Kidding (n = 33,116) and monthly milking control (n = 96,359) records of Florida goats (n = 13,194) from the Spanish Florida Goat Breeders Association, collected between 2007 and 2016, were used to determine whether the presence of male co-twins affected the productive lifespan, and kid and milk production of does. The dataset included single-born (n = 3727), twin-born (n = 7573), triplet-born (n = 1784) and quadruplet-born (n = 110) goats. Information for each goat included birth date; type of birth (single, twin, triplet, or quadruplet), sex of the co-twin(s), reproductive traits of the goat throughout its productive life, and mean milk quality and quantity of the lactations. Singleton and twin-born goats had significantly longer productive lifespans than did triplet- (P < 0.05) or quadruplet-born animals (P < 0.01). Females born with male co-twins had a shorter (P < 0.05) productive lifespan than did goats born with no male co-twins, and had more parturitions and kids born per year (P < 0.05). In particular, goats that had three female littermates had the fewest kids per year (P < 0.01). Does born with male littermates had a higher daily milk yield and total milk yield (P < 0.01) than did goats born with no male co-twins; however, the former had the shortest on-farm longevity, which caused them to have a lower (P < 0.05) lifetime milk production than did goats born with no male co-twins. In conclusion, the presence of male co-twins had a positive effect on the production traits of dairy goats; however, the shorter reproductive lifespan of these goats limited their lifetime milk production. If reproductive lifespan could be extended, possibly through management practices or by identifying the factors that reduce lifespan, goats that have male co-twins might be the most suitable candidates for replacement does. Thus, in addition to litter composition, kid body mass, or maternal milk production, the sex of co-twins might be included in selection programs.

 从2007年至2016年之间收集的来自西班牙佛罗里达山羊饲养员协会 的佛罗里达山羊（n = 13,194）的开玩笑（n  = 33,116）和每月挤奶控制（n = 96,359）记录用于确定是否存在雄性双胞胎影响了生产寿命，以及孩子和牛奶的生产量。数据集包括单胎（n  = 3727），双胎（n  = 7573），三胞胎（n  = 1784）和四胞胎（n = 110）山羊。每只山羊的信息包括出生日期；出生类型（单胎，双胎，三胞胎或四胞胎），双胞胎的性别，山羊在整个生产寿命中的生殖特性以及平均泌乳质量和泌乳量。单胎和双胎山羊的生产寿命比三联体（P  <0.05）或四联体（P  <0.01）的动物更长。 与没有雄性双生子的山羊相比，具有雄性双生子的雌性的生产寿命短（P <0.05），并且每年分娩的孩子和分娩次数更多（P  <0.05）。特别是，有三个雌性同窝仔的山羊每年生孩子最少（P <0.01）。 与没有雄性双胞胎的山羊相比，有雄性同窝出生的山羊的每日产奶量和总产奶量更高（P <0.01）；但是，前者的农场寿命最短，这导致他们的寿命较低（P 与没有雄性双胞胎的山羊相比，一生的乳汁产量<0.05）。总之，雄性双胞胎的存在对奶山羊的生产性状具有积极影响。但是，这些山羊的生殖寿命较短，限制了它们一生的奶产量。如果可以通过管理实践或确定减少寿命的因素来延长生殖寿命，那么具有雄性双胞胎的山羊可能是最合适的替代者。因此，除了产仔组成，孩子的体重或产妇的产奶量外，同卵双生的性别可能也包括在选择程序中。