C. C. Aperce

Capacity of the bovine intestinal mucus and its components to support growth of Escherichia coli O157:H7.

Colonization of the gastrointestinal tract of cattle by Shiga toxin-producing Escherichia coli increases the risk of contamination of food products at slaughter. Our study aimed to shed more light on the mechanisms used by E. coli O157:H7 to thrive and compete with other bacteria in the gastrointestinal tract of cattle. We evaluated, in vitro, bovine intestinal mucus and its constituents in terms of their capacity to support growth of E. coli O157:H7 in presence or absence of fecal inoculum, with and without various enzymes. Growth of E. coli O157:H7 and total anaerobic bacteria were proportionate to the amount of mucus added as substrate. Growth of E. coli O157:H7 was similar for small and large intestinal mucus as substrate, and was partially inhibited with addition of fecal inoculum to cultures, presumably due to competition from other organisms. Whole mucus stimulated growth to the greatest degree compared with other compounds evaluated, but the pathogen was capable of utilizing all substrates to some extent. Addition of enzymes to cultures failed to impact growth of E. coli O157:H7 except for neuraminidase, which resulted in greater growth of E. coli O157 when combined with sialic acid as substrate. In conclusion, E. coli O157 has capacity to utilize small or large intestinal mucus, and growth is greatest with whole mucus compared with individual mucus components. There are two possible explanations for these findings (i) multiple substrates are needed to optimize growth, or alternatively, (ii) a component of mucus not evaluated in this experiment is a key ingredient for optimal growth of E. coli O157:H7.

Effects of Menthol Supplementation in Feedlot Cattle Diets on the Fecal Prevalence of Antimicrobial-Resistant Escherichia coli

The pool of antimicrobial resistance determinants in the environment and in the gut flora of cattle is a serious public health concern. In addition to being a source of human exposure, these bacteria can transfer antibiotic resistance determinants to pathogenic bacteria and endanger the future of antimicrobial therapy. The occurrence of antimicrobial resistance genes on mobile genetic elements, such as plasmids, facilitates spread of resistance. Recent work has shown in vitro anti-plasmid activity of menthol, a plant-based compound with the potential to be used as a feed additive to beneficially alter ruminal fermentation. The present study aimed to determine if menthol supplementation in diets of feedlot cattle decreases the prevalence of multidrug-resistant bacteria in feces. Menthol was included in diets of steers at 0.3% of diet dry matter. Fecal samples were collected weekly for 4 weeks and analyzed for total coliforms counts, antimicrobial susceptibilities, and the prevalence of tet genes in E. coli isolates. Results revealed no effect of menthol supplementation on total coliforms counts or prevalence of E. coli resistant to amoxicillin, ampicillin, azithromycin, cefoxitin, ceftiofur, ceftriaxone, chloramphenicol, ciprofloxacin, gentamicin, kanamycin, nalidixic acid, streptomycin, sulfisoxazole, and sulfamethoxazole; however, 30 days of menthol addition to steer diets increased the prevalence of tetracycline-resistant E. coli (P < 0.02). Although the mechanism by which menthol exerts its effects remains unclear, results of our study suggest that menthol may have an impact on antimicrobial resistance in gut bacteria.

Effects of crystalline menthol on blood metabolites in Holstein steers and in vitro volatile fatty acid and gas production

