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Studies of fescue toxicosis using whole seed diets show reduced feed intake and thermoregulatory ability, but much of the seed passes undigested through the animal. Cattle were fed ground tall fescue seed at different levels to potentially facilitate digestion and absorption of toxins and identify toxin sensitivity for major characteristics of the condition [i.e., hyperthermia, reduced feed intake (FI), reduced blood prolactin]. Steers (n = 18; 350 kg BW) were housed in the Brody Climatology Laboratory at thermoneutrality (TN; 19°C) and randomly assigned to daily diet treatments with either ground endophyte-infected [E+; low and high doses at 20 and 40 pg ergovaline/(kg BW/d), respectively] or endophyte-free [E-; control at 0 pg ergovaline/(kg BW/d)] tall fescue seed. After 12 d at TN, animals received 2 d of transition to heat stress (HS; 36°C daytime, 25°C nighttime) and maintained for 14 more days. Cattle were fed twice daily at 0800 and 1600 h, with water ad libitum. Feed intake was measured at 0700 h, with skin and rectal temperatures, and respiration rate at 0600, 1100, 1600, and 2100 h. Blood was sampled on selected days for prolactin and leptin determinations. Steers fed ground E+ diet decreased (P < 0.0001) FI below controls at TN, with no dose effect. Maximum FI reduction with E+ treatment was 25% at TN, with an additional 46% decrease during HS (P < 0.05). By the end of HS, E+ FI increased (P > 0.05) to that of E-, suggesting recovery. Prolactin was reduced (P < 0.05) in high E+ cattle below controls at study end. Leptin blood concentrations were unaffected by E+ treatment (P > 0.05) but was reduced (P < 0.05) by the end of HS. Pattern of rectal temperature response to HS showed a more rapid initial increase and decline for both E+ groups compared with controls (P < 0.05). Skin temperature was the only variable that identified E+ dose differences. Although there were no treatment differences at TN, skin temperature was lower (P < 0.05) for high E+ steers compared with controls during HS when air temperature was reduced each day. In general, FI was more responsive to E+ toxins than body temperature or blood prolactin, declining even at TN and exhibiting dynamic activity during HS. Although body temperature response to E+ toxins appears to stabilize during HS, this is misleading as rapid change in air temperature exposes effects on skin temperature. [ABSTRACT FROM AUTHOR]

Aflatoxins, especially aflatoxin B1 (AFB1), can be greater in dried distillers grains with solubles (DDGS) because it can be concentrated during the ethanol production process. Increased use of DDGS in swine diets could potentially lead to an increased incidence of aflatoxicosis, a disease associated with decreased feed intake, reduced BW gain, and impaired liver function. The objective of this study was to determine the effects of AFB1 on the health, performance, and serum profile of growing barrows. Ninety Duroc x Yorkshire crossbred barrows were purchased (age = 35 ± 5 d; BW = 14.2 + 3.0 kg), allocated to 9 pens with 10 pigs per pen, and randomly assigned to receive diets containing 0 μg/kg of AFB1 (CON), 250 μg/kg of AFB1 (LO), or 500 μg/kg of AFB1 (HI) for 7, 28, or 70 d in a 3 × 3 factorial arrangement of treatments. Feed intake was measured daily, and pigs were weighed and blood samples collected weekly. Serum was analyzed for concentrations of aspartate aminotransferase (AST), alanine aminotransferase (ALT), total bilirubin (BILI), and blood urea nitrogen (BUN). Both ADFI and ADC were negatively affected (P ≤ 0.00 1) by AFB1 treatment. Average daily feed intake was less (P < 0.05) in HI barrows than in CON barrows from wk 5 to 10 and was less (P < 0.05) in LO barrows than in CON barrows in wk 5 and again from wk 8 to 10. Also, ADFI was less (P = 0.022) in HI barrows than LO barrows in wk 10. Decreased ADG (P < 0.05) was observed in HI barrows than in CON barrows in wk 8 and 10; no differences (P ≥ 0.665) in ADG were noted between CON and LO barrows. There was no effect (P ≥ 0.080) of AFB1 treatment on ALT or BILI concentrations. However, both AST and BUN were affected (P < 0.05) by AFB1 treatment. Serum AST was greater (P = 0.010) in LO barrows than CON barrows in wk 5, and serum BUN was greater (P = 0.004) in CON barrows than LO barrows in wk 3. Results from this study demonstrate that the performance and health of young growing barrows were affected by consumption of an AFB1-contaminated diet, especially when fed for a more extended period. [ABSTRACT FROM AUTHOR]

