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<p>La producción lechera ha sido una de las grandes áreas del desarrollo de la Zootecnia. En ella se reúne el mejoramiento genético, logros en la producción de leche, disposición de la ubre, velocidad de ordeño, variación en la composición química, rendimiento lácteo en subproductos; así mismo, el avance en la nutrición para atender los<br />requerimientos de los altos volúmenes de leche, evolución en los sistemas de producción, innovaciones tecnológicas en el ordeño, higienización y aseguramiento de calidad, uso de biotecnologías para la optimización de la producción y la reproducción, generación de nuevas razas y estudio de posibles bondades productivas de recursos<br />genéticos locales. El objetivo de este documento es: en los ochenta años de la Facultad de Ciencias Agropecuarias, presentar una breve sinopsis de la producción lechera, como un homenaje a los profesionales y productores que han participado en su desarrollo, en especial de los grupos raciales bovinos Lucerna y Hartón del Valle.</p>

Dairy farms of the department of Nariño present nutritional concerns, especially in the transition period and early lactation, because of the energy imbalance of the diets, which causes deficiencies in the productive and reproductive activity of the cows. According to the above, the main idea was to study the metabolic behavior in the transition period and early lactation of dairy cows supplemented energetically with bypass fat in the tropical highlands of Nariño (Colombia), 21 cows (Holstein x Simmental cross) of second and third lactation period were selected. They were distributed in three treatments with seven animals each; the control treatment (T1) received a base diet (forage + concentrate) without fat supplementation; the second treatment (T2) had a base diet plus 250 g/day of bypass fat and the third (T3) had a base diet plus 250 g/day bypass fat enriched with omega 3. The experimental period ranged between days 15 of prepartum to day 105 of lactation, with an interval of 15 days among sampling. To evaluate the matabolyc performance, we evaluated in serum: non-esterified fatty acids (NEFA), betahydroxybutyrate (BHB), cholesterol, triglycerides, glucose, total proteins, albumin, BUN, and globulins. In addition, body condition and reproductive behavior were determined. The results indicated that there was no efect of treatments on metabolic performance, body condition, and reproductive activity. The energy indicators showed no changes, indicating an adequate supply energy supply in the diet; however, in the metabolites associated to nitrogen, differences in protein were observed. The values found in the variables, constitute a reference of the behavior and the nutritional conditions of the dairy farms in the region.

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