O objetivo do trabalho foi verificar o efeito da antecipação de um luteolítico prévio a retirada do dispositivo intravaginal de progesterona (P4) sobre a taxa de prenhez na inseminação artificial em tempo fixo (IATF) de vacas com cria ao pé em comparação com protocolos de IATF tradicionais que utilizam o luteolítico na ocasião da retirada de P4. Também verificar a ação e eficácia dos implantes com um grama de progesterona de primeiro e segundo uso. Utilizou-se 210 vacas de corte amamentando da raça Montana com 48-98 dias pós-parto. Destas, 127 eram vacas multíparas e 83 eram vacas primíparas. Os animais foram divididos em dois lotes de 105 vacas, comparando oito grupos. O lote D6,5 foi tratado no dia zero (data:17/11/2008) com 2mg de benzoato de estradiol i.m. (BE, Estrogin®) juntamente com implante intravaginal de progesterona de 1º uso (G1- Sincrogest®, n=29; G2- Primer®, n=26) e de 2º uso (G3- Sincrogest®, n=26; G4- Primer®, n=24), no dia 6,5 foi aplicado 150mcg i.m. de Cloprostenol Sódico (Sincrocio®), sendo a retirada do implante de P4 no dia 8. Dia 9, ocorreu a aplicação de 1mg de BE i.m. e no dia 10 a tarde a IATF. O lote D8 iniciou o protocolo de IATF no dia 25/11/2008 e foi tratado da mesma forma, à exceção da aplicação do luteolítico que ocorreu no oitavo dia. Os grupos foram formados: implante de 1º uso (G5- Sincrogest®, n=27; G6- Primer®, n=28) e de 2º uso (G7-Sincrogest®, n=26; G8- Primer®, n=24). Foram realizadas duas coletas de sangue (dia 0 e dia 9 do protocolo) para dosagem de progesterona plasmática através do método de radioimunoensaio. As taxas de prenhez dos grupos do lote D6,5 foram de 55,17%(G1), 69,23%(G2), 57,67%(G3), 70,83%(G4) (p=0,263). No lote D8 os grupos G5, G6, G7, G8 deste lote apresentaram 44,44%, 67,86%, 46,15%, e 58,33% de prenhez (p=0,573). As taxas de prenhez para os lotes D6,5 e D8 foram, de 62,86% e 54,29%. Não houve diferença nas taxas de prenhez a IATF entre os lotes (p= 0,262). O teste Qui-quadrado e o T-test foram utiizados para a análise estatística dos dados. O ECC médio dos dois lotes foi de 2,66 (n=210). Não houve influência do ECC sobre as taxas de prenhez a IATF (p=0,562) . Também não houve diferença estatística na taxa de prenhez a IATF e de prenhez final dos animais conforme a idade e dias pós parto. Dezenove vacas apresentaram P4 maior que 1ng/ml no dia 0 (D6,5= 7, com 5 vacas prenhez e 2 vazias; D8= 12, com 7 vacas prenhez e 5 vacas vazias) e quatro vacas do lote D8 apresentaram P4 maior que 1ng/ml no dia 9 do protocolo (com 1 vaca prenhe). Os implantes da Primer ® e Sincrogest® de primeiro e segundo uso foram eficientes para a sincronização da ovulação das vacas com cria ao pé. A antecipação do luteolítico não aumentou as taxas de prenhez a IATF e prenhez final. / The objective of this work was to verify the effect of the anticipation of a luteolytic before the removal of the intravaginal device with progesterone (P4) on the range of pregnancy in the artificial insemination in fixed time (TAI) of post partum cows compared to the IATF traditional protocols that use the luteolytic while removing P4 and also verify the action and efficacy of the implants with a gram of progesterone of first and second use. 210 post partum cows beef cows of Montana breed were used with 48-98 days post partum. Out of these, 127 were multiparous cows and 83 were primiparous cows. The animals were divided in two lots of 105 cows, comparing 8 groups. The lot D6,5 was treated on the day zero (27/11/2008) with 2mg of estradiol benzoate i.m. (BE, Estrogin®) together with the intravaginal implant of progesterone of first use (G1- Sincrogest®, n=29; G2- Primer®, n=26) and of second use (G3- Sincrogest®, n=26; G4- Primer®, n=24), on the day 6,5 150mcg i.m of Cloprostenol (Sincrocio®), the removal of the implant of P4 on the day 8. On the day 9, there was an application 1mg of BE i.m and on the day 10 the IATF. The lot D8 (05/12/2008) was treated on the same way, except for the application of luteolitico, that