No abstract

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.

A field experiment was conducted on continuous barley to evaluate the effects of 3 beef cattle winter feeding systems (bale grazing (BG); swath grazing (SG); straw-chaff grazing (STCH)) and pen manure and compost application on soil N and P amounts and distribution, soil density and barley crop biomass. Cattle winter feeding systems were managed during the winter of 2005-2006. Effects of extensive winter feeding system on soil nutrients and soil density were determined in the spring of 2006 after winter feeding. Nitrate nitrogen (NO 3 -N) amounts at the low slope position in the 0-15 cm depth were 53% higher (P \ 0.10) on BG sites than STCH sites. This may be attributed to the larger concentration of feed, thus feed nutrients, in the BG wintering system. Phosphorus amounts on the BG wintering sites at high slope were 34% higher (P \ 0.10) than amounts at the same slope on the SG or STCH sites. Soil density was 21% greater (P \ 0.10) where cows BG compared to where cows grazed straw-chaff piles, indicating differences in soil strength and resistance to penetration by roots. Soil density decreased on compost and raw manure sites in comparison to where no manure was applied, thus validating the benefits of manure on soil structure. Crop biomass measured on BG sites was consistent with soil nutrients captured, resulting in a 15% greater (P \ 0.10) total biomass compared to STCH and SG wintering sites. Soil nutrient and crop biomass distribution was consistent among winter feeding sites with the STCH sites having the most uniform distribution of nutrients and crop biomass, and the BG sites having the least. Managing manure nutrients from winter feeding systems can be beneficial when followed by an annual cropping system.

The effect of cicer milkvetch (Astragalus cicer L.) and sainfoin (Onobrychis viciifolia Scop.) on ruminal fermentation, methane production, and microbial nitrogen synthesis was assessed in two experiments. Experiment 1 analyzed 2 legumes, cicer milkvetch and sainfoin at 2 stages (vegetative and late flower) incubated with alfalfa (Medicago sativa) at 5 inclusion rates 0:100; 25:75, 50:50, 75:25 and 100:0 (as DM) in batch culture. Experiment 2 analyzed vegetative cicer milkvetch and alfalfa incubated in ratios of 25:75, 50:50, 75:25 and 100:0 (as DM) in continuous culture systems (RUSITEC). In batch culture, increased dry matter disappearance (DMD), and propionate percentage (%, total), and reduced methane (mg g-1 DMD) occurred with vegetative cicer milkvetch inclusion. In RUSITEC, DMD linearly increased (P < 0.01), acetate:propionate ratio quadratically decreased, while ammonia (NH3-N) concentration (P<0.01) and butyrate percentage (% total) linearly decreased (P<0.05) with increasing inclusion of cicer milkvetch. No differences were observed for methane (CH4) production (mg g-1 DMD), or short chain fatty acid (SCFA) production (mmol d-1). Microbial nitrogen synthesis and efficiency of protein synthesis linearly increased (P<0.05) with increased inclusion of cicer milkvetch. Results suggest cicer milkvetch may result in synchronicity of energy and nitrogen during rumen fermentation, which could enhance cattle production.

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; P < 0.01) in yr 1 in the sainfoin and cicer milkvetch treatments compared to control. DMI of steers was greater only in yr 5 and ADG was greater (P < 0.01) in sainfoin and cicer milkvetch treatments compared to control. At Lethbridge, sainfoin decreased (treatment × year; P = 0.01) from 46 to 17% (% DM yield), while cicer milkvetch maintained its proportion at 11%. Forage yield increased (treatment × year; P < 0.01) only in yr 2 and 3 of sainfoin, compared to cicer milkvetch or control. ADG gain was not affected by treatment. At Lanigan, sainfoin and cicer milkvetch generated greater gross returns compared to control; however, once establishment costs were applied there were no differences in present value of net returns.