This thesis deals with the evaluation of selected influences on the milk production and fertility of dairy cows in a herd of Holstein cattle. The cattle husbandry sector, in recent years, has been facing a worsening of the indicators of reproduction and longevity in dairy cows. It is primarily the requirement of constantly increasing the milk yield of dairy cows that has had an adverse impact on these indicators. The worsening of these indicators can result in a reduction of the cost-effectiveness of the production of milk and meat. The evaluation of influences on milk production and fertility in a herd of Holstein cattle was carried out at the AGRODAM Hořepník s.r.o. company. The selected influences included milk yield quantity, parity, age at first calving, calving interval, insemination index, and conception rate after first insemination. Two hundred and two Holstein dairy cows were included in the monitoring. Data on milk yield and reproduction were obtained from milk yield records and zootechnical records. The results showed that milk production of the monitored group of dairy cows was at a high level (10,025 kg of milk). The highest milk yield in kilograms of milk during first lactation was achieved by dairy cows that calved at the age of 27 to 29 months (9,335 kg of milk). According to the milk yield during the first lactation, the highest milk yield during three lactations was by dairy cows that had a milk yield exceeding 10,000 kg of milk during the first lactation (35,515 kg). When utilizing the DOUBLE OVSYNCH synchronization protocol, the average calving interval was 412 days, and a higher conception rate after first insemination (43%) was found as compared to the nationwide average in the Czech Republic (34.2%). The average number of culled dairy cows was 32%; from this the highest proportion of culled dairy cows was for other medical reasons (31%). Due to low milk yields, 25% of the dairy cows were culled.

Made available in DSpace on 2014-06-11T19:26:06Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-02-25Bitstream added on 2014-06-13T19:12:54Z : No. of bitstreams: 1 terakado_apn_me_jabo.pdf: 667390 bytes, checksum: 399d8e8c22f913c5f186b90a10416c4e (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Os objetivos deste estudo foram estimar associações genéticas entre o perímetro escrotal obtido aos 9 (PE9), 12 (PE12) e 18 meses de idade (PE18) e características reprodutivas medidas diretamente em novilhas tais como: idade ao primeiro parto (IPP), ocorrência de prenhez aos 16 meses de idade (Pr16) e reconcepção de fêmeas primíparas (REC), utilizando inferência Bayesiana, com intuito de verificar a possibilidade de incluí-las como critérios de seleção em programas de melhoramento genético de bovinos de corte. Foram analisados 158.148 dados de animais da raça Nelore, nascidos entre 1990 e 2006 e pertencentes ao arquivo zootécnico da Agropecuária Jacarezinho Ltda., localizada no município de Valparaíso, São Paulo. Foram realizadas análises uni e bi-características. Em análises bicaracterísticas, as estimativas de herdabilidade foram iguais a 0,22±0,05; 0,39±0,09; 0,20±0,06; 0,20±0,01; 0,54±0,03 e 0,17±0,03 para PE9, PE12, PE18, IPP, Pr16 e REC, respectivamente. As correlações genéticas estimadas entre PE9 e IPP, Pr16 e REC foram de -0,48±0,13; 0,51±0,13 e 0,02±0,19, respectivamente. As correlações genéticas entre PE12 e IPP, Pr16 e REC foram de -0,41±0,12; 0,35±0,12 e -0,16±0,17, respectivamente. As correlações genéticas entre PE18 e IPP, Pr16 e REC foram de - 0,29±0,13; 0,28±0,14 e -0,03±0,18, respectivamente. Esses resultados sugerem que a seleção de animais com maior perímetro escrotal, principalmente aos 12 meses de idade deverá ocasionar maior ocorrência de prenhez aos 16 meses e menor idade ao primeiro parto em fêmeas da raça Nelore / The objectives of this study were estimate genetic associations between scrotal circumference obtained at 9 (SC9),12 (SC12) and 18 months of age (SC18) and reproductive traits measured directly in heifers as: age at first calving (AFC) occurrence of pregnancy at 16 months of age (HP16) and heifers subsequent rebreeding (HSR), using Bayesian inference, in order to verify the possibility of including them as criteria for selection in breeding programs for beef cattle. It were analyzed 158,148 records from Nelore cattle, born between 1990 and 2006 and belonging to Agropecuária Jacarezinho Ltda., located in Valparaíso council, São Paulo state. Single and two-trait analyses were accomplished. In two-trait analysis, the heritability estimates were equal