occurred on the eighth day. The groups were formed this way: first use (G5- Sincrogest®, n=27; G6- Primer®, n=28) and second use (G7-Sincrogest®, n=26; G8- Primer®, n=24). Two blood sample collections were performed (Day 0 and Day 9 of protocol) for plasma progesterone dosage through the radioimunoensaio method. The ranges of pregnancy of the groups in the lot D6,5 were 55,17%(G1), 69,23%(G2), 57,67%(G3), 70,83%(G4) (p=0,263). In the lot D8 the groups G1, G2, G3, G4 of this lot presented 44,44%, 67,86%, 46,15%, e 58,33% of pregnancy (p=0,573). The ranges of pregnancy for the lots D6,5 and D8 were 62,86% e 54,29%. There was no difference in the ranges of pregnancy TAI between the lots (p= 0,262). The test Qui- Quadrado and T-test was used for the statistics analysis of the data. The average body condition of the two lots was 2,66 (n=210). There was no influence of the body condition on the ranges od pregnancy TAI (p=0,562). There was no statistic difference in the range TAI and final pregnancy of the animals according to the age and post partum days. Nineteen cows presented P4 maior que 1ng/ml no dia 0 (D6,5= 7, with 5 cows pregancy and 2 empty; D8=12, with 7 cows pregnancy and 5 cows empty) and four cows of the lot D8 presented P4 maior que 1ng/ml on the Day 9 of the protocol (with only one cow pregnant). The implants of PRIMER and SINCROGEST of first and second use were efficient for the synchronization of the ovulation of the post partum cows. The anticipation of luteolytic treatment did not increase pregnancy rates to TAI and also the final pregnancy rate.

Developing solutions to the metabolic stress experienced by cows during the transition period is very important because it can negatively influence lactational performance. The objectives were to: 1) compare physiological changes through body weight (BW) and concentrations of non-esterified fatty acids (NEFA) and β-hydroxybutyric acid (BHBA) and 2) evaluate feed intake, milk production, and energy balance (EB) of cows fed brown midrib corn silage (BMRCS)-based diets when compared with conventional corn silage (CCS)-based diets during the transition. At 4 wk prior to parturition, 40 dry multiparous Holstein cows were randomly assigned treatments. The treatment groups consisted of 2 close-up transition diets (CCS-based and BMRCS-based diet) offered to 2 groups of 20 cows each beginning at 4 wk prepartum. After calving, 10 cows from each prepartum group were individually fed one of four dietary treatments. The four dietary treatments postpartum were defined as follows: 1) CC = CCS-based close-up diet + CCS-based lactation diet; 2) CB = CCS-based close-up diet + BMRCS-based lactation diet; 3) BB = BMRCS-based close-up diet + BMRCS-based lactation diet; 4) BC = BMRCS-based close-up diet + CCS-based lactation diet. Cows were sampled weekly for feed intake, and feed composition was taken monthly. After calving, milk yields were recorded daily and milk components were analyzed monthly. Body weights were taken twice per week on wk -4, -2, 1, 2, 3, 4, 8, 12, 16, and 20. Blood serum was sampled 3 times per week from wk -4 through 4 and then on wk 6, 8, 14, and 20. Rumen fluid was sampled on wk -4, 4, 8, 14, and 20. Feeding BMRCS-based diets during the transition did have a positive influence on dry matter intake, milk production, and energy balance. Interestingly, feeding BMRCS-based diets only during the close-up period and feeding a CCS-based diet during the lactation had similar positive effects as feeding a BMRCS-based diet through the dry period and during the lactation. This finding is meaningful because producers, especially in the Intermountain West, have experienced BMR crop yields that have been less than that of conventional crop yields and may be unwilling to utilize BMRCS in dairy rations. However, if feeding a BMRCS-based diet for a limited amount of time is beneficial, producers could be more willing to utilize this silage hybrid as an important transition period management tool.

