Productive and reproductive performance of females F1 Holstein x Gir daughters of proven bulls.

Records of 234 lactations from F1 Holstein x Gyr daughters of proven bulls were used in this study for the evaluation of productive and reproductive characteristics of cows. Data were collected from a private farm located in the municipality of Santo Antônio do Monte, MG, Brazil. The objective of this study was to evaluate the effects of Holstein bull's PTA milk (predicted transmitting ability) calving year, season, and parity on the productive and reproductive characteristics of F! cows. The productive characteristics analyzed were total milk production (TMP), average daily production (ADP), days in milk (DIM), and milk yield per day of calving interval (MYDCI). The studied reproductive characteristics were service interval (SI), calving interval (CI), and gestation length (GL). The results were subjected to statistical analysis and means for significant effects were compared using Duncan's test at a significance level of 5%. F1 animals efficiently expressed their genetic potential for milk production with an average total milk production of 7842.61 kg and average daily production of 24.53 kg. Means for days in milk, milk yield per day of calving interval, service interval, calving interval, and gestation length were 322.52 days, 20.73 kg, 106.0 days, 383.23 days, and 276.18 days, respectively. Properly managed F1 Holstein x Gyr daughters of proven bulls fed a balanced diet efficiently expressed their genetic potential for milk production without adverse effects on reproduction. Moreover, Holstein x Gyr cows should be selected based on parents' PTA for milk traits and other factors such as environmental conditions and management.

Concordance analysis between estimation methods of milk fatty acid content.

Considering the milk fatty acid influence on human health, the aim of this study was to compare gas chromatography (GC) and Fourier transform infrared (FTIR) spectroscopy for the determination of these compounds. Fatty acid content (g/100g of fat) were obtained by both methods and compared through Pearson's correlation, linear Bayesian regression, and the Bland-Altman method. Despite the high correlations between the measurements (r=0.60-0.92), the regression coefficient values indicated higher measures for palmitic acid, oleic acid, unsaturated and monounsaturated fatty acids and lower values for stearic acid, saturated and polyunsaturated fatty acids estimated by GC in comparison to FTIR results. This inequality was confirmed in the Bland-Altman test, with an average bias varying from -8.65 to 6.91g/100g of fat. However, the inclusion of 94% of the samples into the concordance limits suggested that the variability of the differences between the methods was constant throughout the range of measurement. Therefore, despite the inequality between the estimates, the methods displayed the same pattern of milk fat composition, allowing similar conclusions about the milk samples under evaluation.

Curvas de crescimento de fêmeas da raça nelore e seus cruzamentos / Growth curves of female nelore and their crosses

Seleção para características do crescimento pode ser feita após ajustadas funções de crescimento para todos os animais sob seleção. Porém, a curva de crescimento de fêmeas é influenciada pelas gestações e lactações subsequentes. Neste trabalho, métodos são descritos para selecionar uma função que ajuste a curva de crescimento de fêmeas bovinas considerando-se os efeitos de variação de peso corporal devido a gestação e a lactação. Foram utilizados dados provenientes do Instituto Agronômico do Paraná, constituindo-se de 15.271 observações de pesos de 103 fêmeas, sendo 43 Nelore, 10 F1 Guzerá x Nelore, 29 F1 Red Angus x Nelore, 5 F1 Marchigiana x Nelore e 16 F1 Simental x Nelore. Comparou-se o ajuste das funções de Brody, Gompertz, Logística, Von Bertalanffy e Michaelis-Menten reparametrizada (MMr) aos efeitos do ganho de peso em função da idade, sendo adicionado a todas as funções o ganho de peso durante a gestação e a perda de peso na lactação de fêmeas da raça Nelore e Cruzadas. Ao ajustar as funções, observou-se um Coeficiente de Determinação Múltiplo Ajustado variando entre 0,7552 e 0,9267. Observou-se o menor Quadrado Médio do Resíduo e o Desvio Médio Absoluto para a função de MMr. Para descrição da curva de crescimento em função da idade das fêmeas, deve ser ajustada a função de MMr.

Selection for growth characteristics can be done after fitting growth functions for all breeding animals. However, in the female population the growth curve is influenced by gestation and subsequent lactations. In this work methods are described to select a function that fits a growth curve of bovine females considering the varying effects of body weight due to gestation and lactation. Data from the Paraná Agronomic Institute (IAPAR) were used consisting of 15.271 weight observations of 103 females distributed as 43 Nelore, 10 F1 Guzerá x Nelore, 29 F1 Red Angus x Nelore, 5 F1 Marchigiana x Nelore and 16 F1 Simental x Nelore. The function adjustment of Brody, Gompertz, Logística, Von Bertalanffy and Michaelis-Menten reparametrized MMr were compared to the effects of weight gain as a function of age, adding to all functions the weight gain during gestation and the weight loss in the lactation of Nelore and crossbreed females. It was observed an Adjusted Coefficient of Multiple Determination varying from 0.7552 to 0.9267. Lower Residue Mean Square and Absolute Mean Deviation were observed for the MMr function. The MMr function must be adjusted in order to describe the growth curve as a function of the female age.