Ryegrass Hay Research Articles

Yield, silage quality, and feeding preference of late‐summer sown pearl millet (Cenchrus americanus (L.) Morrone) in Southern Kyushu

AbstractBackgroundPearl millet is characterized by its high dry matter (DM) yields with a high moisture content, which makes it difficult to process as silage.MethodsPearl millet was sown in mid‐September for 3 years to examine its growth, DM yields in early December, and decrease in DM percentage after frost exposure. The crop was processed as round‐bale silage to assess silage quality and preference by breeding beef cattle.ResultsPlants reached a height of 160–200 cm, with heading tiller percentages of 50%–70% in early December. With frost exposure, DM percentage increased in leaves and panicles, followed by stems, reaching over 40%, 1 month after exposure. These increases were positively correlated with cumulative frost exposure. After frost exposure, in vitro DM digestibility and crude protein content declined while acid detergent fiber content increased. Repeated cafeteria feeding experiments showed a reduced preference for either pearl millet silage or Italian ryegrass hay. The silage showed moderate acidity at pH 4.73–5.40, with lactic acid at 0.58%–1.62% DM, acetic acid at 0.03%–0.10% DM, and negligible butyric acid, indicating a satisfactory quality.ConclusionsIn Southern Kyushu, pearl millet sown in late summer can be processed into low‐moisture round‐bale silage in January, the year following sowing.

Effect of soil compaction and cover crop management on soil physical quality, biomass production and corn and soybean yield

ABSTRACT No-till with cover crop (CC) has been marketed to growers as a sustainable way to increase soil quality and crop yields. Our goal was to better understand the effect of CC management strategies on crop yield and mitigation of soil compaction. The compaction treatments were: four (C4) and eight (C8) wheel passes of a tractor, and without additional compaction (C0). CCs in autumn/winter were Italian ryegrass (IR) hay, IR as CC, and mix of IR and forage radish as CC. In the spring/summer, corn and soybean were cultivated. The reduction of hydraulic conductivity (0–6 cm depth) after first season in the IR hay was 74.9% in C4 and 96.2% in C8 comparted with C0. Overall, harvested CC has limited capacity to respond to compaction, decreasing root growth (root biomass of 2191, 2753, and 3744 kg ha−1, IR hay, IR CC, and mix, respectively). Further, the negative effects of compaction on crop yield were modest, probably because of the low axle loads and contact stresses; high inherent structural stability of Oxisols; and permanent no-till and CC roots which favored soil structure stability. Future works should use higher axle loads and surface stresses and a control treatment without CC.

Evaluation of a Saccharomyces cerevisiae Fermentation Product on the Feedlot Performance and Carcass Merit of Hair Lambs Offered an Annual Ryegrass-Hay-Based Finishing Diet: A Pilot Study.

Hair sheep production has increased in recent years, which has resulted in an increased presence in feedlots. Additionally, grass-based finishing systems for ruminant animal production have increased. Data are limited for finishing hair lambs on diets based on cool-season hay. The objective was to evaluate a Saccharomyces cerevisiae fermentation product (SCFP) on the feedlot performance and carcass characteristics of Katahdin lambs offered an annual ryegrass (Lolium multiflorum)-hay-based diet. Twenty-four Katahdin lambs (21.5 ± 2.5 kg BW) were assigned to either the control (CON) or the yeast-supplemented group (SCFP) in a completely randomized design. Lambs were offered a 14% crude protein total mixed ration diet based on annual ryegrass hay. The SCFP group also received the yeast supplement in their diet. Lambs in the SCFP group had a higher final body weight (p < 0.01) and ADG (p = 0.01). Less maximum and total energy were required to cut SCFP lamb meat compared to CON lamb meat (p < 0.03). Results from this study indicated that SCFP supplementation may prove to be beneficial in hair lamb finishing diets. Future research will need to specifically evaluate the use of these products in hair lambs with a larger sample size.