To analyze fluctuation of indexes of consist and quality of milk of black and white and red-spotted cows during different months and seasons of lactation. The work was performed in Lithuanian Academy of Veterinary, department of stockbreeding as well as public enterprise Pieno Tyrimai during Master studies 2005-2007. During the analysis, data of controlled cows’ productivity was analyzed according to accounting information of cattle breeding. During the analysis we evaluated 98 Lithuanian black and white cows, Lithuanian red-spotted cows, as well as Ayrshire cows. Milk yield of Lithuanian black and white cows was 1160 kg of milk more than Ayrshire and 252 kg of milk more than Lithuanian red-spotted. Average milk yield of Ayrshire cows was 92 kg more than Lithuanian red-spotted. There was 0.53–0.83% of fat in milk of Lithuanian black and white cows, protein was 0.24–0.25% less than in Ayrshire or Lithuanian red-spotted. Lithuanian black and white cows had 1.0–15.0 kg of milk fat (or 0.3 –4.8%), milk protein – 23.0–25.0 kg (or 11.2–9.4%) more than in Ayrshire or Lithuanian red-spotted. During all periods of lactation most milk fat were found in milk of Ayrshire cows (5.05%), least in Lithuanian black and white cows (4.21%). Milk fat of Lithuanian black and white and Lithuanian red-spotted was less in comparison with Ayrshire cows. During all months of lactation most amount of protein was found in Lithuanian red-spotted and Ayrshire (3.69-3.68%), and least – in Lithuanian black... [to full text]

O objetivo do trabalho foi verificar o efeito da antecipação de um luteolítico prévio a retirada do dispositivo intravaginal de progesterona (P4) sobre a taxa de prenhez na inseminação artificial em tempo fixo (IATF) de vacas com cria ao pé em comparação com protocolos de IATF tradicionais que utilizam o luteolítico na ocasião da retirada de P4. Também verificar a ação e eficácia dos implantes com um grama de progesterona de primeiro e segundo uso. Utilizou-se 210 vacas de corte amamentando da raça Montana com 48-98 dias pós-parto. Destas, 127 eram vacas multíparas e 83 eram vacas primíparas. Os animais foram divididos em dois lotes de 105 vacas, comparando oito grupos. O lote D6,5 foi tratado no dia zero (data:17/11/2008) com 2mg de benzoato de estradiol i.m. (BE, Estrogin®) juntamente com implante intravaginal de progesterona de 1º uso (G1- Sincrogest®, n=29; G2- Primer®, n=26) e de 2º uso (G3- Sincrogest®, n=26; G4- Primer®, n=24), no dia 6,5 foi aplicado 150mcg i.m. de Cloprostenol Sódico (Sincrocio®), sendo a retirada do implante de P4 no dia 8. Dia 9, ocorreu a aplicação de 1mg de BE i.m. e no dia 10 a tarde a IATF. O lote D8 iniciou o protocolo de IATF no dia 25/11/2008 e foi tratado da mesma forma, à exceção da aplicação do luteolítico que ocorreu no oitavo dia. Os grupos foram formados: implante de 1º uso (G5- Sincrogest®, n=27; G6- Primer®, n=28) e de 2º uso (G7-Sincrogest®, n=26; G8- Primer®, n=24). Foram realizadas duas coletas de sangue (dia 0 e dia 9 do protocolo) para dosagem de progesterona plasmática através do método de radioimunoensaio. As taxas de prenhez dos grupos do lote D6,5 foram de 55,17%(G1), 69,23%(G2), 57,67%(G3), 70,83%(G4) (p=0,263). No lote D8 os grupos G5, G6, G7, G8 deste lote apresentaram 44,44%, 67,86%, 46,15%, e 58,33% de prenhez (p=0,573). As taxas de prenhez para os lotes D6,5 e D8 foram, de 62,86% e 54,29%. Não houve diferença nas taxas de prenhez a IATF entre os lotes (p= 0,262). O teste Qui-quadrado e o T-test foram utiizados para a análise estatística dos dados. O ECC médio dos dois lotes foi de 2,66 (n=210). Não houve influência do ECC sobre as taxas de prenhez a IATF (p=0,562) . Também não houve diferença estatística na taxa de prenhez a IATF e de prenhez final dos animais conforme a idade e dias pós parto. Dezenove vacas apresentaram P4 maior que 1ng/ml no dia 0 (D6,5= 7, com 5 vacas prenhez e 2 vazias; D8= 12, com 7 vacas prenhez e 5 vacas vazias) e quatro vacas do lote D8 apresentaram P4 maior que 1ng/ml no dia 9 do protocolo (com 1 vaca prenhe). Os implantes da Primer ® e Sincrogest® de primeiro e segundo uso foram eficientes para a sincronização da ovulação das vacas com cria ao pé. A antecipação do luteolítico não