Diet and monensin influence the temporal dynamics of the rumen microbiome in stocker and finishing cattle

Background Stocker cattle diet and management influence beef cattle performance during the finishing stage,but knowledge of the dynamics of the rumen microbiome associated with the host are lacking.A longitudinal study was conducted to determine how the feeding strategy from the stocker to the finishing stages of production affects the temporal dynamics of rumen microbiota.During the stocker phase,either dry hay or wheat pasture were provided,and three levels of monensin were administrated.All calves were then transported to a feedlot and received similar finishing diets with or without monensin.Rumen microbial samples were collected on d 0,28,85 during the stocker stage(S0,S28 and S85)and d 0,14,28,56,30 d before slaughter and the end of the trial during the finishing stage(F0,F14,F28,F56,Pre-Ba,and Final).The V4 region of the bacterial 16S rRNA gene of 263 rumen samples was sequenced.Results Higher alpha diversity,including the number of observed bacterial features and the Shannon index,was observed in the stocker phase compared to the finishing phase.The bacterial amplicon sequence variants(ASVs)differentiating different sampling time points were identified.Dietary treatments during the stocker stage temporally impact the dynamics of rumen microbiota.For example,shared bacteria,including Bacteroidales(ASV19)and Streptococcus infantarius(ASV94),were significantly higher in hay rumen on S28,S85,and F0,while Bacteroidaceae(ASV11)and Limivicinus(ASV15)were more abundant in wheat.Monensin affected rumen microbial composition at a specific time.Transportation to feedlot significantly influenced microbiome structure and diversity in hay-fed calves.Bacterial taxa associated with body weight were classified,and core microbiotas interacted with each other during the trial.Conclusions In summary,the temporal dynamics of the rumen microbiome in cattle at the stocker and finishing stage are influenced by multiple factors of the feeding strategy.Diet at the stocker phase may temporarily affect the microbial composition during this stage.Modulating the rumen microbiome in the steers at the stocker stage affects the microbial interactions and performance in the finishing stage.

Effect of simulated gastrointestinal digestion on antioxidant,and anti-inflammatory activities of bioactive peptides generated in sausages fermented with Staphylococcus simulans QB7

Dry-fermented sausages are a good source of bioactive peptides,whose stability against gastrointestinal(GI)digestion determines their bioaccessibility.This study focused on evaluating the effect of peptide extracts from sausages fermented with Staphylococcus simulans QB7 during in vitro simulated GI digestion,including peptide profiles and antioxidant and anti-inflammatory activities.Peptides present in sausages were degraded during digestion,with molecular weight reduced from>12 kDa to<1.5 kDa.Besides,the content of amino acids increased from 381.15 to 527.07 mg/g,especially tyrosine being found only after GI digestion.The anti-inflammatory activities were increased after GI digestion,however,the changes in antioxidant activities were the opposite.A total number of 255,252 and 386 peptide sequences were identified in undigested,peptic-digested and GI-digested samples,respectively.PeptideRanker,BIOPEP-UWM and admetSAR were used to further predict the functional properties and intestinal absorption of the identified peptide sequences from GI digestion.Finally,18 peptides were discovered to possess either antioxidant or anti-inflammatory capacities.

Body Weight and Steroidal Implants Impact Animal Growth Performance, Sera Metabolites, and Pulmonary Arterial Pressure in Feedlot Cattle