33 Supplementation Level Effects on Early-Weaned Beef Calves Receiving Annual Ryegrass

Abstract The objective of this study was to evaluate the effects of concentrate supplementation levels on performance and DM intake of early-weaned beef calves consuming annual ryegrass (Lolium multiflorium). The experiments were conducted at the UF/IFAS Range Cattle Research and Education Center, Ona, FL from January to May 2022. In experiment 1, treatments were two levels of concentrate supplementation (0.75% or 1.0% of BW) distributed in a randomized complete block design with four replicates. Concentrate was fed daily and had 18% CP and 78% TDN. Thirty-two Angus crossbred calves were weaned with 90 ± 14 kg BW at 76 ± 10 d of age and allocated to 1 of 8 annual ryegrass pastures (experimental units; 0.3 ha/pasture; 4 calves/pasture) with a continuous and fixed stocking rate. Herbage mass and nutritive value were estimated every 14 d and calves were weighed every 28 d. There was no difference in herbage mass (mean = 1.300 kg DM/ha; P = 0.44; SE = 0.46), herbage allowance (mean = 0.86 kg DM/kg LW; P = 0.66; SE = 0.03), CP (mean = 24.4%; P = 0.46; SE = 0.78), and in vitro digestible organic matter (mean = 77%; P = 0.49; SE = 1) concentration between treatments. There was a treatment × month interaction on ADG and the interaction occurred because calves receiving 1% BW had greater ADG than 0.75% BW in April (1.0 vs. 0.8 kg/d; P = 0.04; 0.03) but there were no differences between treatments in February, March, and May. In experiment 2, treatments were supplementation with 0.75% or 1.0% BW concentrate distributed in a complete randomized design with seven replicates. Fourteen steers calves (166 ± 17 kg BW) from experiment 1 were maintained in the same treatment, transferred to a drylot (1 steer/pen), and evaluated for forage and total DM intake, and in vivo DM digestibility. Ground annual ryegrass hay (11% CP, 58% IVDOM) was offered and adjusted to allow 10% refusals. There was no difference in forage DM intake (mean = 1.8 kg DM/d; P = 0.3; SE = 0.06) between treatments but calves receiving 1.0% BW had greater total DM intake (2.7 vs. 2.5 kg DM/d; P = 0.05; SE = 0.06) and in vivo DM digestibility (77 vs. 75%; P &amp;lt; 0.01; SE = 0.53) than 0.75% BW. Decreasing concentrate supplementation level from 1.0 to 0.75% BW may be a viable management practice to reduce cost of developing early weaned beef calves grazing annual ryegrass.

Effects of frequency of concentrate supplementation on performance of early-weaned beef calves consuming annual ryegrass

The objectives of this study were to evaluate the growth performance during a grazing period (experi- ment 1) and forage intake and apparent in vivo digestibil- ity (experiment 2) of early-weaned beef calves consuming annual ryegrass (Lolium multiflorum) and supplemented with concentrate either daily or 3 times weekly. The experiment was con- ducted in Ona, Florida. Treatments consisted of similar weekly concentrate amounts (1% of BW × 7 d) divided into equal amounts and then offered daily (7×) or 3 times weekly (3×) to early-weaned beef calves consuming annual ryegrass pastures from d 0 to 84 (experiment 1) and annu- al ryegrass hay in drylot from d 84 to 105 (experiment 2). From d 0 to 84, reducing the frequency of concentrate supplementation did not influ- ence herbage mass, herbage allowance, or nutritive value of annual ryegrass pastures, or calf ADG, BW, or plasma concentrations of glucose and urea N. The overall forage DM intake was 15% less for 3× versus 7× calves (1.51 vs. 1.78% of BW, respectively). Total DM intake did not differ between 3× and 7× (2.63 vs. 2.73% of BW, respec- tively), whereas in vivo apparent digestibility decreased for 3× versus 7× (85.3 vs. 86.5%, respectively). Reducing frequen- cy of concentrate supplementation from daily to 3 times weekly did not affect overall growth performance of early- weaned beef calves consuming annual ryegrass and can successfully be implemented to reduce feeding costs.

