M.Sc. / The remarkable adaptability of the ruminant with respect to the variety of feeds of different composition which it can utilize is attributable to the presence, in the rumen, of a complex microbial population with diverse nutritional requirements and enzymatic activities. For economic reasons it is essential in feedlot practice to meet, as closely as possible, the energy requirements of ruminants being rounded off for slaughter purposes. This necessitates adapting the animals in the shortest possible time from predominantly pasture to high-concentrate diets, i.e. diets containing a high proportion of readily fermentable carbohydrates. However, a very rapid transition between these diets frequently results in a perturbation of the microbial population of the rumen. In particular, the sudden increase in the concentration of readily fermentable carbohydrates favours the proliferation of lactic acid-producing species, whereas the numbers of lactic acid-utilizing species increase more slowly. The resulting accumulation of lactic acid in the rumen causes a marked drop in pH which has an adverse effect on digestive processes in general. In mild cases, this may merely have a temporary negative effect on food intake and growth of the animal, but in the worst cases it may lead to ruminal stasis, cause permanent damage to the lining of the rumen wall and even result in death. Even though the incidence and severity of acute lactic acidosis may be restricted through careful diet formulation and inclusion of buffers and ionophore antibiotics in the diet, a small proportion of the animals brought into feedlots do not adapt readily to the highconcentrate diets and the performance of a larger proportion is probably negatively affected by sub-acute acidosis. The Nutritional Microbiology Section of the ARC Animal Nutrition and Animal Products Institute at Irene therefore embarked on the development of an alternative preventative and therapeutic treatment against lactic acidosis, viz. the administration of live, laboratory-grown cultures of highly-active lactate utilizers, specially selected for their potential for survival and multiplication in the rumen of animals on feedlot diets. By selective enrichment and extensive screening procedures a collection of phenotypically similar isolates of anaerobic, large, Gram-negative, acid-tolerant and ionophore-resistant cocci was obtained, which were presumptively identified as strains of Megasphaera elsdenii. These organisms utilized both L(+) and D(-) lactate and showed high specific growth rates on relatively inexpensive media even at low pH values, and they appeared to hold good promise for the intended application. In order to test the effectiveness of treatment of acidosis-compromised animals with cultures of these bacteria, information on their persistence in the rumen was required. Conventional microbiological counting methods were unsuitable for this purpose because of slowness and unsatisfactory specificity and precision. The present investigation deals primarily with the design and evaluation of a speciesspecific 16S rRNA probe for M elsdenii. It was intended for following the contribution of this species to the total microbial population of the rumen, as affected by the sudden exposure to high-concentrate diets. Furthermore, the phylogenetic relationship between the recent isolates, the type strain and previously sequenced strains of M elsdenii and M cerevisiae, as well as representatives of other rumen bacteria was investigated. In conclusion, the method for measuring the relative abundance of M elsdenii in rumen microbial populations with the aid of a custom-designed rRNA probe satisfactorily met the requirements of the proposed application.

Master of Science / Department of Animal Sciences and Industry / James M. Lattimer / Three experiments were conducted to determine the impact of novel probiotic (NP) supplementation in monogastric livestock and poultry. Experiment 1 evaluated effects of the probiotic on growth performance and cecal parameters in broiler chickens (n = 2520). Birds in treatment groups 1 and 2 were administered NP culture as either an oral gavage (OG) or an aerosolized mist (AM), respectively. Treatment group 3 served as a negative control (C). Growth performance and feed efficiency (FE) were unaffected by treatment (P > 0.10). Cecal pH was reduced in AM and OG birds compared to C (P < 0.05). This novel probiotic is most effective in altering cecal VFA profile before d 21 post-administration, after which no differences in VFA concentrations were detected between treatments. Reduction in cecal pH in response to NP indicates potential application of this probiotic as an acidifier, commonly used in poultry production as an antibiotic alternative. Experiment 2 was a swine performance study conducted to determine effects of treating sows or piglets or both with an oral gavage of NP. Factor 1 consisted of administration of NP oral gavage administered to sows or a negative control (n = 28). Factor 2 consisted of either a negative control or oral gavage of NP administered to litters of piglets shortly after birth and at weaning. Sow weight loss during lactation was unaffected by treatment (P > 0.10). Feed intake upon introduction to the nursery was greater in piglets that received NP directly than those that did not (P < 0.05). Large intestinal fermentation in both sows and piglets was affected by NP administration. Fecal VFA concentrations tended to be greater in animals that received NP either indirectly through the sow or directly via oral gavage (P < 0.05). Direct supplementation of piglets with NP is more effective in altering fermentation after d 21 than indirect administration, as VFA concentrations in piglets that received NP indirectly are similar to the control by d 28. Butyrate concentrations were greater in piglets that received NP; this VFA is important in prevention of intestinal atrophy and recovery from physiological stress of weaning. Experiment 3 examined effects of NP administered as either an oral drench (OD) or a lyophilized powder (LP) on equine cecal fermentation compared to a negative control (NC). Cecally cannulated horses (n = 8) were transitioned to a 1:1 roughage to concentrate diet over a period of 5 d. Cecal pH was greater than NC in OD and LP horses on d 5 and d 7, respectively (P < 0.10). Acetate:propionate ratio, valerate, and caproate concentrations also were greater in LP horses than NC on d 7 (P < 0.05). This may indicate improved gut health and fiber digestion in supplemented horses. The novel probiotic used in these studies is able to effectively alter large intestinal fermentation in monogastric species and may have potential to improve gut health and performance of these species.