The study objective was to evaluate steer growth performance, sera metabolite responses, carcass characteristics, and pulmonary arterial pressure as affected by body weight at time of implantation and steroidal implant administration. Crossbred steers (n = 20) were used in a 2 × 2 factorial arrangement of treatments in a completely randomized design experiment, Factors included: body weight: light (L), or heavy (H) and implant: Non-implanted (NoIMP), or Implanted (IMP) with steer serving as the experimental unit for all analyses. Initial weights for L and H steers were 398 ± 27.6 and 547 ± 25.2 kg, respectively. Implanted steers received a terminal implant (200 mg trenbolone acetate and 20 mg estradiol-17β;Revalor-200;Merck Animal Health, Madison, NJ) on d 0. Cattle within treatments were group housed in common pens (n = 5 steers/pen). Bodyweight, blood samples, and pulmonary arterial pressure were collected on d 0, 14, 35, 70 and 104. Cattle were fed a common diet once daily to provide ad libitum access to feed. The finishing diet contained (DM basis) 13.3% CP, 2.13 Mcal/kg NEm, and 1.45 Mcal/kg NEg. Growth performance (body weight and ADG) and carcass traits were analyzed using the MIXED procedure of SAS 9.4 (SAS Inst. Inc., Cary, NC). Sera metabolites were analyzed as repeated measures over time, with day as the repeated measure. For all analyses, α level < 0.05 determined significance. Heavy steers consumed 2.2 kg more per head of DM daily than L cattle and IMP steers consumed 1.0 kg more DM daily than NoIMP steers. Cumulative ADG did not differ between the L and H steers (1.41 vs. 1.52 ± 0.060 kg;P = 0.20). Implanting increased (P < 0.01) ADG by 39% (1.22 vs. 1.70 ± 0.060 kg). No differences (P > 0.05) in ADG were observed in NoIMP vs. IMP cattle beyond d 70 (1.21 vs. 1.01 ± 0.16 kg;P = 0.38). Sera urea-N concentrations were decreased (P < 0.01) in L cattle subjected to IMP during the study and tended to increase over time for the other treatments. Ribfat, HCW, LM, marbling score, calculated YG, and estimated EBF were greater (P ≤ 0.05) in H compared to L. Steers from IMP had heavier HCW (P < 0.01) but decreased marbling scores (P = 0.05) compared to NoIMP. Mean pulmonary arterial pressure was greater (P < 0.01) for H compared to L steers which may predispose heavier cattle to right-sided heart failure. The steroid implant had no effect on pulmonary arterial pressure (P > 0.49). The study reaffirms the effects of implanting on animal growth performance and carcass characteristics in cattle. In addition, elevated BW leads to increased pulmonary arterial pressures which may increase the risk of right-sided heart failure.

Maternal Supplementation of Saccharomyces cerevisiae var. boulardii to Sows from Late Gestation through Lactation Impacts the Neutrophil Function of the Sow and the Innate Immune Status of Progeny Short-Term

The primary objective of this study was to evaluate the potential immunomodulatory effect of maternal supplementation of Saccharomyces cerevisiae var. boulardii (Scb) from late gestation until the end of lactation on the immune phenotype of her progeny. Eighteen sows were fed 2 boluses per day of Saccharomyces cerevisiae var. boulardii CMCN-1079 (probiotic;PRO, n = 9) or placebo (CON, n = 9) starting at gestational day (GD) 84 and continuing until 21 days post-farrowing (end of lactation). Sow blood samples were collected every 7 days post-supplementation during gestation and 24-h post-farrowing and end of lactation. Blood samples were taken from 84 female pigs (n = 42 per sow treatment group) at 1, 7, 14, 21, 28, and 35 days old to assess innate and adaptive immune measures. Minimal effects of Scb supplementation were found on sow immune status during gestation and lactation, except for PRO-treated sows that had enhanced neutrophil function (P and mitogen-induced lymphocyte proliferation after 51 days of treatment (P < 0.0001). Overall, pigs from PRO-treated sows had higher C5a- and IL-8-induced neutrophil chemotaxis, NK cytotoxicity, and mitogen-induced B-lymphocyte proliferation than those from CON sows (P inimal effect on the sows but postnatal maternal exposure to Saccharomyces cerevisiae var. boulardii supplementation modulated the immune status of the progeny beyond the lactation period resulting in those from PRO-treated sows having more enhanced neutrophil function and B-cell proliferative response in the short term. Therefore, these data imply that including yeast probiotics in maternal diets may have carry-over effects in priming offspring’s immune function, especially neutrophil function and B-cell proliferation in the short term.