Exposure to ergot alkaloids in endophyte-infected fescue (E+) is associated with impaired animal productivity, especially during heat stress, which is commonly referred to as fescue toxicosis. To elucidate the pathogenesis of this condition, the effects of short-term heat stress (HS) on hepatic gene expression in rats exposed to endophytic ergot alkaloids were evaluated. Rats implanted with telemetric transmitters to continuously measure core temperature were fed an E+ diet and maintained under thermoneutral (TN) conditions (21°C) for 5 d, followed by TN or 31°C (HS) conditions for 3 d. Feed intake (Fl) and BW were monitored daily. The E+ and HS-induced alterations in hepatic genes were evaluated using DNA microarrays and PCR analyses. Hepatic antioxidant enzyme activities, as well as the incidence of apoptosis, were determined. As expected, intake of E+ reduced Fl and BW from pretreatment levels under TN conditions, with greater reductions during short-term HS. Genes involved in gluconeogenesis and apoptosis were upregulated, whereas genes associated with oxidative phosphorylation, xenobiotic metabolism, antioxidative mechanisms, immune function, cellular proliferation, and chaperone activity were all downregulated with short-term HS. Hepatocytic apoptosis was increased and antioxidant enzyme activity decreased in the livers of rats exposed to HS. The hypothesized, exacerbating effects of HS on the direct, endophytic toxin-related and indirect, reduced caloric intake-associated alterations in hepatic gene expression were clearly demonstrated in rats and may help to elucidate the pathogenesis of fescue toxicosis in various animal species. [ABSTRACT FROM AUTHOR]

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. Bulls were blocked by BW, scrotal circumference (SC), and pregrazing sperm characteristics and randomly assigned to graze toxic endophyte-infected (El; 4 bulls/pasture; 2 pastures) or novel endophyte-infected (NE; 4 bulls/pasture; 2 pastures) tall fescue for 121 d. Semen was collected by electroejaculation, and SC was measured and blood samples collected monthly. Sperm were evaluated for motility and morphology with an integrated visual optical system. Overall mean concentration of prolactin was decreased more (P < 0.01) in EI bulls than NE bulls from May to August. Scrotal circumference was not affected by fescue type (P = 0.58); overall SC averaged 36.7 + 2.3 cm. Percentage of live sperm was not different (P = 0.24) between NE bulls (80%) than El bulls (67%) in July and August. Bulls grazing NE fescue had more (P < 0.06) motile sperm than El bulls in July and August. Percentages of progressive (57 vs. 38%, NE and El, respectively; P < 0.06) and rapid (67 vs. 46%, NE and El, respectively; P = 0.04) sperm were greater from bulls grazing NE than El bulls in July and August. Average velocity of the smoothed sperm path and progressive velocity in a straight line from the beginning to the end of the sperm track were slower (P < 0.09) in El bulls than NE bulls and were slower (P = 0.04) in August compared with July. Mean width of head oscillation as the sperm swims was less (P < 0.06) in August than July. Concentrations of cortisol and testosterone were not (P > 0.10) influenced by fescue type. Semen from bulls grazing EI had reduced motility and morphology than bulls grazing NE. Detrimental effects of toxic fescue may not be mediated by cortisol, testosterone, or both. Semen quality of bulls grazing toxic El tall fescue was decreased with increased maximum ambient temperatures. [ABSTRACT FROM AUTHOR]

