与放牧奶牛青春期开始相关的动物和群体水平因素。

IF 1.1 4区 农林科学 Q3 VETERINARY SCIENCES
N M Steele, M A Stephen, B Kuhn-Sherlock, S J Hendriks, S Meier, Cvc Phyn, C R Burke
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引用次数: 0

摘要

目的:探讨动物和群体水平的危险因素影响青春期年龄,主要是在季节性牧场系统管理的荷斯坦-弗里西亚乳牛。方法:在新西兰54个商业奶牛群中,对2018年春季出生的小母牛(n = 5010)进行了三次访问,当时牛群内的小母牛平均年龄为10岁(访问1;V1)、11 (V2)和12 (V3)月龄。每次访视均采集血样,并于V2时测定活重、身高和肛门生殖器距离(AGD)。小牛被定义为在第一次访问时已进入青春期,血液黄体酮升高(≥1 ng/mL)。动物水平的反应变量包括V1、V2和V3期的青春期状态,以及青春期的年龄(V3期年龄加31天,V3期未达到青春期)。为了探讨畜群管理因素,农民回答了一份有关动物位置、土地类型、健康状况、饲养和断奶至交配期间管理的问卷。采用偏最小二乘回归来确定畜群内与青春期率影响最大的相关因素。结果:青春期平均年龄352天(SD 34.9)。根据其活重的育种价值,体重较重且在预期成熟活重中所占比例较大的动物,或泽西品种比例较高而荷斯坦品种比例较低的动物,青春期提前。牛群的青春期率在登记的牛群中差异很大,V1、V2和V3的平均青春期率分别为20%、39%和56%。活重对群体发育率的影响最大,其次是品种和土地类型。平均活重(绝对和预期成熟体重的比例)或泽西比例较高的小牛群在任何一次访问中都有更多的动物进入青春期,而位于陡峭土地上或荷斯坦品种比例较高的小牛群的青春期率较低。与管理相关的因素,如疫苗接种、饲料补充的提供和称重频率,也是群体水平的青春期危险因素,但影响较小。结论和临床意义:本研究强调了拥有发育良好的小母牛对于增加早熟的机会以及品种和幼畜管理对实现生长目标的影响的重要性。这些结果对母牛在初次繁殖前达到青春期的最佳管理以及在遗传评估中可能纳入青春期特征的测量时间具有重要意义。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Animal- and herd-level factors associated with onset of puberty in grazing dairy heifers.

Aims: To explore animal- and herd-level risk factors influencing age at puberty in predominantly Holstein-Friesian dairy heifers managed in seasonal, pasture-based systems.

Methods: Heifers born in spring 2018 (n = 5,010) from 54 commercial dairy herds in New Zealand were visited on three occasions when the mean heifer age, within herd, was 10 (visit 1; V1), 11 (V2) and 12 (V3) months old. Blood samples were collected on each visit and liveweight, stature and anogenital distance (AGD) were measured at V2. Heifers were defined as having reached puberty at the first visit where blood progesterone was elevated (≥ 1 ng/mL). Animal-level response variables included pubertal status by V1, V2 and V3, and age at puberty (or age at V3 plus 31 days for those that had not attained puberty by V3). To explore herd-level management factors, farmers answered a questionnaire relating to animal location, land type, health, feeding, and management between weaning and mating. A partial least squares regression was undertaken to identify herd-level factors associated with the greatest influence on puberty rate within herd.

Results: The mean age at puberty was 352 (SD 34.9) days. Heavier animals at a greater proportion of expected mature liveweight based on their breeding value for liveweight, or animals with a higher breed proportion of Jersey and lower breed proportion of Holstein, were associated with earlier puberty. Herd puberty rates varied widely among enrolled herds, and averaged 20%, 39% and 56% by V1, V2 and V3, respectively. Liveweight, followed by breed and land type, had the greatest influence on the herd puberty rate. Heifer herds with a greater mean liveweight (absolute and proportion of expected mature weight) or greater Jersey proportion had more animals that reached puberty at any visit, whereas herds located on steep land or with greater Holstein breed proportions had lower puberty rates. Management-related factors such as vaccinations, provision of feed supplements, and weighing frequency were also herd-level risk factors of puberty but had less influence.

Conclusions and clinical relevance: This study highlights the importance of having well-grown heifers for increasing the chances of earlier puberty onset and the effect of breed and youngstock management to achieve growth targets. These outcomes have important implications for the optimal management of heifers to achieve puberty before their maiden breeding and for the timing of measurements to potentially incorporate a puberty trait in genetic evaluations.

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来源期刊
New Zealand veterinary journal
New Zealand veterinary journal 农林科学-兽医学
CiteScore
3.00
自引率
0.00%
发文量
37
审稿时长
12-24 weeks
期刊介绍: The New Zealand Veterinary Journal (NZVJ) is an international journal publishing high quality peer-reviewed articles covering all aspects of veterinary science, including clinical practice, animal welfare and animal health. The NZVJ publishes original research findings, clinical communications (including novel case reports and case series), rapid communications, correspondence and review articles, originating from New Zealand and internationally. Topics should be relevant to, but not limited to, New Zealand veterinary and animal science communities, and include the disciplines of infectious disease, medicine, surgery and the health, management and welfare of production and companion animals, horses and New Zealand wildlife. All submissions are expected to meet the highest ethical and welfare standards, as detailed in the Journal’s instructions for authors.
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