to 0.22 ± 0.05, 0.39 ± 0.09, 0.20 ± 0.06, 0.20 ± 0.01, 0.54 ± 0.03, and 0.17 ± 0.03 for SC9, SC12, SC18, AFC, HP16 and HSR, respectively. The genetic correlation between AFC and SC9, HP16 and HSR were -0.48±0,13, 0.51±0,13 and 0.02±0,19, respectively. Genetic correlations between SC12 and AFC, HP16 and REC were -0.41±0,12, 0.35±0,12 and - 0.16±0,17, respectively. Genetic correlations between SC18 and AFC, HP16 and HSR were -0.29±0,13, 0.28±0,14 and -0.03±0,18, respectively. These results suggest that selection of animals with larger scrotal circumference, especially at 12 months of age should result in a higher incidence of pregnancy at 16 months and a decrease in age at first calving in Nellore females

Submitted by Cássia Santos (cassia.bcufg@gmail.com) on 2016-10-18T13:06:50Z No. of bitstreams: 2 Tese - Mariana Márcia Santos Mamede - 2015.pdf: 1724340 bytes, checksum: a5ca2ef74472295a32091a286312f2c5 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Jaqueline Silva (jtas29@gmail.com) on 2016-10-18T16:26:34Z (GMT) No. of bitstreams: 2 Tese - Mariana Márcia Santos Mamede - 2015.pdf: 1724340 bytes, checksum: a5ca2ef74472295a32091a286312f2c5 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-10-18T16:26:34Z (GMT). No. of bitstreams: 2 Tese - Mariana Márcia Santos Mamede - 2015.pdf: 1724340 bytes, checksum: a5ca2ef74472295a32091a286312f2c5 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2015-07-09 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Genetic parameters were estimated for growth traits involving the weights at 120 (P120), 210 (P210), 365 (P365), and 450 (P450) days of age, reproductive traits, such as scrotal circumference calculated at 365 (PE365) and 450 (PE450) days of age, age at first calving (IPP), accumulated productivity (PAC) in kg of weaned calves, and cow stayability (STAY - Stayability), carcass, considering ribeye area (REA), subcutaneous fat thickness (EG), and fat thickness on the back (EGP8), and the tenderness of the meat, as measured by Warner-Bratzler shear force (WBSF) in polled Nellore cattle reared in the Cerrado biome. For all features, Bayesian analysis bi characteristics were performed by adopting linear animal model, whereas for the analyzes involving STAY, the linear threshold model was used. Mean posterior heritability estimates for P120 (0.20), P210 (0.21), P365 (0.44), P450 (0.40), PE365 (0.31), PE450 (0.37), IPP (0.16), PAC (0.25), STAY (0.16), AOL (0.30), EG (0.13), EGP8 (0.24), and WBSF (0.16) indicate response to the selection process. Estimates of maternal heritability for P120 (0.10) and P210 (0.09) suggest genetic effects of breeding in contributing to the performance of calves at weaning. Estimates of genetic and environmental correlation obtained for the growth characteristics were of high magnitude. By analyzing the growth characteristics with carcass, the genetic and residual correlations between AOL weights at 210 (0.46 and 0.37, respectively), 365 (0.59 and 0.39, respectively), and 450 (0.56 and 0.50, respectively) days old stood out. Genetic and residual correlations between PE365 and PE450 were high and positive (0.91 and 0.74, respectively), as well as the genetic correlations of the CAP with PE365, PE450, IPP, and STAY (0.61, 0.62, -0.69 and 0.83, respectively). Therefore, PE365, PE450, and CAP are important selection criteria, which result in genetic progress for IPP and STAY. The AOL genetic correlations with EG (0.25) and EGP8 (0.06) were of low magnitude, however moderate between EG and EGP8 (0.49). The residual correlation between carcass traits showed low non-additive genetic association and/or of the environment. The WBSF mean estimates of genetic and residual correlations with reproductive and carcass traits were favorable, although they exhibited high standard deviations. The genetic correlation of WSBF with the weights were higher at the pre-weaning phase (-0.70 ± 0.26 with P120 and -0.78 ± 0.23 with P210) and lower at the post-weaning phase (-0.44 ± 0.43 with P365 and -0.22 ± 0.34 with P450). Estimates of genetic correlation of WBSF with EG, EGP8, and AOL were negative and close to zero. Residual correlations of WBSF with all the growth and carcass traits were negligible. / Foram estimados os parâmetros genéticos para as características de crescimento envolvendo os pesos aos 120 (P120), 210 (P210), 365 (P365) e 450 (P450) dias de idade, reprodutivas de perímetro escrotal calculados aos 365 (PE365) e 450 (PE450) dias de idade, idade ao primeiro parto (IPP), produtividade acumulada (PAC) em kg de bezerros desmamados, e