The objective of this thesis was to test for associations between genetic polymorphisms of genes related to immune response (growth hormone (GH), growth hormone receptor (GHR), ornithine decarboxylase (ODC), insuline-like growth factor-1 (IGF-1), adrenocorticotropin hormone (ACTH), corticotrophin releasing hormone (CRH), and prolactin (PRL)) and mastitis resistance traits (incidence of clinical mastitis (ICM), occurrence of clinical mastitis (OCM), culling due to mastitis (CDM), and somatic cell scores (SCS)) in Canadian Holsteins. / Using lactation records of cows enrolled in milking recording in Quebec (Programme d'Analyse des Troupeaux Laitiers du Quebec, PATLQ from 1980 to 1994 (411,291 first, 238,432 second, and 130,983 third lactations, respectively) Estimated Transmitting Abilities of traits were generated with a model that included the random effect of sire, and fixed effects of herd-year-season-of calving, age at calving, and genetic group. 721 bulls which had daughters in the phenotypic data sets were genotyped for twenty polymorphisms of the above genes located on autosomes (BTA) 5, 11, 14, 19, 20, and 23. / Two types of analysis of associations were performed: analysis across-population with a model that included the fixed effect of marker and random effect of the son of grandsire, and within-family analysis with a model that included the fixed effects of the grandsire, marker nested within grandsire, and the random effect of son nested within marker and grandsire. Permutation tests were performed to reduce Type I error probability. / Significant associations were found within families for markers of IGF-1 (BTA5), ODC (BTA11), GH (BTA 19), GHR (BTA 20), and PRL (BTA 23) for ICM, OCM, CDM, and SCS in different lactations. Some of these putative quantitative trait loci (QTL) are located on BTA where other authors have reported QTL affecting SCS and udder conformation. The results from this study may contribute to efforts to dissect the genetic basis of mastitis resistance in dairy cattle.

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No description available.

Two trials using 32 heifers each evaluated response to undegraded intake protein (UIP) (30 or SO% CP), energy (supporting .S9 or .91 kg ADG), and source of UIP (blood meal or combination protein supplement). Trial one was a 2x2 factorial, with two levels of energy and UIP. High UIP was achieved with blood meal supplementation. From 6-13 mo of age (phase I), high energy increased ADG and DMI, and high UIP decreased DMI. DM efficiencies (kg DMIlkg BW gain) improved with high energy and high UIP, and roN efficiencies (kg IDN/kg BW gain) improved with high UIP. From 13 mo until calving (phase n), heifers were housed together and fed a common diet. Low energy, high UIP treatment had the highest ADG (1.01 kg/day) for phase I, but the lowest for phase n (.33 kg/day), and low energy, low UIP treatment had the lowest ADG (.62 kg/day) for phase I, but the highest for phase n (.S3 kg/day). Overall ADG from 6 mo until calving averaged .S9 kg/day, and was not affected by energy or UIP. In trial 2, two levels of energy and two sources ofUIP were compared, resulting in four treatments: low energy, high UIP with combination protein supplement; low energy, high UIP with blood meal; low energy, low VIP with soybean meal; and high energy, low UIP with soybean meal. Combination protein supplement contained blood meal, com gluten meal, and fish meal. Trial was 300 days long, and began at 6.5 mo. of age. Dry matter intake and ADO were increased with high energy, but not affected by VIP. Overall DM efficiency was not affected by VIP or energy level. Results of both trials indicate VIP may improve feed efficiency of growing Holstein heifers. / Master of Science

Growth and body composition of 121 Holstein heifers (4.6 to 18 mo and 129 to 407 kg) reared on pasture, drylot and pasture-drylot systems were evaluated in 6 experiments. Heifers were switched from drylot to pasture or the reverse to study carry-over effects from previous treatments; both systems were satisfactory. Alternate 28-day periods of supplement feeding to grazing heifers did not affect final body weight nor wither height, but ADF and heart girth varied during 2 yr. When switching drylot heifers previously fed low and high TDN, to pasture, gains were best for heifers fed the lower TDN diet; also, gains on pasture were best for light heifers. Gains by all heifers grazing mainly orchardgrass-clover pasture were acceptable, but supplementing with a 19% CP concentrate or lasalocid, usually improved gains. Heifers with lowest BW during grazing made compensatory gains in drylot. Urea space estimation technique showed that compensatory gains were mainly fat. Lasalocid feeding increased daily gain and subcutaneous fat deposition but reduced feed intake and ribeye area. When moving grazing heifers to drylot a total mixed ration with fishmeal or soybean meal as protein sources gave similar responses. DM intake of grazing heifers ranged from 8.1 to 10.1 kg/d, vs 7.5 kg/d for arylot. Supplementing grazing heifers with degradable or undegradable protein gave similar responses in growth and body composition. Based on growth and body composition, seasonal grazing of Holstein heifers may reduce costs for rearing replacement heifers. A corn silage-alfalfa silage-orchardgrass hay mixed ration without concentrates when fed ad libitum to heifers in drylot resulted in gain of 934 g/d. Pasture alone heifers gained from 368 to 755 g/d depending on drought and heifer age. Calculations of costs of rearing Holstein replacement heifers were prepared accounting for observations of response to grazing, supplements to grazing and drylot diets. Well managed grazing reduces costs of rearing. / Ph. D.