Next Generation Lubricants and Their Potential Use in Fertility Treatment

While generally recognized as a potential source of contamination during the collection process, lubricants are often used at the preference of the male partner to prevent irritation. While older lubricants have been studied, there is currently no conscience within programs as to what constitutes a “safe” lubricant. The object of the current study was designed to evaluate chemically unique “next generation” lubricants in comparison to lubricants currently in use in fertility treatment and/or recognized as fertility safe;the first was a silicone-based lubricant, the second is a water-based, plant-based organic compound, in comparison to two established medical lubricants and a control. Twelve deidentified semen samples from the clinical andrology laboratory were used to test the lubricants following semen analysis. In order to enter the study, the sample had to have a minimum of 30 × 106 motile cells. Samples were then processed using a simple sperm wash modified to reconstitute the pellet into a final volume of 7 mL. Half-milliliter aliquots were then transferred into 13 wells of a standard 24-well culture plate. One well was used as a control. The remaining wells received one of the four lubricants at one of three volumes (10, 50, or 100 uL), producing 12 treatment combinations (four lubricants + 3 concentration levels) and the control. The samples were then cultured at room temperature for 24 hours. At times 0, 1, 3, 12, and 24 hrs, the plate was agitated to remix the sample, and a 4 uL aliquot of each well was analyzed for standard semen parameters using a computer-assisted semen analyzer. Results indicated the expected decrease in semen parameters over time in all treatments (P < 0.001). There was also a dose-dependent drop in most of the lubricants. However, samples contaminated with the newer lubricants appeared to maintain semen parameters similar to the controls at all but the 100 ul level of contamination, while the older lubricants caused decreases in sperm function at much lower concentrations. While semen parameters alone should not be the only criteria for the selection of a lubricant, the present study suggests newer formulations of lubricant are less likely to interfere with sperm function.

Partially defatted black soldier fly larva meal inclusion in piglet diets: effects on the growth performance, nutrient digestibility,blood profile, gut morphology and histological features

Background:The aim of this trial was to investigate the effects of different inclusion levels of a partially defatted black soldier fly (BSF,Hermetia illucens L.) larva meal on the growth performance,nutrient digestibility,blood profile,gut morphology and histological features of piglets.A total of 48 newly weaned piglets were individually weighed (initial body weight (IBW):6.1 ± 0.16 kg) and randomly allocated to 3 dietary treatments (4 boxes as replicates/treatment and 4 animals/box).BSF larva meal was included at increasing levels (0% [BSF0],5% [BSFS] and 10% [BSF10]) in isonitrogenous and isoenergetic diets formulated for two feeding phases:Ⅰ (from d 1 to d 23) and Ⅱ (from d 24 to d 61).The weight gain (WG),average daily gain (ADG),average daily feed intake (ADFI) and feed conversion ratio (FCR) were calculated for each feeding phase and for the whole trial.The haematochemical parameters and nutrient digestibility of the piglets were also evaluated.A total of 3 piglets per box were slaughtered on d 61 and the slaughtered piglets were submitted to morphometric investigations and histopathological examinations.Results:No overall significant differences were observed for growth performance (P > 0.05),except for the ADFI of phase Ⅱ,which showed a linear response to increasing BSF meal levels (P < 0.05,maximum for the BSF10 group).Dietary BSF meal inclusion did not significantly influence the blood profile,except as far as monocytes and neutrophils are concerned,and these showed a linear and quadratic response,respectively,to increasing BSF meal levels (P < 0.05,maximum for the BSF10 and BSF5 groups,respectively).On the other hand,the nutrient digestibility,gut morphology and histological features were not affected by dietary BSF meal inclusion (P > 0.05).Conclusions:The obtained results show that a partially defatted BSF larva meal can be used as a feed ingredient in diets for weaned piglets without negatively affecting their growth performance,nutrient digestibility,blood profile,gut morphology or histological features.

Linkage between the intestinal microbiota and residual feed intake in broiler chickens

Background:Intestinal microbiota plays a key role in nutrient digestion and utilization with a profound impact on feed efficiency of livestock animals.However,the intestinal microbes that are critically involved in feed efficiency remain elusive.Methods:To identify intestinal bacteria associated with residual feed intake(RFI)in chickens,male Cobb broiler chicks were individually housed from day 14 to day 35.Individual RFI values were calculated for 56 chickens.Luminal contents were collected from the ileum,cecum,and cloaca of each animal on day 35.Bacterial DNA was isolated and subjected to 16S rRNA gene sequencing.Intestinal microbiota was classified to the feature level using Deblur and QIIME 2.High and low RFI groups were formed by selecting 15 and 17 chickens with the most extreme RFI values for subsequent LEfSe comparison of the difference in the microbiota.Spearman correlation analysis was further performed to identify correlations between the intestinal microbiota composition and RFI.Results:No significant difference in evenness,richness,and overall diversity of the microbiota in the ileum,cecum,or cloaca was observed between high and low RFI chickens.However,LEfSe analysis revealed a number of bacterial features being differentially enriched in either high or low RFI chickens.Spearman correlation analysis further identified many differentially enriched bacterial features to be significantly correlated with RFI(P<0.05).Importantly,not all short-chain fatty acid(SCFA)producers showed a positive association with RFI.While two novel members of Oscillibacter and Butyricicoccus were more abundant in low-RFI,high-efficiency chickens,several other SCFA producers such as Subdoligranulum variabile and two related Peptostreptococcaceae members were negatively associated with feed efficiency.Moreover,a few closely-related Lachnospiraceae family members showed a positive correlation with feed efficiency,while others of the same family displayed an opposite relationship.Conclusions:Our results highlight the complexity of the intestinal microbiota and a need to differentiate the bacteria to the species,subspecies,and even strain levels in order to reveal their true association with feed efficiency.Identification of RFI-associated bacteria provides important leads to manipulate the intestinal microbiota for improving production efficiency,profitability,and sustainability of poultry production.

