Effect of winter feeding systems on soil nutrients

Non-Peer Reviewe

Legume based pasture rejuvenation for greenhouse gas outcomes

Non-Peer ReviewedIncorporating legumes into a grass based pasture system has multiple benefits. A grass/legume blend increases the dietary protein of foraging cattle over grass alone. Furthermore, symbiotic biological nitrogen fixation introduces additional nitrogen to the pasture system thereby potentially lessening the need for synthetic fertilizers. However, over time, pastures initially seeded with a blend of grasses and legumes will tend towards increasing grass dominance such that the presence and benefits of legumes diminishes. Reestablishing legumes on a mature pasture can restore these important functions. By improving ruminant diet and therefore feed conversion ratios as well as decreasing nitrogen fertilizer applications, pasture rejuvenation, through the introduction of legumes, is expected to lower the greenhouse gas cost of grazing livestock on a per output basis. However, disturbance of soils, which can be part of various rejuvenation techniques, can result in losses of soil carbon thereby offsetting potential at least some of the greenhouse gas benefits. Sod-seeding may be an effective strategy to establish legumes in a mature pasture thereby incurring benefits without heavily disrupting soils and incurring soil carbon loss. To test this, a multiyear experiment, including cattle, vegetation (specifically the incorporation of non-bloat legumes: cicer milkvetch and sainfoin), soils and microbiota, was established near Lanigan, SK to examine the impact of sod-seeded legume pasture rejuvenation on greenhouse gases

Impact of condensed tannin containing legumes on ruminal fermentation, nutrition and performance in ruminants: a review

Legume forages, such as sainfoin, and birdsfoot trefoil can increase the forage quality and quantity of western Canadian pastures, thus increasing producer profitability due to increased gains in grazing ruminants, while reducing risk of bloat in legume pastures due to the presence of proanthocyanidins. Proanthocyanidins or condensed tannins (CT) are secondary plant polyphenol compounds that have been regarded as anti-nutritional due to their ability to bind protein in feeds, enzymes, and microbial cells, therefore disrupting microbial digestion and slowing ruminal protein and dry matter digestion. Research has shown that at high concentrations (>50 g kg-1 DM), CT can disrupt microbial digestion. However, at low dietary inclusion rates (5-10 g kg-1 DM) they reduce bloat risk, and increase ruminal undegradable protein (RUP), reduce enteric methane production, and confer anthelmintic activity. Yet, research gaps still exist regarding grazing persistence and forage yield of novel CT containing forages and their biological activity due to their vast differences in CT stereochemistry, polymer size, and intermolecular linkages. The objectives of this review are to summarize information regarding the impact of CT on ruminal fermentation, carbohydrate and protein metabolism, and the potential to identify and select for forages that contain condensed tannins for ruminant production.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Effect of sod-seeding bloat-free legumes on pasture productivity, steer performance, and production economics

A five-year experiment evaluated the effects of sod-seeding sainfoin and cicer milkvetch into monoculture grass (Lanigan, SK) or legume (Lethbridge, AB) stands on pasture productivity, steer performance, and economics. At Lanigan, sainfoin decreased (treatment year P = 0.01) from 13% in yr 1 to 2% in yr 2 (% plant population) and did not differ thereafter, while cicer milkvetch, maintained a proportion of 16% in the stand. Forage yield was greater (treatment year; PThe accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Intraspecific venom variation in the medically significant Southern Pacific Rattlesnake (Crotalus oreganus helleri): biodiscovery, clinical and evolutionary implications

Due to the extreme variation of venom, which consequently results in drastically variable degrees of neutralization by CroFab antivenom, the management and treatment of envenoming by Crotalus oreganus helleri (the Southern Pacific Rattlesnake), one of the most medically significant snake species in all of North America, has been a clinician's nightmare. This snake has also been the subject of sensational news stories regarding supposed rapid (within the last few decades) evolution of its venom. This research demonstrates for the first time that variable evolutionary selection pressures sculpt the intraspecific molecular diversity of venom components in C. o. helleri. We show that myotoxic beta-defensin peptides (aka: crotamines/small basic myotoxic peptides) are secreted in large amounts by all populations. However, the mature toxin-encoding nucleotide regions evolve under the constraints of negative selection, likely as a result of their non-specific mode of action which doesn't enforce them to follow the regime of the classic predator prey chemical arms race. The hemorrhagic and tissue destroying snake venom metalloproteinases (SVMPs) were secreted in larger amounts by the Catalina Island and Phelan rattlesnake populations, in moderate amounts in the Loma Linda population and in only trace levels by the Idyllwild population. Only the Idyllwild population in the San Jacinto Mountains contained potent presynaptic neurotoxic phospholipase A(2) complex characteristic of Mohave Rattlesnake (Crotalus scutulatus) and Neotropical Rattlesnake (Crotalus durissus terrificus). The derived heterodimeric lectin toxins characteristic of viper venoms, which exhibit a diversity of biological activities, including anticoagulation, agonism/antagonism of platelet activation, or procoagulation, appear to have evolved under extremely variable selection pressures. While most lectin alpha- and beta-chains evolved rapidly under the influence of positive Darwinian selection, the beta-chain lectin of the Catalina Island population appears to have evolved under the constraint of negative selection. Both lectin chains were conspicuously absent in both the proteomics and transcriptomics of the Idyllwild population. Thus, we not only highlight the tremendous biochemical diversity in C. o. venom-arsenal, but we also show that they experience remarkably variable strengths of evolutionary selection pressures, within each toxin class among populations and among toxin classes within each population. The mapping of geographical venom variation not only provides additional information regarding venom evolution, but also has direct medical implications by allowing prediction of the clinical effects of rattlesnake bites from different regions. Such information, however, also points to these highly variable venoms as being a rich source of novel toxins which may ultimately prove to be useful in drug design and development