Coulter G H, Carruthers T D, Amann R P, Kozub G C
J Anim Sci. 1987 Jan;64(1):254-60. doi: 10.2527/jas1987.641254x.
Bull calves (n = 143) were obtained from two strains of Angus and two strains of Hereford cattle for which replacements were selected on the basis of superior feedlot growth performance on either high- or medium-energy diets. From weaning to slaughter at 15 mo of age, bulls were fed either the high-energy (80% grain + 20% forage) or medium-energy diet (100% forage) corresponding to their strain. Bulls in high-energy diet groups had a greater (P less than .05) scrotal circumference at 12 mo, but not 15 mo of age, than bulls in medium-energy diet groups. Compared with Hereford bulls, Angus had greater (P less than .01) scrotal circumference (36.1 vs 33.9 cm) and greater (P less than .05) paired testes weight (570 vs 464 g) at 15 mo of age. Daily sperm production per gram testicular parenchyma (DSP/g) was affected by strain-diet (P less than .01) but not by breed. Bulls in medium-energy diet groups had 12% greater DSP/g than did high-energy diet bulls (17.4 X 10(6) vs 15.5 X 10(6)). Daily sperm production (DSP) was 9% and 30% greater (P less than .01) for medium-energy diet bulls in 1980 (8.2 X 10(9) vs 7.5 X 10(9)) and 1981 (8.0 X 10(9) vs 6.2 X 10(9)), respectively, compared with high-energy diet bulls. The effect (P less than .01) of breed on DSP was attributed to breed differences in paired testes weight.(ABSTRACT TRUNCATED AT 250 WORDS)
选取了143头公牛犊，它们来自两个安格斯牛品系和两个赫里福德牛品系，这些牛品系的后备牛是根据在高能或中能日粮条件下育肥场生长性能优良而挑选出来的。从断奶到15月龄屠宰，公牛按照其所在品系分别饲喂高能日粮（80%谷物 + 20%草料）或中能日粮（100%草料）。高能日粮组的公牛在12月龄时阴囊周长比中能日粮组的公牛更大（P < 0.05），但在15月龄时并非如此。与赫里福德公牛相比，安格斯公牛在15月龄时阴囊周长更大（P < 0.01）（36.1对33.9厘米），双侧睾丸重量也更大（P < 0.05）（570对464克）。每克睾丸实质的每日精子生成量（DSP/g）受品系 - 日粮影响（P < 0.01），但不受品种影响。中能日粮组的公牛DSP/g比高能日粮组的公牛高12%（17.4×10⁶对15.5×10⁶）。1980年（8.2×10⁹对7.5×10⁹）和1981年（8.0×10⁹对6.2×10⁹），中能日粮组公牛的每日精子生成量（DSP）分别比高能日粮组公牛高9%和30%（P < 0.01）。品种对DSP的影响（P < 0.01）归因于双侧睾丸重量的品种差异。（摘要截短至250字）
