Effect of hay type on cecal and fecal microbiome and fermentation parameters in horses.

The effect of hay type on the microbiome of the equine gastrointestinal tract is relatively unexplored. Our objective was to characterize the cecal and fecal microbiome of mature horses consuming alfalfa or Smooth Bromegrass (brome) hay. Six cecally cannulated horses were used in a split-plot design run as a crossover in two periods. The whole plot treatment was ad libitum access to brome or alfalfa hay fed over two 21-d acclimation periods with subplots of sampling location (cecum and rectum) and sampling hour. Each acclimation period was followed by a 24-h collection period where cecal and fecal samples were collected every 3 h for analysis of pH and volatile fatty acids (VFA). Fecal and cecal samples were pooled and sent to a commercial lab (MR DNA, Shallowater, TX) for the amplification of the V4 region of the 16S rRNA gene and sequenced using Illumina HiSeq. The main effects of hay on VFA, pH, and taxonomic abundances were analyzed using the MIXED procedure of SAS 9.4 with fixed effects of hay, hour, location, period, and all possible interactions and random effect of horse. Alpha and beta diversities were analyzed using the R Dame package. Horses fed alfalfa had greater fecal than cecal pH (P ≤ 0.05), whereas horses fed brome had greater cecal than fecal pH (P ≤ 0.05). Regardless of hay type, total VFA concentrations were greater (P ≤ 0.05) in the cecum than in feces, and alfalfa resulted in greater (P ≤ 0.05) VFA concentrations than brome in both sampling locations. Alpha diversity was greater (P ≤ 0.05) in fecal compared with cecal samples. Microbial community structure within each sampling location and hay type differed from one another (P ≤ 0.05). Bacteroidetes were greater (P ≤ 0.05) in the cecum compared with the rectum, regardless of hay type. Firmicutes and Firmicutes:Bacteroidetes were greater (P ≤ 0.05) in the feces compared with cecal samples of alfalfa-fed horses. In all, fermentation parameters and bacterial abundances were impacted by hay type and sampling location in the hindgut.

Caecal fermentation characteristics of commonly used feed ingredients.

BACKGROUND: Commercial horse feeds use cereal grains and by-products; however, their effects on the caecal environment remain poorly characterised. OBJECTIVE: Characterise the effect of commonly used feed ingredients on caecal pH and volatile fatty acid (VFA) concentration. STUDY DESIGN: 6 × 6 Latin square. METHODS: Two days prior to the start of the study, 6 caecally cannulated Quarter horses were moved into individual stalls where Smooth bromegrass hay (brome) was offered at 2.0% BW/d split between 2 feedings (0600 and 1800). On day 0, caecal digesta was collected every 2 h for 12 h relative to the 0600 feeding to establish control values for horses consuming only brome (HAY). On day 1, horses began consuming their respective treatments which consisted of beet pulp (BP), maize (M), dehydrated alfalfa (A), oats (OAT), soybean hulls (SBH), or wheat middlings (WM) at 0.25% BW/d split into 2 feedings. On day 7 of each treatment period, caecal digesta was collected every 2 h for 12 h and analysed for pH and VFA. Data were analysed using mixed ANOVA with repeated measures, fixed effects of treatment and time and random effects of horse and period. RESULTS: There was a main effect of hour (P ≤ .05) indicative of post-prandial shifts in caecal metabolites. There were no main effects of treatment on pH or VFA concentration (P ≥ .3). Effects of hour × treatment (P ≤ .04) were observed for all response variables. Regardless of treatment or hour, caecal pH remained well within normal limits. Three horses exhibited signs of lower oesophageal choke immediately after consumption of BP pellets. LIMITATIONS: Interactions between ingredients when mixed for formulation of a concentrate warrant further research. Furthermore, a short adaptation period was chosen to mimic common management practices. CONCLUSION: Minimal differences in caecal fermentation parameters were detected when ingredients were fed at a common inclusion level.

