RESUMO
The aims of this study were to estimate the genetic parameters for fat-to-protein ratio (F:P) within the first 90 days of lactation and to examine their genetic associations with daily milk yield (MY), somatic cell score (SCS), and calving interval between the first and second calving (IFSC) and between the second and third calving (ISTC) during the first three lactations of Holstein cows. We utilized 200,626 production-related data officially recorded from 77,436 cows milked two or three times a day from 2012 to 2022, sourced from the Holstein Cattle Breeders Association of Paraná State, Brazil. The (co)variance components were estimated using animal models, adopting the restricted maximum likelihood (REML) method with single-trait analysis (for heritability and repeatability) and two-trait analysis (for genetic and phenotypic correlations), per lactation. Regardless of lactation number, heritability estimates were relatively low, ranging from 0.08 ± 0.005 to 0.10 ± 0.003 for F:P; 0.08 ± 0.01 to 0.18 ± 0.005 for MY; 0.04 ± 0.01 to 0.07 ± 0.004 for SCS; and 0.03 ± 0.01 for both IFSC and ISTC. Repeatability estimates within the same lactation were low for F:P (ranging from 0.17 ± 0.002 to 0.19 ± 0.03), high for MY (between 0.50 ± 0.003 and 0.53 ± 0.002), and moderate to high for SCS (between 0.39 ± 0.003 and 0.44 ± 0.004). Genetic correlations between F:P and MY ranged from -0.26 ± 0.03 to -0.15 ± 0.02; F:P and SCS, from -0.06 ± 0.03 to -0.03 ± 0.08; F:P and IFSC, 0.31 ± 0.01; F:P and ISTC, 0.20 ± 0.01; MY and IFSC, 0.24 ± 0.05; and MY and ISTC, 0.13 ± 0.08. The fat-to-protein ratio during early lactation showed low genetic variability, regardless of lactation number. Furthermore, it was genetically correlated with MY, IFSC, and ISTC, although there is an antagonistic and unfavorable correlation between traits that can limit genetic progress.
Assuntos
Lactação , Leite , Feminino , Bovinos/genética , Animais , Brasil , Lactação/genética , FenótipoRESUMO
The intense production of fishes and the use of water resources can compromise the quality and the availability of water, besides its affects in the environment carrying capacity, causing eutrophization and consequently water pollution. Therefore the objective of this study was to monitor the physical-chemical water variables and to measure the total phosphorus (total-P) in sediment, feed and fish in cage culture on an aquaculture area situated at the Itaipu reservoir in Santa Helena Parana state, observing the water quality and determining the total eutrophic level on the aquaculture area, in addition to analyze the total-P bioaccumulation in fish and sediment. The physical-chemical water variables presented normal values as indicated from CONAMA. The mean concentration of total-P for the aquaculture area was 28.41 IET and Secchi disc transparency of 2.74 m, giving it an oligotrophic classification. There was a correlation of 0.55 (p
A intensa produção de peixes e uso dos recursos hídricos pode comprometer a qualidade e disponibilidade da água, além de afetar a capacidade de suporte do ambiente, causando eutrofização e conseqüentemente a poluição do mesmo. Realizou-se um estudo das variáveis físico-químicas da água e dos teores de fósforo total (P-total) no sedimento, rações e peixes cultivados em tanques-rede em uma área aqüícola localizada no reservatório da Itaipu, no município de Santa Helena PR, objetivando monitorar a qualidade da água e determinar o índice de eutrofização total da área de cultivo, além de analisar a bioacumulação de P-total nos peixes e sedimento. As variáveis físico-químicas da água mantiveram valores normais indicados pelo CONAMA. A concentração média de P-total na área aqüícola foi de 28,41 IET e com transparência por disco de Secchi de 2,74 m, enquadrando o ambiente como oligotrófico. Houve correlação de 0,55 (p
