Thirty-four cows (26 Holsteins and 8 Jerseys) were subjected to an estrous synchronization protocol administering 2 PGF2Æ Ã injections 11 d apart prior to beginning the lactation-induction protocol. Artificial induction of lactation yielded a 92% success rate for Holstein cows with success defined as achieving >9 kg milk/d, and a 88% success rate for Jersey cows with success defined as achieving > 5 kg milk/d. Mean accumulated milk yield for induced cows at 150 DIM was 65% of mean yield for nontreated cows. Mean peak milk yield for lactation- induced Holsteins and Jerseys was 32 kg/d and 20 kg/d, respectively. Mean serum and milk progesterone concentrations for samples collected during the first 6 d of lactation were not different between lactation-induced and nontreated cows. However, mean serum estradiol concentrations for induced cows were higher (P <0.05) in samples collected 3 and 5 DIM. Lactation-induced cows exhibited an increase in serum alpha-lactalbumin concentrations 2 d prior to initiation of milking, reaching values of ~260 ng/ml. Mean days-to-first service was greatly reduced in cows induced into lactation compared to nontreated cows, while mean services per conception was similar between induced and nontreated cows. Mean days to conception was lower for induced cows than for nontreated cows. By 150 DIM, pregnancy rate of induced cows was 70%, whereas nontreated cows averaged 56% pregnancy rate. / Master of Science

O estudo teve como objetivos avaliar: 1) produção e composição do leite de novilhas submetidas a protocolo de indução de lactação (PIL); 2) eficácia de antibiótico injetável associado a selante de tetos sobre a prevalência de infecções intramamárias (IIM) e contagem de células somáticas (CCS) e 3) eficácia de GnRH sobre regressão de cistos foliculares (CFs) e taxa de concepção inicial e prenhez acumulada em novilhas tardias. Foram utilizadas 114 novilhas da raça Jersolando (Holandesa x Jersey), com 34,7 &#177; 4,8 (média &#177; desvio padrão) meses de idade, 439 &#177; 56,35 kg de peso corporal e 3,00 &#177; 0,30 de escore de condição corporal (ECC). O utilizado PIL era composto por benzoato de estradiol, progesterona injetável, prostaglandina, dexametasona e somatotropina recombinante bovina. Dezesseis dias antes do PIL as novilhas foram aleatoriamente distribuídas em dois grupos: a) ATBS (n=57, 1mL/kg Norfloxacina injetável Norflomax&reg;, Ourofino Saúde Animal), via intramuscular associado com selante de tetos (4g subnitrato de bismuto Sellat&reg;, Ourofino Saúde Animal), e b) CONT (n=57) sem a aplicação de nenhum medicamento. A lactação iniciou-se no 21º dia do PIL e os animais foram submetidos à duas ordenhas diárias. No 15º dia de lactação (DEL) foi realizado diagnóstico de CFs e mais dois grupos foram criados de acordo com peso corporal, ECC e presença/ausência de CFs: a) GnRH (n=53, 5 mL de GnRH injetável Sincrofort&reg;, Ourofino Saúde Animal) e b) Controle (n=53). Do total (n=104), 91% das novilhas induzidas responderam com sucesso ao PIL com média de produção de leite de 15,19 kg/leite/dia durante as primeiras 22 semanas de lactação. Os tratamentos foram avaliados em fatorial 2x2, sendo o fator 1 correspondente ao tratamento com ATBS e o fator 2 correspondente ao tratamento com GnRH. O ATBS não alterou a produção de leite quando comparado com o GnRH. A prevalência de IIM nas duas primeiras semanas de lactação foi de 18% com o ATBS e 28% nas não tratadas, e Staphylococcuscoagulase negativa (SCN) foi o patógeno mais frequentemente isolado no 7º (20,95%) e 14º (17,11%) DEL. Os quartos mamários tratados com ATBS tiveram 0,56 vezes menos risco de IIM e diminuíram a CCS em relação aos controles. A aplicação de GnRH não influenciou na cura dos CFs em relação aos controles. A ciclicidade aos 45 dias de lactação foi de 68% e 35% para os animais tratados com ATBS e controle, respectivamente. Já para os tratados com GnRH, a ciclicidade foi de 57% e 46% para o controle. No tratamento com ATBS houve taxa de prenhez acumulada de 60% contra 89% no controle, enquanto que o tratamento com GnRH não influenciou esta variável. A indução de lactação foi eficaz em novilhas e o tratamento com ATBS diminuiu a prevalência de IIM nas duas primeiras semanas de lactação. / The present study aimed