aumentou as taxas de prenhez a IATF e prenhez final. / The objective of this work was to verify the effect of the anticipation of a luteolytic before the removal of the intravaginal device with progesterone (P4) on the range of pregnancy in the artificial insemination in fixed time (TAI) of post partum cows compared to the IATF traditional protocols that use the luteolytic while removing P4 and also verify the action and efficacy of the implants with a gram of progesterone of first and second use. 210 post partum cows beef cows of Montana breed were used with 48-98 days post partum. Out of these, 127 were multiparous cows and 83 were primiparous cows. The animals were divided in two lots of 105 cows, comparing 8 groups. The lot D6,5 was treated on the day zero (27/11/2008) with 2mg of estradiol benzoate i.m. (BE, Estrogin®) together with the intravaginal implant of progesterone of first use (G1- Sincrogest®, n=29; G2- Primer®, n=26) and of second use (G3- Sincrogest®, n=26; G4- Primer®, n=24), on the day 6,5 150mcg i.m of Cloprostenol (Sincrocio®), the removal of the implant of P4 on the day 8. On the day 9, there was an application 1mg of BE i.m and on the day 10 the IATF. The lot D8 (05/12/2008) was treated on the same way, except for the application of luteolitico, that occurred on the eighth day. The groups were formed this way: first use (G5- Sincrogest®, n=27; G6- Primer®, n=28) and second use (G7-Sincrogest®, n=26; G8- Primer®, n=24). Two blood sample collections were performed (Day 0 and Day 9 of protocol) for plasma progesterone dosage through the radioimunoensaio method. The ranges of pregnancy of the groups in the lot D6,5 were 55,17%(G1), 69,23%(G2), 57,67%(G3), 70,83%(G4) (p=0,263). In the lot D8 the groups G1, G2, G3, G4 of this lot presented 44,44%, 67,86%, 46,15%, e 58,33% of pregnancy (p=0,573). The ranges of pregnancy for the lots D6,5 and D8 were 62,86% e 54,29%. There was no difference in the ranges of pregnancy TAI between the lots (p= 0,262). The test Qui- Quadrado and T-test was used for the statistics analysis of the data. The average body condition of the two lots was 2,66 (n=210). There was no influence of the body condition on the ranges od pregnancy TAI (p=0,562). There was no statistic difference in the range TAI and final pregnancy of the animals according to the age and post partum days. Nineteen cows presented P4 maior que 1ng/ml no dia 0 (D6,5= 7, with 5 cows pregancy and 2 empty; D8=12, with 7 cows pregnancy and 5 cows empty) and four cows of the lot D8 presented P4 maior que 1ng/ml on the Day 9 of the protocol (with only one cow pregnant). The implants of PRIMER and SINCROGEST of first and second use were efficient for the synchronization of the ovulation of the post partum cows. The anticipation of luteolytic treatment did not increase pregnancy rates to TAI and also the final pregnancy rate.

O objetivo do trabalho foi verificar o efeito da antecipação de um luteolítico prévio a retirada do dispositivo intravaginal de progesterona (P4) sobre a taxa de prenhez na inseminação artificial em tempo fixo (IATF) de vacas com cria ao pé em comparação com protocolos de IATF tradicionais que utilizam o luteolítico na ocasião da retirada de P4. Também verificar a ação e eficácia dos implantes com um grama de progesterona de primeiro e segundo uso. Utilizou-se 210 vacas de corte amamentando da raça Montana com 48-98 dias pós-parto. Destas, 127 eram vacas multíparas e 83 eram vacas primíparas. Os animais foram divididos em dois lotes de 105 vacas, comparando oito grupos. O lote D6,5 foi tratado no dia zero (data:17/11/2008) com 2mg de benzoato de estradiol i.m. (BE, Estrogin®) juntamente com implante intravaginal de progesterona de 1º uso (G1- Sincrogest®, n=29; G2- Primer®, n=26) e de 2º uso (G3- Sincrogest®, n=26; G4- Primer®, n=24), no dia 6,5 foi aplicado 150mcg i.m. de Cloprostenol Sódico (Sincrocio®), sendo a retirada do implante de P4 no dia 8. Dia 9, ocorreu a aplicação de 1mg de BE i.m. e no dia 10 a tarde a IATF. O lote D8 iniciou o protocolo de IATF no dia 25/11/2008 e foi tratado da mesma forma, à exceção da aplicação do luteolítico que ocorreu no oitavo dia. Os grupos foram formados: implante de 1º uso (G5- Sincrogest®, n=27; G6- Primer®, n=28) e de 2º uso (G7-Sincrogest®, n=26; G8- Primer®, n=24). Foram realizadas duas coletas de sangue (dia 0 e dia 9 do protocolo) para dosagem de progesterona plasmática através do método de radioimunoensaio. As taxas de prenhez dos grupos do lote D6,5 foram de 55,17%(G1), 69,23%(G2), 57,67%(G3), 70,83%(G4) (p=0,263). No lote D8 os grupos G5, G6, G7, G8 deste lote apresentaram 44,44%, 67,86%, 46,15%, e 58,33% de prenhez (p=0,573). As taxas de prenhez para os lotes D6,5 e D8 foram, de 62,86% e 54,29%. Não houve diferença nas taxas de prenhez a IATF entre os lotes (p= 0,262). O teste Qui-quadrado e o T-test foram utiizados para a análise estatística dos dados. O ECC médio dos dois lotes foi de 2,66 (n=210). Não houve influência do ECC sobre as taxas de prenhez a IATF (p=0,562) . Também não houve diferença estatística na taxa de prenhez a IATF e de prenhez final dos animais conforme a idade e dias pós parto. Dezenove vacas apresentaram P4 maior que 1ng/ml no dia 0 (D6,5= 7, com 5 vacas prenhez e 2 vazias; D8= 12, com 7 vacas prenhez e 5 vacas vazias) e quatro vacas do lote D8 apresentaram P4 maior que 1ng/ml no dia 9 do protocolo (com 1 vaca prenhe). Os implantes da Primer ® e Sincrogest® de primeiro e segundo uso foram eficientes para a sincronização da ovulação das vacas com cria ao pé. A antecipação do luteolítico não aumentou as taxas de prenhez a IATF e prenhez final. / The objective of this work was to verify the effect of the anticipation of a luteolytic before the removal of the intravaginal device with progesterone (P4) on the range of pregnancy in the artificial insemination in fixed time (TAI) of post partum cows compared to the IATF traditional protocols that use the luteolytic while removing P4 and also verify the action and efficacy of the implants with a gram of progesterone of first and second use. 210 post partum cows beef cows of Montana breed were used with 48-98 days post partum. Out of these, 127 were multiparous cows and 83 were primiparous cows. The animals were divided in two lots of 105 cows, comparing 8 groups. The lot D6,5 was treated on the day zero (27/11/2008) with 2mg of estradiol benzoate i.m. (BE, Estrogin®) together with the intravaginal implant of progesterone of first use (G1- Sincrogest®, n=29; G2- Primer®, n=26) and of second use (G3- Sincrogest®, n=26; G4- Primer®, n=24), on the day 6,5 150mcg i.m of Cloprostenol (Sincrocio®), the removal of the implant of P4 on the day 8. On the day 9, there was an application 1mg of BE i.m and on the day 10 the IATF. The lot D8 (05/12/2008) was treated on the same way, except for the application of luteolitico, that occurred on the eighth day. The groups were formed this way: first use (G5- Sincrogest®, n=27; G6- Primer®, n=28) and second use (G7-Sincrogest®, n=26; G8- Primer®, n=24). Two blood sample collections were performed (Day 0 and Day 9 of protocol) for plasma progesterone dosage through the radioimunoensaio method. The ranges of pregnancy of the groups in the lot D6,5 were 55,17%(G1), 69,23%(G2), 57,67%(G3), 70,83%(G4) (p=0,263). In the lot D8 the groups G1, G2, G3, G4 of this lot presented 44,44%, 67,86%, 46,15%, e 58,33% of pregnancy (p=0,573). The ranges of pregnancy for the lots D6,5 and D8 were 62,86% e 54,29%. There was no difference in the ranges of pregnancy TAI between the lots (p= 0,262). The test Qui- Quadrado and T-test was used for the statistics analysis of the data. The average body condition of the two lots was 2,66 (n=210). There was no influence of the body condition on the ranges od pregnancy TAI (p=0,562). There was no statistic difference in the range TAI and final pregnancy of the animals according to the age and post partum days. Nineteen cows presented P4 maior que 1ng/ml no dia 0 (D6,5= 7, with 5 cows pregancy and 2 empty; D8=12, with 7 cows pregnancy and 5 cows empty) and four cows of the lot D8 presented P4 maior que 1ng/ml on the Day 9 of the protocol (with only one cow pregnant). The implants of PRIMER and SINCROGEST of first and second use were efficient for the synchronization of the ovulation of the post partum cows. The anticipation of luteolytic treatment did not increase pregnancy rates to TAI and also the final pregnancy rate.

