Abstract This study examined the relationship between age at first calving and milk production in Holstein heifers within an intensive system in the dairy basin of Córdoba, Argentina. Retrospective data from 452 cows calving between 2016 and 2017, aged between 23 and 32 months, were collected. The results revealed a significant decrease in adjusted 305-day milk yield as age at first calving increased. Cows calving at 24 months yielded higher total milk production by the end of lactation compared to those calving at 31 and 32 months. A significant difference in daily milk yield during lactation was observed based on age at first calving, while no significant effect of calving year was found. Total daily milk yield was also influenced by age at first calving, with cows calving at 24 months exhibiting higher production compared to those calving at 32 months. The dry period, representing the days from drying off to the start of the subsequent lactation, was also influenced by age at first calving, with significant differences observed between cows calving at 23 and 31 months, as well as at 24 and 31 months. In terms of reproductive variables, a significant difference in the calving interval was found based on age at first calving. No significant interaction between age at first calving and calving year was identified for any of the analyzed variables. In conclusion, this study demonstrated that age at first calving has a significant impact on milk production in Holstein cows within an intensive system. The findings suggest that placing greater emphasis on achieving first calving between 23 and 25 months of age may enhance productive and reproductive efficiency in dairy farms.

Resumen Este estudio analizó la relación entre la edad al primer parto y la producción de leche en vacas Holstein en un sistema intensivo en la cuenca lechera de Córdoba, Argentina. Se recopilaron datos retrospectivos de 452 vacas que parieron entre 2016 y 2017, con edades comprendidas entre 23 y 32 meses. Los resultados mostraron que a medida que la edad al primer parto aumenta, la producción de leche ajustada a los 305 días disminuye significativamente. Las vacas que parieron a los 24 meses produjeron más leche total al final de la lactancia en comparación con aquellas que parieron a los 31 y 32 meses. Se observó una diferencia significativa en la producción diaria de leche en lactancia según la edad al primer parto, pero no se encontró un efecto significativo del año de parto. La producción diaria total de leche también fue afectada por la edad al primer parto, con las vacas que parieron a los 24 meses mostrando una mayor producción en comparación con las que parieron a los 32 meses. El período seco, que representa los días desde el secado hasta el inicio de la próxima lactancia, también fue influenciado por la edad al primer parto, con diferencias significativas entre las vacas que parieron a los 23 y 31 meses, y a los 24 y 31 meses. En cuanto a las variables reproductivas, se encontró una diferencia significativa en el intervalo entre partos según la edad al primer parto. No se encontró una interacción significativa entre la edad al primer parto y el año de parto para ninguna de las variables analizadas. En conclusión, este estudio demostró que la edad al primer parto tiene un impacto significativo en la producción de leche de vacas Holstein en un sistema intensivo. Los resultados sugieren que un mayor énfasis en alcanzar un primer parto a una edad entre los 23 y 25 meses podría mejorar la eficiencia productiva y reproductiva en las explotaciones lecheras.

The Modeling and Remodeling processes are conducted through the process of replacement bone at specific sites called Units Bone Remodeling (URO).These can be evaluated by biochemical markers of formation and resorption that reflect changes in skeletal metabolism. These markers of bone turnover are used for research óseo-metabolic diseases because they provide dynamic information of bone metabolism and can be quantified in serum or urine. The variation of these markers is mainly due to preanalytical, analytical and biological variables and should be interpreted taking into account the Reference Value Change (VRC), which results from a calculation in which the biological variability (VB) of the analyte and the random error of the method used in the laboratory are involved.

La Modelación y el Remodelado de hueso son llevados a cabo a través del proceso de Recambio Óseo en sitios específicos llamados Unidades de Remodelación Ósea (URO). Este proceso puede evaluarse a través de marcadores bioquímicos de Formación y de Resorción que reflejan cambios globales del metabolismo esquelético. Estos marcadores de remodelado óseo son utilizados para investigación de enfermedades óseo-metabólicas, porque proveen información dinámica del metabolismo del hueso y pueden ser cuantificados en suero o en orina. La variación de estos marcadores se deben principalmente a variables preanalíticas, analíticas y biológicas y debe interpretarse teniendo en cuenta el Valor de Referencia para el Cambio significativo (VRC), que resulta de un cálculo en el que intervienen la variabilidad biológica (VB) del analito y el error aleatorio del método utilizado en el laboratorio.