Digestibility of diets containing calcium salts of fatty acids or soybean oil in horses.

Calcium salts of fatty acids (CSFAs) frequently are fed to ruminants, but their fate in the equine digestive system is unknown. The purpose of this study was to compare Enertia s/f, a proprietary CSFAs, and soybean (SB) oil with respect to impact on apparent total tract nutrient digestion and cecal fermentation parameters in horses. Eight cecally cannulated Quarter Horses were used in a crossover design in which horses consumed a diet for 32 d consisting of 1.5% body weight (BW) (as-fed) smooth bromegrass hay and 0.5% BW (as-fed) pelleted concentrate containing 4.9% CSFAs or 4.1% SB oil. Fecal samples were collected every 4 h from day 30 to 32 of each period and analyzed for apparent total tract digestibilities of dry matter (DM), neutral detergent fiber (NDF), acid detergent fiber (ADF), crude protein (CP), crude fat (CF), and gross energy (GE) using acid detergent insoluble ash as an internal marker. Cecal digesta was obtained at 0, 2, 4, 6, 8, 10, and 12 h following the morning meal on day 29 of each period and analyzed for pH and concentrations of volatile fatty acid (VFA) and long-chain fatty acids (LCFAs). Serum was collected on day 33 of each period following a 16-h fast and analyzed for triglycerides and cholesterol. Apparent total tract digestibilities of DM, NDF, ADF, CP, CF, and GE were unaffected by lipid source (P > 0.10). Serum triglycerides tended to be greater in horses consuming CSFAs compared to SB (P = 0.10); however, serum cholesterol was not different (P = 0.45). In horses consuming SB, cecal pH decreased below baseline (hour 0) at hours 2, 4, and 6 (P < 0.01), whereas cecal pH in horses consuming CSFAs was below baseline at hours 4 and 6 (P < 0.01). There were no treatment or time effects on cecal pH (P > 0.10). Cecal concentrations of total VFAs were greater in horses consuming SB compared to CSFAs at hour 2 (P = 0.01). Cecal concentrations of acetate, propionate, acetate:propionate (A:P), and butyrate were affected by time (P < 0.01). Propionate was less at hour 2 in horses fed CSFAs compared to horses fed SB (P = 0.04). A treatment × time interaction was detected for total cecal LCFAs concentration (P < 0.01); LCFAs concentration was greater at hour 2 for horses consuming CSFAs compared to horses fed SB (P = 0.02). SB oil and CSFAs have similar effects on the digestion of DM, NDF, ADF, GE, CF, and CP.

Effects of corn distillers dried grains with solubles in finishing diets on pig growth performance and carcass yield with two different marketing strategies.

Feeding diets high in corn distillers dried grains with solubles (DDGS) before market can negatively impact carcass yield, hot carcass weight (HCW), and belly fat iodine value (IV). Two experiments were conducted to evaluate the effects of switching from DDGS-based to corn-soybean meal (CSBM)-based diets at increasing intervals (withdrawal periods) before harvest on finishing pig performance and carcass characteristics. Diets in both experiments contained either 0% or 30% DDGS and were balanced for net energy (NE). In Exp. 1, 985 pigs (initially 99.6 kg body weight [BW]) were used with 12 pens per treatment. The four treatments were increasing DDGS withdrawal periods: 28, 21, 14, or 0 d (no dietary switch) before marketing. All pens were marketed by removing the 17% heaviest pigs 21 d before slaughter and the remaining 83% all slaughtered 21 d later. Overall, there was no evidence for treatment differences on final BW, average daily feed intake, or feed efficiency (G:F; P > 0.10); however, average daily gain (ADG) increased (linear, P = 0.022) and belly fat IV decreased (linear, P = 0.001) the longer pigs were fed CSBM diets. There was no evidence for differences for HCW (P > 0.10); however, carcass yield increased (linear, P = 0.001) with increasing time following the switch to CSBM. Backfat depth decreased and percentage lean increased as CSBM feeding time increased (quadratic; P < 0.05). In Exp. 2, 1,158 pigs (initially 105 kg BW) were used in a 35-d study. There were 15 pens per treatment and four treatments of increasing DDGS withdrawal periods: 35, 28, 14, or 0 d (no dietary switch). All pens were marketed by removing the 15% heaviest pigs on day 28, the 28% heaviest pigs on day 14, and a final marketing of approximately 57% of starting barn inventory. There was no evidence that final BW, ADG, G:F, or HCW differed among dietary treatments (P > 0.10). Average daily feed intake and carcass yield increased and belly fat IV decreased (P < 0.050); the longer pigs were fed CSBM. In conclusion, growth performance was minimally impacted following dietary switch from DDGS- to CSBM-based diets, possibly due to similar dietary NE. For carcass yield and belly fat IV, the optimal time to make a dietary switch from high to low fiber appears to be linear in nature and at least 28 d before marketing.