A combinação das funções de Green para operadores de criação e destruição de bosons com as transformações de Holstein e Primakoff é utilizada na análise de sistemas antiferromagnéticos, isolantes e anisotrópicos, na região de baixas temperaturas. Os limites de estabilidade das fases antiferromagnética e \"spin-flop\", assim como a transição \"spin-flop\"-paramagnética são determinados em função da temperatura. A Hamiltoniana modelo considerada leva em conta as interações de intercâmbio anisotrópicas entre primeiros e segundos dos vizinhos numa rede cúbica simples e anisotropias de íon único, dos tipos uniaxial e ortorrômbico. Em particular, as fronteiras de fase \"spin-flop\"-paramagnéticas dos antiferromagnetos NiCl2.6H2O, CoCl2. 6H2O, NiCl2.4H2O e MnCl2.4H2O são determinadas e comparadas com os dados experimentais. As interações dipolares são consideradas explicitamente no circulo da fronteira de fase \"spin-flop\"-paramagnética do EuTe, obtendo-se boa concordância com a experiência. / The combination of Greens functions for boson creation and destruction operators with the Holstein - Primakoff transformations is employed in the analysis of insulating and anisotropic antiferromagnetic systems at very low temperatures. The stability limits of antiferromagnetic and spin- flop phases, as well as the spin-flop-paramagnetic transition are determined as a function of temperature. The model Hamiltonian considered takes account of the anisotropic exchange interactions between first and second neighbors for a simple cubic lattice and of single ion anisotropies, of the uniaxial and orthorhombic types. Particularly, the spin-flop-paramagnetic phase boundaries of the antiferromagnetics NiCl2.6H2O, CoCl2. 6H2O, NiCl2.4H2O and MnCl2.4H2O are determined and compared with experimental values. The dipolar interactions are explicitly considered in the calculation of the spin-flop-paramagnetic phase boundary of antiferromagnetic EuTe, and we obtain good agreement with the experiments.

O formalismo matemático da teoria das ondas de spin é analisado. A equivalência entre as transformações de Dyson-Malleev e Holstein-Pr imakoff é demonstrada. Os problemas envolvendo a interação cinemática são discutidos em detalhe. Uma nova divisão do Hamiltoniano de Heisenberg, desenvolvida no espaço de configuração, é usada para estudar a interação dinâmica entre as ondas de spin a baixa temperatura e para grandes valores do número quântico de spin S. Assumindo que a restrição cinemática pode ser neglicenciada, a expansão da energia livre é desenvolvida em potências da temperatura e os resultados estão em acordo com os de Dyson. A relevância da aproximação diagonal de Mattis é demonstrada. Usando o método da positividade por reflexão, limites superiores e inferiores para a contribuição da energia livre são encontrados. Dentro de certa aproximação, estes limites significam que a interação dinâmica pode ser neglicenciada caso o inverso da temperatura (=1/KT), eo número quântico de spin S, forem grandes o suficiente, porém com dependente de S nestas estimativas. Este fato, que não ocorre no limite clássico, é uma característica na região das ondas de spin. / The mathematical formalismo f the spin wave theory is analysed. The thermodynamical equivalence between the Dyson-Malleev and Holstein-Primakoff transformations is proved. The problems involving the kinematical interaction are also discussed in detail. A new splitting of the Heisenberg Hamiltonian, perfomed in configuration space, is used to study the spin wave dynamical interaction at low temperature and for large values of the spin quantum number S. Assuming the the kinematical restriction may be lifted, a low temperature espansion of the free energy is developed with results in agreement with Dysons. The relevance of the Mattis diagonal approximation for the dynamical interaction is demonstrated. Using the method of reflection positivity, upper and lower bounds to the contribuition of the dynamical interaction to the free energy are provided. In a certain approximation, these bounds mean that the dynamical interaction may be dropped IF the inverse temperature (=1/KT) and the spin quantum number S are large enough but depends on S in the estimates, a novel feature wich does not occur in the classical limit but is characteristic of the spin-wave limit.

A combinação das funções de Green para operadores de criação e destruição de bosons com as transformações de Holstein e Primakoff é utilizada na análise de sistemas antiferromagnéticos, isolantes e anisotrópicos, na região de baixas temperaturas. Os limites de estabilidade das fases antiferromagnética e \"spin-flop\", assim como a transição \"spin-flop\"-paramagnética são determinados em função da temperatura. A Hamiltoniana modelo considerada leva em conta as interações de intercâmbio anisotrópicas entre primeiros e segundos dos vizinhos numa rede cúbica simples e anisotropias de íon único, dos tipos uniaxial e ortorrômbico. Em particular, as fronteiras de fase \"spin-flop\"-paramagnéticas dos antiferromagnetos NiCl2.6H2O, CoCl2. 6H2O, NiCl2.4H2O e MnCl2.4H2O são determinadas e comparadas com os dados experimentais. As interações dipolares são consideradas explicitamente no circulo da fronteira de fase \"spin-flop\"-paramagnética do EuTe, obtendo-se boa concordância com a experiência. / The combination of Greens functions for boson creation and destruction operators with the Holstein - Primakoff transformations is employed in the analysis of insulating and anisotropic antiferromagnetic systems at very low temperatures. The stability limits of antiferromagnetic and spin- flop phases, as well as the spin-flop-paramagnetic transition are determined as a function of temperature. The model Hamiltonian considered takes account of the anisotropic exchange interactions between first and second neighbors for a simple cubic lattice and of single ion anisotropies, of the uniaxial and orthorhombic types. Particularly, the spin-flop-paramagnetic phase boundaries of the antiferromagnetics NiCl2.6H2O, CoCl2. 6H2O, NiCl2.4H2O and MnCl2.4H2O are determined and compared with experimental values. The dipolar interactions are explicitly considered in the calculation of the spin-flop-paramagnetic phase boundary of antiferromagnetic EuTe, and we obtain good agreement with the experiments.

No description available.

No description available.