The Effect of Ryegrass Silage Feeding on Equine Fecal Microbiota and Blood Metabolite Profile

Silage is fed to horses in China and other areas in the world, however, knowledge about the impact of feeding silage on horse health is still limited. In the current study, 12 horses were assigned into two groups and fed ryegrass silage and ryegrass hay, respectively, for 8 weeks. High-throughput sequencing was applied to analyze fecal microbiota, while liquid chromatography–tandem mass spectrometry (LC–MS/MS) based metabolomics technique was used for blood metabolite profile to investigate the influence of feeding ryegrass silage (group S) compared to feeding ryegrass hay (group H) on equine intestinal and systemic health. Horses in group S had significantly different fecal microbiota and blood metabolomes from horses in group H. The results showed that Verrucomicrobia was significantly less abundant which plays important role in maintaining the mucus layer of the hindgut. Rikenellaceae and Christensenellaceae were markedly more abundant in group S and Rikenellaceae may be associated with some gut diseases and obesity. The metabolomics analysis demonstrated that ryegrass silage feeding significantly affected lipid metabolism and insulin resistance in horses, which might be associated with metabolic dysfunction. Furthermore, Pearson’s correlation analysis revealed some correlations between bacterial taxa and blood metabolites, which added more evidence to diet-fecal microbiota-health relationship. Overall, ryegrass silage feeding impacted systemic metabolic pathways in horses, especially lipid metabolism. This study provides evidence of effects of feeding ryegrass silage on horses, which may affect fat metabolism and potentially increase risk of insulin resistance. Further investigation will be promoted to provide insight into the relationship of a silage-based diet and equine health.

Field-Deployable Recombinase Polymerase Amplification Assay for Specific, Sensitive and Rapid Detection of the US Select Agent and Toxigenic Bacterium, Rathayibacter toxicus

Rathayibacter toxicus is a toxigenic bacterial pathogen of several grass species and is responsible for massive livestock deaths in Australia and South Africa. Due to concern for animal health and livestock industries, it was designated a U.S. Select Agent. A rapid, accurate, and sensitive in-field detection method was designed to assist biosecurity surveillance surveys and to support export certification of annual ryegrass hay and seed. Complete genomes from all known R. toxicus populations were explored, unique diagnostic sequences identified, and target-specific primers and a probe for recombinase polymerase amplification (RPA) and endpoint PCR were designed. The RPA reaction ran at 37 °C and a lateral flow device (LFD) was used to visualize the amplified products. To enhance reliability and accuracy, primers and probes were also designed to detect portions of host ITS regions. RPA assay specificity and sensitivity were compared to endpoint PCR using appropriate inclusivity and exclusivity panels. The RPA assay sensitivity (10 fg) was 10 times more sensitive than endpoint PCR with and without a host DNA background. In comparative tests, the RPA assay was unaffected by plant-derived amplification inhibitors, unlike the LAMP and end-point PCR assays. In-field validation of the RPA assay at multiple sites in South Australia confirmed the efficiency, specificity, and applicability of the RPA assay. The RPA assay will support disease management and evidence-based in-field biosecurity decisions.

Agronomic and In Vitro Quality Evaluation of Dual-Purpose Cereals Clipped at Variable Ages and Their Utilization in Rabbit Feeding

The present study included two experiments; the first one investigated the forage productivity and in vitro quality of a single cut taken at different plant ages (45, 60, and 75 days after sowing—DAS) from four prominent cereal crops, namely, barley, oat, triticale, and ryegrass, grown during two successive winter seasons in Northern Egypt. In addition, the effect of plant age at forage removal on the crop’s regrowth ability and final grain yield was quantified. The second experiment studied the biological in vivo effects of the four crops’ hay cut at the optimum plant age on growth performance, feed utilization, and apparent nutrients’ digestibility of growing rabbits. Despite the progressive increase in the fresh and dry matter yields produced from the four crops with later forage removal and the relatively high quality of the forage removed at 45 DAS, 1st experiment concluded that forage removal at 60 DAS produced a reasonable amount of fresh and dry matter yields with appropriate in vitro quality. Meanwhile, the gain in forage yield, when forage was removed at 60 DAS, was enough to compensate for the consequent reduction in grain yield of the four evaluated crops. The inclusion of variable percentages (0, 10, and 20%) of the four tested crops’ hay, when cut at 60 DAS, in the rabbit’s diet (2nd experiment), resulted in non-significant variations in the rabbit’s final body weight. Meanwhile, regardless of the percentage, the rabbits that were fed on diets including ryegrass hay and barley hay had the highest significant daily weight gain. The best feed conversion ratios were obtained by the rabbits that were fed on diets containing 10 and 20% ryegrass hay as well as 20% triticale hay. The highest dry matter, organic matter, and crude protein digestibility coefficients were obtained by both groups of rabbits that were fed on diets containing 20% ryegrass hay and barley hay. The inclusion of any of the four crops’ hay in the rabbits’ diet resulted in significantly higher digestibility coefficients for all nutrients compared to the control rabbits except for ether extract digestibility. Among the four evaluated crops’ hay, ryegrass hay was found to have an outstanding impact on the productive performance and digestibility of growing rabbits. In growing dual-purpose cereals, it is recommended to cut the crops at 60 DAS to achieve the optimum balance between forage yield and quality on the one hand and final grain yield on the other hand. Moreover, when cut at 60 DAS, the evaluated hay of the four crops was adequate to be included in the rabbits’ diet up to 20% substitution of the commercial fiber sources.