Intake, digestibility and ruminal parameters of lambs fed with increasing levels of wheat bulgur.

The aim was to evaluate the effect of the inclusion of wheat bulgur in the diet on intake, digestibility, N balance and ruminal parameters in cannulated lambs. Four castrated Santa Ines×Dorper lambs, cannulated in the rumen, (45 ± 9 kg) were housed in metabolism crates. They were randomly distributed in a 4×4 Latin Square,10-day adaption, a 6-day sampling period. The base diet was composed by ryegrass hay and concentrate, in a 40:60 roughage:concentrate ratio and four inclusions of wheat bulgur on the total diet: 0, 190, 380 and 570 g/kg dry matter. The inclusion of wheat bulgur did not affect the intake of non-structural carbohydrates. The intake of dry matter, fiber, crude protein, organic matter and crude fat decreased linearly (P<0.05). The digestibility of neutral detergent fiber decreased linearly (P=0.001). The N retained and the excreted in urine were not affected by wheat bulgur inclusion. Fecal excretion, total excretion and absorbed N, decreased linearly (P<0.05). There was no change on pH, ammonia, soluble carbohydrates and protozoa population in rumen. Increasing of wheat bulgur in the diet of lambs decrease the nutrient intake and fiber digestibility without affecting the digestibility of other compounds, ruminal parameters, and the protozoa count.

Desempenho zootécnico de cordeiros Dorper x Santa Inês criados em diferentes sistemas de produção

Abstract The objective of this work was to compare the zootechnical performance of Dorper x Santa Inês crossbred lambs finished in grazing systems on Megathyrsus maximus Aruana cultivar pasture, with and without shading, and in a feedlot. Twenty-four non-castrated lambs were used in a completely randomized experimental design, with the three following treatments with eight replicates each: 'Aruana' pasture without shading + supplement; 'Aruana' pasture with shading + supplement; and feedlot, with diet containing ryegrass hay and concentrate at a 20:80 ratio. The treatments did not influence lamb age at slaughter, birth weight, leg compactness, true yield, and main cut yield, except that of breast tip + flank that was lower for the pasture with shading. However, average daily gain, body condition score, live weight at slaughter, carcass compactness index, cold carcass and empty body weights, and cold carcass yield differed between treatments, showing higher values in the feedlot. Termination in the feedlot increases the zootechnical performance of Dorper x Santa Inês sheep and favors a lower age at slaughter, as well as a greater weight of the main commercial cuts, but not their yield.

New temperate seaweed targets for mitigation of ruminant methane emissions: an in vitro assessment

ABSTRACT Methane is a potent greenhouse gas with a comparatively short (9 yr) atmospheric lifetime; therefore effective strategies for methane mitigation will contribute significantly to meeting the UN Sustainable Development Goal #13 of taking rapid action against climate change. Methane emissions from enteric fermentation constitute a large proportion of agricultural greenhouse gas emissions. Low inclusions of red seaweed from the genus Asparagopsis have demonstrated near elimination of enteric methane from ruminants; however, only a limited number of other seaweeds have been assessed for their anti-methanogenic potential. New Zealand red seaweed species Bonnemaisonia hamifera, Euptilota formisissima, Plocamium cirrhosum, Vidalia colensoi, and identified aquaculture target species Ecklonia radiata and Ulva sp. B were investigated as anti-methanogenic feed additives. Seaweeds were included at 0%, 2%, 6%, or 10% of feed organic matter (OM, ryegrass hay) during in vitro fermentation assays using rumen inoculant from non-lactating Friesian x Jersey dairy cows, using Asparagopsis armata as a positive control. Total gas, methane, hydrogen, volatile fatty acids, and organic matter degradation were measured over a 48 h incubation. Inclusion of all seaweeds except Ulva sp. B reduced the production of methane at either 6 or 10% OM. Bonnemaisonia hamifera was the best performing seaweed, reducing the production of methane by 17.1%, 95.4%, and 98.8% relative to the basal feed substrate control at inclusion levels of 2%, 6%, and 10% OM, respectively, with notable increases in the production of hydrogen. Euptilota formisissima and P. cirrhosum reduced the production of methane by up to 50.5 and 39.5%, respectively, at an inclusion level of 10%, with minimal effects on measured fermentation parameters. Bromoform, the primary bioactive component in Asparagopsis, was not detected in any of the new seaweeds tested. Our results therefore identify potential alternative anti-methanogenic seaweed targets that are less susceptible to the loss of volatile bioactives during processing.

