Todd R Callaway's research while affiliated with University of Georgia and other places

Introduction Medicinal plants, rich in phytochemicals like phenolic acids, flavonoids, and tannins, offer potential benefits in enhancing productivity, quality, and animal health. Amla fruit (Phyllanthus emblica) is one such plant with promising attributes. This study aimed to investigate the impact of fresh Amla fruit (FAF) supplementation on ruminal microbial composition and its correlation with rumen fermentation in lactating dairy cows. Methods The study employed a repeated crossover design involving eight ruminally cannulated mid-lactation Holstein dairy cows. Animals received varying levels of fresh Amla fruit supplementation (0, 200, 400, and 600 g/d). Results When 400 g/d of FAF was added to the diet, there was a significant increase in the relative abundance of Firmicutes (p = 0.02). However, at 200 g/d, the relative abundance of ruminal Bacteroidota was higher than the 0 and 400 g/d FAF supplementation (p < 0.01). LEfSe analysis identified distinct taxa, such as Clostridia vadinBB60 in the 200 g/d group, Oscillospiraceae in the 400 g/d group, and Elusimicrobium in the 600 g/d group. Notably, the random forest species abundance statistics identified Oscillospiraceae V9D2013 as a biomarker related to milk yield. Oscillospiraceae, Bacilli RF39, norank_f Prevotellaceae, and Bifidobacterium were positively correlated with ruminal total VFA and molar proportion of propionate, while Rikenellaceae RC9 gut group and Clostridia vadinBB60 were negatively correlated. Discussion FAF supplementation affects the abundance of beneficial microbes in a dose-dependent manner, which can improve milk yield, efficiency, rumen health, desirable fatty acids, and animal health.

In recent years, there has been an exponential increase in the number of papers that have investigated the microbiome of animals and humans [...]

The catabolic activity of the ruminal microbial community of cattle enables the conversion of low-quality feedstuffs into meat and milk. The rate at which this conversion occurs is termed feed efficiency, which is of crucial importance given that feed expenses account for up to 70% of the cost of animal production. The present study assessed the relationship between cattle feed efficiency and the composition of their ruminal microbial communities during the feedlot finishing period. Angus steers (n = 65) were fed a feedlot finishing diet for 82 days and their growth performance metrics were evaluated. These included the dry matter intake (DMI), average daily gain (ADG), and residual feed intake (RFI). Steers were rank-ordered based upon their RFI, and the five lowest RFI (most efficient) and five highest RFI (least efficient) steers were selected for evaluations. Ruminal fluid samples were collected on days 0 and 82 of the finishing period. Volatile fatty acids (VFA) were quantified, and microbial DNA was extracted and the 16S rRNA gene was sequenced. The results showed that the ADG was not different (p = 0.82) between efficiency groups during the 82-day feedlot period; however, the efficient steers had lower (p = 0.03) DMI and RFI (p = 0.003). Less-efficient (high RFI) steers developed higher (p = 0.01) ruminal Methanobrevibacter relative abundances (p = 0.01) and tended (p = 0.09) to have more Methanosphaera. In high-efficiency steers (low RFI), the relative abundances of Ruminococcaceae increased (p = 0.04) over the 82-day period. The molar proportions of VFA were not different between the two efficiency groups, but some changes in the concentration of specific VFA were observed over time. The results indicated that the ruminal microbial populations of the less-efficient steers contained a greater relative abundance of methanogens compared to the high-efficiency steers during the feedlot phase, likely resulting in more energetic waste in the form or methane and less dietary energy being harvested by the less-efficient animals.