Bacterial Colonization of the Equine Gut;Comparison of Mare and Foal Pairs by PCR-DGGE

Horses, like all animals, are born without the symbiotic microbes that occupy the gastrointestinal tracts of mature animals. As grazing animals, horses rely on these microbes to fully utilize the grasses and other cellulosic feeds that they consume. Thus, colonization of the foal's gastrointestinal tract must occur between birth and weaning. The feces of nine mare and foal pairs were sampled from the day of parturition until 12 weeks of age, and the samples were analyzed by polymerase chain reaction amplification of the bacterial 16S rRNA gene and denaturing gradient gel electrophoresis (PCR-DGGE). The gels from feces of day (d) 0 foals had no or very few ( x = 3, n = 6) bands, which indicates that species richness was low. The number of bands increased during the first 4 days of life, and by d 14 the foals and mares had similar numbers of bands ( x = 28, n = 23). Some bands were present in young foals, but not in mares or in foals on d 42 or d 84, which indicated succession of bacterial species. When the PCR-DGGE profiles were compared with Dice's algorithm, all mare-foal pairwise similarities on d 14 and later were as great as the pairwise similarities between mares. These results are consistent with the idea that foals are born with a sterile gut, colonization proceeds rapidly, and a mature microbial community is present in the first few weeks of life.

Dietary branched-chain amino acids modulate the dynamics of calcium absorption and reabsorption in proteinrestricted pigs

Background:Very low-protein(VLP)diets negatively impact calcium(Ca)metabolism and absorption.The objective of this study was to investigate the effect of supplemental branched-chain amino acids(BCAA)and limiting amino acids(LAA)on Ca digestibility,absorption and reabsorption in pigs fed with VLP diets.Forty-eight piglets were assigned to six treatments:positive control(PC),negative control(NC),and NC containing LAA 25%,LAA 50%,LAA+BCAA 25%(LB25)and LAA+BCAA 50%(LB50)more than recommendations.Results:Relative to PC or NC,LB25 and LB50 had higher digestibility of Ca and plasma Ca and phosphorus(P),but lower plasma vitamin D3.LB50 tended to increase vitamin D receptor transcript and protein in the gut,but decreased mRNA or protein abundance of parathyroid hormone 1 receptor(PTH1R),calbindin 1(CALB1),cytochrome P450 family 27 subfamily B member 1 and occludin in small intestine.LB50 increased the transcript of cytochrome P450 family 24 subfamily A member 1 and PTH1R but decreased the transcript of transient receptor potential cation channel subfamily V member 5,CALB1 and solute carrier family 17 member 4 in kidney.Conclusion:Overall,BCAA increased Ca digestibility through regulating the transcellular and paracellular Ca absorption in the gut and reabsorption in kidney during protein restriction.