Similar distribution of 15N labeled cattle slurry and mineral fertilizer in soil after one year

Targeted use of animal manures as a nitrogen (N) fertilizer is challenging because of their poorly predictable N fertilizer value. An enhanced understanding of their N transformation processes in soil under field conditions is necessary to better synchronize N availability and crop N demand. 15N labeled cattle slurry, produced by feeding a heifer with 15N labeled ryegrass hay, was used in an on-farm trial on two neighboring fields, cropped with maize or grass-clover, in order to assess crop N uptake and N dynamics in the topsoil. Recovery of applied total N in plant biomass was higher for mineral fertilizer (Min) (45–48%) than for slurry (Slu) (17–22%) when applied at the same rate of mineral N. Also, N derived from fertilizer in plant biomass was higher for Min than for Slu, due to both greater NH3 emissions and greater initial immobilization of slurry N. Despite initial differences between the two in the relative distribution of residual fertilizer N in soil N pools, already in the following spring the majority (77–89%) of residual N from both fertilizers was found in the non-microbial organic N pool. Of the applied total N, 18–26% remained in the topsoil after the first winter for Min, compared to 32–52% for Slu. Thus, the proportion of fertilizer N not taken up by the first crop after application, enters the soil organic N pool and must be re-mineralized to become plant available.

Influence of pasture, silvopastoral, and feedlot production systems and the recording interval of behavioral activities on the ingestive behavior of lambs

The evaluation of the ingestive behavior of ruminant animals is important to identify the animal response to the particularities of the different production systems. However, the five-minute evaluation technique requires personnel, making it difficult to adhere to farms and research in more complex pastoral systems. Thus, this study objected to evaluating the influence of pasture, silvopastoral, and feedlot production systems on the ingestive behavior of lambs and to defining the behavior recording interval in each of the systems. Twenty-four lambs were distributed in an experimental design in split plots. The plots were the production systems (pasture without shading - PS, silvopastoral - SS, and feedlot systems - FS) and the subplots were the behavior observation intervals (5, 10, 15, and 20 min.). In the pasture without shading and silvopastoral systems, the lambs were kept on Aruana grass (Megathyrsus maximus) pasture and supplemented with concentrate at 1.5% of body weight per day, on a dry matter (DM) basis. In the feedlot system, the lambs received a diet consisting of 200 g kg DM-1 of annual ryegrass hay (Lolium multiflorum Lam.) and 800 g kg DM-1 of concentrate. There was no interaction (P &gt; 0.05) between the production system and the recording interval of behavioral activities. The time spent on food intake was higher (P &lt; 0.05) in the pasture (533 min d-1) and silvopastoral (513 min d-1) systems than in the feedlot (225 min d-1). In contrast, for water intake, time was higher (P &lt; 0.05) in the feedlot (21 min d-1) and lower in the silvopastoral system (5 min d-1). There was no difference (P &gt; 0.05) between the systems for rumination and idle activities, of which daily averages were 378 and 587 min d-1, respectively. There was also no difference (P &gt; 0.05) between the observation intervals for feed, water, rumination, and idleness activities. Lambs in pasture-based systems spend more time feeding, and feedlot lambs spend more time ingesting water. Feedlot lambs ruminate as much as grazing animals when fed hay, even though hay represents only 20% of the total diet. The recording interval of behavioral activities in these production systems can be up to 20 minutes.