Two vaginal phylotypes of the genus Megasphaera (phylotype 1 and phylotype 2) were recently associated with bacterial vaginosis (BV), an infection characterized by vaginal dysbiosis. Through an analysis of 16S rRNA profiles of 3,986 women enrolled in the Vaginal Human Microbiome Project, we confirmed that while both phylotypes were associated with BV, Megaspheara phylotype 1 had higher specificity for the condition. Megasphaera phylotype 2 was strongly associated with trichomoniasis. Previous studies have reported that BV-associated organisms are excluded in pregnancy. We observed that Megasphaera phylotype 1, which has been associated with adverse pregnancy outcomes, exhibited a trend of increased prevalence in the pregnant cohort. We sequenced the genomes of isolates of the two phylotypes and performed comparative analyses. We demonstrate that these two phylotypes have distinct genomic features and unique potential for metabolic processes that reveal niche specialization. These findings may provide insight into their differential associations with vaginal infections.

Master of Science / Department of Animal Sciences and Industry / James M. Lattimer / Eight cecally cannulated horses were used in a replicated, 4 x 4 Latin square design conducted in 4, 14-d periods to determine effects of sodium caseinate on equine hindgut fermentation and fiber digestion. Horses were maintained on an ad libitum diet of Smooth Bromegrass hay and treatments consisted of cecal infusions of water (CON), 0.125 g sodium caseinate/kg BW (LOW), 0.25 g sodium caseinate/kg BW (MED), and 0.50 g sodium caseinate/kg BW (HI). Cecal NH3 concentrations increased (P < 0.01) as casein increased. Horses on the CON and MED treatments had greater cecal pH (P < 0.01) than horses on the LOW and HI treatments; however, there was no effect of treatment of fecal pH. Dry matter, OM, NDF, and ADF digestibility were unaffected by treatment (P > 0.10). There were no differences in dry matter intake (DMI), regardless of treatment. There was no treatment effect on cecal acetate, propionate, butyrate, total VFA concentration or acetate:propionate (A:P) ratio. Inter-horse variability and a small sample size may contribute to the lack of statistical differences amongst treatments. Results from this study may imply that medium quality, roughage based protein supplies an adequate level of nitrogen to the microflora of the hindgut. A performance study was conducted to evaluate the effect of strain and method of administration of Megasphaera elsdenii on growth performance in broiler chickens. In Experiment 1, pens were randomly assigned to 1 of 6 treatments: 0.2 mL oral gavage containing 1.97 x 10⁹ CFU/mL of M. elsdenii strain NCIMB 41125 (Lactipro, MS-Biotec, Wamego, KS; O-L), 0.2 mL of fresh culture containing 0 CFU/mL of M. elsdenii strain KS 249 (O-KS; Attempts to grow this strain were unsuccessful), 0.2 mL of a fresh culture containing 1.06 x 10⁹ CFU/mL of M. elsdenii strain B52-2083 (O-B52), aerosolized mist at rate of 15 mL per pen containing 1.97 x109 CFU/mL of M. elsdenii strain NCIMB 41125 (~1.88 mL/bird; MS-Biotec, Wamego, KS; OM), topdressing (mixture of diet and freeze dried M. elsdenii strain NCIMB 41125; TD) containing 1.18 x 10⁷ CFU/g of M. elsdenii strain NCIMB 41125 at a rate of a quarter teaspoon per bird, or negative control that had no contact with the probiotic product. Broilers across all treatment groups showed similar ADFI (P = 0.82), ADG (P = 0.89), gain:feed (P = 0.93), and mortality rates (P = 0.54). In Experiment 2, chicks were assigned to 1 of 2 treatments consisting of lyophilized M. elsdenii strain NCIMB 41125 in the form of a topdressing (TD) or a negative control that had no contact with the probiotic product (C). Average daily gain (P = 0.02) and gain:feed (P = 0.04) were both greater in birds receiving the TD when compared to the C birds. Feed intake (P = 0.70) and mortality rates (P = 0.31) were not different between treatments. Administration of lyophilized M. elsdenii strain NCIMB 41125 may be an effective means to improve growth rate and feed efficiency of broiler chicks.