Complementary Feeding of Sorghum-Based and Corn-Based Fortified Blended Foods Results in Similar Iron, Vitamin A, and Anthropometric Outcomes in the MFFAPP Tanzania Efficacy Study.

BACKGROUND: Fortified blended foods (FBFs) are micronutrient-fortified food aid products containing cereals and pulses. It has been suggested to reformulate FBFs to include whey protein concentrate, use alternative commodities (e.g., sorghum and cowpea), and utilize processing methods such as extrusion to produce them. The Micronutrient Fortified Food Aid Pilot Project (MFFAPP) efficacy study was designed to test the efficacy of complementary feeding of newly formulated FBFs. OBJECTIVES: The aim of this study was to test the effectiveness of 5 newly formulated FBFs in combating iron deficiency anemia and vitamin A deficiency compared with traditionally prepared corn-soy blend plus (CSB+) and no intervention. A secondary aim was to determine the impact on underweight, stunting, wasting, and middle-upper arm circumference. METHODS: A 20-wk, partially randomized cluster study was completed. Two age groups (aged 6-23 and 24-53 mo) with hemoglobin status <10.3 g/dL, and weight-for-height z scores >-3 were enrolled and assigned to diet groups. Biochemical and anthropometric measurements were collected at 0, 10, and 20 wk. RESULTS: Both hemoglobin concentrations and anemia ORs were significantly improved in all intervention groups except for CSB+ and the no-intervention groups at week 20. Only extruded corn-soy blend 14 and the no-intervention age groups failed to significantly decrease vitamin A deficiency risk (P < 0.04). There were no consistent significant differences among groups in anthropometric outcomes. CONCLUSIONS: FBFs reformulated with sorghum, cowpea, corn, and soy significantly improved anemia and vitamin A deficiency ORs compared with week 0 and with no intervention. Although newly formulated FBFs did not significantly improve vitamin A deficiency or anemia compared with CSB+, CSB+ was the only FBF not to significantly improve these outcomes over the study duration. Our findings suggest that newly formulated sorghum- and cowpea-based FBFs are equally efficacious in improving these micronutrient outcomes. However, further FBF refinement is warranted. This trial was registered at clinicaltrials.gov as NCT02847962.

Statistical analyses of chicken intestinal lesion scores in battery cage studies of anti-coccidial drugs.

Establishing the efficacy of an anti-coccidial drug in poultry begins with conducting multiple battery cage studies, where the target animals are challenged with single and mixed Eimeria species inoculum under controlled laboratory conditions. One of the primary outcomes in a battery cage study is the intestinal lesion score defined on a discrete ordinal scale of 0 to 4. So far, the statistical analysis of lesion scores has routinely employed the linear mixed model (LMM). This present work proposes to apply the generalized linear mixed model (GLMM) with the cumulative logit link to statistically analyze coccidial lesion scores collected from battery cage studies. Upon applying this new approach on 9 datasets generated by challenging battery-cage-housed broilers with various mixtures of Eimeria species, it is observed that the GLMM fitted adequately to the data, produced variance component estimates that agreed with the experimental setup, and, at the 0.05 significance level, generated statistical results in complete concordance with the LMM approach. Advantages of the proposed GLMM over the LMM are discussed from several standpoints. Parallel to the regulatory requirement of a ≥1-unit reduction in the mean lesion score for clinical relevant efficacy under the LMM, the clinical relevancy criterion under the GLMM could be set as a ≥10-fold increase in the odds of having low lesion scores. That is, the effect of an anti-coccidial drug product would be deemed clinically relevant in battery-cage studies when the odds of having low lesion scores with the medication is 10 times or more than the odds without the medication.