Though much effort has been made to characterize the in vivo (IV) and in situ (IS) dry matter digestibility (DMD) of southeastern forages, there is a lack of information identifying methods that best represent the in vivo digestibility of these forages. Thus, the objective of our study was to compare IV and IS methods to determine which technique best represents the in vivo DMD of four bermudagrass (Cynodon dactylon [L.] Pers.) cultivars. In an IV experiment, ruminally fistulated heifers (n = 4) were randomly assigned to one of four bermudagrass cultivars (Coastal [COS], Russell [RUS], Tifton 44 [T44], or Tifton 85 [T85]) for four 30-d in vivo periods (21-d adaptation and 9-d collection) in a Latin square design. On d 28 of each period, rumen fluid was collected 4 h post-feeding for an accompanying IV experiment using a completely randomized design with a 4 × 2 factorial treatment structure. Factors in the IV experiment included bermudagrass cultivar (COS, RUS, T44, and T85) and digestibility method (Tilley and Terry [TT] or Goering and Van Soest [GVS]). On d 31 of in vivo periods 3 and 5, an accompanying IS experiment was conducted as a randomized complete block design with three treatment factors (in vivo diet [previous described], bermudagrass cultivar [previously described], and incubation timepoint [0, 0.25, 0.50, 0.75, 1, 2, 3, 4, 8, 12, 16, 20, 24, 48, 72, 96, 120, 144, and 168 h]). Correlations were computed between in vivo DM disappearance and each of the IV (TT and GVS) and IS (24, 48, and 72 h) methods. Regressions were calculated for each of the individual IV and IS measurements, and a stepwise regression was used to determine the predictive value of linear combinations of the measurements. None of the IV or IS DMD values were correlated with in vivo DMD (P ≥ 0.18). Individual IV and IS DMD values did not yield significant models through linear regression (P ≥ 0.18), though the best model (based on AIC) was TT IVDMD (r2 = 0.09; P = 0.26). Stepwise regression revealed that there was no linear combination of IV or IS DMD that improved prediction beyond single predictor models. While both IV and IS experiments remain viable tools to screen forages and make relative comparisons, results from this experiment are interpreted to mean that neither of these methods is suitable for prediction of in vivo performance.

Livestock producers need new technologies to maintain the optimal health and well-being of their animals while minimizing the risks of propagating and disseminating pathogenic and antimicrobial-resistant bacteria to humans or other animals. Where possible, these interventions should contribute to the efficiency and profitability of animal production to avoid passing costs on to consumers. In this study, we examined the potential of nitroethane, 3-nitro-1-propionate, ethyl nitroacetate, taurine and L-cysteinesulfinic acid to modulate rumen methane production, a digestive inefficiency that results in the loss of up to 12% of the host’s dietary energy intake and a major contributor of methane as a greenhouse gas to the atmosphere. The potential for these compounds to inhibit the foodborne pathogens, Escherichia coli O157:H7 and Salmonella Typhimurium DT104, was also tested. The results from the present study revealed that anaerobically grown O157:H7 and DT104 treated with the methanogenic inhibitor, ethyl nitroacetate, at concentrations of 3 and 9 mM had decreased (p < 0.05) mean specific growth rates of O157:H7 (by 22 to 36%) and of DT104 (by 16 to 26%) when compared to controls (0.823 and 0.886 h−1, respectively). The growth rates of O157:H7 and DT104 were decreased (p < 0.05) from controls by 31 to 73% and by 41 to 78% by α-lipoic acid, which we also found to inhibit in vitro rumen methanogenesis up to 66% (p < 0.05). Ethyl nitroacetate was mainly bacteriostatic, whereas 9 mM α-lipoic acid decreased (p < 0.05) maximal optical densities (measured at 600 nm) of O157:H7 and DT104 by 25 and 42% compared to controls (0.448 and 0.451, respectively). In the present study, the other oxidized nitro and organosulfur compounds were neither antimicrobial nor anti-methanogenic.

Infection with the foodborne pathogen Campylobacter is the leading bacterial cause of human foodborne illness in the United States. The objectives of this experiment were to test the hypothesis that mixed microbial populations from the bovine rumen may be better at excluding Campylobacter than populations from freshly voided feces and to explore potential reasons as to why the rumen may be a less favorable environment for Campylobacter than feces. In an initial experiment, C. jejuni cultures inoculated without or with freshly collected bovine rumen fluid, bovine feces or their combination were cultured micro-aerobically for 48 h. Results revealed that C. jejuni grew at similar growth rates during the first 6 h of incubation regardless of whether inoculated with the rumen or fecal contents, with rates ranging from 0.178 to 0.222 h−1. However, C. jejuni counts (log10 colony-forming units/mL) at the end of the 48 h incubation were lowest in cultures inoculated with rumen fluid (5.73 log10 CFUs/mL), intermediate in cultures inoculated with feces or both feces and rumen fluid (7.16 and 6.36 log10 CFUs/mL) and highest in pure culture controls that had not been inoculated with the rumen or fecal contents (8.32 log10 CFUs/mL). In follow-up experiments intended to examine the potential effects of hydrogen and hydrogen-consuming methanogens on C. jejuni, freshly collected bovine feces, suspended in anaerobic buffer, were incubated anaerobically under either a 100% carbon dioxide or 50:50 carbon dioxide/hydrogen gas mix. While C. jejuni viability decreased <1 log10 CFUs/mL during incubation of the fecal suspensions, this did not differ whether under low or high hydrogen accumulations or whether the suspensions were treated without or with the mechanistically distinct methanogen inhibitors, 5 mM nitrate, 0.05 mM 2-bromosulfonate or 0.001 mM monensin. These results suggest that little if any competition between C. jejuni and hydrogen-consuming methanogens exists in the bovine intestine based on fecal incubations.