Master of Science / Department of Animal Sciences and Industry / James S. Drouillard / Ruminal characteristics and feedlot performance were measured for steers adapted to a high-grain diet using a traditional 22-d step-up program (Control) and for steers adapted over 10 d with the aid of M. elsdenii NCIMB 41125 fresh culture administered as an oral gavage (Fresh), an oral gavage of rehydrated lyophilized culture (Rehyd), or Rehyd combined with lyophilized culture powder administered daily as a ration top-dress (Rehyd+Daily). Yearling steers (n = 435; initial BW = 408 ± 5 kg) were blocked by weight and randomly allocated to 64 concrete surfaced pens with 7 steers/pen and 16 pens/treatment. Step-up diets contained 40, 30, and 20% corn silage, and were followed by a finishing diet containing 10% corn silage and 90% concentrate. Ruminal fluid was obtained from a subset of steers by rumenocentesis 26 h after their first feeding, and inoculated into culture tubes containing lactate medium to determine differences in capacity for lactate metabolism over 24 h. A radiofrequency pH bolus was placed in the reticulorumen of 32 steers, that measured ruminal pH every 10 min for 124 d. Steers were fed once daily ad libitum for 156 d, then weighed, and transported 450 km to a commercial abattoir for harvest. HCW and incidence of liver abscesses were determined at harvest and carcass traits were evaluated after 36 h of refrigeration. No differences were detected for feedlot performance (P > 0.20), liver abscesses (P = 0.45), or carcass traits (P > 0.20). Capacity for lactate utilization was increased with all forms of M. elsdenii, as evidenced by increases in optical density (absorbance) of M. elsdenii cultures, disappearance of lactate, and increase in butyrate production (P < 0.01). Steers on Rehyd and Rehyd+Daily treatments spent less time between pH thresholds of 5.6 > pH > 5.2 (P < 0.01); 5.2 > pH > 5.0 (P < 0.01); and pH < 5.0 (P < 0.01) than Controls throughout the finishing period. In conclusion, steers dosed with M. elsdenii can be stepped up to finishing diets in 10 d with no adverse effects on performance. Ruminal fluid containing fresh cultures or freeze-dried and rehydrated cultures of M. elsdenii NCIMB 41125 were equally effective in metabolizing lactic acid. Lyophilized M. elsdenii resulted in less time below important pH thresholds, but no further benefit of daily administration was realized in this experiment.

Rumen acidosis is a common problem under feedlot conditions where cattle change from a roughage-based to a high concentrate-based diet. It is associated with an imbalance between lactic acid producing and lactic acid utilizing bacteria. Megasphaera eldenii is an important lactic acid utilizing bacteria which can now be produced for commercial use and supplemented for the prevention of lactic acid build up in the rumen and subsequent acidosis. The adaptation period is required in order for numbers of lactate utilizers such as M. elsdenii to increase to levels effective against subsequent build up of lactic acid. The purpose of this trial is to identify the effects of a strain, NCIMB 41125 (MeCH4), of Megasphaera elsdenii on the adaptation period of feedlot cattle on diets formulated for high starch levels. MeCH4 was isolated from the rumen of cattle adapted to high starch diets. By converting lactic acid in the rumen to volatile fatty acids (VFA’s) such as butyrate, M. elsdenii should be able to at least reduce the adaptation phase, if not totally eliminate the need for it without effects on intake patterns, feed conversion rates, health and carcass yield. . If results are positive, this strain of M. eldenii will have great economic implications to all feedlot farmers. There may be one major conclusion to be drawn from this trail and this was the fact that a decrease in adaptation days to reach the high concentrate grower diet had no statistically significant influence on key performance parameters relevant to the feedlot industry However, possibly the most attractive implication of these results is the lower need for roughage and therefore the implications tied in with the buying in and storage thereof. / Dissertation (MSc)--University of Pretoria, 2010. / Animal and Wildlife Sciences / unrestricted

No description available.