Technical Note: Assessment of sampling technique from feeders for copper, zinc, calcium, and phosphorous analysis.

Diet treatments were arranged in a split-plot design with the whole-plot consisting of 1 of 6 concentrations of dietary Cu (22 to 134 mg/kg total Cu) and the subplot using 1 of 2 sampling techniques (probe vs. hand grab). A total of 6 feeders per treatment were sampled using a brass open handle probe. The probe was inserted into the feeder 4 times to obtain a 900 g of sample. The hand-collected samples were obtained by inserting a bare hand into the feeder approximately 8 times to obtain a 900 g of sample. Within a feeder and sampling technique, subsamples (200 g) were created by using a sample splitting device. In addition to the 6 individual feeder samples, a subsample (33 g) from each individual feeder was pooled within dietary treatment and sampling technique to form a single composite sample (200 g). This process was repeated until 4 individual composite samples were created for each diet and sampling technique. Next, all samples were ground through a centrifugal mill and submitted for mineral analysis in duplicate for Cu, Zn, Ca, and P analysis. Results indicated variability when sampling feeders with a probe were reduced (P = 0.013) for Cu and marginally reduced (P = 0.058) for Ca when compared with hand-sampling. However, no evidence for differences was detected among sampling techniques for Zn and P for the individual feeder analysis. When samples were pooled from 6 feeders to form a single composite sample, there was no evidence for differences detected among sampling techniques for Cu, Zn, Ca, and P analysis. From these results, sampling frequency calculations were determined to assess sampling accuracy within a 95% confidence interval. Results indicated that the number of feeders or composite samples required to analyze was less for Cu, Zn, Ca, and P analysis when using a probe compared with a hand sampling. In summary, sampling with a probe is associated with less variability on an individual sample basis, but when individual samples are pooled to form a composite sample, there was no evidence for difference among sampling techniques. Our results suggest samples collected for these analyses with a probe and composited would be the best option to minimize variation and analytical costs.

An epidemiological investigation to determine the prevalence and clinical manifestations of slow-moving finished cattle presented to slaughter facilities.

Cattle mobility is routinely measured at commercial slaughter facilities. However, the clinical signs and underlying causes of impaired mobility of cattle presented to slaughter facilities are poorly defined. As such, the objectives of this study were 1) to determine the prevalence of impaired mobility in finished cattle using a 4-point mobility scoring system and 2) to observe clinical signs in order to provide clinical diagnoses for this subset of affected cattle. Finished beef cattle (n = 65,600) were observed by a veterinarian during the morning shift from six commercial abattoirs dispersed across the United States; the veterinarian assigned mobility scores (MS) to all animals using a 1-4 scale from the North American Meat Institute's Mobility Scoring System, with 1 = normal mobility and 4 = extremely limited mobility. Prevalence of MS 1, 2, 3, and 4 was 97.02%, 2.69%, 0.27%, and 0.01%, respectively. Animals with an abnormal MS (MS > 1) were then assigned to one of five clinical observation categories: 1) lameness, 2) poor conformation, 3) laminitis, 4) Fatigued Cattle Syndrome (FCS), and 5) general stiffness. Of all cattle observed, 0.23% were categorized as lame, 0.20% as having poor conformation, 0.72% as displaying signs of laminitis, 0.14% as FCS, and 1.68% as showing general stiffness. The prevalence of lameness and general stiffness was greater in steers than heifers, whereas the prevalence of laminitis was the opposite (P < 0.05). FCS prevalence was higher in dairy cattle than in beef cattle (0.31% vs. 0.22%, respectively; P ≤ 0.05). These data indicate the prevalence of cattle displaying abnormal mobility at slaughter is low and causes of abnormal mobility are multifactorial.

