S. Uwituze

Prior adaptation improves crude glycerin utilization by cattle

Introduction Crude glycerin has increased in availability as a feedstock for cattle as a result of expansion of the biodiesel industry in the United States. This byproduct, when ingested by cattle, is fermented by ruminal bacteria to yield volatile fatty acids that are used as sources of energy by cattle. The primary component of crude glycerin is glycerol, and the fermentation of glycerol is carried out by specific populations of microorganisms. Anecdotal observations from our previous research with crude glycerin in feedlot cattle have suggested that a period of adaptation may be necessary to achieve optimal utilization of the byproduct. Our objective in this study was to evaluate this adaptive response by measuring in vitro digestion by ruminal microbes that were obtained from cattle fed diets with or without added glycerin.

Effects of feeding diets rich in α-linolenic acid and copper on performance, carcass characteristics, and fatty acid profiles of feedlot heifers.

Our objective was to evaluate whether feeding elevated Cu concentrations in conjunction with Linpro, a co-extruded blend of field peas and flaxseed, affected in vitro fermentation, performance, and plasma lipid profiles of fattening beef heifers. In study 1, 2 in vitro trials were conducted as randomized complete experiments with a 2×2 factorial treatment arrangement (10 or 100 mg/kg added Cu and 0 or 10% Linpro, DM basis) to determine VFA/gas production and IVDMD. Linpro contains 12% α-linolenic acid and added vitamins and minerals. In study 2, a randomized complete block experiment with a 2×2 factorial treatment arrangement was conducted with the same previously described treatment. Crossbred yearling heifers (n=261; 351±23 kg initial BW) were blocked by weight into heavy and light groups and randomly assigned to experimental pens containing 10 or 11 heifers each. In study 1, no interactions between levels of Cu and Linpro were observed. Copper concentration did not affect IVDMD (P>0.2) but increased (P<0.05) by 1.2% when Linpro was included. Final pH was not effected by added Cu (P>0.05), but pH increased when Linpro was added (P<0.05). Total VFA were greater in high-Cu treatments (P=0.038) and molar proportions were not affected (P>0.34). Linpro had no effect on total VFA (P=0.46) and molar proportions of propionate and isobutyrate increased whereas acetate and the acetate:propionate ratio decreased (P<0.01). Linpro increased the production of H2S (30% higher; P=0.05), and Cu inclusion slightly increased CO2 proportion (64.06 vs. 67.58% for Linpro vs. Cu treatments, respectively). In study 2, there were no interactions between levels of Linpro and supplemental Cu except for plasma n-6:n-3 ratio (P<0.01). Final BW were similar for cattle fed 0 and 10% Linpro (581 vs. 588 kg; P>0.20), but cattle fed diets with Linpro consumed less feed (14.08 vs. 13.59 kg/d; P<0.05) and were therefore more efficient (0.129 vs. 0.137 for 0 vs. 10% Linpro, respectively; P<0.01). Carcass traits were not affected by treatment. Feeding elevated levels of Cu did not appreciably alter PUFA proportions in plasma and LM. Plasma and LM concentrations of omega-3 fatty acids, including C18:3, C20:5, and C22:5, were greater for heifers fed Linpro (P<0.05). Increasing dietary Cu was not effective as a strategy for decreasing ruminal biohydrogenation and subsequent tissue deposition of PUFA.

Crude glycerin improves feed efficiency in finishing heifers

Introduction Crude glycerin is the principal byproduct of biodiesel production. The raw feedstocks, animal fats and vegetable oils, yield approximately 90 lb of biodiesel and 10 lb of crude glycerin for each 100 lb of input. When ingested by cattle, glycerin has two major fates: (1) direct absorption by the rumen epithelium, and (2) fermentation by microorganisms within the rumen to generate volatile fatty acid, mainly propionate. Using glycerin in feedlot cattle diets has become common, particularly as a component of liquid feed supplements.

Influence of Linpro and dietary copper on feedlot cattle performance, carcass characteristics, and fatty acid composition of beef

Introduction Human diets often contain high levels of saturated fatty acids that can have deleterious health consequences such as obesity, diabetes, and heart disease. In contrast, omega-3 fatty acids, which are essential for human nutrition, are consumed at relatively low levels despite of their positive effects on health. Natural sources of omega-3 fatty acids include fresh legumes, cool-season grasses, flaxseed, and fish oil. In spite of the fact that fresh forages often are a key part of the cattle diet, beef is a relatively poor source of omega-3 fatty acids because of biohydrogenation, the action of microorganisms in the rumen that convert polyunsaturated fatty acids, including the omega-3 fats, into saturated fats. Previous research at Kansas State University has shown that feeding cattle flax-based feeds can increase concentrations of omega-3 fatty acids in beef. Researchers at Colorado State University have reported that elevated levels of dietary copper can inhibit the biohydrogenation process to yield beef with greater proportions of polyunsaturated fatty acids. Our objective was to evaluate whether feeding elevated copper concentrations in conjunction with Linpro (OT Regina, Saskatchewan, Canada), a co-extruded blend of field peas and flaxseed, could be used to further improve the levels of omega-3 fatty acids in beef.