to evaluate: 1) the milk production and composition of heifers submitted to lactation induction protocol (PIL), 2) the effectiveness of injectable antibiotic treatment associated with teat sealant on the prevalence of intramammary infections (IMI) and somatic cell count (SCC), and 3) the effectiveness of GnRH treatment on follicular cyst (FC) regression and optimization of the accumulated pregnancy rate in late heifers. Thus, 114 heifers of Jersolando breed (Holstein x Jersey) were used, with 34.7 &#177; 4.8 (mean &#177; standard deviation) months of age, 439 &#177; 56.35 kg of body weight and 3.00 &#177; 0.30 body condition score (BCS). The heifers were housed in Compost bedded-pack barns shed and submitted to the PIL consisting of estradiol benzoate, injectable progesterone, prostaglandin, dexamethasone and bovine recombinant somatotropin. Sixteen days prior to initiation of PIL, heifers were randomly assigned to two groups: a) ATBS (n = 57, 1mL/kg Norfloxacin injectable Norflomax&reg;, Ourofino Animal Health), intramuscularly, associated with internal teat sealant (4g bismuth subnitrate Sellat&reg;, Ourofino Animal Health), and b) CONT (n=57) without the application of any medication. Lactation began on the 21stday of the PIL and the animals were submitted to two daily milking. On the 15th day in milk (DIM) a diagnosis of FC was performed and two other groups were created according to body weight, BCS and presence / absence of CFs: a) GnRH (n = 53, 5 mL of Sincrofort&reg; injectable GnRH, Ourofino Animal Health) and b) Control (n = 53). From 104 induced heifers, 91% responded successfully to PIL, with a mean milk yield of 15.19 kg/milk/day during the first 22 weeks of lactation. The treatments were evaluated in a 2x2 factorial, with factor 1 corresponding to the ATBS treatment and factor 2 corresponding to GnRH treatment. The ATBS treatment did not change the milk production when compared to those treated with GnRH. The prevalence of IMI during the first two weeks of lactation was 18% for ATBS-heifers and 28% for untreated heifers. Staphylococcus coagulase negative (SCN) was the most frequently isolated pathogen in the 7th (20.95 %) and 14th (17.11%) DIM. The ATBS-treated mammary quarters had a 0,56lower times risk of infection and decreased the SCC compared to controls, with or without GnRH. The GnRH application did not influence on the cure of FCs in relation to control. Cyclicity at 45 days of lactation was 68% for the animals treated with ATBS and 35% for the control, while the animals treated with GnRH had a cyclicity of 57% and 46% for the control. The ATBS had cumulative pregnancy rate of 60%, in the control was 89% and the GnRH treatment did not influence this variable. Induction of lactation was effective in heifers and treatment with ATBS decreased the prevalence of IMI in the first two weeks of lactation.

O estudo teve como objetivos avaliar: 1) produção e composição do leite de novilhas submetidas a protocolo de indução de lactação (PIL); 2) eficácia de antibiótico injetável associado a selante de tetos sobre a prevalência de infecções intramamárias (IIM) e contagem de células somáticas (CCS) e 3) eficácia de GnRH sobre regressão de cistos foliculares (CFs) e taxa de concepção inicial e prenhez acumulada em novilhas tardias. Foram utilizadas 114 novilhas da raça Jersolando (Holandesa x Jersey), com 34,7 &#177; 4,8 (média &#177; desvio padrão) meses de idade, 439 &#177; 56,35 kg de peso corporal e 3,00 &#177; 0,30 de escore de condição corporal (ECC). O utilizado PIL era composto por benzoato de estradiol, progesterona injetável, prostaglandina, dexametasona e somatotropina recombinante bovina. Dezesseis dias antes do PIL as novilhas foram aleatoriamente distribuídas em dois grupos: a) ATBS (n=57, 1mL/kg Norfloxacina injetável Norflomax&reg;, Ourofino Saúde Animal), via intramuscular associado com selante de tetos (4g subnitrato de bismuto Sellat&reg;, Ourofino Saúde Animal), e b) CONT (n=57) sem a aplicação de nenhum medicamento. A lactação iniciou-se no 21º dia do PIL e os animais foram submetidos à duas ordenhas diárias. No 15º dia de lactação (DEL) foi realizado diagnóstico de CFs e mais dois grupos foram criados de acordo com peso corporal, ECC e presença/ausência de CFs: a) GnRH (n=53, 