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Four alternative methods were examined with computer simulated data to improve accuracy of animal model genetic evaluations by including records lacking sire identification. Methods 1 and 2 assumed genetic values of cows missing sire identity were population and management group average, respectively. Methods 3 and 4 accounted for genetic values through producing abilities estimated as random and fixed effects, respectively. Correlations between true and estimated management group effects and breeding values of cows and sires were used as measures of estimation accuracy. Alternative methods were examined to determine 1) optimum, minimum management group size, 2) increases in estimation accuracy of alternative methods relative to the conventional method of discarding records lacking sire identity, 3) the effects on accuracy of missing sire identity for lower true breeding value sires, and 4) the potential to use different alternative methods in herds of varying size, proportion of cows sire identified, and level of variation. Management group effects were estimated more accurately as minimum management group size increased (3 to 6 to 9), but breeding values were less accurate. Accuracies of alternative methods slightly exceeded those of the conventional method for all estimated effects and all minimum group sizes. Accuracies of alternative and conventional methods were compared in 60 population with 250 sires and averages of 11,139 cows with 23,849 records. Alternative methods were always more accurate than the conventional method for estimating group effects. Methods 1 and 3 were uniformly more accurate in estimating breeding values of cows, and estimated breeding values of sires more accurately in 55 and 54, respectively, of 60 populations. Increases in accuracy were largest for method 3, but small for all methods. Intentionally omitting identity for daughters of sires with low breeding value reduced accuracy of estimation for breeding values but not for group effects. However, alternative methods were more accurate than the conventional method. Alternative methods were relatively most accurate for estimating breeding values in small herds having high variance and low proportions of sire identified cows. Method 3 had uniformly highest accuracy but method 1 often was similar with less computing cost. / Ph. D.

Masculinization of the female fetus by administration of androgens has been studied in domestic and many laboratory species. Research concerned with cattle has been based solely on neonatal examination of the genital structures; no studies have reported on postnatal growth and development of androgenized offspring. In the present study, pregnant cows were treated with l 7α-methyl-testosterone (MET, 250 mg/d, sq) from day 40 through 60 of gestation to induce virilization of female fetuses. Control cows received no treatment. At parturition, the phenotypic characteristics of each calf were recorded, including birth weight, ano-genital distance and the appearance of the external genitalia. Calves were weighed every 28 days, and the effects of sex and age on body weight were determined. Blood serum was obtained twice weekly from female calves beginning at ≃230 days of age. Serum was analyzed for progesterone (P₄) concentration by radioimmunoassay and the P₄ profiles were used to estimate the age at puberty and estrous cycle lengths. At 4, 8 and 12 months of age blood samples were collected every 15 min for 12 h from three male, female and androgenized female calves. Serum was analyzed for growth hormone (GH), prolactin (PRL) and thyroxine (T₄) concentrations by radioimmunoassay. Visual examination of female calves born after MET exposure revealed that no external vulval opening was present; a penis, prepuce and scrotum had developed and gonads were not palpable in the scrotum. Mean birth weights were similar among male, untreated female and androgenized female calves, whereas weanling and yearling weights were greater (P < .07) in males and androgenized females than in untreated females. Androgen exposure did not affect the initiation or length of estrous cycles in female calves, however, puberty occurred at an earlier age (P < .05) compared with untreated heifers. Concentrations of GH in serum from androgenized female calves were generally lower than both males and untreated females, whereas concentrations of PRL and T₄ were similar to those of control female calves. / Master of Science

A stochastic computer model was constructed to simulate cow reproductive performance. Parameters for single-service conception rate and days from calving to first service (postpartum interval) were developed from the literature. Estimates of the heritability and repeatability (h², t) of each of these traits in four simulated data sets were RUN1 (.20, .20), RUN2 (.15, .20), RUN3 (.10, .10), RUN4 (.05, .10). Binomial conception rate parameters were normalized to simulate assumed normal underlying genetic and environmental distributions. Postpartum interval has a non-normal phenotypic distribution that was produced by combining an assumed normal genetic distribution with a Pearson III gamma distribution of environmental effects. The breeding season was 63 d. Simulation outputs included annual conception rate (BCR), first service conception rate (FSCR), date of first service (FS), number of services (NS), conception-calving date (CD), postpartum interval (PPI), actual weaning weight (ACTWW) and adjusted 205-d weaning weight (ADJWW). Realized heritabilities and repeatabilities for these outputs were estimated from half-sib intraclass correlations based on 5 yr of records on 100 herds of 50 cows each. Realized heritabilities (RUN1-RUN4) for BCR, FSCR, FS, NS, CD, PPI, ACTWW and ADJWW ranged from .165-.028, .187-.055, .023-.010, .227-.071, .071-.032, .158-.022, .148-.176 and .156-.203, respectively. Repeatability estimates (RUN1- RUN4) for BCR, FSCR, FS, NS, CD, PPI, ACTWW and ADJWW ranged from .178-.059, .212-.108, .125-.101, .244-.118, .187-.155, .207-.116, .266-.263 and .280-.286, respectively. / Master of Science