Influência da inclusão de farinha de batata-doce (Ipomoea batatas) sobre a digestibilidade, o consumo e a retenção de nitrogênio em ovinos alimentados com feno de azevém anual (Lolium multiflorum Lam)

ABSTRACT This study aimed to evaluate sweet potato feed as an alternative energy supplement for ovine. A latin-square design was used to assess the effects of feeding the animals 0, 0.5, 1 and 1.5% their body weight in sweet potato as well as ryegrass hay (Lolium multiflorum) twice daily, mineral salt and water ad libitum. During this study 8 males were housed in metabolic cages with urine and feces collectors. Each round of experimentation consisted of 14 days adaptation followed by 5 days evaluating the diet, left-overs, feces, and urine to determine intake, digestibility, and nitrogen retention. The results show a linear increase in intake of ryegrass hay, FDN, DM and OM because of the increasing supplementation levels. Similarly, we observed a linear increase in DM and OM intake, as well as in the OM digestibility. Additionally, BP digestibility decreased considering nitrogen excretion. In conclusion, sweet potato feed is a viable alternative for ovine receiving ryegrass hay since it increased DM and OM digestibility, albeit reducing NDF and BP digestibility.

Biochemical Properties of Black and Green Teas and Their Insoluble Residues as Natural Dietary Additives to Optimize In Vitro Rumen Degradability and Fermentation but Reduce Methane in Sheep.

Simple SummaryAnimal nutritionists are challenged to increase animal production with respect to competitiveness and efficiency yet at the same time produce products that are healthy for the consumer and friendly to the environment. Black (BTL) or green (GTL) tea leaves and their spent tea leaf residues (STL) are rich in polyphenols, and can be used to not only supplement animal diets but also reduce the environmental burden of their safe disposal. These tea products were assessed for their potential use as natural dietary additives in ruminant diets to not only optimize rumen in vitro digestibility and fermentation but also reduce methane (CH4) emission. Both types of tea leaves were effective in significantly reducing ammonia (NH3) and CH4 production without decreasing rumen degradability. Tea leaves and their STL inclusions increased the acetate to propionate (A:P) ratio significantly. The GTL-containing diets had significantly greater rumen degradability but lower rumen NH3 compared with the BTL diets. Decreased rumen NH3 production in ruminants can be a possible sign of increasing bypass protein whilst reduced rumen CH4 release can be useful for enhancing energy use efficiency and environmentally friendly ruminant production. Black (BTL) or green (GTL) tea and their spent tea (STL) leaves can be used as natural dietary additives for ruminants. Experiment 1 used a 3 × 2 × 2 factorial arrangement, with four replicates (n = 4) to test the effects of three different inclusions of tea leaves at 0 (control), 50, and 100 g/kg DM of two different tea types (BTL and GTL) in two different total mixed diets containing either ryegrass hay (RH) or rice straw (RS) on in vitro rumen organic matter degradability (IVOMD), volatile fatty acids (VFA), pH, ammonia (NH3), and methane (CH4) outputs over a 24 h incubation time. Experiment 2 followed a 3 × 2 × 2 factorial arrangement, with eight replicates (n = 8) to study the impacts of three different STL inclusions at 0, 100, and 200 g/kg DM of two different STL types (black and green) into two different total mixed diets containing either RH or RS on the same in vitro measurements. Both types of tea leaves decreased NH3 (p < 0.001) and CH4 (p < 0.01) without affecting (p > 0.05) rumen degradability, but the effect of their STL was less remarkable. Tea leaves and their STL inclusions improved (p < 0.01 and p < 0.001, respectively) the acetate to propionate (A:P) ratio. Compared with BTL, GTL containing diets had higher IVOMD (p < 0.05) and A:P ratio (p < 0.05) but lower NH3 (p < 0.001). Reduced rumen NH3 and CH4 outputs can be useful for protein and energy use efficiency while an increased A:P ratio might lead to increased milk fat synthesis and reduced low-fat milk syndrome. The surplus or wasted tea leaf products could be used as sustainable sources of nutrients to optimize rumen function and minimize environmental impacts of feeding ruminant animals.

