-From day 23 of pregnancy, 24 gilts received either a medium (M, n = 16) or a high (H, n = 8) level of feeding calculated to meet 115% or 190% of energy for maintenance, respectively. During lactation, all H sows were fed ad libitum (H-AL) whereas M sows were fed either ad libitum (M-AL, n = 8) or were restricted (M-RE, n = 8) to the amount of feed ingested by H-AL sows. Increased feed intake during pregnancy increased live weight, backfat thickness, and estimated body lipid and protein on days 4 and 25 of lactation (P < 0.05). It also resulted in lower feed intake and higher lipid mobilisation during lactation (P < 0.05) without a detrimental influence on milk production. Activities of malic enzyme and glucose-6-phosphate dehydrogenase from neck fat samples were higher in H than M sows on day 4 (P < 0.05). They decreased during lactation in H sows (P < 0.05). Mean diameter of adipocytes decreased during lactation in the 3 groups (P < 0.05) but did not differ between groups on days 4 and 25. Plasma leptin on days 4, 11, 18 and 25 was higher in H than in M sows (P < 0.05) but was not influenced by lactational feed intake. Neither measured characteristics of gonadotrophin secretion on day 22, nor of ovarian activity on day 26, were significantly influenced by the level of feeding during pregnancy or lactation.

En esta revisión se hace una retrospectiva de las actividades de investigación realizadas en nutrición porcina por los investigadores del INIFAP en los 35 años de existencia del Instituto. El producto principal de esta actividad, ha sido el sentar las bases para una mejor alimentación del hato reproductor y del cerdo para abasto, enfocándola a resolver los problemas particulares de la porcicultura mexicana, con respecto al uso de las materias primas utilizadas en la alimentación del cerdo; así como la evaluación y mejora de la calidad de la canal, el enriquecimiento de la carne con metabolitos que incrementan su vida de anaquel y mejoran sus propiedades organolépticas. Asimismo, se hace una reflexión sobre los retos que enfrentará la nutrición porcina en el presente siglo, proponiendo las áreas que se tendrán que investigar para garantizar la sustentabilidad del sector, así como las acciones que los investigadores del programa y el INIFAP tendrán que realizar para responder adecuadamente a los desafíos a los que se enfrenta la porcicultura mexicana.