RESUMO
For dairy cattle breeds, mainly the taurine ones, the selection emphasized for many years the increase in milk yields and, as a consequence, the adaptive and reproductive traits were negatively affected. The aim of this study was to verify the influence of genetic and environmental effects on the reproductive traits in a dairy herd selected for high milk production levels. The data set comprised 1,737 first lactations Holsteins cows of Agrindus Farm, located at Southeastern region of Brazil. The records of the following reproductive traits: calving to first heat interval (CFHI), calving to conception interval (CCI) and first to second calving interval (FCI) were analyzed as dependent variables by least squares method using GLM procedure (SAS). Linear models were considered including two production levels (1= less than 9,500 kg and 2= more than 9,501 kg of total milk yield), contemporary group (year and months calving), management group, sire of cow, and the sire used to breeding cows, as classificatory variables. As covariates were included for all traits the peak milk yield in lactation (linear effect), age at calving only for CFHI (linear and quadratic effects) since this effect was not significant for other traits, and CFHI (linear effect) only for FCI. The coefficients of determination represented 24%, 74% and 75%, respectively for CFHI, FCI and CCI models. Production level
O artigo não apresenta resumo em português.
RESUMO
Mastitis is an inflammation of the mammary gland, caused by bacteria, viruses, fungi and yeasts. During the processes of inflammation, chloride (Cl) and sodium (Na) ions, immunoglobulins and other serum proteins present in blood, flow through capillaries direct to the alveoli lumen of the gland, thus increasing its concentration. This is due to the increase of vascular permeability, the destruction of tight junctions and the active ion-pumping system, while the concentration of casein, lactose, triglycerides and potassium (K) decreases. This work aimed to study a method to evaluate mastitis in Gir dairy cattle, where the milk electric conductivity (EC) was correlated to milk somatic cell count (SCC). This method will provide an early diagnosis, which can be used daily with conductivity meter in mechanical milking machine or weekly in properties with manual milking. The measurement of EC in milk was accomplished through the appliance of AK83 BENCHTOP PORTATIL. The experiment was conducted in two farms: Calciolândia, Arcos/MG and Bom Jardim da Serra, Mococa/SP, totaling 123 Gir cows. In Calciolândia farm, milking was manual and in Bom Jardim da Serra milking was manual and mechanical but both with the presence of the calf . The milk collection took place in 10 ml bottles at ambience temperature, and the samples were in duplicate, one to measure the EC and the other for SCC and co
O artigo não apresenta resumo em português.
RESUMO
Electrical conductivity of milk is an indirect method for diagnosis of mastitis that can be used as criterion of selection in breeding programs, to obtain more resistant animals to infection. Data from 9,302 records of electrical conductivity from the morning milking (ECM), 13,070 milk yield records (MY) and 11,560 records of milking time (MT), of 1,129 first lactation Holstein cows, calving from 2001 to 2011, were used in statistical analysis. Data of eight herds of Southeast region of Brazil were obtained by the WESTFALIA® electronic milking machines, with Dairyplan management system. Two analysis were performed: a multitrait, including MY, MT and ECM, and an unitrait, considering only test-day morning electrical conductivity. The model included additive genetic, permanent environmental and residual effects as random. Additionally, contemporary groups (CG), the age of cow at calving (AGC) and days in milk (DIM) (linear and quadratic regression) were included as fixed effects. The CG was composed by herd, year and month of test. DIM classes were formed with weekly intervals, constituting a total of 42 classes. The variance components were estimated by Restricted Maximum Likelihood Method (REML), using the Wombat software. The average and standard deviation of ECM were 4.80 mS cm-1 and 0.54 mS cm-1, respectively. The heritability estimates by multitrait model and their standa
O artigo não apresenta resumo em português.
RESUMO
Electrical conductivity of milk is an indirect method for diagnosis of mastitis that can be used as criterion of selection in breeding programs, to obtain more resistant animals to infection. Data from 9,302 records of electrical conductivity from the morning milking (ECM), 13,070 milk yield records (MY) and 11,560 records of milking time (MT), of 1,129 first lactation Holstein cows, calving from 2001 to 2011, were used in statistical analysis. Data of eight herds of Southeast region of Brazil were obtained by the WESTFALIA® electronic milking machines, with Dairyplan management system. Two analysis were performed: a multitrait, including MY, MT and ECM, and an unitrait, considering only test-day morning electrical conductivity. The model included additive genetic, permanent environmental and residual effects as random. Additionally, contemporary groups (CG), the age of cow at calving (AGC) and days in milk (DIM) (linear and quadratic regression) were included as fixed effects. The CG was composed by herd, year and month of test. DIM classes were formed with weekly intervals, constituting a total of 42 classes. The variance components were estimated by Restricted Maximum Likelihood Method (REML), using the Wombat software. The average and standard deviation of ECM were 4.80 mS cm-1 and 0.54 mS cm-1, respectively. The heritability estimates by multitrait model and their standa
O artigo não apresenta resumo em português.
RESUMO
Mastitis is an inflammation of the mammary gland, caused by bacteria, viruses, fungi and yeasts. During the processes of inflammation, chloride (Cl) and sodium (Na) ions, immunoglobulins and other serum proteins present in blood, flow through capillaries direct to the alveoli lumen of the gland, thus increasing its concentration. This is due to the increase of vascular permeability, the destruction of tight junctions and the active ion-pumping system, while the concentration of casein, lactose, triglycerides and potassium (K) decreases. This work aimed to study a method to evaluate mastitis in Gir dairy cattle, where the milk electric conductivity (EC) was correlated to milk somatic cell count (SCC). This method will provide an early diagnosis, which can be used daily with conductivity meter in mechanical milking machine or weekly in properties with manual milking. The measurement of EC in milk was accomplished through the appliance of AK83 BENCHTOP PORTATIL. The experiment was conducted in two farms: Calciolândia, Arcos/MG and Bom Jardim da Serra, Mococa/SP, totaling 123 Gir cows. In Calciolândia farm, milking was manual and in Bom Jardim da Serra milking was manual and mechanical but both with the presence of the calf . The milk collection took place in 10 ml bottles at ambience temperature, and the samples were in duplicate, one to measure the EC and the other for SCC and co
O artigo não apresenta resumo em português.
RESUMO
For dairy cattle breeds, mainly the taurine ones, the selection emphasized for many years the increase in milk yields and, as a consequence, the adaptive and reproductive traits were negatively affected. The aim of this study was to verify the influence of genetic and environmental effects on the reproductive traits in a dairy herd selected for high milk production levels. The data set comprised 1,737 first lactations Holsteins cows of Agrindus Farm, located at Southeastern region of Brazil. The records of the following reproductive traits: calving to first heat interval (CFHI), calving to conception interval (CCI) and first to second calving interval (FCI) were analyzed as dependent variables by least squares method using GLM procedure (SAS). Linear models were considered including two production levels (1= less than 9,500 kg and 2= more than 9,501 kg of total milk yield), contemporary group (year and months calving), management group, sire of cow, and the sire used to breeding cows, as classificatory variables. As covariates were included for all traits the peak milk yield in lactation (linear effect), age at calving only for CFHI (linear and quadratic effects) since this effect was not significant for other traits, and CFHI (linear effect) only for FCI. The coefficients of determination represented 24%, 74% and 75%, respectively for CFHI, FCI and CCI models. Production level
O artigo não apresenta resumo em português.