Fifty-two Holstein steers (573 ± 9.92 kg BW) were used to determine if oral administration of crystalline menthol would induce changes in endogenous secretions of IGF-1 and circulating concentrations of glucose, lactate, and plasma urea nitrogen (PUN). Steers were blocked by BW and assigned within block to treatment. Treatments consisted of 0, 0.003, 0.03, or 0.3% crystalline menthol (DM basis) added to the diet. Animals were housed in individual, partially covered pens equipped with feed bunks and automatic water fountains. On d 1 of the experiment, blood samples were obtained via jugular venipuncture at 0, 6, 12, 18, and 24 h after feeding. Treatment administration commenced on d 2, and blood samples were again drawn at 0, 6, 12, 18, and 24 h after feeding. This blood-sampling schedule was repeated on d 9, 16, 23, and 30. Plasma was analyzed for PUN, glucose, and lactate concentrations. Serum was used to analyze IGF-1 concentration. Body weights were measured on d 1, 9, 16, 23, and 30. To accompany the live animal phase, in vitro fermentations were performed using ruminal fluid cultures. Measurements included VFA concentrations and fermentative gas production for cultures containing crystalline menthol at 0, 0.003, 0.03, or 0.3% of substrate DM. Addition of menthol to the diet of steers resulted in a treatment × day interaction ( < 0.01) for concentrations of IGF-1, PUN, and plasma glucose. Cattle fed 0 and 0.003% menthol had greater serum IGF-1 concentrations on d 2 compared with steers fed 0.03% menthol. Steers fed 0% menthol had greater serum IGF-1 concentrations on d 9 compared with steers fed 0.03 and 0.3% menthol, whereas no differences were observed on d 23 or 30. Plasma glucose was similar among treatments until d 23, when steers supplemented with 0.03% menthol had lower glucose concentrations. Plasma urea nitrogen concentrations were not different among treatments; however, PUN concentrations varied by day. A linear response was detected for BW ( = 0.03), with steers consuming 0% menthol having the greatest BW and steers that consumed 0.3% menthol having the lightest BW until d 30. A menthol × day interaction was observed for daily feed deliveries ( < 0.01): cattle fed 0.3% menthol consumed less feed from d 5 through 12. Furthermore, in vitro gas production and VFA concentrations were unaffected by addition of menthol ( > 0.21). In conclusion, menthol supplementation minimally affected blood parameters associated with growth or ruminal fermentative activity.

Effects of flaxseed encapsulation on biohydrogenation of polyunsaturated fatty acids by ruminal microorganisms: feedlot performance, carcass quality, and tissue fatty acid composition

The objective of this study was to evaluate the efficacy of protecting PUFA within ground flaxseed against ruminal biohydrogenation by encapsulating them in a matrix consisting of a 1:1 blend of ground flaxseed and dolomitic lime hydrate (L-Flaxseed). Crossbreed heifers ( = 462, 346 ± 19 kg) were blocked by weight and randomly assigned to pens. Pens were assigned to 1 of 6 dietary treatments in a randomized complete block design. Treatment 1 consisted of a combination of 54.6% steam-flaked corn (SFC), 30.0% wet corn gluten feed, 8.0% roughage, and supplement (0% flaxseed). In treatments 2 and 3, a proportion of SFC was replaced with 3 and 6% flaxseed, respectively; in treatments 4, 5, and 6, SFC was replaced with 2, 4, or 6% L-Flaxseed, respectively. Cattle were fed for 140 or 168 d and then harvested in a commercial abattoir where carcass data were collected. Approximately 24 h after harvest, carcasses were evaluated for 12th-rib fat thickness, KPH, LM area, marbling score, and USDA yield and quality grades. Samples of LM were also obtained for determination of long-chain fatty acid profiles. Cattle that were fed diets with 4 and 6% L-Flaxseed consumed less feed than other treatments ( < 0.05), which adversely affected ADG. Compared with cattle fed 0% flaxseed, cattle in these treatments had lower final BW (18 and 45 kg less for the 4 and 6% L-Flaxseed treatments, respectively), less ADG (0.16 and 0.48 kg/day less for the 4 and 6% L-Flaxseed treatments, respectively), and lower carcass weights, dressing percentages, LM areas, backfat thicknesses, and marbling scores ( < 0.05). The addition of flaxseed or 2% L-Flaxseed did not affect performance or carcass traits ( > 0.05). Supplementation with flaxseed increased ( < 0.05) the concentration of α-linolenic acid (ALA) in meat (0.173, 0.482, 0.743 mg/g for 0, 3, and 6% flaxseed, respectively). Furthermore, proportionate increases in the ALA content of muscle tissue were 47% greater when flaxseed was encapsulated within the dolomitic lime hydrate matrix (0.288, 0.433, 0.592 mg/g for 2, 4, and 6% L-Flaxseed, respectively). Both products showed a linear response in ALA concentration ( > 99%; increases for Flaxseed and L-Flaxseed of 0.095 and 0.140 mg of ALA/g of tissue for each percentage of flaxseed added). This study indicates that a matrix consisting of dolomitic lime hydrate is an effective barrier to ruminal biohydrogenation of PUFA; however, adverse effects on DMI limit the amounts that can be fed.