Objective: To identify effective strategies to increase the consumption of the product "Purita Mama" in pregnant and lactating women from Ñuble. Subjects and methods: Observational cross sectional study; two instruments were applied, the first one observing of consumption and acceptability of the product in pregnant and lactating women from a non-probabilistic sample; the second one applied to the health team showing major variations in the consumption from a non-probabilistic "intentional" sample. Results: The product was consumed by 38% of pregnant and 34.6% of lactating women; acceptability was regular in 54.6% and 48.2% of pregnant and lactating women, respectively. On the other hand, 34% of the professionals and technicians who work directly with pregnant and lactating women "did not know" the product. The main effective educational strategy implemented (60.2%), is product tasting. Conclusion: The largest consumption of the product is seen in those establishments who implement effective instructional strategies.

Objetivo: identificar estrategias efectivas para que los equipos de salud de la provincia de Ñuble - Chile incrementen el consumo del producto lácteo "Purita Mama" para gestantes y nodrizas. Sujetos y métodos: estudio observacional, pasivo de caso y control donde se aplicaron dos instrumentos, el primero de consumo y aceptabilidad del producto en gestantes y nodrizas a una muestra no probabilística "por cuota"; y el segundo, aplicado a los equipo de salud que presentó mayores variaciones en el consumo a una muestra no probabilística "intencional". Resultados: Consumen el producto 38% de las gestantes y 34,6% de las nodrizas; de las que lo consumen su aceptabilidad es regular en 54,6% de las gestantes y en 48,2% de las nodrizas. Por otra parte "no conocen el producto" 34% de los profesionales y técnicos que trabajan directamente con gestantes y nodrizas. La principal estrategia educativa efectiva implementada (60.2%), es la "degustación del producto". Conclusión: El mayor consumo del producto, se presenta en aquellos establecimientos donde se implementan estrategias educativas efectivas.

Dados cariotípicos de Iheringichthys labrosus de várias populações do Rio Paraná/Argentina são apresentados. O número diploide foi 2n=56 e o cariótipo constituído de 42m/sm + 14st/a (NF= 98). As AgNORs foram observadas telomericamente no braço longo de um par cromossômico st/a. Estes sítios também apresentaram bandas positivas após bandamento C. Heterocromatina foi observada em posição telomérica em alguns pares cromossômicos e podem ser encontradas em um ou ambos os braços de cromossomos metacêntricos. Os resultados obtidos foram comparados com aqueles reportados em diferentes populações de rios brasileiros e foi evidente uma similaridade entre eles. Entretanto, fórmulas cariotípicas discordantes e características cariotípicas entre exemplares deveriam ser cuidadosamente observadas porque, em alguns casos, eles parecem ser mais artefatos de técnica que diferenças reais.

Karyotypic data on Iheringichthys labrosus from several populations of Paraná River/Argentina are presented. The diploid number was 2n=56 and the karyotype consisted of 42m/sm + 14st/a (NF= 98). The AgNORs were observed in telomeres of the long arm of a st/a chromosome pair. These sites were also positive after C-banding. Heterochromatin was observed in the telomeric position in some chromosomal pairs and can be found in one or both metacentric chromosome arms. The obtained results were compared with those reported for different populations from Brazilian rivers and the similarity among them was evident. However, discordant chromosome formulae and karyotype features between samples should be carefully taken because, in some cases, they seem to be more technical artifacts than real differences.

O ácido periódico e reagentes fotográficos têm sido usados para remover resíduos de nitrato de prata de preparações citológicas. Nós usamos ferricianeto de potássio para remover sais de AgNO3 em casos de impregnação cromossômica excessiva. Este método produziu descoloração parcial, acentuando o contraste. Coloração subseqüente com Giemsa também causou um contraste melhor entre os braços cromossômicos e NORs que foram preservados e retiveram uma cor escura. O uso deste procedimento para preparações cromossômicas tratadas seqüencialmente por bandamento CBG e coloração por AgNO3 levou a descoloração global das regiões C+, causando um bandamento C "reverso", geralmente com alto contraste.

Both periodic acid and photographic reagents have been used to remove the silver nitrate residues from cytological preparations. We used potassium ferricyanide to remove AgNO3 salts in cases of excessive chromosome impregnation. This method produced partial decolorization, with contrast enhancement. Counterstaining with Giemsa also promoted a better contrast between chromosome arms and NORs, which were preserved and retained a dark color. Application of this procedure to chromosome preparations treated sequentially for CBG banding/AgNO3 staining promoted complete decolorization of C+ regions, leading to "reverse" C-banding, generally with high contrast.