Tusell L, García-Tomás M, Baselga M, Rekaya R, Rafel O, Ramon J, López-Bejar M, Piles M
Unitat de Cunicultura, Institut de Recerca i Tecnologia Agroalimentàries, Torre Marimon s/n, Caldes de Montbui, Barcelona, Spain.
J Anim Sci. 2010 Nov;88(11):3475-85. doi: 10.2527/jas.2009-2773. Epub 2010 Aug 20.
Failures in fertilization or embryogenesis have been shown to be partly the result of poor semen quality. When AI is practiced, fertilization rate depends on the number and quality of spermatozoa in the insemination dose around the time of application. Individual variation in the male effect on fertility (success or failure to conceive; Fert) and prolificacy (total number of kids born per litter; TB) could also depend on these factors, and it could be better observed under limited conditions of AI, such as decreased sperm concentration, small or null preselection of ejaculates for any semen quality trait, or a long storage period of the AI doses. The aim of this research was to determine if an interaction existed between male genotype and the AI conditions for male effects on Fert and TB after AI was performed under different conditions. Fertility and TB were assumed to be different traits and were analyzed in 2 sets of independent analyses. In the first step, the different conditions were determined uniquely by the sperm dosage. Artificial insemination was performed at 10 and 40 × 10(6) spermatozoa/mL. In the second step, the different conditions were determined by all the factors involved in the AI process as a whole (conditions and duration of the storage period of the dose, genetic type of the female, and environmental conditions on the farm). Data from AI from the former experiment were analyzed with data from AI performed under different conditions. Threshold and linear 2-trait models were assumed for Fert and TB, respectively. The sperm dosage had a clear effect on Fert and TB, which favored the greater dosage (+0.13% and +1.25 kids born, respectively). Prolificacy was more sensitive to sperm reduction than was fertility. Male heritabilities for Fert were 0.09 for both sperm dosages, and were 0.08 and 0.06 for male TB with a smaller and larger sperm dosage, respectively. No genotype × sperm dosage interaction was found. Therefore, the same response to selection to improve male Fert and TB could be achieved at any sperm concentration. However, an interaction between male genotype and the AI conditions as a whole seemed to exist, indicating that the AI conditions for selection for Fert and TB could be modified to maximize genetic progress. Consequently, the optimization of a breeding program for male Fert and TB under a given set of semen utilization conditions is achievable.
受精或胚胎发育失败已被证明部分是精液质量差的结果。进行人工授精时，受精率取决于授精时授精剂量中精子的数量和质量。雄性对繁殖力（受孕成功或失败；Fert）和产仔数（每窝出生的幼崽总数；TB）影响的个体差异也可能取决于这些因素，并且在人工授精的有限条件下，如精子浓度降低、对任何精液质量性状的射精进行少量或无预筛选，或人工授精剂量的储存期较长时，可能会更好地观察到这种差异。本研究的目的是确定在不同条件下进行人工授精后，雄性基因型与人工授精条件之间是否存在相互作用，从而影响雄性对Fert和TB的作用。繁殖力和TB被假定为不同的性状，并在两组独立分析中进行分析。第一步，不同条件仅由精子剂量决定。人工授精分别在每毫升10×10⁶和40×10⁶精子时进行。第二步，不同条件由人工授精过程中涉及的所有因素共同决定（剂量的储存条件和持续时间、雌性的遗传类型以及农场的环境条件）。将前一实验中人工授精的数据与在不同条件下进行人工授精的数据进行分析。分别假设Fert和TB的阈值模型和线性双性状模型。精子剂量对Fert和TB有明显影响，较大剂量更有利（分别增加0.13%的受孕率和1.25只出生幼崽）。产仔数比繁殖力对精子减少更敏感。两种精子剂量下雄性Fert的遗传力均为0.09，精子剂量较小和较大时，雄性TB的遗传力分别为0.08和0.06。未发现基因型×精子剂量的相互作用。因此，在任何精子浓度下，对选择以提高雄性Fert和TB的反应都是相同的。然而，雄性基因型与整个人工授精条件之间似乎存在相互作用，这表明可以修改用于选择Fert和TB的人工授精条件，以最大化遗传进展。因此，在给定的精液利用条件下，实现雄性Fert和TB育种计划的优化是可行的。
