Effects of protein concentration and beta-adrenergic agonists on ruminal bacterial communities in finishing beef heifers.

To improve animal performance and modify growth by increasing lean tissue accretion, beef cattle production has relied on use of growth promoting technologies such as beta-adrenergic agonists. These synthetic catecholamines, combined with the variable inclusion of rumen degradable (RDP) and undegradable protein (RUP), improve feed efficiency and rate of gain in finishing beef cattle. However, research regarding the impact of beta-adrenergic agonists, protein level, and source on the ruminal microbiome is limited.

Effects of supplementing milk replacer with essential amino acids on blood metabolites, immune response, and nitrogen metabolism of Holstein calves exposed to an endotoxin.

This study evaluated the effects of supplementing calf milk replacer with essential AA on immune responses, blood metabolites, and nitrogen metabolism of 32 Holstein bull calves [28 d of age, 44 ± 0.8 kg of body weight (BW)] exposed to lipopolysaccharide (LPS). Calves were bottle-fed a commercial milk replacer (20% crude protein and 20% fat, dry matter basis) twice daily along with a calf starter (19% crude protein, dry matter basis) for 45 d.

Influence of Monensin and Diflubenzuron on the Control of Immature Horn Fly and House Fly (Diptera: Muscidae) and Chemical Composition of Cattle Feces.

Twelve Angus × Hereford crossbred heifers were used in a completely randomized design to evaluate the effects of monensin and diflubenzuron feed additives on horn fly (Haematobia irritans) (L.) and house fly (Musca domestica) (L.) immature development.

The Effect of Horn Fly (Diptera: Muscidae) Infestation on Behavior, Water, and Feed Intake, and Digestion Characteristics of Beef Cattle.

Seven mature Angus × Hereford crossbreed cows (544 ± 23.2 kg of body weight) fitted with duodenal and ruminal cannulas were used in a crossover design to evaluate the effects of horn fly (Haematobia irritans) (L.) infestation on horn fly-induced defensive behaviors, feed and water intake, as well as digestion characteristics of beef cows.

Effects of lipopolysaccharide on beta-catenin, aromatase, and estrogen production in bovine granulosa cells in vivo and in vitro.

Diseases resulting from Gram-negative bacterial infection can induce an immune response by releasing a lipopolysaccharide (LPS) endotoxin that may lead to impaired fertility in cows. To evaluate the effects of LPS on follicular dynamics in a subacute inflammatory disease state, 14 Angus heifers (BW = 413 kg±14) were blocked by weight and assigned to vehicle (n = 7) or LPS treated (n = 7) groups. Heifers received subcutaneous injections of saline (CON) or 2.

Evaluation of Cattle for Naturally Colonized Shiga Toxin-Producing Requires Combinatorial Strategies.

Shiga toxin-producing (STEC) serogroups O157, O26, O103, O111, O121, O145, and O45 are designated as food adulterants by the U.S. Department of Agriculture-Food Safety and Inspection Service.

Crude glycerin alters beef cow ruminal fluid degradability of nutrients in vitro.

Crude glycerin () is used as an energy supplement for cattle and has been shown to increase propionate and decrease acetate concentrations in the rumen. Glycerin also decreases ruminal NH, and therefore, we hypothesized that GLY in rumen fluid would decrease protein degradability of feedstuffs. The objective was to evaluate the effect of GLY in bovine rumen fluid on extent of protein degradability of alfalfa hay (), dried distiller's grains (), and soybean meal ().

Post-ruminal branched-chain amino acid supplementation and intravenous lipopolysaccharide infusion alter blood metabolites, rumen fermentation, and nitrogen balance of beef steers.

Steers exposed to an endotoxin may require additional branched-chain AA (BCAA) to support an increase in synthesis of immune proteins. This study evaluated effects of bacterial lipopolysaccharide (LPS) and BCAA supplementation on blood metabolites and N balance of 20 ruminally-cannulated steers (177 ± 4.2 kg BW).

Effects of dietary urea concentration and zilpaterol hydrochloride on performance and carcass characteristics of finishing steers.

Cattle receiving zilpaterol hydrochloride () may recycle less N and require a greater supply of RDP. This study evaluated effects of ZH on performance and carcass characteristics of steers fed diets with increasing dietary RDP concentrations supplied as urea. Steers (429 animals; BW = 423 ± 4.

Nutritional recommendations of feedlot consulting nutritionists: The 2015 New Mexico State and Texas Tech University survey.

The 2015 feedlot consulting nutritionist survey is a collaborative project between New Mexico State University and Texas Tech University that focuses on summarizing the professional practices of consulting feedlot nutritionists and updates a 2007 survey. Forty-nine consulting feedlot nutritionists were asked to participate, of which 24 completed the survey. The nutritionists surveyed service over 14,000,000 cattle annually and were representatives from individual consulting practices (54.

Beef Species Symposium: an assessment of the 1996 Beef NRC: metabolizable protein supply and demand and effectiveness of model performance prediction of beef females within extensive grazing systems.

Interannual variation of forage quantity and quality driven by precipitation events influence beef livestock production systems within the Southern and Northern Plains and Pacific West, which combined represent 60% (approximately 17.5 million) of the total beef cows in the United States. The beef cattle requirements published by the NRC are an important tool and excellent resource for both professionals and producers to use when implementing feeding practices and nutritional programs within the various production systems.