Doctor of Philosophy / Department of Animal Sciences and Industry / J. S. Drouillard / Four experiments were conducted to evaluate the potential for accelerating adaption to high-concentrate diets and improving the health of high-risk calves, by administering an oral dose of Megasphaera elsdenii. Lactipro, a probiotic containing a live culture of Megasphaera elsdenii (10[superscript]9 CFU/mL), was orally dosed to cattle (100 mL) at initial processing. In experiment 1, heifers were adapted to a high-concentrate diet in 21 d without Lactipro or dosed with Lactipro and adapted in 16 d, 11 d, 6 d, or fed the high-concentrate diet d 1. Accelerating adaptation decreased DMI (P = 0.09), ADG, and efficiency (P < 0.05) during the first 30 d compared to cattle adapted over 21 d. Over 129 d, DMI and ADG were not different (P ≥ 0.12), but efficiency tended (P = 0.08) to be better for cattle adapted over 21 d. Liver abscesses and carcass traits were not different between treatments, with the exceptions of LM area (quadratic, P < 0.01) and marbling (linear, P = 0.07), which tended to increase with accelerated adaptation protocols. In experiment 2, cattle dosed with Lactipro and placed directly onto the finishing diet required less roughage (P < 0.01), tended to have lower DMI (P = 0.07), better quality grade (P ≤ 0.07), and similar ADG and efficiency (P ≥ 0.14) compared to cattle adapted over 18 d without Lactipro. Over the first 24 d DMI, DM fecal output, and apparent total tract NDF digestibility were greater (P < 0.01) for cattle adapted over 18 d. In Experiment 3, dosing calves, of Mexican origin, with Lactipro did not affect performance (P ≥ 0.16). Second antibiotic therapies for undifferentiated bovine respiratory disease (UBRD) tended (P = 0.06) to be lower in calves dosed Lactipro. In Experiment 4, dosing calves from Texas with Lactipro increased DMI, ADG, and efficiency (P ≤ 0.05). The incidence of 1st and 2nd antibiotic therapies for UBRD (P < 0.01) and medical cost were decreased for calves dosed Lactipro (P < 0.05). Dosing cattle with Lactipro allows for accelerated adaption to high-concentrate diets, decreases reliance on roughages, and improves health during the receiving period.

Master of Science / Department of Animal Sciences and Industry / James S. Drouillard / Two experiments were conducted to evaluate the efficacy of [italic]Megasphaera elsdenii[italic] strain NCIMB 41125 and its potential use in the mitigation of ruminal acidosis. In experiment 1, a metabolism study was conducted to evaluate ruminal parameters, quantify changes in ruminal bacterial populations, and determine in vitro capacity for lactate utilization following intraruminal dosing of a placebo or [italic]M. [italic]elsdenii strain NCIMB 41125 and an abrupt diet change. Angus crossbred steers (n=20; average BW=253 ± 24 kg) fitted with ruminal cannulas were blocked by BW and assigned randomly to treatments. Treatments consisted of intraruminal dosing with a placebo (100 mL of autoclaved culture), or 10, 100, or 1,000 mL of a live culture containing 1.62×108 CFU/mL of [italic]M. elsdenii[italic] strain NCIMB 41125. Prior to inoculation, cattle were placed into individual pens in an enclosed facility and allowed free access to alfalfa hay, salt, and water. Feed and water were removed for 24 h prior to administering treatments, after which, cattle were allowed free access to a diet consisting of 34% alfalfa hay and 66% steam-flaked corn-based concentrate. On d 7, cattle were fed an 80% concentrate diet. On d 12, steers were started on the final finishing diet of 94% concentrate. Ruminal pH and concentrations of lactate and VFAs were monitored following introduction of each concentrate diet. Ruminal samples were collected at 0, 2, 4, 6, 8, and 24 h after feeding for quantitative rt-PCR detection of native and introduced strains of [italic]M. elsdenii[italic], as well as total bacterial genomes. Capacity for metabolism of lactic acid was evaluated by inoculating 0.2 mL of strained ruminal fluid into anaerobic culture tubes containing 15 mL of semi-defined lactate medium. Tubes were incubated at 39˚C, and turbidity changes were determined by measuring absorbance at 2 h intervals up to 12 h. Experiment 2 was conducted in a commercial feedlot to evaluate the efficacy of [italic]M. elsdenii[italic] strain NCIMB 41125 for improving feedlot performance. A second objective of the study was to determine if oral dosing of [italic]M. elsdenii[italic] has the potential for reducing the number of cattle treated for bovine respiratory disease. Angus steers and heifers (n = 3179; average BW = 356 ± 58.4kg) were used in a randomized complete block design with two treatments. Cattle were assigned to treatment on an every-other-head basis such that every-other-animal was orally drenched with 100 mL of a culture medium containing 1.5×108 cfu/mL [italic]M. elsdenii[italic] strain NCIMB 41125 at processing. Cattle were blocked by gender and date of arrival. To maximize profitability, cattle were sorted via visual appraisal to identify cattle that were market ready. Cattle were shipped to a commercial abattoir in Lexington, NE for harvest. Data obtained for each pen of cattle included feedlot performance, morbidity, mortality, carcass characteristics, and grid-based program carcass qualifications. In trial 1, compared to the placebo group, cattle administered [italic]Megasphaera[italic] maintained higher ruminal pH 24 h after the carbohydrate challenge (P < 0.05). Ruminal lactate concentrations increased in response to the diet change (P < 0.05), but concentrations were lower for cattle that received [italic]Megasphaera[italic] compared to the placebo group (P < 0.05). Total number of bacterial genomes 24 h after inoculation was unaffected by intraruminal dosing of [italic]M. elsdenii[italic] strain NCIMB 41125 (P > 0.05), but populations of undifferentiated [italic]M. elsdenii[italic] and strain NCIMB 41125 increased by 24 h after inoculation (P < 0.05). Turbidity of cultures inoculated with ruminal fluid increased in response to [italic]M. elsdenii[italic] administration (P < 0.05), suggesting a greater capacity for lactate utilization in inoculated cattle compared to the placebo group. In trial 2, no differences in feed efficiency were observed (P > 0.05). Compared to cattle dosed with [italic]Megasphaera[italic], the control group had more USDA yield grade 2 carcasses (P < 0.05), and cattle dosed with [italic]M. elsdenii[italic] had more USDA yield grade 5 carcasses (P < 0.05). [italic]Megasphaera[italic] cattle also tended to have more USDA Prime carcasses (P = 0.14). No effects on incidence of liver abscesses were observed. Dosing cattle with [italic]M. elsdenii[italic] prior to introduction of typical concentrate diets may be useful in preventing ruminal lactate accumulation and associated depressions in ruminal pH. Inoculating cattle with [italic]M. elsdenii[italic] is effective in bolstering populations of ruminal lactate utilizers, and may be useful in preventing ruminal lactate accumulation in grain-fed cattle. No effects on reducing episodes of BRD were noted.