5 mL de GnRH injetável Sincrofort&reg;, Ourofino Saúde Animal) e b) Controle (n=53). Do total (n=104), 91% das novilhas induzidas responderam com sucesso ao PIL com média de produção de leite de 15,19 kg/leite/dia durante as primeiras 22 semanas de lactação. Os tratamentos foram avaliados em fatorial 2x2, sendo o fator 1 correspondente ao tratamento com ATBS e o fator 2 correspondente ao tratamento com GnRH. O ATBS não alterou a produção de leite quando comparado com o GnRH. A prevalência de IIM nas duas primeiras semanas de lactação foi de 18% com o ATBS e 28% nas não tratadas, e Staphylococcuscoagulase negativa (SCN) foi o patógeno mais frequentemente isolado no 7º (20,95%) e 14º (17,11%) DEL. Os quartos mamários tratados com ATBS tiveram 0,56 vezes menos risco de IIM e diminuíram a CCS em relação aos controles. A aplicação de GnRH não influenciou na cura dos CFs em relação aos controles. A ciclicidade aos 45 dias de lactação foi de 68% e 35% para os animais tratados com ATBS e controle, respectivamente. Já para os tratados com GnRH, a ciclicidade foi de 57% e 46% para o controle. No tratamento com ATBS houve taxa de prenhez acumulada de 60% contra 89% no controle, enquanto que o tratamento com GnRH não influenciou esta variável. A indução de lactação foi eficaz em novilhas e o tratamento com ATBS diminuiu a prevalência de IIM nas duas primeiras semanas de lactação. / The present study aimed to evaluate: 1) the milk production and composition of heifers submitted to lactation induction protocol (PIL), 2) the effectiveness of injectable antibiotic treatment associated with teat sealant on the prevalence of intramammary infections (IMI) and somatic cell count (SCC), and 3) the effectiveness of GnRH treatment on follicular cyst (FC) regression and optimization of the accumulated pregnancy rate in late heifers. Thus, 114 heifers of Jersolando breed (Holstein x Jersey) were used, with 34.7 &#177; 4.8 (mean &#177; standard deviation) months of age, 439 &#177; 56.35 kg of body weight and 3.00 &#177; 0.30 body condition score (BCS). The heifers were housed in Compost bedded-pack barns shed and submitted to the PIL consisting of estradiol benzoate, injectable progesterone, prostaglandin, dexamethasone and bovine recombinant somatotropin. Sixteen days prior to initiation of PIL, heifers were randomly assigned to two groups: a) ATBS (n = 57, 1mL/kg Norfloxacin injectable Norflomax&reg;, Ourofino Animal Health), intramuscularly, associated with internal teat sealant (4g bismuth subnitrate Sellat&reg;, Ourofino Animal Health), and b) CONT (n=57) without the application of any medication. Lactation began on the 21stday of the PIL and the animals were submitted to two daily milking. On the 15th day in milk (DIM) a diagnosis of FC was performed and two other groups were created according to body weight, BCS and presence / absence of CFs: a) GnRH (n = 53, 5 mL of Sincrofort&reg; injectable GnRH, Ourofino Animal Health) and b) Control (n = 53). From 104 induced heifers, 91% responded successfully to PIL, with a mean milk yield of 15.19 kg/milk/day during the first 22 weeks of lactation. The treatments were evaluated in a 2x2 factorial, with factor 1 corresponding to the ATBS treatment and factor 2 corresponding to GnRH treatment. The ATBS treatment did not change the milk production when compared to those treated with GnRH. The prevalence of IMI during the first two weeks of lactation was 18% for ATBS-heifers and 28% for untreated heifers. Staphylococcus coagulase negative (SCN) was the most frequently isolated pathogen in the 7th (20.95 %) and 14th (17.11%) DIM. The ATBS-treated mammary quarters had a 0,56lower times risk of infection and decreased the SCC compared to controls, with or without GnRH. The GnRH application did not influence on the cure of FCs in relation to control. Cyclicity at 45 days of lactation was 68% for the animals treated with ATBS and 35% for the control, while the animals treated with GnRH had a cyclicity of 57% and 46% for the control. The ATBS had cumulative pregnancy rate of 60%, in the control was 89% and the GnRH treatment did not influence this variable. Induction of lactation was effective in heifers and treatment with ATBS decreased the prevalence of IMI in the first two weeks of lactation.