Testing for bioequivalence of highly variable drugs from TR-RT crossover designs with heterogeneous residual variances.

Traditional bioavailability studies assess average bioequivalence (ABE) between the test (T) and reference (R) products under the crossover design with TR and RT sequences. With highly variable (HV) drugs whose intrasubject coefficient of variation in pharmacokinetic measures is 30% or greater, assertion of ABE becomes difficult due to the large sample sizes needed to achieve adequate power. In 2011, the FDA adopted a more relaxed, yet complex, ABE criterion and supplied a procedure to assess this criterion exclusively under TRR-RTR-RRT and TRTR-RTRT designs. However, designs with more than 2 periods are not always feasible. This present work investigates how to evaluate HV drugs under TR-RT designs. A mixed model with heterogeneous residual variances is used to fit data from TR-RT designs. Under the assumption of zero subject-by-formulation interaction, this basic model is comparable to the FDA-recommended model for TRR-RTR-RRT and TRTR-RTRT designs, suggesting the conceptual plausibility of our approach. To overcome the distributional dependency among summary statistics of model parameters, we develop statistical tests via the generalized pivotal quantity (GPQ). A real-world data example is given to illustrate the utility of the resulting procedures. Our simulation study identifies a GPQ-based testing procedure that evaluates HV drugs under practical TR-RT designs with desirable type I error rate and reasonable power. In comparison to the FDA's approach, this GPQ-based procedure gives similar performance when the product's intersubject standard deviation is low (≤0.4) and is most useful when practical considerations restrict the crossover design to 2 periods.

Incidence of lameness and association of cause and severity of lameness on the outcome for cattle on six commercial beef feedlots.

OBJECTIVE To describe the incidence of specific causes of lameness and the associations of cause and severity of lameness on the outcome for cattle on commercial feedlots. DESIGN Dynamic population longitudinal study. ANIMALS Cattle on 6 commercial feedlots in Kansas and Nebraska during a 12-month period (mean daily population, 243,602 cattle; range, 223,544 to 252,825 cattle). PROCEDURES Feedlot personnel were trained to use a standardized diagnostic algorithm and locomotion score (LMS) system to identify and classify cattle by cause and severity of lameness. Information regarding lameness cause, severity, and treatments was recorded for individual cattle. Cattle were monitored until they left the feedlot (ie, outcome; shipped with pen mates [shipped], culled prematurely because of lameness [realized], or euthanized or died [died]). Incidence rates for various causes of lameness, LMSs, and outcomes were calculated. The respective associations of cause of lameness and LMS with outcome were evaluated. RESULTS Lameness was identified in 2,532 cattle, resulting in an overall lameness incidence rate of 1.04 cases/100 animal-years. Realized and mortality rates were 0.096 cattle/100 animal-years and 0.397 deaths/100 animal-years, respectively. Injury to the proximal portion of a limb was the most frequently identified cause of lameness followed by undefined lameness, septic joint or deep digital sepsis, and interdigital phlegmon (foot rot). As the LMS (lameness severity) at lameness detection increased, the percentage of cattle that died but not the percentage of cattle that were realized increased. CONCLUSIONS AND CLINICAL RELEVANCE Results provided clinically useful prognostic guidelines for management of lame feedlot cattle.

Human Food Safety Implications of Variation in Food Animal Drug Metabolism.