A study was conducted to develop a model for fescue toxicosis using rats fed a diet containing endophyte-infected tall fescue seed (E+). Rats implanted with telemetric transmitters to continuously monitor core body temperature (Tc) and activity were housed at thermoneutrality (21°C) and were fed a diet containing endophyte-free fescue seed (E-). After 2 wk, they were assigned to either E+ or E- diets and initially maintained at thermoneutrality (preheat) for 8 d. They were then exposed to heat stress (31°C) for 22 d, followed by 1 wk of recovery at thermoneutrality (post-heat). Body weight and feed intake were measured daily. Rats receiving the E+ diet showed decreased feed intake (P = 0.001) and weight gains (P = 0.003) during the preheat period. The decrease in Tc from the pretreatment level was greater in E+ than in E- rats during the preheat (P = 0.001) and postheat (P = 0.001) periods. With heat stress, both groups showed parallel decreases in feed intake. The increase in Tc from preheat to heat conditions was greater in E+ vs. E- rats (P = 0.001). Activity level was lower in E+ than in E- rats during heat stress (P = 0.009) and postheat (P = 0.037) periods. These results show that the rat model for fescue toxicosis is extremely useful because many of the observed responses to E+ diet are similar to those noted for cattle, and additional variables that are difficult to measure in cattle, such as activity, can be easily evaluated. [ABSTRACT FROM AUTHOR]

Diets rich in soy phytoestrogens have many potential health benefits but isoflavones such as genistein may suppress cell mediated immune function. The effect of dietary phytoestrogens on the host response to infection has not been extensively examined. Mice were fed a diet containing soy phytoestrogens and infected with Mycobacterium avium to establish a chronic infection and inflammatory response. As phytoestrogens may act through classical oestrogen receptors (ER), mice deficient in ER α signalling and wild type mice were evaluated for a panel of Type 1-associated cytokines (IFN γ, IL-12 and IL-18) in the spleen. IFN γ production in the spleen was increased approximately 4-fold in ER α-deficient mice fed a casein-based diet over wild type mice fed a casein-based diet ( P < 0·05), suggesting a role for ER α in suppressing IFN γ production. IL-18 levels in spleens of wild type mice were decreased compared to ER α-deficient mice on a casein diet. Splenic IL-12 and IL-18 levels were not affected in wild type and ER α-deficient mice on the phytoestrogen containing diets, with the exception that whole soy increased IL-12 levels in the tissues of ER α deficient mice. We conclude that ER α and dietary phytoestrogens can influence production of key regulatory cytokines in response to chronic bacterial infection. [ABSTRACT FROM AUTHOR]

Presents a study which characterized the diurnal core temperature rhythm of beef cattle under constant thermoneutral and heat stress conditions. Results of previous studies on affected animals during heat challenge; Exposure response of skin temperature to thermoneutral and heat stress conditions; Thermoregulatory mechanisms responsible for the induced shifts in homeothermy.