The objective of this study was assessing of utility and fertility in Montbéliarde cows and comparing with utility and fertility in Czech Spotted cows, bred in the same conditions. The recording was performed in the agricultural cooperative Bělčice, where both breeds are bred in the same conditions of environment, nutrition and care. The recording includes 366 cows (123 Montbéliarde cows {--} I, 109 Czech Spotted cows {--} C and 134 50 % Montbéliarde and 50 % Czech Spotted crossbreds - CI), which finished their lactation from 1.10.2004 until 13.7.2007. The fertility was assessed by reproduction indexes as first calving age, insemination period, meantime; and milk yield by utility indexes as quantity of milk; fat, protein, lactose contain, lactation persistence, length of lactation. There have been found important differences in reproduction indexes such as length of service period, length of meantime and first calving age. On I cows there was the biggest length of service period (124.5 days), even the length of meantime (414.6 days), on the contrary the CI group has reached the lowest numbers (99.7 and 377.2 days). Montbéliarde cows reached 844.7 days age when first calving, that is 52.6 days earlier than C group. Czech Spotted cows produced in average 7672.7 kg of milk per lactation when cross breeds produced 7677.1 kg and Montbéliarde cows produced 8708.5 kg of milk. Differences were statistically very significant. Montbéliarde cows had demonstrably lower (P $łeq$ 0,001) fat contain in milk (4.06 % in compare with 4.23 % by C and 4.21 % by CI). There wasn{\crq}t statistically significant difference recorded in protein contain among breeds by numbers 3.46 for C; 3.48 for CI and 3.46 for I. Because of the high milk yield of Montbéliarde cows, there was reached the highest production of fat (352.3 kg) even proteins (300.8 kg) in this breed. The highest index of lactation persistence was documented in Montbéliarde cows in level 89,9 in compare with the lowest reached level 85.4 (P $łeq$ 0.001) in the group of Czech Spotted cows.

The subject of my thesis was an analysis that deals with the level of nutrition of holstein cattle, witch evaluates feeding, drinking, silage quality techniques and optimalization of the feed ration in 2017 and 2018. In 2017 the feed ration used for dairy cows contained more PDIE. In 2018 the feed ration contained lower amount of energy (6MJ NEL/ 1kg of dry matter) and NL (138,6 g NL/kg of dry matter). After comparing of these two diets for dairy cows with nutrient need, there was recommended an increase of dry matter content in feeding ration. In the milk productivity assessement, the fat and protein content, SC, total aerobic microbial count, was reviewed. The statistic shows the impact of the season of the year on the fat and protein content, SC, total aerobic microbial count in milk. From ecomomy point of view, costs per litre of selled milk was 7,69 Kč in 2017, which was lowered to 7,28 CZK per litre of selled milk. Both years was profitable, and in comparing the economy from 2017 with Czech republic average, tracked stable was more profitable 3 662 CZK per dairy cow.