Butyrate in combination with forskolin alleviates necrotic enteritis,increases feed efficiency,and improves carcass composition of broilers

Background:The emergence of antimicrobial resistance has necessitated the development of effective alternatives to antibiotics for livestock and poultry production.This study investigated a possible synergy between butyrate and forskolin(a natural labdane diterpene)in enhancing innate host defense,barrier function,disease resistance,growth performance,and meat quality of broilers.Methods:The expressions of representative genes involved in host defense(AvBD9 and AvBD10),barrier function(MUC2,CLDN1,and TJP1),and inflammation(IL-1β)were measured in chicken HD11 macrophages in response to butyrate and forskolin in the presence or absence of bacterial lipopolysaccharides(LPS).Intestinal lesions and the Clostridium perfringens titers were also assessed in C.perfringens-challenged chickens fed butyrate and forskolincontaining Coleus forskohlii(CF)extract individually or in combination.Furthermore,growth performance and carcass characteristics were evaluated in broilers supplemented with butyrate and the CF extract for 42 d.Results:Butyrate and forskolin synergistically induced the expressions of AvBD9,AvBD10,and MUC2 in chicken HD11 cells(P<0.05)and the synergy was maintained in the presence of LPS.Butyrate and forskolin also suppressed LPS-induced IL-1βgene expression in HD11 cells in a synergistic manner(P<0.05).The two compounds significantly reduced the intestinal lesions of C.perfringens-challenged chickens when combined(P<0.05),but not individually.Furthermore,butyrate in combination with forskolin-containing CF extract had no influence on weight gain,but significantly reduced feed intake(P<0.05)with a strong tendency to improve feed efficiency(P=0.07)in a 42-d feeding trial.Desirably,the butyrate/forskolin combination significantly decreased abdominal fat deposition(P=0.01)with no impact on the carcass yield,breast meat color,drip loss,or pH of d-42 broilers.Conclusions:Butyrate and forskolin has potential to be developed as novel antibiotic alternatives to improve disease resistance,feed efficiency,and carcass composition of broilers.

Oleic acid Stimulates the Formation of Adipocyte-Like Cells from Bovine Satellite Cells via <i>G-Protein Coupled Receptor 43</i>and <i>CCAAT/Enhancer-Binding Protein Beta</i>

Numerous physiological and pathological processes are controlled by free fatty acids, which act as signaling molecules in mammals. We hypothesized that oleic acid (Ole) might stimulate the formation of satellite-cell-derived intramuscular adipose tissue. The role of Ole as a ligand of G-protein-coupled receptor 43 (GPR43) was previously identified. Thus, the objective of the current study was to determine the effect of Ole on GPR43 and factors related to the adipogenic differentiation of bovine satellite cells (BSC). Treatments of 100 μM and 500 μM Ole tended to induce greater (P < 0.10) mRNA expression of CCAAT/enhancer-binding protein β (C/EBPβ) compared to all other doses. The mRNA abundance of peroxisome proliferator-activated receptor γ (PPARγ) was not altered (P > 0.10) by treatment. The addition of 100 μM and 500 μM of Ole upregulated (P < 0.05) GPR43 mRNA expression. Protein level of GPR43 was increased (P < 0.05) by 100 μM of Ole treatments. Addition of Ole to BSC cultures induced transformation of myogenic cells into adipocyte-like cells that formed cytoplasmic lipid droplets. Increased expression of C/EBPβ in response to Ole might suppress myogenic differentiation. After the treatment of cells with Ole, increased expression of GPR43 could lead to phosphorylation of 5’ AMP-activated protein kinase α (AMPKα). Altogether, the results indicated that increased Ole might stimulate adipose tissue accumulation within the skeletal muscle of cattle by promoting adipogenic differentiation and activation of GPR43 in satellite cells.

Estimation of Weight and Lipid Composition in Preimplantation Embryos from Jersey and Beef Breeds of Cattle

Cryopreservation is the main functional means for storage of excess embryos produced from artificial reproductive technologies;the process assumes embryos chemical nature is highly conserved across embryos of the same species. However, in practice there appears to be a high degree of variability in embryo tolerance to cryopreservation, suggesting potential differences in embryo chemistry. The objective of the current study was to develop reproducible means of estimating relative embryos weight and associating those weights to lipid content. Relative embryo weights of frozen/thawed in-vivo Jersey and Crossbred beef breed embryos were determined using a modified specific gravity chamber. Embryo weights were then correlated with lipid content. Results suggest that beef cattle embryos are 20% - 27% heavier than Jersey embryos

Genomic patterns of homozygosity and inbreeding depression in MurcianoGranadina goats