The objective was to investigate effects of Toxy-Nil (TN) or Unike Plus (UP) on gene expression profiles of blood leukocytes and milk somatic cells (MSC) in dairy cows challenged with dietary aflatoxin B1 (AFB1). Sixteen mid-lactation Holstein cows were assigned to receive one of the following treatments: 1) 2.8 mg of AFB1/cow/day (positive control, PC); 2) 2.8 mg of AFB1 + 100 g of TN/cow/day; 3) 2.8 mg of AFB1 + 100 g of UP/cow/day; or 4) no AFB1 and no adsorbents (negative control, NC). Treatments were administered for 7 days by top-dressing onto a standard TMR diet. Feed and water were available ad libitum throughout the trial. Blood and milk samples were obtained on day 7. Subsequently, mRNA from blood leukocytes and MSC were isolated and sequenced. Genes were considered differentially expressed (DE) when P < 0.001 and FDR ≤ 0.10. There were few differences in gene expression of blood leukocytes. No DE genes were observed when comparing cows not fed AFB1 to those that were fed AFB1 (NC vs average of PC/TN/UP). Comparing cows fed AFB1 alone to cows also receiving adsorbents (PC vs average of TN/UP) revealed one downregulated gene, which was related to mitotic processes and five upregulated genes, which related to nitric oxide generation, signaling, and platelet activation. Comparing TN to UP revealed downregulation of two genes related to platelet activation and iron ion and oxygen binding. In MSC, numerous changes in gene expression were observed. Three annotated genes were DE between NC and TN/UP. No genes were DE between adsorbent treatments (TN vs UP). However, comparing cows not fed AFB1 to those fed AFB1 alone (NC vs PC) revealed 120 DE genes, and 70 genes were DE between cows fed AFB1 without or with adsorbents (PC vs TN/UP). Of those DE genes, 49 were common to the comparisons PC vs NC and PC vs TN/UP. These genes represented functional clusters including glycoproteins and milk proteins, secretion, signaling, protein binding, transporter activity, and response to steroid hormones. Protein domains found to be differentially expressed included a- and b-caseins. Furthermore, approximately 20% of the common DE genes in MSC were mammary gland-specific. In summary, daily feeding of 2.8 mg of aflatoxin B1 to lactating dairy cows resulted in few DE genes in blood leukocytes, but elicited numerous changes in gene expression in milk somatic cells, many of which were modulated in cows fed TN or UP. [ABSTRACT FROM AUTHOR]

T-2 toxin (T), a type-A trichothecene is a mycotoxin that has been found to contaminate feeds fed to dairy cattle. The effect of T-2 toxin on ruminal bacterial growth and fermentation was measured in a batch culture experiment. Feeds were incubated (39°C) in fermenters with buffer and ruminal fluid containing 0, 100, 200, 400 and 800 ppm T. Culture optical density (OD) was measured to estimate microbial populations. The cultures were sampled at 0, 6, 12 and 24 h to measure fermentation end products, pH and OD. The experimental treatments were arranged as a completely randomized design and analyzed with Proc MIXED procedures of SAS. Differences were identified at P<0.05. Optical density increased over time with no differences among treatments. Culture pH decreased over time and was significantly higher at 12 and 24 h for the cultures with T at 800 ppm compared to all other treatments. The pH at 24 h was 6.08b, 6.10b, 6.09b, 6.10b and 6.18a for 0, 100, 200, 400 and 800 ppm T, respectively. Total concentration of VFA increased overtime with differences at 12 h, but VFA concentration was similar after 24 h (P>0.05). Propionic acid increased over time with feed containing no T having lower propionic concentration than other treatments at 24 h (19.8b, 24.8a, 24.9a, 24.4a and 24.7a mM for 0, 100, 200, 400 and 800 ppm T). Feed containing no T supported higher concentration of butyric acid at all time points, including 24 h (19.6a, 17.3b, 17.8b, 17.9b, 17.8b mM) and ammonia at 24 h (31.5a, 29.2b, 27.0c, 28.2b, 26.9c mM) versus other treatments at 100, 200, 400 and 800 ppm. The results indicate that T-2 toxin altered ruminal microbial fermentation. The effect of these changes in rumen fermentation on animal performance should be investigated. [ABSTRACT FROM AUTHOR]

