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Showing 1 to 20 of 22 for “"genetic merit"”.
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Accuracy of predicting genetic merit of A.I. sampled bulls for final score from pedigree information
A total of 1926 A.I. sampled Holstein bulls born from 1984 to 1988 and with first proofs from Summer 1991 to Summer 1993 were used to determine the accuracy of predicting PTAT and DTD from different sources of pedigree information obtained before the bull had daughter information. Pedigree sources …
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Accuracy of predicting genetic merit of A.I. sampled bulls from pedigree information and the impact of son's proof on dam's PTA
A total of 1,644 A.I. sampled bulls born from 1984 to 1986 with first proofs from Winter 90 to Summer 91 were used to determine the accuracy of predicting DYD and PTA from different sources of pedigree information obtained before the bull had daughter information. Traits evaluated were milk, fat …
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Aspects of lactation endocrinology: I. lactogenic receptors in bovine mammary tissue at different stages of lactation: II. growth hormone concentrations in Holstein cattle of differing genetic merit
… hormone profiles in Holstein cattle of differing genetic merit at several ages. Control animals were randomly bred to non-AI sires originating in the Virginia Tech Dairy herd. Selected animals were offspring of commercially available AI sires. In one experiment, mean plasma Prl was greater in …
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Transition cows: hepatic endocannabinoid system gene expression in response to prepartal plane of nutrition and the effects of genetic merit on genes of lipid metabolism in adipose tissue
… to prepartal plane of nutrition. 2) effects of genetic merit on lipid metabolism in adipose tissue. For the objective of first experiment, we examined mRNA expression via qPCR of endocannabinoid receptors (CNR1, CNR2), enzymes that synthesize FAE (HRASLS5, NAPEPLD), enzymes that degrade FAE …
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A comparison of herdmate, iterative, and mixed model sire summaries for type in Holstein cattle
… between herdmate average and two measures of genetic merit of herdmates, average PDT of herdmates' sires and average cow index of herdmates, were .48 and .45. Positive regression coefficients of final score and herdmate average on two measures of genetic merit of herdmates also indicated a …
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Studies of grazing and nursing behavior in Angus crossbred cattle
… from < 20% to approximately 60%. Cows with (+) genetic merit for maternal weaning weight were nursed a similar number of times per day as cows with (-) genetic merit. Sire origin likewise did not affect nursing behavior.
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Examination of the expression of genes and proteins controlling M. longissimus thoracis et lumborum growth in steers
… investigated the effect of sire breed and genetic merit for growth potential of the transcriptional regulation of the somatotropic axis followed by a proteomic approach to assess differentially abundant proteins. Following this, a second study was set up to examine the compensatory growth …
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The effect of selection for milk yield on net energy balance and plasma concentrations of endogenous hormones and metabolites in primiparous Holsteins
The effect of genetic selection for milk yield on lactation yield, net energy balance (NEB) and on plasma growth hormone (GH), insulin (INS), prolactin (PRL), nonesterified fatty acids (NEFA) and glucose was studied in primiparous Holstein cows. Net energy balance was calculated and serial blood …
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Altered microrna expression profiles in bovine fetuses with an assisted reproduction-induced congenital overgrowth syndrome
… of infertility and in ruminants to improve genetic merit. The use of ART can induce congenital overgrowth conditions in humans and ruminants, namely Beckwith-Wiedemann syndrome (BWS) and large offspring syndrome (LOS), respectively. Shared phenotypes and epigenotypes have been found between …
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Next generation dairy systems for Canterbury: A dissertation submitted in partial fulfilment of the requirements for the Degree of Bachelor of Agricultural Science with Honours at Lincoln University
… 5% higher in HSE potentially due to the lower genetic merit of animals used. Under the current regulations and status the LSE system provides the best solution at lowering dairy farm environmental footprint. However if total production was to become the number one system driver then the HSE …
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Influence of hormones on synthesis and secretion of milk proteins by mammary tissue from male and female cattle of beef and dairy breeds
… can be hormonally induced to express it's genetic merit for milk production (based on breed differences), through synthesis and secretion of milk proteins. Prolactin stimulated protein production in bulls but not in heifers. These findings indicate that similar methods of stimulating …
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The Influence of Artificial Insemination in Three Midwestern States
… of dairy cattle depends in part upon genetic changes brought about by select ion. Because of the long generation interval and low reproductive rate, genetic improvement in dairy cattle is slow. For this reason, the accuracy and effectiveness of selection of sires is of utmost …
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Genetic improvement of swine
… in mind. The first was the identification of genetically superior litters and the second was the evaluation of heritability estimates for various performance traits and of the genetic and phenotypic correlations between them. In order to achieve the first objective it was necessary to …
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INVESTIGATION OF RESILIENCE AND ITS GENETICSTHROUGH THE USE OF LONGITUDINAL DATA
… that resilience indicators possess some genetic merit to some extent, their true significance and methodological foundations require further investigation to enhance the understanding of these phenotypes and their application in breeding programs. Lactation curve models aiming to …
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Breeding for robustness in maternal sheep.
… performance. This thesis explores the genetic variation of ewe body composition across her production life and the ability to select for it to improve the maternal performance of the ewe in variable environments. The quantitative genetic analyses were carried out on four data sets; 1. …
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Genetic evaluation of ewe productivity and its component traits in Katahdin and Polypay sheep
… objectives of this dissertation were to evaluate genetic influences on ewe productivity, its growth and reproductive components, and measures indicative of accelerated lambing performance. Genetic parameters were estimated for total weight of litter weaned per ewe lambing (TW) and its components, …
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MORPHOMETRIC AND MOLECULAR STUDIES OF THE CORRELATION BETWEEN CHRONIC MASTITIS AND INFERTILITY IN DAIRY CATTLE
… recent developments in functional genomics and genetic selections. There is overwhelming evidence that increasing genetic merit for milk yield considerably reduces fertility and the strength of negative associations between yield and fertility is obviously towards a rising trend. The …
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Effects of selection for milk yield on dairy cattle performance and endocrine regulation
… of first lactation Holstein cows of differing genetic merit (selection vs control). Dry matter intake (DMI) was measured at 45, 90, 180, 225, 270, and 315 d postpartum. Serial blood samples were collected at 30 d intervals for a 5 hr period at 15 min intervals. Selection group cows were heavier …
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Modelling New Zealand dairy farm systems to design greenhouse gas mitigation strategies
… Improved reproductive performance and improved genetic merit of the herd were selected as optimal in all cases where specific mitigation strategies were available. Profit was reduced by 1.6%, on average, in this case when 10% GHG emissions reductions were imposed. To adapt to this constraint, …
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