Background:Inbreeding depression can adversely affect traits related to fitness,reproduction and productive performance.Although current research suggests that inbreeding levels are generally low in most goat breeds,the impact of inbreeding depression on phenotypes of economic interest has only been investigated in a few studies based on genealogical data.Results:We genotyped 1040 goats with the Goat SNP50 BeadChip.This information was used to estimate different molecular inbreeding coefficients and characterise runs of homozygosity and homozygosity patterns.We detected38 genomic regions with increased homozygosity as well as 8 ROH hotspots mapping to chromosomes 1,2,4,6,14,16 and 17.Eight hundred seventeen goats with available records for dairy traits were analysed to evaluate the potential consequences of inbreeding depression on milk phenotypes.Four regions on chromosomes 8 and 25were significantly associated with inbreeding depression for the natural logarithm of the somatic cell count.Notably,these regions contain several genes related with immunity,such as SYK,IL27,CCL19 and CCL21.Moreover,one region on chromosome 2 was significantly associated with inbreeding depression for milk yield.Conclusions:Although genomic inbreeding levels are low in Murciano-Granadina goats,significant evidence of inbreeding depression for the logarithm of the somatic cell count,a phenotype closely associated with udder health and milk yield,have been detected in this population.Minimising inbreeding would be expected to augment economic gain by increasing milk yield and reducing the incidence of mastitis,which is one of the main causes of dairy goat culling.

Effects of Spent Craft Brewers’ Yeast on Fermentation and Methane Production by Rumen Microorganisms

Saccharomyces cerevisiae is a key component of beer brewing and a major by-product. The leftover, spent brewers’ yeast from large breweries has been used as a protein supplement in cattle;however the possible advantages of spent yeast from smaller craft breweries, containing much higher levels of bioactive hop acids, have not been evaluated. Hops secondary metabolites from the hops (Humulus lupulus L.) used to make beer are concentrated in the yeast during brewing, and have antimicrobial activity against Gram-positive bacteria. Uncultivated suspensions of bovine rumen microorganisms produced less methane during fructose fermentation when exposed to inactivated, and freeze-dried spent craft brewers’ yeast than a bakers’ yeast control. The experiment was repeated with caprine rumen microorganisms and ground grass hay as the substrate. Likewise, in the presence of craft brewers’ yeast less methane was produced (2.7% vs. 6.9% CH4). Both experiments also revealed a decrease in acetic acid production, but not propionic acid production, when craft brewers’ yeast was included. These results indicated that spent yeast could represent a co-product for craft breweries, and a feed supplement for ruminants that has a favorable impact on methane production.

Disappearance and appearance of an indigestible marker in feces from growing pigs as affected by previous-and currentdiet composition

Background: Indigestible markers are commonly utilized in digestion studies, but the complete disappearance or maximum appearance of a marker in feces can be affected by diet composition, feed intake, or an animal's BW.The objectives of this study were to determine the impact of previous(Phase 1, P1) and current-(Phase 2, P2)diet composition on marker disappearance(Cr) and appearance(Ti) in pigs fed 3 diets differing in NDF content.Results: When pigs were maintained on the 25.1, 72.5, and 125.0 g/kg NDF diets, it took 5.1, 4.1, and 2.5 d, respectively,for Cr levels to decrease below the limit of quantitation; or 4.6, 3.7, or 2.8 d, respectively, for Ti to be maximized. These effects were not, however, independent of the previous diet as indicated by the interaction between P1 and P2 diets on fecal marker concentrations(P < 0.01). When dietary NDF increased from P1 to P2, it took less time for fecal Cr to decrease or fecal Ti to be maximized(an average of 2.5 d), than if NDF decreased from P1 to P2 where it took longer for fecal Cr to decrease or fecal Ti to be maximized(an average of 3.4 d).Conclusions: Because of the wide range in excretion times reported in the literature and improved laboratory methods for elemental detection, the data suggests that caution must be taken in considering dietary fiber concentrations of the past and currently fed diets so that no previous dietary marker addition remains in the digestive tract or feces such that a smal amount of maker is present to confound subsequent experimental results, and that marker concentration have stabilized when these samples are col ected.

The relationship between maternal body fat and pre-implantation embryonic weight: Implications for survival and long-term development in an assisted reproductive environment

There can be little argument that embryo quality is one of the most critical factors in the success of assisted reproductive techniques. Yet the current methods of grading embryos are subjective at best. While a number of different groups have described more qualitative means of assessing embryo quality, the current standard remains morphology. Morphology has proven a good standard, but it does not allow for the detection of chromosomal abnormalities nor can it assess the biochemical status of the embryo prior to transfer. This laboratory recently described a method to estimate embryo weight and suggested weight might be a good indicator of biochemical status. The objective of the present study was to determine the relationship between maternal body composition and embryo weight and determine the influence maternal chemistry had on embryo development. The data continue to suggest that maternal body composition, especially body fat, influences the chemical nature of the embryo and may play a critical role in long-term survival.