Cattle from Southeast to Midwest regions of the US often experience fescue toxicosis during summer months following intake of tall fescue infected with the endophyte Neotyphodium coenophialum (E+). Recent studies in our lab have attempted to enhance this condition by feeding cattle a diet containing ground E+ seed under heat stress conditions, which resulted in a large reduction in feed intake. The objectives of the present study were to separate out the oral effect of ground E+ seed by using ruminal administration, and determine a dose-response to ergovaline (i.e., a primary toxin found in E+ seed). Steers (n=6, 350kg avg. BW) were housed in the Brody Environmental Center at the University of Missouri and used in four trials over a 5 month period to ultimately expose each animal to each of the four treatments. All animals were originally housed at 19C for seven days and received endophyte-free ground seed (E-; Miller Seed Company, MO) in the diet. This was followed by 11 days of cycling heat stress (i.e., 26 to 36C). After this time, steers either continued on the E- supplementation or switched to E+ seed (Seed Research of Oregon, OR) at 5, 10 or 20μg ergovaline/kg BW for five days. Respiration rate, skin, and rectal temperatures were taken six times daily, along with daily measurement of feed intake. Fescue seed was mixed directly into the rumen four times daily to ensure the animal received the entire dose. Results were analyzed using ANOVA. Only the highest dose resulted in a significant change in performance. Treatment at this level resulted in a 30% rapid reduction in feed intake (P=0.02) below E- level. In contrast, hyperthermia associated with the highest dose developed gradually over four days of treatment to peak at 0.85C above E- level (P=0.01). Feed intake is more responsive to fescue toxicosis than indicators of thermal stress, which develop gradually. These results also suggest that the reduction in feed intake is not a taste issue, since bypassing the mouth still results in decreased intake. [ABSTRACT FROM AUTHOR]

The objective was to investigate effects of Toxy-Nil (TN) or Unike Plus (UP) on gene expression profiles of blood leukocytes and milk somatic cells (MSC) in dairy cows challenged with dietary aflatoxin B1 (AFB1). Sixteen mid-lactation Holstein cows were assigned to receive one of the following treatments: 1) 2.8 mg of AFB1/cow/day (positive control, PC); 2) 2.8 mg of AFB1 + 100 g of TN/cow/day; 3) 2.8 mg of AFB1 + 100 g of UP/cow/day; or 4) no AFB1 and no adsorbents (negative control, NC). Treatments were administered for 7 days by top-dressing onto a standard TMR diet. Feed and water were available ad libitum throughout the trial. Blood and milk samples were obtained on day 7. Subsequently, mRNA from blood leukocytes and MSC were isolated and sequenced. Genes were considered differentially expressed (DE) when P < 0.001 and FDR ≤ 0.10. There were few differences in gene expression of blood leukocytes. No DE genes were observed when comparing cows not fed AFB1 to those that were fed AFB1 (NC vs average of PC/TN/UP). Comparing cows fed AFB1 alone to cows also receiving adsorbents (PC vs average of TN/UP) revealed one downregulated gene, which was related to mitotic processes and five upregulated genes, which related to nitric oxide generation, signaling, and platelet activation. Comparing TN to UP revealed downregulation of two genes related to platelet activation and iron ion and oxygen binding. In MSC, numerous changes in gene expression were observed. Three annotated genes were DE between NC and TN/UP. No genes were DE between adsorbent treatments (TN vs UP). However, comparing cows not fed AFB1 to those fed AFB1 alone (NC vs PC) revealed 120 DE genes, and 70 genes were DE between cows fed AFB1 without or with adsorbents (PC vs TN/UP). Of those DE genes, 49 were common to the comparisons PC vs NC and PC vs TN/UP. These genes represented functional clusters including glycoproteins and milk proteins, secretion, signaling, protein binding, transporter activity, and response to steroid hormones. Protein domains found to be differentially expressed included a- and b-caseins. Furthermore, approximately 20% of the common DE genes in MSC were mammary gland-specific. In summary, daily feeding of 2.8 mg of aflatoxin B1 to lactating dairy cows resulted in few DE genes in blood leukocytes, but elicited numerous changes in gene expression in milk somatic cells, many of which were modulated in cows fed TN or UP. [ABSTRACT FROM AUTHOR]