Estimation of Alfalfa Pasture Intake and Nutrient Utilization by Growing-Finishing Swine1

Abstract

One hundred and eighty (90 in confinement and 90 on alfalfa pasture) growing-finishing pigs were fed pelleted diets in which dehydrated alfalfa meal was substituted for 0, 2, 4, 8, 16 and 32% of the corn. The digestibility coefficients of dry matter, crude protein, energy and crude fiber were lowered as a result of increased alfalfa intake in either form, dehydrated alfalfa meal or alfalfa pasture. Dilution of the pelleted diets by alfalfa pasture intake, as measured by the chromium oxide-chlorophyll technique, tended to depress digestibility of dry matter, crude protein, gross energy and crude fiber as compared to the pigs fed the respective diets in confinement. The use of a double indicator method (chromium oxide-chlorophyll technique) in this study enabled the estimation of alfalfa pasture intake by growing-finishing pigs. The estimated alfalfa pasture intake values observed ranged from a low 5 to a high of 12% of the total dry matter intake. Chlorophyll proved satisfactory as an indicator for diets high in chlorophyll content but was poor for diets low in its content. Dietary levels of 0 to 16% dehydrated alfalfa meal did not significantly affect average daily gain but 32% dehydrated alfalfa meal significantly (P<.01) reduced daily gain as did the feeding of the experimental diets on alfalfa pasture. Feed required per kilogram gain increased significantly as the level of dehydrated alfalfa was increased in the diet. There was no significant difference due to location (confinement vs. alfalfa pasture) in feed conversion. When comparing location, pigs fed the experimental diets on alfalfa pasture had significantly less backfat thickness and significantly more ham and loin-eye area than the pigs fed the diets in confinement. The lack of statistically significant interaction between location (pasture vs. confinement) and the levels of added dehydrated alfalfa meal in the pelleted diets indicates that the same response from adding dehydrated alfalfa meal to growing-finishing swine diets would be expected on alfalfa pasture as in confinement.