162 The Effects of a Saccharomyces Cerevisiae Fermentation Product on the Digestibility of an Annual Rye Grass Hay Based Finishing Diet for Lambs

Interest in the use of yeast fermentation products has grown in recent years as a natural feed additive for the growth of ruminants in a feedlot setting. The purpose of this study was to determine if the supplementation of a Saccharomyces cerevisiae fermentation product (SCFP) had an effect on apparent digestibility in Katahdin lambs offered an annual ryegrass hay-based finishing diet. Six Katahdin wethers (n = 6) were divided into two groups CON and TRT and placed into individual metabolism crates in a temperature-controlled room, (21.1° C), and fitted with fecal collection bags. Lambs were offered a TMR diet that was formulated to be isocaloric and isonitrogenous at 14% CP, and annual ryegrass hay based with a top dress of ground corn to be used as a carrier. The TRT received the yeast supplement at a rate of 4g/head/day. The diet was offered ad libitum with orts collected daily to maintain a 5% refusal rate. Lambs were housed in the metabolism crates for 1-wk before the start of the study for adjustment, followed by 4 days of data collection. Feed, orts, fecal, and urine samples were collected and recorded daily during the collection period for each wether and compiled by animal for chemical analysis of DM, NDF, ADF, CP, and ether extract. Indigestible ADF was used as a digestibility marker to determine apparent digestibility. Data were analyzed by PROC GLM for statistical significance. There was no statistical significance found for apparent digestibility of DM (CON=64.6 ±2.5; TRT=63.4±2.5), CP (CON=65.0 ±2.1; TRT=65.9±2.1), NDF (CON=41.2±1.9; TRT=43.0±1.9), or ADF (CON=26.1 ±4.7; TRT=33.8±4.7) between the two groups (P > 0.05). This study concluded that the supplementation of a SCFP had no significant effect on the apparent digestibility of Katahdin wether lambs that were offered an annual ryegrass hay-based finishing diet.

191 The effects of a yeast fermentation product on the average daily gain and digestibility on a rye grass hay-based finishing diet for lambs

The purpose of this study was to determine if supplementation of a yeast fermentation product had an effect on the ADG, performance, and meat quality characteristics of Katahdin sheep fed a ryegrass hay based diet in drylot. Twenty-four Katahdin lambs were divided into two groups (male, n = 8; female n = 16) based on weight and gender: a control (CON) and treatment (TRT) used in a repeated block design. The lambs had a BW of 21.5 ± 2.5 kg, and concluded with a finishing weight of 36.3 ± 3.4 kg. Lambs were housed on dirt drylot with shade structures, and offered an ad libitum TMR diet was formulated to be isocaloric and isonitrogenous at 14% CP and was ryegrass hay based, and top dressed with ground corn as a carrier. The TRT received the yeast supplement at a rate of 4/g/h/d. The diet was offered at 2% of the group’s body weight ad libitum. A 1-wk standardization period was conducted before the start of the study to obtain a 5% refusal rate. Orts were collected and recorded, as well as weekly feed samples were collected twice a week, and compiled for a chemical analysis for NDF, ADF, ASH, CP, and ether extract. Temperature and humidity data was also collected throughout the study. Lambs were weighed weekly with a rolling weight being used for the ADG of the lambs. Proc mixed procedures of SAS was used for data analysis. We found no statistical significance in DMI (CON=11.14 ±3.36 kg/d and TRT= 10.89 ±3.55 kg/d per group), and no statistical significance by gender (P < 0.11). There was a statistical significance (P < 0.03), for ADG per group. This suggests that there is a tendency for greater performance and ADG for lambs supplemented with a yeast fermentation product.

17 The effects of a yeast fermentation product on the average daily gain and digestibility on a rye grass hay based finishing diet for lambs

The purpose of this study was to determine if supplementation of a yeast fermentation product had an effect on the ADG, performance, and meat quality characteristics of Kathadin sheep fed a ryegrass hay based diet in drylot. Twenty-four Katahdin lambs were divided into two groups (male, n = 8; female n = 16) based on weight and gender: a control (CON) and treatment (TRT) used in a repeated block design. The lambs had a BW of 21.5 ± 2.5 kg, and concluded with a finishing weight of 36.3 ± 3.4 kg. Lambs were housed on dirt drylot with shade structures, and offered an ad libitum TMR diet was formulated to be isocaloric and isonitrogenous at 14% CP and was ryegrass hay based, and top dressed with ground corn as a carrier. The TRT received the yeast supplement at a rate of 4/g/h/d. The diet was offered at 2% of the group’s body weight ad libitum. A 1-wk standardization period was conducted before the start of the study to obtain a 5% refusal rate. Orts were collected and recorded, as well as weekly feed samples were collected twice a week, and compiled for a chemical analysis for NDF, ADF, ASH, CP, and ether extract. Temperature and humidity data was also collected throughout the study. Lambs were weighed weekly with a rolling weight being used for the ADG of the lambs. Proc mixed procedures of SAS was used for data analysis. We found no statistical significance in DMI (CON=11.14 ±3.36 kg/d and TRT= 10.89 ±3.55 kg/d per group), and no statistical significance by gender (P < 0.11). There was a statistical significance (P < 0.03), for ADG per group. This suggests that there is a tendency for greater performance and ADG for lambs supplemented with a yeast fermentation product.