Opportunity cost of postponed replacement (OC) is the income forfeited by keeping a cow for an extra day and is estimated by the income produced by an average replacement. The effect of adjusting a measure of net income, relative net income (RNI), for OC (RNIOC) by lactation was studied. After edits, the data set consisted of 2,982,001 Holstein cows. Prediction factors were developed for RNI and days of productive life (DPL) so that OC could be estimated from cows with shorter herd life opportunities. Within-herd correlations of RNI estimated from 84 month herdlife opportunity with that predicted from cows still alive at 36, 48, 60 and 72 months were .46, .59, .72 and .76, respectively and predictions reflected phenotypic trends of increased net income over time. Corresponding correlations for predicted 84 month DPL at the same ages were .28, .36, .41 and .47 and predictions conflicted with phenotypic trends of decreased herdlife over time. Total OC for cows with 84 month opportunity were raised by an average of $34 when OC was estimated specific to each lactation. The 433,116 cows with classification records and 84 month herdlife opportunity were used to estimate genetic and phenotypic (co)variances among type traits, production, and months in milk (MIM), RNI and RNIOC with a multiple trait Sire model. Production information from all cows in classified herds indicated that classified cows are not a random sample of cows in those herds. Heritability of RNIOC (.17) was higher than RNI (.12), but the genetic correlation between the traits was high (.97). Heritability of MIM was .06. Genetic correlations of MIM to the yield and linear type traits were less than -31 in absolute value. Evaluation of net merit using economic weights developed with RNIOC was more accurate than indirect prediction of MIM. Approximate reliability of a first crop AI sire evaluation for net merit is .65 compared to .42 for MIM. / Ph. D.