Violative drug residues in animal-derived foods are a global food safety concern. The use of a fixed main metabolite to parent drug (M/D) ratio determined in healthy animals to establish drug tolerances and withdrawal times in diseased animals results in frequent residue violations in food-producing animals. We created a general physiologically based pharmacokinetic model for representative drugs (ceftiofur, enrofloxacin, flunixin, and sulfamethazine) in cattle and swine based on extensive published literature. Simulation results showed that the M/D ratio was not a fixed value, but a time-dependent range. Disease changed M/D ratios substantially and extended withdrawal times; these effects exhibited drug- and species-specificity. These results challenge the interpretation of violative residues based on the use of the M/D ratio to establish tolerances for metabolized drugs.

Medical treatment of horses with deep digital flexor tendon injuries diagnosed with high-field-strength magnetic resonance imaging: 118 cases (2000-2010).

OBJECTIVE: To describe the location and severity of deep digital flexor tendon (DDFT) lesions diagnosed by means of high-field-strength MRI in horses and to identify variables associated with return to activity following medical treatment. DESIGN: Retrospective case series. ANIMALS: 118 horses. PROCEDURES: Medical records of horses with DDFT injury diagnosed with MRI over a 10-year period (2000-2010) and treated medically (intrasynovial administration of corticosteroids and sodium hyaluronan, rest and rehabilitation, or both) were reviewed. History, signalment, use, results of lameness examination and diagnostic local anesthesia, MRI findings, and treatment details were recorded. Outcome was obtained by telephone interview or follow-up examination. Horses were grouped by predictor variables and analyzed with logistic regression to identify significant effects. RESULTS: Overall, of 97 horses available for follow-up (median time to follow-up, 5 years; range, 1 to 12 years), 59 (61%) returned to activity for a mean duration of 22.6 months (median, 18 months; range, 3 to 72 months), with 25 (26%) still sound at follow-up. Of horses with mild, moderate, and severe injury, 21 of 29 (72%), 20 of 36 (56%), and 18 of 32 (56%), respectively, returned to use. Horses treated with intrasynovial corticosteroid injection and 6 months of rest and rehabilitation returned to use for a significantly longer duration than did horses treated without rest. Western performance horses returned to use for a significantly longer duration than did English performance horses. CONCLUSIONS AND CLINICAL RELEVANCE: Results of the present study suggested that outcome for horses with DDFT injuries treated medically depended on injury severity, presence of concurrent injury to other structures in the foot, type of activity, and owner compliance with specific treatment recommendations. Although some horses successfully returned to prior activity, additional treatment options are needed to improve outcome in horses with severe injuries and to improve long-term prognosis.

Comparison of anamnestic responses to rabies vaccination in dogs and cats with current and out-of-date vaccination status.

OBJECTIVE: To compare anamnestic antibody responses of dogs and cats with current versus out-of-date vaccination status. DESIGN: Cross-sectional study. ANIMALS: 74 dogs and 33 cats. PROCEDURES: Serum samples were obtained from dogs and cats that had been exposed to rabies and brought to a veterinarian for proactive serologic monitoring or that had been brought to a veterinarian for booster rabies vaccination. Blood samples were collected on the day of initial evaluation (day 0) and then again 5 to 15 days later. On day 0, a rabies vaccine was administered according to label recommendations. Paired serum samples were analyzed for antirabies antibodies by means of a rapid fluorescent focus inhibition test. RESULTS: All animals had an antirabies antibody titer ≥ 0.5 IU/mL 5 to 15 days after booster vaccination. Dogs with an out-of-date vaccination status had a higher median increase in titer, higher median fold increase in titer, and higher median titer following booster vaccination, compared with dogs with current vaccination status. Most (26/33) cats, regardless of rabies vaccination status, had a titer ≥ 12 IU/mL 5 to 15 days after booster vaccination. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that dogs with out-of-date vaccination status were not inferior in their antibody response following booster rabies vaccination, compared with dogs with current vaccination status. Findings supported immediate booster vaccination followed by observation for 45 days of dogs and cats with an out-of-date vaccination status that are exposed to rabies, as is the current practice for dogs and cats with current vaccination status.