Rumen acidosis is a metabolic disorder of ruminants, characterized by a severe drop in rumen pH. This is due to an accumulation of acids, especially lactic acid in the rumen. Lactic acid is one of the strongest acids with a major effect on rumen pH. A low and / or fluctuating rumen pH can have a severe impact on the productivity and health of dairy cattle, especially during the early lactation period. Rumen acidosis can, for example, occur during the rapid change from a low concentrate to a high concentrate diet. Megasphaera elsdenii (Me) is a lactate-utilizing micro-organism that converts the lactic acid that is produced from the fermentation of starch in the rumen, to propionic acid. Based on the ability of Me to convert lactic acid to propionic acid, a study was conducted to determine the effect of dosing live sources of Me on the level of rumen acidosis, general health and productivity. Sixty high-producing multiparous dairy cows were used in a randomized complete block design experiment. Cows were blocked according to milk production during the previous lactation and, thereafter, randomly allocated, within each block, to one of the following treatments: <ol> <li> 60% concentrate TMR;</li> <li> 60% concentrate TMR with Me dosing;</li> <li> 70% concentrate TMR;</li> <li> 70% concentrate TMR with Me dosing.</li></ol> The experimental period was 60 days and cows were dosed on day 2, 10 and 20 post-partum. Cows were housed in a semi-intensive housing unit equipped with Calan gates for determining individual feed intake. Daily milk production and dry matter intake were measured, as well as body mass and body condition score. Milk was analyzed for fat, protein, lactose and MUN; rumen fluid for pH, volatile fatty acids and lactic acid; faecal samples for pH and starch and feed refusal samples for nutrient components. In addition the health statuses of the cows were also monitored. In general the results did not show a clear advantage of dosing Me, regardless of the level of concentrate. Dry matter intake, milk production, milk composition, feed efficiency, body mass and body condition score were not affected by treatment (P > 0.05). Contrary to expectation, treatment did not affect rumen pH, rumen lactic acid or volatile fatty acid concentrations (P > 0.05). Faecal pH, however, was higher and the starch content lower in cows dosed with Me (P < 0.05) suggesting a positive effect on rumen fermentation and more efficient total tract starch fermentation. Furthermore only two cows were culled from the dosed group, compare to eleven from the control group, suggesting a positive influence of Me on the general health of stress, early lactation cows. Further research is needed to better quantify the potential role of Me in preventing SARA. / Dissertation (MSc(Agric))--University of Pretoria, 2008. / Animal and Wildlife Sciences / unrestricted