Interactive Effects of Zinc and Zilpaterol Hydrochloride on Bovine <i>β</i>-Adrenergic Receptors

The objective of this study was to determine if the addition of zinc (Zn) in combination with zilpaterol HCL (ZH) affected the interaction of ZH with the beta2-adrenergic receptor (β-AR) by altering cAMP production, gene expression, and protein abundance in cultured skeletal muscle cells. Cultures of muscle bovine satellite cells were established and treated at 120 h with: 1) 0 μM Zn/zilpaterol hydrochloride (ZH;CON);2) 0 μM Zn/10 μM ZH (ZH);3) 1 μM Zn from Zn chloride/0 μM ZH (Zn);4) 1 μM Zn from Zn chloride/10 μM ZH (ZN/ZH) in differentiation media for an additional 0, 6, 24, 48 and 96 h. Protein and mRNA were isolated and quantified at 24 and 96 h, and cAMP was measured at 0, 6, 24, 48 and 96 h. At 0, 24, 48 and 96 h, no differences (P > 0.05) were detected in cAMP production. At 6 h, Zn cells had the greatest concentration of cAMP (P < 0.05) compared to ZH treatments. No differences (P > 0.05) were detected in mRNA abundance at 24 h. At 96 h, 0 μM Zn/10 μM ZH cells had an increased abundance of myosin heavy chain (MHC)-I mRNA (P < 0.05) compared to CON. Furthermore, ZH had a greater abundance of MHC-IIX mRNA (P < 0.05) and a tendency for a greater abundance of IGF-1 mRNA (P < 0.15) compared to CON and ZN/ZH. No differences (P > 0.05) were detected in the protein abundance of β1AR and the β2AR. These results indicated Zn and ZH in combination did not have an additive effect on β2-AR function as indicated by cAMP concentrations.

Ractopamine Hydrochloride and Estradiol + Trenbolone Acetate Implants Alter Myogenic mRNA, <i>β</i>-Adrenergic Receptors, and Blood Metabolites

Two commonly used growth promotants in the United States beef industry are β-agonists and anabolic steroid hormones. Each has been shown to increase lean muscle deposition in cattle provided treatments of each growth technology, but much is still unknown of how steroidal implants and β-agonists work in combination. It was our goal to determine the effect of implant strategy and β-agonist administration in beef feedlot heifers (n = 264). A 3 × 2 factorial randomized complete block design was used with 2 levels of OPT and 3 different durations of terminal implant (TI) windows for a total of 6 treatment groups with 9 replications. Terminal implants (20 mg estradiol/200 mg trenbolone acetate implant, Component TE-200) were provided to heifers 140 d from slaughter (TI140), 100 d from slaughter (TI100), or 60 d from slaughter (TI60). Animals receiving the later two TI being first implanted on day 0 (8 mg estradiol/80 mg trenbolone acetate implant, Component TE-IH). The second treatment of the cattle received was the orally active beta adrenergic agonist, ractopamine-hydrochloride (RH) in the form of Optaflexx®(OPT;0 (NO) or 200 (YES) mg/hd·d-1) over the final 28 days of the trial. Thirty animals were subjected to longissimus muscle (LM) biopsies on d 0, 40, 80, 112, and at slaughter on d 140 to view mRNA levels of myogenic related genes and protein quantities of the β1-adrenergic receptor (β1 AR) and β2-adrenergic receptor (β2 AR). On the same days, blood samples were taken from 108 animals to assess changes in plasma blood urea nitrogen (BUN), non-esterified fatty acids (NEFA) and progesterone due to treatments. Relative mRNA levels of myosin heavy chain IIX (MHC IIX), AMPKα, and IGF-I were increased (P < 0.05) in animals receiving a TI100 over the other two implant dates after OPT was fed to animals. After OPT administration myosin heavy chain IIA (MHC IIA) mRNA levels tended to decrease (P = 0.09) due to OPT. An interaction between TI d and OPT administration caused an increase (P < 0.05) in MHC IIA mRNA level in the TI60/Yes treatment group over all other treatments except the TI100/No treatment group. Protein intensity of the β2 AR was decreased (P < 0.05) by the latest TI d (TI60) during OPT feeding, while β1 AR protein intensity tended to be lower (P < 0.10) in animals fed OPT. Plasma BUN levels were reduced (P < 0.05) after terminal implants and OPT feeding;while progesterone was decreased (P < 0.05) by OPT alone. Neither growth promotant affected NEFA levels in plasma. Collectively, these data indicate that ractopamine hydrochloride and estradiol + trenbolone acetate implants alter myogenic mRNA, β-adrenergic receptors, and blood metabolites in finishing beef heifers.