Orientador: Henrique Nunes de Oliveira / Banca: Raysildo Barbosa Lobo / Banca: Maria Eugenia Zerlotti Mercadante / Banca: Marcílio Dias Silveira da Mota / Banca: Luiz Artur Loyola Chardulo / Resumo: Foram utilizados dados de 116406 bovinos da raça Nelore, participantes do Programa de Melhoramento Genético da Raça Nelore (PMGRN), nascidos entre 1995 e 2005, com o objetivo de estimar parâmetros genéticos para os pesos padronizados aos 120(P120), 210(P210), 365(P365), 450(P450) e 730(P730) dias de idade e para os ganhos em peso do nascimento aos 120(GP120), dos 120 aos 210 (GP210), dos 210 aos 365(GP365), dos 365 aos 450(GP450) e dos 450 aos 730(G730), além de avaliar a tendência genética das características citadas, tanto para efeito direto como materno. Os componentes de variância foram estimados pelo método de máxima verossimilhança restrita utilizando o programa AIREMLF90, sob modelo animal, o qual incluiu como efeitos fixos, os grupos de contemporâneos e idade da vaca ao parto e como aleatórios, efeito genético aditivo direto para todas as características estudadas e efeito genético materno para P120, P210, P365, GP120, GP210 e GP365. As estimativas de herdabilidade direta foram 0,21, 0,22, 0,22, 0,34, 0,28, para cada peso, respectivamente, e 0,19, 0,20, 0,18, 0,18 e 0,20, para os respectivos ganhos em peso. As herdabilidades maternas foram 0,26, 0,25 e 0,12, para P120, P210 e P365 e 0,23, 0,17, 0,12 para GP120, GP210 e GP365. As correlações direto-maternas foram todas negativas, exceto para P365 (0,06). As tendências genéticas diretas foram todas positivas. As tendências maternas foram quase nulas para todas as características. As estimativas de herdabilidade para os pesos padronizados e para os ganhos em peso indicam que a seleção pode promover mudanças genéticas. As herdabilidades maternas para P120, P210, P365 e GP365 indicam que a seleção nestas características pode contribuir para melhorar a habilidade materna do rebanho. Os ganhos genéticos diretos observados, para todas as características estão aquém dos ganhos potenciais da raça Nelore... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Data of 116406 bovines of the Nellore beef cattle, participants of the Programa de Melhoramento Genético da Raça Nelore (PMGRN), been born between 1995 and 2005 were used with the objective to estimate genetic parameters for the 120-days weight (P120), 210-days weight (P210), 365-days weight (P365), 450-days weight (P450) and 730-days weight (P730) and for the weight gain from birth to 120(GP120), from 120 to 210(GP210), from 210 to 365(GP365), from 365 to 450(GP450) and from 450 to 730 days weight(GP730), besides evaluating the genetic trends of the traits, so much for the direct effect as for the maternal. The variance components were estimated by the restricted maximum likelihood method using the program AIREMLF90. The animal model included fixed effects for contemporary groups and age of the dam at calving, and also included random effects for genetic direct effects for all the studied traits and genetic maternal effect for P120, P210, P365, GP120, GP210 and GP365. The estimative of direct heritability were 0,21, 0,22, 0,22, 0,34, 0,28, for each weight, respectively and 0,19, 0,20, 0,18, 0,18 and 0,20, for the respective weight gains. The maternal heritability were 0,26, 0,25 and 0,12, for P120, P210 and P365 and 0,23, 0,17, 0,12 for GP120, GP210 and GP365. The direct-maternal correlations were all negatives except for P365 (0,06). The direct genetic trends were all positive ones. The maternal trends were almost null for all the traits. The estimative of heritability for the adjusted weights and for the weight gains indicated that the selection could promote genetic changes. The maternal heritability for P120, P210, P365 and GP365 indicated that the selection in these traits could contribute to improve the maternal ability of the herd. The direct genetic gain observed, for all the traits were on this side of the potential gain of the Nellore beef cattle... (Complete abstract click electronic access below) / Doutor

Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2016-10-19T20:20:44Z No. of bitstreams: 1 2015 - Samara de Paula Lopes.pdf: 774906 bytes, checksum: beec1ed8a186efbae7cf579c985f50e3 (MD5) / Made available in DSpace on 2016-10-19T20:20:44Z (GMT). No. of bitstreams: 1 2015 - Samara de Paula Lopes.pdf: 774906 bytes, checksum: beec1ed8a186efbae7cf579c985f50e3 (MD5) Previous issue date: 2015-07-21 / CAPES / This study evaluated the economic and reproductive aspects of beef cows raised in tropical pastures and submitted to two different daily intake of phosphorus present in two mineral supplements during the period from 2012 to 2014. The fertility rate and the rate of pregnancy after time fixed artificial insemination were measured in more than five hundred beef cows during the experimental period. At the beginning and at the ending of breeding season fifteen cows were submitted to the needle test to evaluate the bone resistance. Monthly the total costs and the intake of mineral supplements were measured and registered in a spreadsheet. There was no difference in the reproductive parameters when cows were fed with commercial supplement (3,8 gP/day) or a selective mineral supplement (0,39 gP/day). However, the annual cost with commercial supplement was 203,9 @ of beef cattle whereas the selective supplement was only 51,4@. During the time where the herd was supplemented with selective mineral mixture, there was no sign of mineral deficiency; e.g. phosphorus deficiency. / O presente estudo avaliou os aspectos reprodutivos e econ?micos de matrizes bovinas de corte submetidas a dois tipos de suplementa??o mineral, contendo diferentes quantidades de f?sforo, durante o per?odo de 2012 a 2014. O rebanho foi proveniente de duas fazendas situadas no munic?pio de Valen?a-RJ. Foram utilizadas aproximadamente 500 matrizes de v?rios grupos gen?ticos (Nelore, ? e ? de sangue da ra?a Nelore), mantidas exclusivamente a pasto e submetidas ? monta natural ou ? IATF. As vari?veis avaliadas foram a fertilidade geral do rebanho, total de matrizes prenhes com IATF e total de matrizes prenhes pelo repasse dos touros. No in?cio e no fim da esta??o de monta as matrizes foram submetidas ao teste da agulha, com objetivo de verificar a resist?ncia ?ssea. Mensalmente foi realizada a coleta de dados referente aos gastos e ao consumo com os suplementos minerais para estimar a quantidade adquirida, o custo total com a suplementa??o mineral, o consumo total e o consumo m?dio di?rio (g/UA/dia). N?o foram observadas diferen?as em rela??o aos ?ndices reprodutivos do rebanho frente aos dois esquemas de suplementa??o mineral. Entretanto, a despesa anual com a suplementa??o mineral seletiva foi equivalente a 51,4@ de gado de corte/ano e os gastos anuais com a suplementa??o mineral completa foram de 203,9@/ano, resultando em expressiva economia para o pecuarista. Durante o per?odo de estudo o rebanho n?o apresentou sinais de defici?ncia de f?sforo.