A curva de lactação é a descrição gráfica da produção de leite em dado período de tempo, normalmente descrita por modelos matemáticos dos quais podem ser obtidos fatores multiplicativos de predição e estimativas de interesse econômico como o pico, persistência e produção acumulada aos 305 dias. Entretanto, faz-se necessário a seleção de funções de curvas para que as estimativas obtidas apresentem o menor erro de predição associado, bem como, identificar os fatores que influenciam a curva de lactação para que essas estimativas sejam desprovidas de tais fontes de variação. Desta forma, foram utilizadas cinco funções não lineares para modelar 10.679 lactações pertencentes a vacas holandesas, de grupo genético PCOD (puro por cruza de origem desconhecida), PCOC (puro por cruza de origem conhecida) e PO (puro de origem), pertencentes a 38 rebanhos agrupados em três níveis de produção, situados nos estados de São Paulo e Minas Gerais no período de 1997 a 2009. A seleção da função baseou-se simultaneamente no maior valor do coeficiente de determinação e nos menores valores do quadrado médio do erro de predição, raiz quadrada do quadrado médio do erro de predição, critério bayesiano de informação e percentual de curvas atípicas. Independente do nível de produção e ordem de lactação, dentre os modelos avaliados, a função de Wood obteve o melhor ajuste e, portanto, foi utilizada para obter estimativas de pico, tempo de ascensão ao pico, persistência e produção acumulada aos 305 dias. Posteriormente, avaliou-se a influência de fatores ano de parto, época de parto, ordem de lactação, rebanho, nível de produção e duração da lactação sobre os parâmetros a (produção inicia), b (taxa de acréscimo na produção até o pico) e c (taxa de decréscimo na produção após o pico de lactação) e estimativas de pico, tempo de pico, persistência e produção acumulada aos 305 dias das curvas de lactação modeladas pela função de Wood. Em seus respectivos níveis de produção, as médias dos parâmetros e estimativas aumentaram proporcionalmente às classes de duração da lactação e maiores estimativas foram observadas para multíparas na época seca do ano. Dado o exposto, para os rebanhos em estudos, fatores de predição da produção de leite aos 305 dias podem ser construídos de acordo com o nível de produção, ordem, época e duração da lactação. / The lactation curve is a graphic depiction of milk production in a given period of time, usually described by mathematical models which can be obtained by multiplicative factors of prediction and estimates of economic interest as the peak, persistence and cumulative production to 305 days. However, it is necessary to select the functions of curves obtained for the estimates have the smallest prediction error associated, as well as to identify factors that influence the lactation curve for these estimates are devoid of these sources of variation. Thus, five were used to model nonlinear functions belonging to 10,679 lactations Holsteins, genetic group PCOD (pure by crosses of unknown origin), PCOC (pure by crosses of known origin) and PO (pure original), belonging to 38 herds grouped in three levels of production, located in São Paulo and Minas Gerais from 1997 to 2009. The function selection was based on both the greater coefficient of determination and lower values of mean square prediction error, the square root of mean square prediction error, Bayesian information criterion and the percentage of atypical curves. Regardless of the level of production and parity among the models evaluated, the function of Wood obtained the best fit and therefore was used to estimate the peak, rise time to peak, persistence and cumulative production to 305 days. Subsequently, we evaluated the influence of year of birth, season of calving, lactation order, herd production level and duration of lactation on the parameters a (production starts), b (rate of increase in production to peak) and c (rate of decline in production after peak lactation) and estimates of peak, peak time, persistence and cumulative production to 305 days of lactation curves modeled by the function of Wood. In their production levels, the mean estimates of parameters and increased proportionally to the classes of lactation length and higher estimates were observed for multiparous in the dry season. Given the above, for livestock studies, predictors of milk production to 305 days can be constructed according to the level of production, order, timing and duration of lactation.

In response to LH surge, the selected dominant follicle undergoes a series of complex events viz., meiotic maturation of the oocyte, terminal differentiation of follicular cells, cumulus expansion and follicular rupture leading to ovulation (release of fertilizable oocyte) and formation of corpus luteum. These complex set of events are mediated by dramatic changes in the temporo-spatial transcriptional regulation of a large number of genes in the preovularory follicle. In the present thesis, attempts have been made to delineate the transcriptional changes occurring in the periovulatory follicle in response to gonadotropin surge in monovulatory species (bonnet monkeys and buffalo cows). Further, attempts have also been made to investigate effects of increased circulating IGF-I and glucose on the periovulatory events. Chapter I provides a review of available literature on regulation and factors influencing various aspects of growth and development of ovarian follicles. Chapter II describes initial studies carried out in the bonnet monkeys to examine expression patterns of various genes considered as markers of ovulation and luteinization in granulosa cells of multiple preovulatory-like follicles before and after exposure to luteinizing dose of hCG. Chapter III describes the standardization and validation of an induced ovulation model system in buffalo cows involving determination of the presence of a large follicle by ultrasonography before administering exogenous PGF2αon day 7 of the cycle to induce luteolysis and administration of hCG 36 h post PGF2αto mimic LH surge-like stimulus. Attempts made to characterize the responsiveness of buffalo cows to a range of exogenous doses of GnRH in terms of LH secretion during summer and winter seasons and determination of the exogenous dose of GnRH necessary to elicit a surge-like increase in circulating LH levels during breeding season in buffalo cows are described in Chapter IV. Chapter V describes the global changes in the gene expression pattern in the periovulatory follicle of buffalo cows before and at various time points after the onset of gonadotropin surges. IGF-I is known to regulate the proliferation and survival of follicular cells and play an important role in the selection of dominant follicle however, its role during the periovulatory events remains to be delineated. Chapter VI describes the effects of increased circulating and intrafollicular IGF-I levels on the periovulatory events. An ongoing study to delineate the effects of transient increase in circulating glucose levels on the periovulatory events are described in Appendix I. Thus, this thesis aims at delineating (i) changes in the gene expression patterns regulating periovulatory events and (ii) effects of increased circulating IGF-I and glucose on the periovulatory events.

