Effect Of Maternal Nutrition Restriction On The Muscle Fibers Characteristic Of Adult Pig Offspring

The experiment was designed to investigate the influence of maternal protein restriction in pregnancy and lactation on the property of muscle fibre of the finishing pig offspring. Single factor experiment was design adopted in this experiment and16purebred little meishan sows with similar first mating date, genealogy, weight and age were chosen and divided into two groups randomly:Restriction group and Control group, eight sows in each group. Sows in the restriction group were feed with50%of normal protein content,while those in control group were feed with normal protein content. After normal delivery of the sows,16boars of average weight were choosed and fed to80kg (finishing pigs) with a normal level of dietary protein after weaning. Therefore, this study was designed to investigate the proportion and size, the average area and the density of muscle fibers and the myofybril ratio in longissimus dorsi muscle and psoas muscle, and whether the response to various levels of glycogen content, lactate dehydrogenase activity, succinate dehydrogenase activity and GLUT4caused by maternal undernutrition.The whole experiment can be divided into two parts:1. The effects of maternal nutrition restriction on muscle fiber of adult pig offspringMuscle fibre in longissimus dorsi muscle and psoas muscle were classified by the method of Brooke and Kaiser (1970), which uses the histochemical reactions ATPase, the reaction is highly sensitive for changes in pH and was finely adjusted to allow for clear discrimination between three fibre types, type I, typeⅡA and typeⅡB.(1)The type I fibres area in longissimus dorsi muscle of maternal undernutrition offspring was remarkablely smaller than that in control group (P<0.05), type IIA and type IIB fibres area were smaller than that in control group but not significant (P>0.05),the average area of muscle fiber is also not significant; the type I and type IIA fibres area in psoas muscle of maternal undernutrition offspring were remarkablely bigger than that in control group (P<0.05), type ⅡB fibres area were bigger than that in control group but not significant(P>0.05), and the average area of muscle fiber is markedly increased(P<0.05).(2)By comparing of the proportion of muscle fiber, we found that the ratio of type I in longissimus dorsi muscle of maternal undernutrition offspring was remarkablely decreased than that in control group (P<0.05), as well as the type IIB increased significantly; the ratio of type I and type IIA in psoas muscle of maternal undernutrition offspring were remarkablely decreased than that in control group (P<0.05) and the type ⅡB was significantly increased (P<0.05).(3)The density of muscle fibers was not significantly changed in longissimus dorsi muscle of maternal undernutrition offspring, but markedly decreased in psoas muscle.(4)The difference of the myofybril ratio between maternal undernutrition offspring and control was not significant. It demonstrated that the type ⅡB ratio in longissimus dorsi muscle subjected maternal undernutrition was significantly increased, and the type IIB ratio and the average area in psoas muscle were also increased,as well as the density of psoas muscle fiber was markedly decreased, these changes maybe damaged the meat quality.2. The effects of maternal nutrition restriction on muscle fiber energy metabo-lism of adult pig offspringThe glycogen content and activities of LDH and SDH in longissimus dorsi muscle and psoas muscle were detect by histochemistry method for estimating the muscle energy metabolism capacity, as well as the content of GLUT4by Western blot.(1)The glycogen content in longissimus dorsi muscle of maternal undernutrition offspring was remarkablely increased comparing with that in control group(P<0.01) but this change was not significant in psoas muscle(P>0.05).(2)The difference of Lactate dehydro-genase activity between limited feeding group and control group was not remark-able(P>0.05).(3)The succinic dehydrogenase activity was lower after transport in longissimus dorsi muscle of maternal undernutrition offspring than that in control group (P<0.05), and it was not significant in psoas muscle(P>0.05).(4)There were no marked changes in the GLUT4content of two muscles. These results showed that the maternal undernutrition could decrease the capacity of aerobic metabolism in offsprings’muscle and maybe affected the glycogen synthesis in skeletal muscle fiber.