Prior Forage Type Influences Ruminal Responses to a Wheat Grain Challenge in Lactating Dairy Cows.

Simple SummaryHigh-producing dairy cows require more than just pasture to meet the energy demands of milk production. Wheat is an excellent energy source for milk production; however, cows require careful adaptation and monitoring to avoid ruminal upset when large amounts of wheat are introduced. The results of this study show that careful selection of the forage that precedes wheat could allow safer and more aggressive grain introduction strategies to be used in the dairy industry.To increase the dry matter and metabolisable energy intake of cows, dairy farmers often supplement pasture with concentrates and conserved fodder. Feeding large amounts of highly fermentable concentrates to cows can result in metabolic issues, such as ruminal acidosis, and thus safer but more efficient introduction strategies are desirable. We assessed the role that forages play in ruminal, behavioural and production responses to a wheat grain challenge in dairy cows with no previous wheat adaptation. Multiparous lactating Holstein dairy cows (n = 16) were fed a forage-only diet of either lucerne (Medicago sativa) hay, perennial ryegrass (Lolium perenne L.) hay or one of two cultivars of zero-grazing fresh perennial ryegrass herbage (Bealey or Base), for 3 weeks. The forage diet was then supplemented with crushed wheat grain at 8 kg dry matter/cow day−1, with no adaptation period. Wheat comprised between 32 and 43% of total dry matter intake. Cows fed hay maintained a higher mean ruminal fluid pH than those fed herbage, on both the forage-only diet (6.43 vs. 6.17) and the forage plus wheat diet (6.03 vs. 5.58). Following supplementation of wheat, cows fed herbage exhibited minimum ruminal fluid pH levels indicative of acute ruminal acidosis, at 5.15 and 5.06 for cultivars Bealey and Base, respectively. Furthermore, for both herbage cultivars, adding wheat resulted in a ruminal fluid pH under 6 for >20 h/day. The ruminal environment of cows fed lucerne hay remained most stable throughout the grain challenge, spending the least amount of time below pH 6.0 (9.0 h/day). Hay created a ruminal environment that was better able to cope with the accumulation of acid as wheat was digested. A combination of increased ruminating time and a slower rate of fermentation, due to higher neutral detergent fiber and lower metabolisable energy concentrations in the hays, is likely responsible for the higher ruminal fluid pH values. Forage plays a critical role in wheat introduction strategies; aggressive adaptation strategies could be implemented when a hay such as lucerne is used as the base forage.

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The contributions of replacing rye-grass (Lolium spp.) hay with banana (Musa acuminata) by-products on carcass and tissue characteristics, pH and color, in the Canary hair sheep breed were studied. Twenty-two lambs with an initial live weight of 14.8 ± 2.5 kg were individually housed and fed two different diets for 58 days: The first group (experimental diet) received as forage a mixture of fresh banana (Musa acuminata) by-products composed by leaves and pseudo-stem. The other one got commercial rye-grass (Lolium spp.) hay (conventional diet) as a fiber source. The two groups got an additional commercial concentrate food (CON). After the 58 days growing trial (24.3 kg ± 1.0 kg), seven lambs of each group (n=14) were slaughtered in the experimental slaughterhouse. The muscle, the pH, and the color were measured at the time immediately after slaughter and 24 h later, using the muscles Longissimus thoracis et lumborum and semimembranosus. At that time (after 24 h), the remaining semi-carcass was butchered and dissected for analysis of the carcass´s regional and tissue composition. Although there is no significant difference on the tissue composition, carcass regional and the muscle pH, there are significant differences in the color in the Longisimus toracis et lumborum between the two assessed diets. The incorporation of banana by-products in a diet to fatten lambs Canary hair sheep breed would not grossly alter the carcass quality, at least based on the assessed parameters. Banana by-products as a feeding resource can maintain animal productivity and meat quality. © 2021 Friends Science Publishers

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

Simple SummaryEarly, accurate, and rapid detection of R. toxicus is extremely important to improve inspections of imported annual ryegrass hay and seed at ports of entry and enhance in-field detection. RPA is a comparatively new, easy to use, and robust technology that can be performed in the palm of the hand without losing specificity. The RPA assay was more sensitive than endpoint PCR and did not require lab equipment in the field. The developed assay has tremendous applications for in-field plant diagnostics and biosecurity surveillance.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.