habilidade de permanência da vaca no rebanho (STAY - Stayability), de carcaça, considerando área de olho de lombo (AOL), espessura de gordura subcutânea (EG) e espessura de gordura subcutânea na garupa (EGP8) e a de maciez da carne, medida pela força de cisalhamento Warner-Bratzler (WBSF) em bovinos Nelore Mochos, criados no bioma Cerrado. Para todas as características foram realizadas análises bayesianas bi características adotando-se modelo linear animal, enquanto que para as análises envolvendo a STAY, o modelo adotado foi o linear-limiar. As médias das estimativas posteriores de herdabilidade para o P120 (0,20), P210 (0,21), P365 (0,44), P450 (0,40), PE365 (0,31), PE450 (0,37), IPP (0,16), PAC (0,25), STAY (0,16), AOL (0,30), EG (0,13), EGP8 (0,24) e WBSF (0,16) indicam resposta ao processo de seleção. As estimativas de herdabilidade maternal para P120 (0,10) e P210 (0,09) sugerem efeitos genéticos das reprodutoras na contribuição para o desempenho dos bezerros até a fase de desmame. As estimativas de correlação genética e ambiental obtidas para as características de crescimento foram de elevada magnitude. Ao analisar as características de crescimento com as de carcaça, destacam-se as correlações genéticas e residuais entre AOL com os pesos aos 210 (0,46 e 0,37, respectivamente), 365 (0,59 e 0,39, respectivamente) e 450 (0,56 e 0,50, respectivamente) dias de idade. As correlações genéticas e residuais entre PE365 e PE450 foram elevadas e favoráveis (0,91 e 0,74, respectivamente), assim como as correlações genéticas da PAC com PE365, PE450, IPP e STAY (0,61, 0,62, -0,69 e 0,83, respectivamente). Portanto, em função da o PE365, PE450 e a PAC são importantes critérios de seleção, os quais implicaram em progresso genético para IPP e STAY. As correlações genéticas de AOL com EG (0,25) e com EGP8 (0,06) foram de baixa magnitude, entretanto moderada entre EG e EGP8 (0,49). A correlação residual, entre as características de carcaça, indicou baixa associação genética não-aditiva e, ou, de ambiente. As médias das estimativas de correlações genéticas e residuais de WBSF com as características reprodutivas e de carcaça foram favoráveis, entretanto exibiram desvios padrão elevados. A correlação genética da WSBF com os pesos foi maior na fase pré-desmama, (-0,70±0,26 com P120 e -0,78±0,23 com P210) e menor na fase pós-demama (-0,44±0,43 com P365 e -0,22±0,34 com P450). As estimativas de correlação genética da WBSF com EG, EGP8 e AOL foram negativas e próximas à zero. As correlações residuais de WBSF com todas as características de crescimento e de carcaça foram inexpressivas.

The objective of this study was to estimate the values of the (co)variance components and genetic parameters for reproductive traits in Santa Inês sheep raised in different states and registered with the Associação Sergipana dos Criadores de Caprinos e Ovinos (Goat and Sheep Breeders Association of Sergipe). The database used was provided by the Association and comprised pedigree observations originating from 11,483 registered individuals, out of which 2,238 were born in the program and had calving records, being part of the relationship matrix. After restriction application, there remained 843 animals for analysis which had data related to the age at first calving (IPP1), 151 with data related to the median calving interval (IPM2), and 151 to the interval between first and second calvings (IPS3). To obtain the values of (co)variance components and genetic parameters, we used the Bayesian inference under an animal model with the Gibbs sampling algorithm aided by the MTGSAM program. The two-trait linear model used considered the contemporary group as the fixed effect for IPP1, IPM2, and IPS3, and the type of calving and the age of the animal at calving as the covariate effect. The estimated values of h2 for IPP1, IPM2, and IPS3 were equal to 0.19 ± 0.0459, 0.0169 ± 0:36, and 0:35 ± 0.016 respectively. The estimated heritability for IPP1is considered average and the values for IPM2 and IPS3 were considered high, which leads to the conclusion that these characteristics can be used as selection criteria in a breeding program of Santa Inês sheep. The estimated value for the correlation between IPP1 and IPM2, and IPP1 and IP2, were negative and equal to rg12 = -0.2569 ± 0.0546, rg13= -0.1134 ± 0.0553, which were physiological expected low values that represent a trend which suggests individual selection for those traits. However, the rg23 shows a positive and high trend of 0.9601 ± 0.0091 for IPM2 and IPS3 suggesting indirect selection as the best