Thesis (M. Dev.) -- University of Limpopo, 2017 / There is a gap in the literature about the role and relevance of Indigenous Knowledge and beef cattle welfare in many parts of the Limpopo province. This gap is relevant because many marginalised cattle owners use indigenous knowledge in their day to day management of beef cattle. The aim of the study is to investigate the use of IK methods on beef cattle husbandry in Tshebela village in the Capricorn district of the Limpopo province as a contribution to filling the void identified above. The objectives of the study were as follows:  To investigate the IK methods used in beef cattle husbandry in the area of the study;  To assess if beef farmers use IK to identify medicinal plants to cure beef cattle;  To investigate farmers‘ perceptions and attitudes on the use of IKS on beef cattle husbandry in the area of study. A qualitative methodology that was used was primarily phenomenological in design. A purposive sampling technique was used and twenty seven (27) traditional beef farmers, two (2) local herbalists were recruited as participants. Data was collected through focus group discussions, key informant interviews, and observations. An interpretative phenomenological-based analysis was used to surface the role and relevance of indigenous knowledge in beef cattle husbandry. The findings suggest that indigenous knowledge is used by cattle owners alongside modern knowledge and that communal farming posed some challenges to the farmers

Thesis (MSc. (Pasture Science)) -- University of Limpopo, 2019 / An experiment was conducted at the University of Limpopo to determine the diet selection of cattle in the Petersburg Plateau Bushveld, the aim being to identify important and palatable grass species during four seasons of the year and to determine their above-ground biomass production. For diet selection data, five permanently marked transects were randomly laid out per camp, each 100 m long. On each transect, grass tufts were identified and permanently marked at 1 m intervals (100 tufts per transect). Turfs were surveyed on a weekly basis to determine frequency, intensity of utilization and tuft height. A palatability index was determined for each species. Diet selection data were analysed, using descriptive statistics. For biomass production, five permanent 20 m x 20 m plots were randomly laid out per camp, in which biomass of grass were measured. Within each plot, five 1 x 1 m quadrates were randomly harvested. The biomass data was analysed using the General Linear Mixed Model. Means were compared, using a Tukey test at the 5% significance level. Digitaria eriantha, Eragrostis rigidior and Heteropogon contortus were the dominant grass species. On average, Brachiaria nigropedata, Panicum maximum and Digitaria eriantha were utilized at higher frequencies and intensities. Brachiaria nigropedata, P. maximum, Urochloa mosambicensis, Themeda triandra, D. eriantha, Schmidtia pappophoroides and H. contortus were regarded as the most palatable species. The circumference of the tuft of S. pappophoroides, E. rigidior and D. eriantha decreased highly significantly (P<0.01). The height of utilizable leaves of B. nigropedata, D. eriantha, P. maximum and S. pappophoroides decreased highly significantly, while the height of highest leaves of B. nigropedata, D. eriantha, P. maximum, S. pappophoroides, H. contortus and T. triandra also decreased highly significantly. Total biomass production was significantly higher (P<0.05) during autumn, while total biomass production during winter was low, compared to other seasons. Total biomass production did not differ significantly between spring and summer. Panicum maximum, x B. nigropedata, D. eriantha, T. triandra, H. contortus, S. pappophoroides and U. mosambicensis were regarded as “key species” in the diet selected by cattle. Farmers in the Pietersburg Plateau Bushveld should graze their camps to assure the maintenance or improvement of perennial palatable grasses with high biomass production, which will result in overall improvement of veld condition.