Effect of Direct-Fed Microbial Supplementation on Pathogenic <i>Escherichia coli</i>Fecal Shedding, Live Performance, and Carcass Characteristics in Feedlot Steers

Three experiments were conducted to evaluate direct-fed microbial (DFM) supplementation on live performance, carcass characteristics, and fecal shedding of E. coli in feedlot steers. In Exp. 1, 400 steers (BW = 348 kg) were assigned to treatments: CON = lactose carrier only, BOV = P. freudenreichii (NP24) + L. acidophilus (NP51), BOVD = P. freudenreichii (NP24) + L. acidophilus (NP51), and COMB = BOV fed for the first 101 d on feed, followed by BOVD for the final 28 d prior to harvest. In Exp. 2 (n = 1800;BW = 354 kg) and Exp. 3 (n = 112;BW = 397 kg), steers were utilized in a randomized complete block design and assigned to DFM treatments using low dose and high dose, respectively. Fecal samples were collected prior to harvest and analyzed for E. coli serogroups. In Exp. 1, DFM reduced (P < 0.01) the concentration of E. coli O157. Prevalence of O157 was reduced by BOVD supplementation in Exp. 2 and 3 (P < 0.01 and P = 0.08, respectively), and concentration of E. coli O157 in positive samples was reduced in both experiments where enumeration was performed (P ≤ 0.02). Weighted mean differences across the three experiments were equal to a 33% reduction in the prevalence of E. coli O157:H7 in BOVD treated cattle. A significant reduction in prevalence of O26, O45, O103, and O121 was observed in Exp. 2 (P ≤ 0.03). These results indicate that high levels of L. acidophilus (NP51) may represent an effective pre-harvest food safety intervention to reduce fecal shedding of several E. coli serogroups.

Switchgrass (<i>Panicum virgatum</i>) Fermentation by <i>Clostridium thermocellum</i>and <i>Clostridium beijerinckii</i>Sequential Culture: Effect of Feedstock Particle Size on Gas Production

Fermentation of cellulosic biomass can be done in a single step with cellulolytic, solventogenic bacteria, such as Clostridium thermocellum. However, the suite of products is limited in consolidated bioprocessing. Fortunately, the thermophilic nature of C. thermocellum can be exploited in sequential culture. Experiments were conducted to determine the effect of feedstock particle size on fermentation by sequential cultures and to demonstrate this effect could be shown by gas production. Dual-temperature sequential cultures were conducted by first culturing with C. thermocellum (63°C, 48 h) before culturing with C. beijerinckii (35°C, 24 h). Switchgrass (2, 5 or 15 mm particle size) was the feedstock in submerged substrate (10% w/v) fermentation. The extent of fermentation was evaluated by gas production and compared by analysis of variance with Tukey’s test post hoc. C. thermocellum alone produced 78 kPa cumulative pressure (approx. 680 mL gas) when the particle size was 2 or 5 mm. The C. thermocellum cultures with 15 mm feedstock particles had a mean cumulative pressure of 15 kPa after 48 h, which was less than the 2 and 5 mm treatments (P °C) and inoculated with C. beijerinckii, and the cumulative pressures were reset to ambient, cumulative pressure values as great as 70 kPa (equivalent to an additional 670 mL gas) were produced in 24 h. Again, the longer (15 mm) particle size produced less gas (P < 0.05). When the substrates were inoculated with C. beijerinckii without previous fermentation by C. thermocellum, the mean cumulative pressures were approximately 10 kPa. These results indicate that biological pretreatment with C. thermocellum increased the availability of switchgrass carbohydrates to C. beijerinckii, and that gas production is suitable method to show the effectiveness of a pretreatment.