option for these traits. / Objetivou-se estimar componentes de (co)variância e parâmetros genéticos para características reprodutivas de ovinos Santa Inês, criados em diferentes estados e registrados na Associação Sergipana dos Criadores de Caprinos e Ovinos. O banco de dados utilizado foi fornecido por esta associação, composto por observações de pedigree originadas de 11.483 indivíduos registrados dos quais 2.238 eram nascidos no programa e tinham registro de parto, permanecendo na matriz de parentesco. Após a aplicação das restrições, foram mantidas na análise 843 animais com dados referentes a característica idade ao primeiro parto (IPP1), 151 referentes a intervalo médio ao parto (IPM2) e 151 para intervalo entre primeiro e segundo parto (IPS3). Para obter os valores dos componentes de (co)variância e parâmetros genéticos utilizou-se analise bayesiana sob modelo animal mediante o algorismo Amostrador de Gibbs com o auxilio do programa MTGSAM. O modelo linear bicaracterística utilizado considerava como efeito fixo o grupo contemporâneo para as características IPP1, IPM2 e IPS3, considerou-se o efeito do tipo de parto e a idade do animal ao parto como efeito (co)variável. Os valores de h2 estimados para IPP1, IPM2 e IPS3 foram iguais a 0.19±0.0459, 0.36±0.0169 e 0.35±0.016 respectivamente. O valor estimado da herdabilidade para IPP1 é considerado médio e os valor para IPM2 e IPS3 alto, fato que leva a concluir que estas característica podem ser usadas como critério de seleção em um programa de melhoramento de ovinos da raça Santa Inês. O valor estimado para a correlação entre características IPP1 e IMP2; IPP1 e IPS2 foram negativos e iguais a rg12= -0.2569 ± 0.0546, rg13= -0.1134 ± 0.0553 valores fisiologicamente esperados de baixa magnitude que sugerem seleção individual para essas características, entretanto para IPM2 e IPS3 a rg23 mostra tendência positiva e muito elevada igual a rg23= 0.9601 ± 0.0091 valor que indica a seleção indireta o melhor caminho.

Thesis (M.A. Agricultural Management (Animal Production)) -- University of Limpopo, 2020 / The Nguni is indigenous multi-purpose cattle breed that plays an important role in both commercial and communal farming systems in South Africa (SA). Unfortunately, the breed is currently under threat of diminishing due to farmers’ preference for exotic breeds and cross breeding. In recognition of the above, the Industrial Development Corporation, the Mpumalanga Department of Agriculture, Rural Development, Land and Environmental Affairs and the University of Limpopo established the Nguni cattle breed preservation project. In this project, a herd of 30 Nguni heifers and 1 bull were allocated to 34 Communal Property Associations (CPA) and 40 private farming enterprises each. With its three distinct ecological zones (High, Mid and Low-veld), the Mpumalanga province poses a challenge to the Nguni preservation project since cattle have to adapt to different ecological zones in order to grow and reproduce efficiently. Knowledge of cattle herd productivity improves the understanding of the functional attributes and is useful in determining the constraints and the potential of communal beef cattle production systems. Significant differences between ecological zones were observed for age at first calving, weaning rate, calves’ birth weight and calves’ weaning weight (p < 0.05). Calving of heifers in the Mid-veld zone occurred earlier (24 months) on both ownership types compared to Highveld (28.09 months for private and 26.00 for CPA) and the Lowveld (28.35 months for both ownerships). Nguni cattle on the Highveld performed better in terms of weaning rate under both private and CPA ownerships, where the weaning rate were 93% and 80%, respectively. Calves birth weight was lower in both ownership types in the Midveld zone (22.17 kg), whereas in the CPA, the Lowveld zone had higher calves birth weights (26.80 kg). In the private ownership, the highest calves’ birth weight (25.35 kg) was on the Highveld. The calves weaning weight were significantly higher (p < 0.05) on Highveld in private ownership (190.16 kg) and lowest (160.39 kg) in the Midveld zone. For the CPA, the highest calves weaning weight was also on the Highveld (187.55) and lowest on Midveld (167.50 kg). A full range of backup services that are offered to the communities by stakeholders in the form of a beef package that includes veld and pasture management, nutrition management, beef performance, animal recording keeping, genetic evaluation and animal health management program needs thorough attention.