Changes in concentrations of trace minerals in lambs fed sericea lespedeza leaf meal pellets with or without dietary sodium molybdate.

Prolonged feeding of sericea lespedeza (SL) previously led to reduced serum concentrations of Mo, a cofactor in an enzyme complex that may be involved in weight gain. The current objective was to determine the effect of Mo supplementation on changes in serum, fecal, urine, and liver concentrations of trace minerals in lambs fed SL leaf meal pellets. Thirty ram lambs weaned in May (84 ± 1.

Changes in hematology, serum biochemistry, and gastrointestinal nematode infection in lambs fed sericea lespedeza with or without dietary sodium molybdate.

Sericea lespedeza (SL; Lespedeza cuneata) is a legume rich in condensed tannins that can be grazed or fed to small ruminants for parasite control. Condensed tannins, a secondary plant compound in SL, may lead to unintended consequences such as changes in production. In our preliminary research, there was consistently a reduction in serum and liver concentrations of Mo.

Relationships among ergot alkaloids, cytochrome P450 activity, and beef steer growth.

Determining a grazing animal's susceptibility to ergot alkaloids has been a research topic for decades. Our objective was to determine if the Promega™ P450-Glo assay could be used to indirectly detect ergot alkaloids or their metabolites in urine of steers. The first experiment validated the effects of ergot alkaloids [0, 20, and 40 μM of ergotamine (ET), dihydroergotamine (DHET), and ergonovine (EN)] on human CYP3A4 using the P450-Glo assay (Promega™ V9800).

Milk production traits of beef cows as affected by horn fly count and sire breed type.

Horn fly infestations negatively impact economic traits of beef cattle. Our objective was to determine the impact of horn flies on beef cattle milk yield and quality. Cows (n = 53) were derived from Brangus dams and sired by Bonsmara (n = 7), Brangus (n = 13), Charolais (n = 8), Gelbvieh (n = 5), Hereford (n = 12), and Romosinuano (n = 8) bulls.

Forage and breed effects on behavior and temperament of pregnant beef heifers.

Background: Integration of behavioral observations with traditional selection schemes may lead to enhanced animal well-being and more profitable forage-based cattle production systems. Brahman-influenced (BR; n = 64) and Gelbvieh × Angus (GA; n = 64) heifers consumed either toxic endophyte-infected tall fescue (E+) or one of two nontoxic endophyte-infected tall fescue (NT) cultivars during two yr. Heifers were weighed at midpoint and termination of grazing.

Performance by spring and fall-calving cows grazing with full, limited, or no access to toxic Neotyphodium coenophialum-infected tall fescue.

Replacing toxic, wild-type Neotyphodium coenophialum-infected tall fescue (E+) with nontoxic, N. coenophialum-infected tall fescue (NE+) has improved cow performance, but producer acceptance of NE+ has been slow. The objective was to compare performance by spring- and fall-calving cows grazing either E+ or NE+ at different percentages of the total pasture area.

Effects of forage type, body condition and single-nucleotide polymorphisms in the bovine cytochrome P450 regulatory region on cow productivity.

Single-nucleotide polymorphisms (SNP) in the coding sequence of cytochrome p450 (CYP3A28) have been associated with milk yield and composition, and calving traits in cows. In this study, we aimed to determine whether (i) the CYP3A28 regulatory region was polymorphic and (ii) SNP genotype, forage type, body condition and their interactions affect cow productivity. Primers for CYP3A28 promoter were designed to amplify a 483-bp segment by PCR.

Effects of bovine cytochrome P450 single-nucleotide polymorphism, forage type and body condition on production traits in cattle.

Relating single-nucleotide polymorphisms (SNP) to cows with acceptable productivity could benefit cattle breeders in areas where tall fescue is the predominant forage. This study aimed to (i) identify SNPs in bovine cytochrome P450 3A28 (CYP3A28) and (ii) determine the associations between SNP genotype, forage and cow body condition (BC). Genotype (CC, CG or GG) and forage [Kentucky-31 wild-type endophyte-infected tall fescue (KY+) vs.

Board-invited review: St. Anthony's Fire in livestock: causes, mechanisms, and potential solutions.

After a brief history of ergot alkaloids and ergotism, this review focuses on the metabolism and mechanisms of action of the ergot alkaloids. The authors provide models of how these alkaloids afflict grazing livestock under complex animal-plant/endophyte-environmental interactions. Alkaloid chemistry is presented to orient the reader to the structure-function relationships that are known to exist.