Dietary sulfur concentration has no effect on In Vitro fermentative activity of ruminal mixed microorganisms

Introduction We previously reported that elevated concentrations of dietary sulfur (0.65% sulfur, dry basis) in finishing diets containing dried distillers grains with solubles decreased dry matter intake and average daily gains of feedlot cattle. Furthermore, high dietary sulfur concentrations yielded lower ruminal concentrations of volatile fatty acids, but were associated with increased ruminal ammonia concentrations and improved total tract digestibility of the diet. The objective of this study was to investigate, in culture tubes, effects of added sulfur on in vitro dry matter disappearance, volatile fatty acid profiles, and ammonia concentrations from substrates containing different sulfur concentrations when fermented by mixed ruminal microorganisms from a steer fed a diet based on corn and alfalfa.

High sulfur content in distillers grains altersruminal fermentation and diet digestibility inbeef steers

Introduction Requirements for elemental sulfur in feedlot diets have been established to be approximately 0.15% with a maximum upper threshold of 0.40% of diet dry matter. Feeding ethanol fermentation by-products, such as distillers grains with solubles, that are high in sulfur can result in dietary sulfur levels that exceed the recommended maximum. Previous studies indicated that dietary sulfur influenced the site and extent of fiber and protein digestion. The objective of this study was to evaluate ruminal fermentation characteristics and diet digestibility when 30% (dry matter basis) dried distillers grains with solubles with various levels of sulfur was incorporated into finishing diets based on steam-flaked corn or dry-rolled corn.

Beta acid extracts of hops have a modesteffect on ruminal metabolism and apparenttotal tract digestibility by steers fed high-concentrate diets

Introduction Hops have been used for centuries to control bacterial contamination in beer production. Today, alpha acids are extracted from hops for use in flavoring beer, leaving residues that are rich in beta acids. Beta acid fractions of hops can selectively inhibit specific ruminal Gram-positive bacteria that are responsible for major digestive disturbances, such as acidosis and bloat, and have a chemical structure similar to that of ionophores used in feedlot production. Use of ionophores improves efficiency of feed utilization and decreases the incidence of digestive disturbances that are a major cause of morbidity and mortality in cattle feeding operations. The objectives of this study were to evaluate the effect of beta acid extracts of hops on ruminal fermentation and diet digestibility in cattle fed high-concentrate diets and determine response to different doses of beta acid extracts of hops.

High sulfur content in distillers grains withsolubles may be deleterious to beef steerperformance and carcass quality

Introduction Distillers grains with solubles are becoming an increasingly important staple of cattle diets because of rapid expansion of the fuel ethanol industry. Sulfuric acid often is used in ethanol production processes to clean and control the pH of fermenters. Consequently, distillers grains with solubles can occasionally contain high sulfur concentrations. Within the rumen, sulfur is converted to hydrogen sulfide gas by ruminal microbes. Hydrogen sulfide is eructated from the rumen and subsequently aspirated into the lungs; excess amounts of hydrogen sulfide can cause polioencephalomalacia (brainers). Polioencephalomalacia is characterized by increased respiration, decreased feed intake, listlessness, muscular incoordination, progressive blindness, and necrosis of brain tissue. Elevated sulfur levels also may have deleterious effects on cattle growth performance and carcass characteristics. The objective of this study was to evaluate effects of sulfur content in dried distillers grains with solubles on ruminal gas concentrations, feedlot performance, and carcass characteristics of finishing steers fed diets based on steam-flaked corn or dry-rolled corn.

Higher ruminal pH increases in vitro digestion of diets containing dried distillers grains with solubles

Introduction Advantages of steam flaking grain are less with respect to growth performance and diet digestion when a portion of distillers grains is substituted for grain. Ruminal pH typically is lower in cattle fed flaked-grain diets than in cattle fed rolled-grain diets. Ruminal pH for cattle fed finishing diets based on steam-flaked corn is observed below pH 6.0. Previous research observed a 5% decrease in digestion of organic matter when 13% distillers grains (dry-matter basis) was added to steam-flaked corn finishing diets. A decline in ruminal pH below 6.2 reduces activity of ruminal fiber-digesting organisms. Furthermore, ruminal protein digestion declines with pH below 5.5. It is plausible that low ruminal pH may restrict digestion of distillers grains in flaked-grain diets. The objective of this study was to examine effects of pH on in vitro fermentative activity of ruminal contents from cattle adapted to a finishing diet containing 25% dried distillers grains (dry-matter basis).

Substituting steam-flaked corn with distiller’s grains alters ruminal fermentation and diet digestibility

Rapid expansion of fuel ethanol production in the High Plains, where feedlots commonly use steam-flaked corn diets, has popularized substituting dried distiller’s grains with solubles (DDGS) for a portion of the steamflaked corn. Most of the starch in corn is removed during ethanol production. The residual material is rich in fiber, ruminal undegradable protein, and fat. Adding roughage to high-concentrate finishing diets helps maintain ruminal function by stimulating salivation, rumination, and gut motility. The source and level of roughage can influence dry matter intake. Our objective was to examine ruminal fermentation characteristics and diet digestibility when steam-flaked corn-based finishing diets were fed with either 0 or 25% DDGS, using alfalfa hay or corn silage as roughage sources.