Kinetics of gas production in the presence of Fusarium mycotoxins in rumen fluid of lactating dairy cows

Little is known about the effects of Fusarium mycotoxins on the fermentation potential of rumen fluid sampled from lactating dairy cows ingesting diets contaminated at regular levels of these mycotoxins (i.e., contamination levels that can normally be found on dairy farms). In the current experiment, rumen donor animals received diets contaminated with both deoxynivalenol (DON) and fumonisins (FB) with or without a mycotoxin-deactivating product. The rumen fluid donor animals were 12 lactating Holstein dairy cows that received one of 3 experimental diets in agreement with a 3 × 3 Latin square design (3 periods and 3 treatments). The 3 diets were as follows: (1) a TMR contaminated with a regular level of Fusarium mycotoxins [340.5 ± 161.0 µg of DON/kg of dry matter (DM) and 127.9 ± 43.9 µg of FB/kg of DM; control diet, CTR], (2) a TMR contaminated with Fusarium mycotoxins at levels higher than CTR but below US and European Union guidelines (733.0 ± 213.6 µg of DON/kg of DM and 994.4 ± 323.2 µg of FB/kg of DM; MTX), and (3) the MTX diet (897.3 ± 230.4 µg of DON/kg of DM and 1,247.1 ± 370.2 µg of FB/kg of DM) supplemented with a mycotoxin-deactivator product (Mycofix, Biomin Holding GmbH; 35 g/animal per day; MDP). Each experimental period lasted 21 d, and rumen fluid was individually sampled from all cows on the last day of each intoxication period. Then, the 4 rumen fluids sampled from cows receiving the same experimental diets were pooled into a single rumen inoculum, which was used in the in vitro gas production test. For the gas production test, 3 different rumen inocula (i.e., CTR, MTX, and MDP) were buffered (buffer:rumen ratio of 2:1, vol/vol) and then used in 3 fermentation runs to evaluate gas production dynamics in the presence of 8 feeds (i.e., corn meal, barley meal, corn silage, sorghum silage, alfalfa hay, ryegrass hay, dry brewers barley grains, and dried distillers grains with solubles). The kinetic parameters of gas production and volatile fatty acid concentrations were evaluated at the end of fermentation. The block run (i.e., fermentation day) effect influenced all of the fermentative and kinetic parameters. Greater final volumes or rates of gas production over time were observed for MDP compared with MTX rumen inocula (i.e., 172.6 vs. 147.8 mL/g of organic matter or 0.078 vs. 0.063 h−1, respectively). However, the increase in rate of gas production was not consistent among tested feeds, meaning that a treatment by feed interaction was observed. Volatile fatty acid concentrations were not different among treatments, except for a slight increase of acetic acid in CTR compared with MTX (i.e., 71.0 vs. 67.9 mmol/L). This study showed that Fusarium-produced mycotoxins negatively affected the kinetics of gas production in feeds, whereas the presence of the mycotoxin-deactivator product in the diets of donor animals resulted in an increase in rumen fermentation potential, thus safeguarding the rumen environment.

Effect of solid feed level and types of roughage on passage kinetics of milk replacer, concentrate, and roughage in veal calves