Effects of body condition on measures of intramuscular and rump fat, endocrine factors, and calving rate of beef cows grazing common bermudagrass or endophyte-infected tall fescue.

Multiparous beef cows were managed to achieve marginal (BCS = 4.7 ± 0.07; n = 106) or good (BCS = 6.

Calving traits of crossbred Brahman cows are associated with Heat Shock Protein 70 genetic polymorphisms.

Stress proteins and their genetic polymorphisms have been associated with decreased male and female fertility. Objectives were to: (1) identify single nucleotide polymorphisms (SNP) located in the promoter region of the bovine heat shock protein 70 (Hsp70) gene, and (2) evaluate associations between Hsp70 SNP, Julian calving date, and calving rates of crossbred Brahman cows. Specific primers were designed for PCR amplification of a 539 base segment of the bovine Hsp70 promoter (GenBank accession number M98823).

Influence of body condition and forage type on prevalence of Escherichia coli O157:H7 and Salmonella in grazing beef cows.

Aim: To determine the influence of body condition (BC) and forage type on the prevalence of faecal shedding of Escherichia coli O157:H7 and Salmonella from beef cows.

Methods And Results: Thin or moderately conditioned cows (n = 115) were randomly assigned to graze either common bermudagrass (n = 3 pastures) or toxic endophyte-infected tall fescue (n = 3 pastures) for 62 days. Faecal samples were collected on day 0, 30 and 62.

Involvement of signaling pathways in bovine sperm motility, and effect of ergot alkaloids.

There is evidence that ergot alkaloids can directly interact with mammalian spermatozoa affecting sperm functions. Ergot alkaloids exert their toxic or pharmaceutical effects through membrane receptor-mediated activities. This study investigated the signaling pathways involved in the in vitro inhibitory effects of both ergotamine (ET) and dihydroergotamine (DEHT) on the relative motility of bovine spermatozoa using specific inhibitors.

Fate of Escherichia coli O157:H7 and Salmonella from contaminated manure slurry applied to soil surrounding tall fescue.

Aim: To investigate the potential transfer of Escherichia coli O157:H7 and Salmonella from contaminated manure slurry into the tissue of tall fescue plants.

Methods And Results: Tall fescue plants (n = 50) were fertilized with a manure slurry inoculated with E. coli O157:H7 and Salmonella.

Influence of toxic endophyte-infected fescue on sperm characteristics and endocrine factors of yearling Brahman-influenced bulls.

Sixteen (mean age = 1.1 +/- 0.1 yr; mean BW = 478 +/- 34 kg) Brahman-influenced bulls were used to determine the influence of fescue type on sperm characteristics and serum concentrations of prolactin, cortisol, and testosterone.

Effects of the ergot alkaloids dihydroergotamine, ergonovine, and ergotamine on growth of Escherichia coli O157:H7 in vitro.

A series of experiments were conducted to evaluate the effects of ergot alkaloids (dihydroergotamine, ergonovine, and ergotamine) on E. coli O157:H7 in both pure and mixed ruminal fluid culture. Alkaloids were added to solutions of E.

Effects of fescue type and sampling date on the nitrogen disappearance kinetics of autumn-stockpiled tall fescue.

Two tall fescue [Lolium arundinaceum (Schreb.) Darbysh] forages, one an experimental host plant/endophyte association containing a novel endophyte that produces low or nil concentrations of ergot alkaloids (HM4) and the other a typical association of Kentucky 31 tall fescue and the wild-type endophyte (Neotyphodium coenophialum; E+), were autumn-stockpiled following late-summer clipping and fertilization with 56 kg/ha of N to assess N partitioning and ruminal disappearance kinetics of N for these autumn-stockpiled tall fescue forages. Beginning on December 4, 2003, sixteen 361 +/- 56.

Endocrine factors and ovarian follicles are influenced by body condition and somatotropin in postpartum beef cows.

Multiparous beef (1/4 to 3/8 Bos indicus; n = 99) cows were managed to achieve low (BCS = 4.3 +/- 0.1; n = 50) or moderate (BCS = 6.

Effects of fescue type and sampling date on the ruminal disappearance kinetics of autumn-stockpiled tall fescue.

