Department of Production Animal Clinical Sciences, Norwegian School of Veterinary Science, Oslo, Norway.
Acta Vet Scand. 2010 Nov 8;52(1):60. doi: 10.1186/1751-0147-52-60.
The aims of this study were to establish the incidence of cystic ovarian disease (COD) and its geographical and seasonal variation in Norway, investigate the effect of COD on culling rates, and describe the effects of COD on subsequent reproductive performance and its association to twins.
Diagnosis of COD was made by veterinary surgeons in the field. Four statistical models were made all including herd as random effect: The four different dependent variables investigated were: 1) Diagnosis of COD between 40 and 165 days in milk or not; (n = 511,657); 2) Twins or singleton; data restricted to lactations with new calving (n = 156,661): 3) Culling/removal or not (n = 573,184): 4) Culling due to reproductive problems; data included only lactations which ended in culling (n = 234,232). Model 1, 3 and 4 applied Cox regression models, and model 2 logistic regression. Independent variables were parity, twins/singletons, calving season, herd size, region, COD occurrence in present lactation (if not dependent), and COD diagnosis in previous lactation.
The incidence was 0.82% per lactation. COD increased with increasing parity, was smallest at herd size between 35 and 85 cows. Cows in 1st parity and calved in spring had lowest hazard of COD and hazard for COD diagnosis was highest in autumn with HR = 2.6 (1.9-3.4) compared to spring. There was an interaction between parity and season. COD incidence was lower south of 60°N. Cows which experienced COD had an increased odds of giving birth to twins OR = 2.2 (1.7-2.7). Of those that were culled, those with COD were culled more frequently because of reproductive problems; HR = 2.1 (1.9-2.3) for higher parity than 2. Having COD diagnosed in the preceding lactation was a hazard for diagnosis in the lactation studied.
COD diagnosis is strongly associated with season (autumn calving) and parity. Herds north of 60°N have more COD. Occurrence of COD is associated with twin births as well as culling due to reproduction.
本研究旨在确定挪威囊性卵巢疾病（COD）的发病率及其地理和季节性变化，研究 COD 对淘汰率的影响，并描述 COD 对随后的繁殖性能及其与双胞胎的关系的影响。
COD 的诊断由兽医在现场进行。建立了四个均包含畜群作为随机效应的统计模型：四个不同的因变量分别为：1）产奶 40-165 天之间的 COD 诊断；（n = 511657）；2）双胞胎或单胎；仅限于新产奶牛的泌乳期数据（n = 156661）：3）淘汰/去除；（n = 573184）；4）因繁殖问题淘汰；仅包括淘汰泌乳期的数据（n = 234232）。模型 1、3 和 4 应用 Cox 回归模型，模型 2 应用逻辑回归。自变量为胎次、双胞胎/单胎、产犊季节、畜群规模、地区、本泌乳期的 COD 发生情况（如果不是依赖的）以及上一泌乳期的 COD 诊断。
发病率为每泌乳期 0.82%。COD 随胎次增加而增加，畜群规模在 35-85 头之间时最小。初产奶牛在春季分娩的 COD 发生风险最低，秋季的 COD 诊断风险最高，HR = 2.6（1.9-3.4）与春季相比。胎次和季节之间存在交互作用。北纬 60°以南的 COD 发生率较低。患有 COD 的奶牛生出双胞胎的几率增加，OR = 2.2（1.7-2.7）。那些被淘汰的奶牛，由于繁殖问题而被淘汰的奶牛，COD 的比例更高；HR = 2.1（1.9-2.3），比 2 更高。在上一个泌乳期诊断出 COD 是在研究泌乳期诊断出的一个危险。
COD 诊断与季节（秋季产犊）和胎次密切相关。北纬 60°以北的畜群有更多的 COD。COD 的发生与双胞胎的出生以及由于繁殖而被淘汰有关。
