Coulter G H, Cook R B, Kastelic J P
Research Centre, Agriculture and Agri-Food Canada, Lethbridge, Alberta, Canada.
J Anim Sci. 1997 Apr;75(4):1048-52. doi: 10.2527/1997.7541048x.
The objective of this study was to determine the effect of dietary energy, breed (British vs Continental x British crosses), and their interactions on scrotal surface temperature (SST), seminal quality, and sperm production in bulls. This experiment, replicated over 2 yr, included 72 Angus, Angus x Simmental, or Hereford x Simmental bulls fed either a moderate- (100% forage) or high-energy (80% grain, 20% forage) diet for 168 d after weaning. At the end of the feeding period, SST was determined by infrared thermography, seminal samples (two ejaculates) were collected by electroejaculation, and reproductive tracts were collected at slaughter. Bulls fed the high-energy diet were heavier (P < .0001; diet x time interaction), had thicker backfat (P < .05; diet x line x time interaction), and had a larger scrotal circumference (P < .05). Testicular tone decreased over time (P < .0001) with a diet x time interaction (P < .05). There was no significant effect of diet on top, bottom, or average SST. However, bulls fed the moderate-energy diet had a larger (P < .02) SST gradient (3.9 vs. 3.4 degrees C). Bulls fed the moderate-energy diet had more (P < .01) morphologically normal spermatozoa (68.8 +/- 2.1 vs 62.5 +/- 2.5%) and a higher proportion (P < .006) of progressively motile spermatozoa (53.4 +/- 2.1 vs 44.5 +/- 2.4%). No effects (P > .05) of dietary energy on epididymal sperm reserves or daily sperm production were detected. Increased dietary energy may affect scrotal or testicular thermoregulation by reducing the amount of heat that can be radiated from the scrotal neck, thereby increasing the temperature of the testes and scrotum.
本研究的目的是确定日粮能量、品种（英国品种与欧洲大陆品种×英国品种杂交）及其相互作用对公牛阴囊表面温度（SST）、精液品质和精子生成的影响。本试验重复进行了2年，包括72头安格斯牛、安格斯×西门塔尔杂交牛或赫里福德×西门塔尔杂交牛，断奶后饲喂中等能量（100%粗饲料）或高能量（80%谷物、20%粗饲料）日粮168天。在饲喂期结束时，通过红外热成像测定SST，通过电刺激采精收集精液样本（两次射精），并在屠宰时收集生殖道。饲喂高能量日粮的公牛体重更重（P < 0.0001；日粮×时间交互作用），背膘更厚（P < 0.05；日粮×品系×时间交互作用），阴囊周长更大（P < 0.05）。随着时间的推移，睾丸张力下降（P < 0.0001），存在日粮×时间交互作用（P < 0.05）。日粮对阴囊顶部、底部或平均SST没有显著影响。然而，饲喂中等能量日粮的公牛SST梯度更大（P < 0.02）（3.9℃对3.4℃）。饲喂中等能量日粮的公牛形态正常的精子更多（P < 0.01）（68.8±2.1%对62.5±2.5%），进行性运动精子的比例更高（P < 0.006）（53.4±2.1%对44.5±2.
