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The predominant cool-season forage in the southeastern United States is the tall fescue cultivar Kentucky 31 (KY31). Kentucky 31 possesses an endophyte (), which produces a family of toxins called ergot alkaloids. These toxins negatively affect the physiology of animals on consumption and result in the syndrome known as fescue toxicosis. Currently, the United States annually produces approximately 11.4 billion kg of beef, of which 25% originates in the southeastern region of the United States where forage systems frequently are tall fescue based. Cattle within this forage system exhibit reduced gains and reproductive performance. The result is a reduction in the nation's beef supply with annual revenue losses recently estimated at approximately US$1 billion. Our hypothesis is that exposure to these ergot alkaloids in conjunction with limited availability of nutrients decreases bull semen quality and fertility. Although the literature is clear that these toxins affect BW, body temperature, blood flow, hair growth, and female reproduction in cattle, their effect on bull reproduction and the mechanisms through which the toxins act are not well defined. Six studies published from 2004 to 2015 assessed bull growth, body composition, and semen quality of young beef bulls exposed to ergot alkaloids. If semen quality or fertility is altered, the mechanisms involved may be either direct effects of ergot alkaloids through neurotransmitter receptors or indirect effects such as inhibiting the release of prolactin (PRL). The possible effects of ergot alkaloids or PRL require establishing the presence or absence of dopamine, adrenergic, serotonin, or PRL receptors in the testis, epididymis, and sperm cell of the bull. The objective of this review is to relate our findings to the few previous studies conducted that evaluated the impact of fescue toxicosis on bull reproduction and to propose possible mechanisms of action for lowered semen quality.

Tall fescue possesses heat, drought, and pest resistance conferred to the plant by its mutualistic relationship with the ergot alkaloid producing fungal endophyte, Neotyphodium coenophialum. The objective of this study was to evaluate the impact of ergot alkaloid consumption on growth, scrotal circumference (SC), and semen quality. The SC measurement and percentage of motile and normal sperm were used to determine if a bull passed the breeding soundness exam (BSE) requirements. Bulls (n = 14) between 13 and 16 mo of age exhibiting ≥32 cm SC and having passed a BSE were assigned to 1 of 2 dietary treatments accounting for BCS and BW. Bulls were fed the treatment diet containing toxic tall fescue seed (E+; 0.8 μg of ergovaline and ergovalanine/g DM) or the control diet containing endophyte-free nontoxic tall fescue seed (E-) for 126 d. Blood samples were collected and BSE and BCS accessed at the start of the test (d 0) and every 21 d to the end of test (d 126). Weights were obtained on d 0 and d 126. Serum prolactin (PRL) concentrations were affected by treatment × day interactions (P = 0.04) verifying the effectiveness of the E+ diet. Bulls consuming the E+ diet exhibited declining PRL concentrations from 250 ± 52.1 ng/mL on d 0 to 30.6 ± 46.9 ng/mL by d 126 whereas bulls receiving the E- ration maintained serum PRL concentrations greater than or equal to 226.7 ± 50.4 ng/mL across the 126-d study. Body condition score (P = 0.4) and BW (P = 0.4) were not different between treatments. No difference due to treatment was observed for the percentage of bulls passing a standard BSE exam (P = 0.6) and no treatment effect was observed for any semen characteristic measured by computer-assisted semen analysis (CASA; P ≥ 0.2). The SC was negatively affected by treatment × day interaction (P = 0.04) with E- bulls exhibiting a larger SC at d 126 compared with E+ bulls of 36.7 ± 0.8 versus 34.3 ± 0.8 cm, respectively. Within treatment, E+ bulls exhibited a decrease in SC (P = 0.0001) with a d 0 SC of 37.3 ± 0.8 cm and dropping to 34.3 ± 0.8 by d 126. Theoretically, reduced SC would negatively impact semen quality, but this was not observed. However, CASA and BSE evaluation data are consistent with recent reports indicating that bulls grazing E+ tall fescue exhibited only subtle, if any, differences on semen characteristics.