Simple Summary Piglets experience great stress when they are weaned from their mothers at about three weeks of age. One of those types of stress occurs at a cellular level and can impact what types of bacteria can grow and live in the piglets’ digestive systems. There are certain enzymes that fight cellular stress, and certain ingredients (manganese and selenium, two mineral feed ingredients) can be provided to the weaned piglets to boost their stress defense. The objective of this study was to demonstrate how increased mineral concentration in the diet can impact how the pig grows and how it affects the piglets’ digestive systems. This study provides preliminary evidence that a specific mineral, manganese, can impact piglet growth and the gut of the pig in a positive way by decreasing bacteria that are considered to be pathogenic or “bad” and increasing bacteria that are considered to be beneficial or “good”. In this study, selenium had no significant impacts on animal or bacterial growth. This study can be used as a foundation for future research that can dive into greater detail into further application of these minerals in the field of animal nutrition. Abstract The objective of this study was to determine the impact of varying dietary manganese and selenium concentrations, antioxidant cofactors, on the growth performance and fecal microbial populations of nursery pigs. The piglets (N = 120) were blocked by weight (5.22 ± 0.7 kg) and sex. The pens (n = 5/treatment) within a block were randomly assigned to diets in a 2 × 3 factorial design to examine the effects of Se (0.1 and 0.3 mg/kg added Se) and Mn (0, 12, and 24 mg/kg added Mn) and were fed in three phases (P1 = d 1–7, P2 = d 8–21, P3 = d 22–35). The pigs and orts were weighed weekly. Fecal samples were collected d 0 and 35 for 16S rRNA bacterial gene sequencing and VFA analysis. The data were analyzed as factorial via GLM in SAS. There was a linear response (p < 0.05) in overall ADG across dietary Mn. Supplementing 24 mg/kg Mn tended to decrease (p < 0.10) the relative abundance of many bacteria possessing pathogenic traits relative to Mn controls. Meanwhile, increasing Mn concentration tended to foster the growth of bacteria correlated with gut health and improved growth (p < 0.10). The data from this study provide preliminary evidence on the positive effects of manganese on growth and gut health of nursery pigs.

The microbial population of the gastrointestinal tract has been studied extensively for many years. The symbiotic relationship between the host animal and the native microbes has been relatively well characterized, given the technical limitations. Next Generation Sequencing techniques have proliferated and have become affordable for researchers, companies, and even individual producers. This reduction of barriers to utilization of NGS techniques has introduced many incorrect conclusions based on population estimates that do not include the estimates of microbial biochemical activities, and ecological niches. As a result, there are many descriptions of products that will make the microbiome “good” for all production situations and diets. Unfortunately, there is no magic bullet that makes a microbiome a universally “good” microbiome. This presentation will discuss how developments in understanding the microbial of the gut has expanded our view of the gut microbial ecology, and how it can be used to improve our understanding of the impacts of the microbiome on animal performance and health. Discussions of how microbiome analyses have been used and misused will be included. Being able to detect small changes in the microbial population of the gut is critical and can elucidate methods to improve animal productivity and protein food production sustainability. This presentation will also discuss challenges facing the animal industry as precision agriculture becomes increasingly important to animal nutrition and sustainability.

The gastrointestinal microbial community in dairy cattle is rich and diverse, and it may be used for a variety of objectives that benefit both producers and consumers, such as decreasing pathogenic bacterial populations, increasing animal production, and lowering environmental consequences. A typical way of improving milk supply and quality uses the local gut bacteria community. The use of probiotic supplements is a standard approach of using the local gastrointestinal bacteria community to boost milk production and efficiency on dairies. The efficiency of probiotics in dairy cattle varies depending on the distinct microbial ecological characteristics within the animal’s gastrointestinal tract and its native microflora, which contribute to the gut’s competing pressures. The increased use of next-generation sequencing has begun to reveal how probiotics interact with the gut’s resident microbial community and how they might influence host animal gene expression. This chapter delves into the ecology of probiotic product effectiveness against foodborne pathogens that live in food animals, and it aims to improve milk production efficiency and the sustainability of dairy production.