Hossein-Zadeh N Ghavi, Nejati-Javaremi A, Miraei-Ashtiani S R, Kohram H
Department of Animal Science, University College of Agriculture and Natural Resources, University of Tehran, 31587-77871 Karaj, Iran.
J Dairy Sci. 2008 Nov;91(11):4198-205. doi: 10.3168/jds.2008-1079.
Calving records of Holstein dairy cows from April 1998 to September 2006 comprising 16 herds with 104,572 calving events representing 4,045 twin births were used to evaluate reported twinning rate, calf sex ratio, stillbirth, and abortion rates in single and twin births. Overall, the reported twinning rate was 3.9%, and twinning increased with parity [1.1% for primiparous cows vs. 5.7% for cows in their fourth or greater lactation; odds ratio (OR) = 5.50]. Regardless of parity, the greatest twinning rate was observed when conception occurred in fall season from September to December (OR = 1.17). Calf stillbirth was greater after twin births, with 18.8% of twin calving events resulting in one or both calves as stillborn, compared with 4.0% for singleton births (OR = 7.58). Calf stillbirth for multiparous cows was 2.9% for single births and 18.0% for twin births (OR = 7.08), whereas for primiparous cows, stillbirth was 6.6% for singletons and 27.7% for twins (OR = 5.85). Calf sex ratios (male, M; female, F) were 52.4% M and 47.6% F for singleton calves and 28.2% MM, 48.9% MF, and 22.9% FF for twin calves. The mean abortion rate was 13.4%, with 13.8% for single births and 4.2% for twin births (OR = 1.22). Abortion rate for multiparous cows was 15.9% for single births and 4.0% for twin births (OR = 4.31), whereas for primiparous cows, abortion rate was 9.4% for single births and 5.4% for twin births (OR = 1.89). Although milk production, as a causative factor associated with twinning, increased in recent years, twinning rate decreased over the years.
1998年4月至2006年9月期间荷斯坦奶牛的产犊记录，涵盖16个牛群，共有104,572次产犊事件，其中包括4,045次双胎分娩，用于评估单胎和双胎分娩中报告的双胎率、犊牛性别比例、死产和流产率。总体而言，报告的双胎率为3.9%，双胎率随胎次增加而升高[初产母牛为1.1%，而第四胎及以上泌乳期的母牛为5.7%；优势比(OR)=5.50]。无论胎次如何，当受孕发生在9月至12月的秋季时，双胎率最高(OR = 1.17)。双胎分娩后的犊牛死产率更高，18.8%的双胎产犊事件导致一头或两头犊牛死产，而单胎产犊的这一比例为4.0%(OR = 7.58)。经产母牛单胎分娩的犊牛死产率为2.9%，双胎分娩为18.0%(OR = 7.08)，而初产母牛单胎死产率为6.6%，双胎为27.7%(OR = 5.85)。犊牛性别比例(雄性，M；雌性，F)单胎犊牛为52.4% M和47.6% F，双胎犊牛为28.2% MM、48.9% MF和22.9% FF。平均流产率为13.4%，单胎分娩为13.8%，双胎分娩为4.2%(OR = 1.22)。经产母牛单胎分娩的流产率为15.9%，双胎分娩为4.0%(OR = 4.31)，而初产母牛单胎分娩的流产率为9.4%，双胎分娩为5.4%(OR = 1.89)。尽管作为与双胎相关的一个致病因素，近年来产奶量有所增加，但双胎率却逐年下降。