Two tall fescue (Festuca arundinacea Schreb.) forages, one an experimental host plant/endophyte association containing a novel endophyte (HM4) that produces low or nil concentrations of ergot alkaloids, and the other a typical association of Kentucky 31 tall fescue and the wild-type endophyte (Neotyphodium coenophialum; E+), were autumn-stockpiled following late-summer clipping and fertilization with 56 kg/ha of N to assess the nutritive value and ruminal disappearance kinetics of autumn-stockpiled tall fescue forages. Beginning on December 4, 2003, sixteen 361 +/- 56.

Influence of body condition and bovine somatotropin on estrous behavior, reproductive performance, and concentrations of serum somatotropin and plasma fatty acids in postpartum Brahman-influenced cows.

Ninety-nine multiparous Brahman-influenced (1/4 to 3/8 Brahman) cows were managed to achieve low (BCS = 4.3 +/- 0.1; n = 50) or moderate (BCS = 6.

Influence of dietary endophyte (Neotyphodium coenophialum)-infected tall fescue (Festuca arundinacea) seed on fecal shedding of antibiotic resistance-selected Escherichia coli O157:H7 in ewes.

The objectives were to determine the effects of short-term feeding of a toxic endophyte (Neotyphodium coenophialum)-infected tall fescue seed (Festuca arundinacea, cultivar 'Kentucky 31') on fecal shedding and intestinal concentrations of Escherichia coli O157:H7 and the concentrations of prolactin, cortisol, and NEFA in experimentally inoculated ewes. Twelve ewes (mean BW = 46 +/- 2 kg) were fed a diet containing either high endophyte-infected (HI-E) or low endophyte-infected (LO-E) tall fescue seed for 7 d. Each diet consisted of 50% (as-fed basis) tall fescue seed.

Estrous behavior and initiation of estrous cycles in postpartum Brahman-influenced cows after treatment with progesterone and prostaglandin F2alpha.

Spring-calving, crossbred (1/4 to 3/8 Brahman) primiparous (n = 56) and multiparous (n = 102) beef cows were used to evaluate the effects of progesterone, delivered via a controlled internal drug-releasing (CIDR) device, and prostaglandin F(2alpha) (PGF(2alpha)) on estrous behavior, synchronization rate, initiation of estrous cycles, and pregnancy rate during a 2-yr period. To determine luteal activity, weekly blood samples were collected 3 wk before initiation of a 75-d breeding season. Treated cows received a CIDR for 7 d beginning on d -7 of the breeding season.

Escherichia coli O157:H7 and Salmonella in water and soil from tall fescue paddocks.

Six 1-ha paddocks of tall fescue (Festuca arundinacea) grazed by Gelbvieh x Angus heifers from 1 March to 21 June 2005 were used to determine the prevalence of Escherichia coli O157:H7 and Salmonella in water tanks, and standing water and surface soil surrounding water tanks in tall fescue paddocks grazed by cattle. Paddocks included two each of Kentucky-31 endophyte-infected tall fescue (E+), Jesup tall fescue with the AR542 endophyte strain (MaxQ), and HiMag tall fescue with strain 4 endophyte (HiMag4). Samples were collected weekly (6 June to 5 July) from water tanks (n = 30), and standing water (n = 18) and surface soil (n = 30) surrounding the water tanks in each paddock commencing 3 weeks prior to termination of grazing until 2 weeks after cattle removal.

Prevalence of Escherichia coli O157:H7 and Salmonella in beef steers consuming different forage diets.

Aims: To compare the prevalence of faecal shedding of Escherichia coli O157:H7 and Salmonella in growing beef cattle consuming various forages.

Methods And Results: In Experiment I, faecal samples were collected from steers grazing either endophyte-infected (E+) tall fescue or common bermudagrass (CB). Steers grazing E+ tall fescue were confined to a dry-lot pen and fed CB hay ad libitum for 10 days.

Effect of rotation frequency and weaning date on forage measurements and growth performance by cows and calves grazing endophyte-infected tall fescue pastures overseeded with crabgrass and legumes.

A grazing study was initiated in April 2000 and continued through three calving and weaning cycles (ending July 2003) to investigate the effects of rotational grazing management (twice monthly [2M] vs. twice weekly [2W]) and weaning date (mid-April [EARLY] vs. early June [LATE]) on production of fall-calving cow-calf pairs (495 +/- 9.