The objective of this study was to evaluate uteroplacental sufficiency, fetal growth, and development in ewes consuming ergot alkaloids found in endophyte-infected tall fescue [Lolium arundinaceum (Schreb.) Darbysh; Schedonorus phoenix (Scop.) Holub] seed at two stages of gestation. Thirty-six Suffolk ewes (78.24 kg ± 9.5) estimated to be carrying twins at d 35 of gestation were randomly assigned to one of two treatments: endophyte-free tall fescue seed (E-; 0.0 µg ergovaline + ergovalinine/g) or endophyte-infected tall fescue seed (E+; 4.14 µg ergovaline + ergovalinine/g) from d 35 - d 85 and d 86 - d 133 of gestation creating four unique dietary treatments: E-E-, E-E+, E+E-, and E+E+. Endophyte-infected tall fescue seed was fed at a level to provide 1772 µg of ergovaline + ergovalinine/hd/d for E+ treatments while an equal weight of endophyte-free seed (0.0 µg ergovaline + ergovalinine) was fed for E- treatments. Ewes were pair-fed across treatments in order to maintain equal DMI. Fetal and maternal necropsies were performed at d 133 of gestation. Muscle, organ, and placental samples were weighed and stored at -20°C and -80°C for later analysis. Data were analyzed as a randomized block design using a 2 x 2 factorial with alkaloid consumption (Eor E+), gestational time period (d 35 - d 85 or d 86 - d 133), and interaction as fixed effects. There was no significant difference (P > 0.05) in actual placental or fetal weights based on E+ or E- treatment between d 35 - d 85. A significant (P = 0.036) interaction between treatment and time was observed wherein the placentome weight to BW ratio was highest for E+E- ewes. Ewes receiving E+ treatment between d 86 - d 133 had lower (P = 0.003) uterine weights and lower (P = 0.0005) placentome weights. Cotyledon and caruncle tissue weights were reduced (P < 0.002) in ewes on E+ treatment between d 86 - d 133 compared to E- treatment. Cotyledon and caruncle weights were reduced by 25% and 19%, respectively. Overall fetal weight was decreased (P = 0.002) by 10% for ewes on E+ treatment compared to E- treatment between d 86 - d 133. Ergot alkaloid exposure during late gestation induces uteroplacental insufficiency and leads to reduced fetal growth. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate uteroplacental sufficiency, fetal growth, and development in ewes consuming ergot alkaloids found in endophyte-infected tall fescue [Lolium arundinaceum (Schreb.) Darbysh; Schedonorus phoenix (Scop.) Holub] seed at two stages of gestation. Thirty-six Suffolk ewes (78.24 kg ± 9.5) estimated to be carrying twins at d 35 of gestation were randomly assigned to one of two treatments: endophyte-free tall fescue seed (E-; 0.0 μg ergovaline + ergovalinine/g) or endophyte-infected tall fescue seed (E+; 4.14 μg ergovaline + ergovalinine/g) from d 35 - d 85 and d 86 - d 133 of gestation creating four unique dietary treatments: E-E-, E-E+, E+E-, and E+E+. Endophyte-infected tall fescue seed was fed at a level to provide 1772 μg of ergovaline + ergovalinine/hd/d for E+ treatments while an equal weight of endophyte-free seed (0.0 μg ergovaline + ergovalinine) was fed for E- treatments. Ewes were pair-fed across treatments in order to maintain equal DMI. Fetal and maternal necropsies were performed at d 133 of gestation. Muscle, organ, and placental samples were weighed and stored at -20°C and -80°C for later analysis. Data were analyzed as a randomized block design using a 2 x 2 factorial with alkaloid consumption (Eor E+), gestational time period (d 35 - d 85 or d 86 - d 133), and interaction as fixed effects. There was no significant difference (P > 0.05) in actual placental or fetal weights based on E+ or E- treatment between d 35 - d 85. A significant (P = 0.036) interaction between treatment and time was observed wherein the placentome weight to BW ratio was highest for E+E- ewes. Ewes receiving E+ treatment between d 86 - d 133 had lower (P = 0.003) uterine weights and lower (P = 0.0005) placentome weights. Cotyledon and caruncle tissue weights were reduced (P < 0.002) in ewes on E+ treatment between d 86 - d 133 compared to E- treatment. Cotyledon and caruncle weights were reduced by 25% and 19%, respectively. Overall fetal weight was decreased (P = 0.002) by 10% for ewes on E+ treatment compared to E- treatment between d 86 - d 133. Ergot alkaloid exposure during late gestation induces uteroplacental insufficiency and leads to reduced fetal growth. [ABSTRACT FROM AUTHOR]

Eight paddocks (0.8 ha/paddock) were utilized near Eatonton, GA to determine the effects of tall fescue endophyte strain and white clover presence on urinary ergot alkaloid excretion and animal performance. Jesup tall fescue infected with a toxic endophyte or a nonergot alkaloid-producing endophyte (AR542; aka "MaxQ") was planted in four paddocks respectively. Two paddocks of each endophyte type were also over-seeded with Durana white clover. Each paddock was grazed with a minimum of two tester steers (mean initial wt 311 kg) in spring of 2003 - 2005. Animal gain, botanical composition, forage availability, and urine alkaloid concentration was monitored at 28 d intervals. Paddocks were grazed for 125, 56, and 113 d in 2003, 2004, and 2005. Put-and-take grazing was utilized to maintain similar forage availability. Data were analyzed as a completely randomized design with a 2X2 factorial arrangement of treatments. Paddock was the experimental unit. Endophyte type and clover were main effects. Drought in 2004 shortened the grazing season and decreased (P<0.01) gain/ha by approximately 50% for all treatments. Daily gain of cattle grazing toxic endophyte was similar (P=0.30) to AR542 in 2003, but was lower (P<0.05) in 2004 and 2005. Cattle grazing toxic endophyte had decreased gain/ha (P<0.01) and increased urine alkaloid concentration (P<0.01) regardless of year. White clover decreased carrying capacity (P<0.01) but improved ADG (P<0.01) and gain/ha (P<0.01). No endophyte x clover interaction was detected for ADG (P = 0.38). Cattle grazing white clover and toxic tall fescue had intermediate (P<0.05) urine alkaloid concentrations compared to toxic fescue without clover or all nontoxic tall fescue treatments. The lack of a significant clover x endophyte type interaction for average daily gain suggests that the alkaloid dilution observed in this study was inadequate to completely offset tall fescue toxicosis and improved animal performance from clover was associated with increased nutrient density. [ABSTRACT FROM AUTHOR]