A curva de lactação é a descrição gráfica da produção de leite em dado período de tempo, normalmente descrita por modelos matemáticos dos quais podem ser obtidos fatores multiplicativos de predição e estimativas de interesse econômico como o pico, persistência e produção acumulada aos 305 dias. Entretanto, faz-se necessário a seleção de funções de curvas para que as estimativas obtidas apresentem o menor erro de predição associado, bem como, identificar os fatores que influenciam a curva de lactação para que essas estimativas sejam desprovidas de tais fontes de variação. Desta forma, foram utilizadas cinco funções não lineares para modelar 10.679 lactações pertencentes a vacas holandesas, de grupo genético PCOD (puro por cruza de origem desconhecida), PCOC (puro por cruza de origem conhecida) e PO (puro de origem), pertencentes a 38 rebanhos agrupados em três níveis de produção, situados nos estados de São Paulo e Minas Gerais no período de 1997 a 2009. A seleção da função baseou-se simultaneamente no maior valor do coeficiente de determinação e nos menores valores do quadrado médio do erro de predição, raiz quadrada do quadrado médio do erro de predição, critério bayesiano de informação e percentual de curvas atípicas. Independente do nível de produção e ordem de lactação, dentre os modelos avaliados, a função de Wood obteve o melhor ajuste e, portanto, foi utilizada para obter estimativas de pico, tempo de ascensão ao pico, persistência e produção acumulada aos 305 dias. Posteriormente, avaliou-se a influência de fatores ano de parto, época de parto, ordem de lactação, rebanho, nível de produção e duração da lactação sobre os parâmetros a (produção inicia), b (taxa de acréscimo na produção até o pico) e c (taxa de decréscimo na produção após o pico de lactação) e estimativas de pico, tempo de pico, persistência e produção acumulada aos 305 dias das curvas de lactação modeladas pela função de Wood. Em seus respectivos níveis de produção, as médias dos parâmetros e estimativas aumentaram proporcionalmente às classes de duração da lactação e maiores estimativas foram observadas para multíparas na época seca do ano. Dado o exposto, para os rebanhos em estudos, fatores de predição da produção de leite aos 305 dias podem ser construídos de acordo com o nível de produção, ordem, época e duração da lactação. / The lactation curve is a graphic depiction of milk production in a given period of time, usually described by mathematical models which can be obtained by multiplicative factors of prediction and estimates of economic interest as the peak, persistence and cumulative production to 305 days. However, it is necessary to select the functions of curves obtained for the estimates have the smallest prediction error associated, as well as to identify factors that influence the lactation curve for these estimates are devoid of these sources of variation. Thus, five were used to model nonlinear functions belonging to 10,679 lactations Holsteins, genetic group PCOD (pure by crosses of unknown origin), PCOC (pure by crosses of known origin) and PO (pure original), belonging to 38 herds grouped in three levels of production, located in São Paulo and Minas Gerais from 1997 to 2009. The function selection was based on both the greater coefficient of determination and lower values of mean square prediction error, the square root of mean square prediction error, Bayesian information criterion and the percentage of atypical curves. Regardless of the level of production and parity among the models evaluated, the function of Wood obtained the best fit and therefore was used to estimate the peak, rise time to peak, persistence and cumulative production to 305 days. Subsequently, we evaluated the influence of year of birth, season of calving, lactation order, herd production level and duration of lactation on the parameters a (production starts), b (rate of increase in production to peak) and c (rate of decline in production after peak lactation) and estimates of peak, peak time, persistence and cumulative production to 305 days of lactation curves modeled by the function of Wood. In their production levels, the mean estimates of parameters and increased proportionally to the classes of lactation length and higher estimates were observed for multiparous in the dry season. Given the above, for livestock studies, predictors of milk production to 305 days can be constructed according to the level of production, order, timing and duration of lactation.