Effects of bacterial lipopolysaccharide injection on white blood cell counts, hematological variables, and serum glucose, insulin, and cortisol concentrations in ewes fed low- or high-protein diets.

Bacterial lipopolysaccharide endotoxins (LPS) elicit inflammatory responses reflective of acute bacterial infection. We determined if feeding ewes high-CP (15.5%) or low-CP (8.

Technical note: Effects of rumen passage on fluoxetine bioavailability in serum and effects of fluoxetine on serum prolactin concentration and demeanor in ewes.

Sheep are becoming increasingly important in medical research. The objective of the present study was to identify changes in bioactivity of fluoxetine during ruminal passage in ewes, and to examine the effects of fluoxetine administration on demeanor and serum prolactin concentration. Twelve mature ewes were administered saline (control), daily oral fluoxetine (40 mg), or alternate-day oral fluoxetine for 10 d.

Effects of dietary protein and bacterial lipopolysaccharide infusion on nitrogen metabolism and hormonal responses of growing beef steers.

Purified lipopolysaccharide (LPS) infusion in cattle induces clinical and metabolic responses similar to gram-negative bacterial infection. Effects of LPS and dietary protein on rectal temperature, serum hormones, haptoglobin, plasma urea N and AA, and N balance were evaluated in 24 steers (250 +/- 2.8 kg of BW).

Effects of rumen-protected methionine supplementation and bacterial lipopolysaccharide infusion on nitrogen metabolism and hormonal responses of growing beef steers.

Metabolic demand for sulfur-containing AA increases during inflammation in nonruminants. Therefore, Met supplementation may alleviate the negative effects of infection on N balance. Effects of gram-negative bacterial lipopolysaccharide (LPS) and supplemental dietary Met on N balance, serum hormones and haptoglobin, and plasma urea-N and AA were evaluated in 20 Angus-cross steers (BW = 262 +/- 6.

Limiting amino acids for growing lambs fed a diet low in ruminally undegradable protein.

Ruminally cannulated Rambouillet wether lambs were used in three 6 x 6 Latin square experiments (n = 6/experiment) to determine which essential AA limit N retention. Lambs (BW = 36.9 +/- 1.

Intrauterine bacterial inoculation and level of dietary methionine alter amino acid metabolism in nulliparous yearling ewes.

Using an intrauterine bacterial inoculation method, our objective was to determine the effects of acute sepsis and level of dietary metabolizable Met (MM) on splanchnic metabolism of AA in ewes. Twenty-four nulliparous yearling Rambouillet-cross ewes (initial BW = 65.1 +/- 0.

Supplemental methionine and urea for gestating beef cows consuming low quality forage diets.

A study was conducted to evaluate Met requirements of late-gestation beef cows consuming low quality forages on the premise that inadequate supply of metabolizable AA may limit protein accretion during pregnancy. Five ruminally cannulated, multiparous late-gestation beef cows (490 +/- 27 kg), of predominantly Angus (> or =75%) with Hereford and Simmental breeding, were used in a 5 x 5 Latin square experiment to evaluate the effects of postruminal dl-Met supplementation on N retention, serum metabolites, and plasma AA concentrations during the third trimester of pregnancy. The basal diet was fed individually, and weights of refusals were recorded for N intake determination.

Effect of glycine and vitamin supplementation on sulphur amino acid utilization by growing cattle.

Effects of glycine (Gly) and B-vitamins on sulphur amino acid (AA) utilization were studied in growing steers maintained under conditions where methionine (Met) was first limiting. Conditions were generated by limit feeding a diet low in ruminally non-degraded protein and abomasally infusing an AA mixture limiting in Met. Retained N tended (p = 0.

Supplemental betaine and peroxide-treated feather meal for finishing cattle.

These studies evaluated the effects of betaine, provided either as feed-grade betaine or as concentrated separator by-product (CSB; desugared beet molasses), on performance and carcass characteristics of finishing cattle. In Exp. 1, 175 steers (410 kg initial BW) were fed a finishing diet based on steam-flaked and dry-rolled corn, and treatments included 10.

Methionine as a methyl group donor in growing cattle.

Holstein steers were used in two 5 x 5 Latin square experiments to evaluate the sparing of methionine by alternative sources of methyl groups (betaine and choline). Steers were housed in metabolism crates and limit-fed a soybean hull-based diet high in rumen degradable protein. To increase energy supply, ruminal infusions of volatile fatty acids and abomasal infusions of glucose were provided.

Methionine supply to growing steers affects hepatic activities of methionine synthase and betaine-homocysteine methyltransferase, but not cystathionine synthase.

The effects of supplemental methionine (Met), supplied abomasally, on the activities of methionine synthase (MS), cystathionine synthase (CS) and betaine-homocysteine methyltransferase (BHMT) were studied in growing steers. Six Holstein steers (205 kg) were used in a replicated 3 x 3 Latin square experiment. Steers were fed 2.

Branched-chain amino acids for growing cattle limit-fed soybean hull-based diets.

Five ruminally cannulated Holstein steers (176 kg) were used in a 5 x 5 Latin square to evaluate the effects of branched-chain AA supplementation on N retention and plasma AA concentrations of steers. Steers were limit-fed (3.0 kg/d of DM) twice daily diets low in ruminally undegradable protein (72% soybean hulls, 19% alfalfa, 5% molasses, and 4% vitamins and minerals).