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.

Menthol Supplementation Has Minimal Effects on Blood Components from Holstein Steers

Menthol is a naturally occurring compound classified as an essential oil that gives plants of the Mentha species their characteristic minty aroma and flavor. Menthol is used as a cooling compound in products ranging from common cold medications to pesticides and has been found to have a wide range of biological activities in different systems within the body. More recently, menthol and other essential oils have been identified as potential alternatives to feed antibiotics and growth promotants. Menthol has been observed to directly affect κ-opioid receptors. Kappa opioid receptors are located in the central nervous system, with a high density found in the hypothalamus. Menthol has been hypothesized to be capable of binding to κ-opioid receptors in the hypothalamus, stimulating neuropeptides involved in the production and release of growth hormone and leading to increased insulin-like growth factor-1 concentration, thus increasing growth. The purpose of this experiment was to evaluate changes in blood metabolites when menthol was incorporated into the diets of steers.

Hydrated lime matrix decreases ruminal biohydrogenation of flaxseed fatty acids

Introduction Omega-3 fatty acids are essential nutrients for humans, but dietary intake of these nutrients by many Americans is inadequate due to low consumption of omega-3-rich foods such as fish, walnuts, and flaxseed. In contrast, per capita consumption of red meat is relatively high, but these products normally contain only small amounts of omega-3 fatty acids. Feeding cattle diets that contain omega-3 fatty acids has consistently increased the proportion of the desirable fats that accumulate in beef. Unfortunately, the proportion of dietary omega-3 fats that are deposited into beef tissues is relatively low, because microorganisms within the rumen biohydrogenate the unsaturated omega-3 fatty acids extensively to produce the saturated fats that are characteristic of beef fat. Encapsulation of fats has been proposed as a method for improving efficiency of transfer of omega-3 fats into beef. Encapsulation processes apply a protective barrier on the surface of fats or fat-containing feeds, which theoretically decreases fats’ susceptibility to microbial biohydrogenation. Protective coatings must remain intact to retain their functionality, and physical damage to the coatings that occurs with normal handling can result in poor efficacy because the core material is exposed to microorganisms in the rumen. Embedding feed particles within a homogeneous protective matrix constitutes a potentially useful alternative to protective surface barriers. The matrix is created by mixing feed particles that are to be protected with a suitable matrix material that is resistant to microbial digestion and subsequently forming the mixture into pills. In cases where physical damage occurs, exposure of the core material is confined to the broken surface, and the remainder of the matrix retains its ruminal stability.

Dosing with Lactipro decreases forage intake and manure output

Introduction High-concentrate diets consisting of cereal grains and grain byproducts have high energy density compared with forage-based diets. To avoid digestive disorders, cattle must be adapted to concentrates, which often entails feeding a series of step-up diets that contain progressively less roughage over a 2to 3-week period. This allows the microbial population to adapt to fermentation of the starches and sugars that are present in high-concentrate diets. If cattle are not properly adapted to concentrate-based diets, lactic acid, which is produced by opportunistic starch-fermenting bacteria like Streptococcus bovis, can accumulate, predisposing the animal to acidosis. Diets used during the adaptation phase are by nature less digestible than the final finishing diet, which results in increased manure output and suboptimal performance during the adaptation period.

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.