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首页> 外文学位 >The summer -fall slump: Seasonal variation in average daily milk production in Prince Edward Island, Canada.
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The summer -fall slump: Seasonal variation in average daily milk production in Prince Edward Island, Canada.

机译：夏秋低迷：加拿大爱德华王子岛的平均每日牛奶产量的季节性变化。

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摘要

Average test-day milk production in Prince Edward Island, Canada, was observed to follow a pronounced and consistent seasonal pattern, with peak and nadir production occurring in June and November, respectively. It was also observed that there was substantial herd-to-herd variation in the seasonal patterns of milk production, with some herds maintaining seasonally consistent average milk yields and others exhibiting a decline in average test-day milk yield of approximately fifty percent during the summer and fall months. There was also controversy surrounding the association of economic performance with seasonal variation in average test-day milk yield.;During the years 1990 to 1994, the average test-day production in November was 74.5% of that observed in June for all Prince Edward Island dairy herds. Herds tended to show similar patterns of milk production from one year to the next.;An income-over-feed-cost (IOFC) analysis was used to determine the relationship between seasonal variation in milk production and economic performance. A positive, linear relationship was found between seasonal patterns of production and IOFC, with seasonally consistent herds demonstrating higher IOFC than herds with marked seasonal variability in production. On average, for every 10 percent reduction in average test-day milk yield from June to November, IOFC of ;Delphi and conjoint analysis techniques were used to obtain estimates of the expected increase in pasture dry matter yield resulting from the use of various pasture management techniques. These two methods yielded results that were highly correlated when combined at the field level (R2 = .89) and that demonstrated good agreement with the appropriate data in the literature.;In-depth examinations of the relationship between nutrition, body condition score, internal parasite exposure and the seasonal pattern of milk production were completed before using multivariable modeling techniques to explain the inter-herd variability in seasonal variation in average test-day milk production in PEI. In addition, information on herd reproductive performance and herd management data were included in the multivariable models. The models explained a significant proportion of the between-herd variability in the seasonal patterns of milk production, and were found to be robust and reliable after thorough examination. A number of factors were found to be statistically associated with the seasonality of herd average test-day milk production. In the most parsimonious model these included herd level factors that measured the reproductive performance. (seasonal difference in days-in-milk), the internal parasite exposure levels (bulk tank milk Ostertagia ostertagi optical density values) and the nutritional management during the summer (kilograms of supplementary, non-forage DM cow-1 day-1 ). To rank the variables as to their relative importance, the regression coefficients were multiplied by the interquartile range of the observed values. Using this technique, reproductive performance and Ostertagia ostertagi optical density values were shown to have a similar impact on the seasonal pattern of milk production in a herd, whereas in absolute terms the daily amount of non-forage dry matter per cow had a marginally lesser effect. (Abstract shortened by UMI.).
机译：据观察，加拿大爱德华王子岛的平均测试日牛奶产量遵循明显且一致的季节性模式，最高产量和最低产量分别发生在6月和11月。还观察到，牛奶生产的季节性模式在各畜群之间存在很大的差异，有些畜群保持季节性一致的平均奶产量，而另一些在夏季表现出平均试验日奶产量下降约百分之五十。和秋天的几个月。经济表现与测试日平均产奶量的季节性变化之间的关系也存在争议;在1990年至1994年期间，爱德华王子岛所有11月的测试日平均产量为6月观察到的平均日产量的74.5％。奶牛群。从一年到下一年，牛群往往会表现出相似的牛奶生产模式。饲料成本收入（IOFC）分析用于确定牛奶生产的季节性变化与经济绩效之间的关系。发现季节性生产模式与IOFC之间呈正线性关系，季节性一致的牛群的IOFC值高于季节性明显变化的牛群。从6月到11月，平均测试日牛奶产量平均降低10％，使用；德尔福（Delphi）的IOFC和联合分析技术来获得使用各种牧场管理方法导致牧场干物质产量预期增加的估计值技术。这两种方法所产生的结果在田间结合时（R2 = .89）高度相关，并且与文献中的适当数据显示出良好的一致性。;深入检查了营养，身体状况评分，内在因素之间的关系在使用多变量建模技术来解释PEI的平均测试日奶产量的季节性变化之间的群体间差异之前，应完成寄生虫暴露和奶产量的季节性模式。此外，多变量模型中还包含了有关牛群繁殖性能和牛群管理数据的信息。该模型解释了奶产量季节性模式中群体间差异的很大一部分，并且经过全面检查后发现它们是可靠且可靠的。发现许多因素与牛群平均测试日产奶量的季节性统计相关。在最简约的模型中，这些因素包括衡量繁殖性能的畜群水平因素。 （牛奶日数的季节差异），内部寄生物暴露水平（大桶牛奶Ostertagia ostertagi光学密度值）和夏季的营养管理（补充的非饲草DM cow-1 day-1千克）。为了对变量的相对重要性进行排名，将回归系数乘以观测值的四分位数范围。使用这种技术，显示出繁殖性能和Ostertagia ostertagi光学密度值对牛群的牛奶生产的季节性模式具有相似的影响，而从绝对意义上讲，每头母牛每天的非草料干物质的量影响较小。 （摘要由UMI缩短。）。

著录项

  • 作者

    Hovingh, Ernest Peter.;

  • 作者单位

    University of Prince Edward Island (Canada).;

  • 授予单位 University of Prince Edward Island (Canada).;
  • 学科 Animal sciences.;Agricultural economics.
  • 学位 Ph.D.
  • 年度 1999
  • 页码 262 p.
  • 总页数 262
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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