This study aimed (1) to provide estimates of total mean retention times of milk replacer (MR), concentrates, and roughage in veal calves fed a mixed diet; (2) to determine the effect of level and type of solid feed (SF) on passage kinetics of MR, concentrates, and roughages in veal calves; and (3) to compare passage kinetics in veal calves using the fecal excretion curves of indigestible markers and a noninvasive 13C tracer breath test approach to determine whether the latter technique can serve as an alternative. At the start of the trial, 48 Holstein-Friesian calves (6 wk of age; 68 ± 7.7 kg of body weight; BW) were assigned to 1 of 4 dietary treatments (for statistical analysis, only 39 calf observations were used). Three treatments contained chopped wheat straw as roughage in the SF mixture in a concentrate:roughage ratio of 90:10 (dry matter basis). The SF level was 20 g/kg of metabolic BW per day (low straw), 30 g/kg of metabolic BW per day (middle straw), or 40 g/kg of metabolic BW per day (high straw). The fourth treatment (high hay) contained long perennial ryegrass hay as roughage in the SF mixture in a concentrate:roughage ratio of 70:30 (dry matter basis, at 40 g/kg of metabolic BW per day). The quantity of MR was fixed for the high straw treatment, whereas the amount of MR for the other treatments during the adaptation period was adjusted based on a pair gain strategy (i.e., exchanging ration components but keeping similar net energy). At the end of the adaptation period, calves ranged from 12 to 15 wk of age with an average BW of 123 ± 8.6 kg. Passage kinetics of concentrates were estimated by measuring 13C enrichment excess of CO2 in breath from a pulsed-dose of [1-13C]octanoate. Passage kinetics of roughage, concentrates, and MR were also estimated using fecal excretion curves obtained after ingestion of chromium-mordanted roughage, Yb2O3, and Co-EDTA, respectively. We conclude that [1-13C]octanoate cannot serve as a measure for oro-duodenal transit of concentrates because of unrealistic estimates. Based on the fecal excretion curves, we concluded that the total mean retention time of MR (i.e., time to peak; the moment that the excretion curve reaches peak concentration) was, on average, 12.4 h, and that the passage kinetics of MR was not affected by the level or type of SF. The mean retention time of concentrates was shorter (21.4 h) than that of both straw (59.1 h) and hay (36.8 h), and was not affected by the level or type of SF. Also, the mean retention time of the slowest compartment (i.e., the rumen) was shorter for concentrates (39.6 h) than that of straw (110.0 h) and hay (59.2 h). Contrary, the passage of roughage was affected by level and type of SF. Long hay increased time to peak by 22.3 h and decreased ruminal mean retention time by 50.8 h relative to chopped straw, indicating that the passage rate of long hay is faster than that of chopped straw. We conclude that the level and type of SF only affects the passage kinetics of roughage and not that of MR and concentrates.

Use of schizochytrium spp. microalgae in suckling Holstein calves at different periods after birth

Calves are born immunologically immature and are highly susceptible to infectious diseases. For these reasons, suitable handling practices that favor health conditions and improve performance are necessary at this phase of life. The aim of this study was to evaluate whether the inclusion of Schizochytrium sp. microalgae for Holstein calves at different ages would improve dry matter intake (DMI), performance and health. Twenty-four newborn Holstein calves (34.0 ± 1.5 kg of BW) were allocated in a completely randomized design and were individually housed over 45 days. Starter and ryegrass hay and water were offered separately and ad libitum after the third day of life. Calves were daily fed five liters of whole milk divided in two equal meals. Treatments were as follows: whole milk without addition of microalgae (CON); addition of 6 g of microalgae/day over 45 days (ENT); addition of 6 g of microalgae/day from the 15th day of life until weaning (A15); and addition of 6 g of microalgae/day from the 30th day of life until weaning (A30). Calves that received microalgae (ENT, A15 and A30) had greater intake of starter in grams per day (P = 0.01) and metabolic weight (P = 0.02), and they tended (P = 0.07) to increase total DMI when compared with CON, without a difference in terms of feed efficiency (P = 0.20). Higher weaning thoracic perimeter (P = 0.03) for supplemented animals were observed. Serum lipid peroxidation (LPO) and reactive oxygen species (ROS) were reduced (P = 0.029 and P < 0.001, respectively) with the addition of microalgae, regardless of the time of supplementation. The inclusion of 6 gs of Schizochytrium spp. microalgae increased starter intake and reduced oxidative reactions regardless of supplementation time, which justifies microalgae supplementation only in the final 15 days of suckling.