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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Body weights and selected organ measurements from pigs stillborn or dying neonatally

Herren, Charles Edward January 2011 (has links)
Typescript. / Digitized by Kansas Correctional Industries
2

Estimation of genetic and phenotypic parameters for stillbirth in South African holstein cattle

Ratshivhombela, Phillipine Mulisa January 2020 (has links)
Thesis (M.Sc. Agriculture (Animal Production)) -- University of Limpopo, 2020 / Stillbirth is a trait of high economic importance in dairy cattle and is increasingly being included in dairy cattle breeding objectives worldwide. In South Africa, however, there is limited information on stillbirth that can be used to improve this trait genetically. Currently, there are no estimated breeding values (EBVs) for any measures of calving performance produced under the national genetic evaluation programme. The current study was, therefore, conducted to assess the incidence of stillbirth and estimate the genetic and environmental influences on maternal effects for stillbirth in South African Holstein cattle, to enable estimation of breeding values for the trait. Data used in the study comprised 13 143 calving records of 7 723 Holstein cows, from 41 herds, participating in the National Dairy Animal Recording and Improvement Scheme during the period 2014 to 2018. Incidence of stillbirth was determined using the PROC FREQ procedure and environmental effects were tested by the General Linear Models (GLM) procedure of Statistical Analysis System (SAS 9.4, 2016). Maternal heritability of stillbirth was estimated by the Restricted Maximum Likelihood (REML) procedure, using the ASReml software (Gilmour et al., 2018). The analyses were carried out using a threshold animal model and a repeatability animal model, where the latter considered stillbirth in different parities as repeated measures of the same trait. Environmental effects significantly influencing stillbirth (p<0.05) were herd-year season of calving, dam parity and calf sex, and these were included in the model for variance component estimation. Estimates of maternal heritability effects from the threshold animal model were 0.12±0.04, 0.15±0.08 and 0.14±0.06 for parities 1 to 3, respectively. The repeatability animal model gave a heritability estimate of 0.09±0.03 and a repeatability of 0.18±0.03. The moderate estimates of maternal heritability indicate scope for reducing incidence of stillbirth by selectively breeding cows that are less genetically predisposed to calving dead calves. Stillbirth in different parities should not be considered as the same trait, as indicated by the low repeatability estimate. Results of the current study estimate genetic parameters that are required to compute accurate estimated breeding values (EBVs) for stillbirth, which will enable South African Holstein farmers to select for reduced stillbirths, thus improving calving performance / National Research Foundation (NRF), University of Limpopo (UL) and Department of Agriculture Forestry and Fisheries (DAFF)
3

Perinatal calf mortality in the Kansas Flint Hills

Cain, Donald Verne. January 1985 (has links)
Call number: LD2668 .T4 1985 C34 / Master of Science

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