Department of Animal and Veterinary Sciences, Clemson University, Clemson, SC 29634, USA.
J Anim Sci. 2013 Aug;91(8):3686-92. doi: 10.2527/jas.2012-6078. Epub 2013 Jun 5.
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.
黑麦草具有耐热、耐旱和抗虫害的特性，这是由于它与产生麦角生物碱的真菌内生菌 Neotyphodium coenophialum 的共生关系。本研究的目的是评估麦角生物碱摄入对生长、阴囊周长（SC）和精液质量的影响。SC 测量和运动和正常精子的百分比用于确定公牛是否通过了繁殖健康检查（BSE）要求。13 至 16 月龄、SC 至少为 32 cm 且已通过 BSE 的公牛被分配到 2 种饮食处理中的 1 种，这 2 种处理考虑了体况评分（BCS）和体重（BW）。公牛被喂食含有毒性黑麦草种子的处理饮食（E+；每克干物质含有 0.8 μg 麦角缬氨酸和麦角缬氨酸）或不含内生菌的无毒黑麦草种子的对照饮食（E-），共 126 天。在试验开始时（d 0）和试验结束前的每 21 天（d 126）采集血液样本，并进行 BSE 和 BCS 评估。在 d 0 和 d 126 时分别测量体重。血清催乳素（PRL）浓度受到处理×天数交互作用的影响（P=0.04），这验证了 E+饮食的有效性。摄入 E+饮食的公牛的 PRL 浓度从 d 0 的 250±52.1ng/mL 下降到 d 126 的 30.6±46.9ng/mL，而接受 E-饮食的公牛在整个 126 天的研究中血清 PRL 浓度保持在 226.7±50.4ng/mL 以上。处理对体况评分（P=0.4）和体重（P=0.4）没有影响。标准 BSE 检查中通过的公牛比例没有因处理而有所不同（P=0.6），通过计算机辅助精液分析（CASA）测量的任何精液特征也没有因处理而受到影响（P≥0.2）。SC 受到处理×天数交互作用的负面影响（P=0.04），E-组公牛在 d 126 时的 SC 比 E+组公牛大，分别为 36.7±0.8cm 和 34.3±0.8cm。在处理内，E+公牛的 SC 下降（P=0.0001），d 0 时的 SC 为 37.3±0.8cm，到 d 126 时降至 34.3±0.8cm。理论上，SC 的减小会对精液质量产生负面影响，但这并没有观察到。然而，CASA 和 BSE 评估数据与最近的报告一致，表明放牧 E+黑麦草的公牛在精液特征上仅表现出细微的、如果有的话差异。
