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首页> 外文学位 >Beef cattle production: Understanding the effect of heifer development system, late gestation protein supplementation, and ovarian steroidogenic environment on productivity, reproduction, and longevity.
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Beef cattle production: Understanding the effect of heifer development system, late gestation protein supplementation, and ovarian steroidogenic environment on productivity, reproduction, and longevity.

机译：肉牛生产：了解小母牛发育系统，妊娠后期补充蛋白质和卵巢类固醇生成环境对生产力，繁殖力和寿命的影响。

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摘要

Beef cattle longevity is related to reproductive success, which can be influenced by development system and maternal environment. Three experiments were conducted to determine the impact of development system, maternal protein supplementation, and ovarian steroidogenic environment on beef cattle reproduction. Experiment 1 evaluated the effect of heifer development system on heifer performance and reproduction. Heifers developed on corn residue (CR) had reduced BW from prebreeding through pregnancy diagnosis compared with drylot (DL) developed heifers, but there was no difference in reproductive performance. A subset DL and CR heifers were placed in an individual feeding system to determine feed efficiency during late gestation. Drylot heifers tended to have increased final BW and ADG. In Exp. 2, primiparous heifers were individually fed grass hay and received either no supplement (CON), a distillers based supplement (HIGH), or a dried corn gluten feed (LOW ) based supplement during late gestation. Weaning calf BW tended to be greater for steers born to HIGH supplemented dams compared with CON. Similarly, carcass characteristics were altered in calves based on maternal nutrition. The objective of Exp. 3 was to identify the effect of ovarian and follicular environment on oocyte molecular phenotype. Ovariectomy was performed on beef cows approximately 36 h after CIDR removal and PGF administration. Cows were classified as high (HGE) or low (LGE) based on granulosa cell efficiency. Cows classified LGE had increased androgen secretion and expression of steroidogenic pathway enzymes in theca cells. Furthermore, mRNA abundance of ZAR1 was reduced in LGE oocytes. In summary, these experiments support the following findings: (1) developing heifers on CR does not reduce reproductive performance or impact late gestation feed efficiency compared with DL-developed heifers; (2) primiparous heifer protein supplementation improved steer calf weaning BW and altered progeny carcass characteristics; (3) Increased androgen production in LGE animals increases steroidogenic enzyme gene expression and/or mRNA stability during oocyte growth and maturation.
机译：肉牛的寿命与生殖成功有关，这可能受到发育系统和母体环境的影响。进行了三个实验，以确定发育系统，母体蛋白质补充和卵巢类固醇生成环境对肉牛繁殖的影响。实验1评估了小母牛发育系统对小母牛性能和繁殖的影响。玉米残渣（CR）育成的小母牛与干育（DL）育成的母牛相比，从育种到妊娠诊断的体重减少，但繁殖性能没有差异。 DL和CR小母牛子集放置在单独的饲喂系统中，以确定妊娠后期的饲喂效率。 Drylot小母牛的最终BW和ADG趋于增加。在实验中如图2所示，分别给初生小母牛喂草干草，并且在妊娠后期不给予任何补充剂（CON），基于蒸馏器的补充剂（HIGH）或基于干玉米蛋白饲料（LOW）的补充剂。与CON相比，HIGH补充水坝出生的ers牛的断奶犊牛体重更趋于大。同样，基于母体营养，犊牛的cas体特征也发生了变化。 Exp。的目标图3是鉴定卵巢和卵泡环境对卵母细胞分子表型的影响。去除CIDR和施用PGF后约36小时，对肉牛进行卵巢切除术。根据颗粒细胞效率，将母牛分为高（HGE）或低（LGE）。分类为LGE的母牛在卵泡膜细胞中雄激素分泌增加和类固醇生成途径酶的表达。此外，LGE卵母细胞中ZAR1的mRNA丰度降低。总之，这些实验支持以下发现：（1）与DL发育的母牛相比，在CR上发育的母牛不会降低繁殖性能或影响后期妊娠饲料的效率； （2）补充初生小母牛蛋白可改善ste牛断奶体重并改变后代pro体特性； （3）LGE动物中雄激素产生的增加在卵母细胞生长和成熟期间增加了类固醇生成酶基因的表达和/或mRNA的稳定性。

著录项

  • 作者

    Summers, Adam F.;

  • 作者单位

    The University of Nebraska - Lincoln.;

  • 授予单位 The University of Nebraska - Lincoln.;
  • 学科 Agriculture Animal Culture and Nutrition.
  • 学位 Ph.D.
  • 年度 2012
  • 页码 223 p.
  • 总页数 223
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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