestinal histology, and gut microbial composition were determined at the end of the trial. Dietary fiber solubility and lipid source did not interact (P > 0.05) on average daily feed intake and average daily gain across all phases. However, the gain to feed ratio (G:F) for CWG-containing diets was lower (P < 0.05) than that for SBO-containing diets for Phase 1. Also, G:F for SBP-containing diets was lower (P < 0.05) than that for SBH-containing diets for Phase 1 and for the entire study period. Pigs fed SBP-containing diets had greater (P < 0.05) stomach weight, and tended to have greater (P < 0.10) small and large intestine weights relative to BW than those fed SBH-containing diets. Duodenal villous height to crypt depth ratio for CWG-based diets tended to be greater (P = 0.09) than that for SBO-based diets. Fiber solubility and lipid source interacted (P < 0.05) on relative abundance of Bacteroides in the colon such that the relative abundance of the Bacteroides for CWG was greater (P < 0.05) than that for the SBO in SBP-based diet, but not in SBH-based diet. Relative abundance of Butyricicoccus in the colon for SBH-based diet was greater (P < 0.05) than that for SBP-based diet. In conclusion, inclusion of SBH instead of SBP in corn-soybean meal-based diets for weaned pigs can result in increased feed efficiency and relative abundance of Butyricicoccus in the colon, which is associated with improved gut health. Also, inclusion of SBO instead of CWG in the diets for weaned pigs can result in improved feed efficiency during Phase 1 feeding; however, the pigs may recover from the low feed efficiency induced by dietary inclusion of CWG instead of SBO after Phase 1 feeding.

Metagenomic characterization of the effect of feed additives on the gut microbiome and antibiotic resistome of feedlot cattle.

In North America, antibiotic feed additives such as monensin and tylosin are added to the finishing diets of feedlot cattle to counter the ill-effects of feeding diets with rapidly digestible carbohydrates. While these feed additives have been proven to improve feed efficiency and reduce liver abscess incidence, how these products impact the gastrointestinal microbiota is not completely understood. In this study, we analyzed the impact of providing antibiotic feed additives to feedlot cattle using metagenome sequencing of treated and control animals. Our results indicate that use of antibiotic feed additives does not produce discernable changes at the phylum level. However, treated cattle had reduced abundance of gram-positive bacteria at the genus level. The abundance of Ruminococcus, Erysipelotrichaceae and Lachnospiraceae in the gut of treated steers was reduced. Functional analysis of the data indicates that there was only minimal impact due to the treatment in the rumen. Genes involved in detoxification were significantly increased in the rumen of AB steers. But the relative abundance of these genes was < 0.3%. However, our results did not show any correlation between the presence of antimicrobial resistance genes in the gut microbiota and the administration of antibiotic feed additives.

Phenotypic and transcriptomic response of auxotrophic Mycobacterium avium subsp. paratuberculosis leuD mutant under environmental stress.

Mycobacterium avium subsp. paratuberculosis (MAP) is the causative agent of severe gastroenteritis in cattle. To gain a better understanding of MAP virulence, we investigated the role of leuD gene in MAP metabolism and stress response. For this, we have constructed an auxotrophic strain of MAP by deleting the leuD gene using allelic exchange. The wildtype and mutant strains were then compared for metabolic phenotypic changes using Biolog phenotype microarrays. The responses of both strains to physiologically relevant stress conditions were assessed using DNA microarrays. Transcriptomic data was then analyzed in the context of cellular metabolic pathways and gene networks. Our results showed that deletion of leuD gene has a global effect on both MAP phenotypic and transcriptome response. At the metabolic level, the mutant strain lost the ability to utilize most of the carbon, nitrogen, sulphur, phosphorus and nutrient supplements as energy source. At the transcriptome level, more than 100 genes were differentially expressed in each of the stress condition tested. Systems level network analysis revealed that the differentially expressed genes were distributed throughout the gene network, thus explaining the global impact of leuD deletion in metabolic phenotype. Further, we find that leuD deletion impacted metabolic pathways associated with fatty acids. We verified this by experimentally estimating the total fatty acid content of both mutant and wildtype. The mutant strain had 30% less fatty acid content when compared to wildtype, thus supporting the results from transcriptional and computational analyses. Our results therefore reveal the intricate connection between the metabolism and virulence in MAP.