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| Almeida,Tatiana Prestes; Kern,Elisandra Lurdes; Daltro,Darlene dos Santos; Braccini Neto,José; McManus,Concepta; Thaler Neto,André; Cobuci,Jaime Araujo. |
| ABSTRACT This study aimed to estimate heritability, genetic, and residual correlations between reproductive traits such as age at first calving, calving interval, dry period, and first service period and linear type traits measured in Holstein cows born between the years 1990 and 2008 in Brazil. The (co)variance components were estimated by restricted maximum likelihood, using the MTDFREML software. The heritability for reproductive traits and linear-type traits ranged from 0.02 to 0.03 and from 0.07 to 0.40, respectively. Estimates of genetic correlations between reproductive and linear-type traits ranged from -0.23 (top line) to 0.28 (angularity) to age at first calving, from -0.54 (final score) to 0.34 (foot angle) to calving interval, from -0.23... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Age at first calving; Dairy cattle; Genetic parameters; Reproductive efficiency. |
| Ano: 2017 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-35982017000200091 |
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| Silva,Mário Henrique Magalhães Araújo da; Malhado,Carlos Henrique Mendes; Kern,Elisandra Lurdes; Daltro,Darlene dos Santos; Cobuci,Jaime Araujo; Carneiro,Paulo Luiz Souza. |
| ABSTRACT The objective of this study was to evaluate inbreeding depression in Holstein cows in Brazil, considering their 305-day milk production (MP), age of first calving (AFC), and calving interval (CI). The effects of inbreeding depression on the traits were determined using four regression models (linear, quadratic, exponential, and Michaelis-Menten) about the errors generated by the animal model. The linear model was significant for CI, and the quadratic model was significant for CI and AFC. The Michaelis-Menten and exponential models were significant for MP, AFC, and CI. Inbreeding depression affected MP and CI. Cows with inbreeding coefficient of 15% produced approximately 260 kg less milk than non-inbred cows. A 1% increase in the inbreeding level... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Calving interval; Inbreeding coefficient; Linear models; Non-linear models. |
| Ano: 2019 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-35982019000100307 |
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| Daltro,Darlene dos Santos; Fischer,Vivian; Alfonzo,Evelyn Priscila München; Dalcin,Vanessa Calderaro; Stumpf,Marcelo Tempel; Kolling,Giovani Jacob; Silva,Marcos Vinícius Gualberto Barbosa da; McManus,Concepta. |
| ABSTRACT The objective of this study was to determine whether infrared thermography is a useful tool for the recognition of dairy cows in a state of thermal heat stress, as well as to identify the best region of the animal to be evaluated for this recognition. Physiological variables, including rectal temperature, respiratory frequency, cardiac frequency, and panting score were recorded in 38 lactating cows. For the assessment of environmental parameters, a digital black globe thermometer (TGD-200 model) was used. Thermographic photographs of different regions of the body of cows were taken using an infrared camera (FLIR® System T300) and indicated respective superficial temperature. Physiological variables and superficial body temperature in different... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Animal welfare; Dairy cattle; Thermal comfort; Thermographic images. |
| Ano: 2017 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-35982017000500374 |
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| Dalcin,Vanessa Calderaro; Fischer,Vivian; Daltro,Darlene dos Santos; Alfonzo,Evelyn Priscila München; Stumpf,Marcelo Tempel; Kolling,Giovani Jacob; Silva,Marcos Vinícius Gualberto Barbosa da; McManus,Concepta. |
| ABSTRACT The objective of this study was to investigate changes in physiological parameters of dairy cows and understand which physiological parameters show greater reliability for verification of heat stress. Blood samples were collected for analysis and included hematocrit (Ht), erythrocyte count (ERY), and hemoglobin count (HEMO). In addition, physiological variables, including rectal temperature (RT), heart rate (HR), respiratory rate (RR), and panting score (PS) were recorded in 38 lactating cows. These varied according to genetic group (1/2, 3/4, and pure bred Holstein (HO)). Analysis of variance considering the effects of genetic group, days, and their interaction as well as linear and quadratic effect of the black globe humidity index (BGHI) was... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Broken line; Critical values; Thermal comfort; Thermoregulation. |
| Ano: 2016 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-35982016000800458 |
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| Padilha,Alessandro Haiduck; Cobuci,Jaime Araujo; Daltro,Darlene dos Santos; Braccini Neto,José. |
| Abstract The objective of this work was to verify the gain in reliability of estimated breeding values (EBVs), when random regression models are applied instead of conventional 305-day lactation models, using fat and protein yield records of Brazilian Holstein cattle for future genetic evaluations. Data set contained 262,426 test-day fat and protein yield records, and 30,228 fat and protein lactation records at 305 days from first lactation. Single trait random regression models using Legendre polynomials and single trait lactation models were applied. Heritability for 305-day yield from lactation models was 0.24 (fat) and 0.17 (protein), and from random regression models was 0.20 (fat) and 0.21 (protein). Spearman correlations of EBVs, between lactation... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Breeding value; Correlation; Legendre polynomials; Reliability. |
| Ano: 2016 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-204X2016001101848 |
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