Dietary Alfalfa Meal for Genetically Obese and Lean Growing Pigs: Effect on Body Weight Gain and on Carcass and Gastrointestinal Tract Measurements and Blood Metabolites

Abstract

Twenty-four barrows from each of three genetic groups-lean (L), obese (O) and contemporary (C)-were assigned randomly within genetic group at 8 weeks of age to one of two corn-soybean meal-type diets (0 or 20% alfalfa meal) and fed ad libitum to slaughter at 96 kilograms. Body weight and feed consumption were recorded, and blood samples were collected at 4-week intervals for serum glucose, cholesterol and triglyceride determinations. Live backfat measurements were taken before slaughter, and carcass length and cross-sectional area of the longissimus muscle were measured after slaughter. Weight of the empty stomach, small intestine, cecum and colon and length of the small intestine were recorded for all pigs. Alfalfa meal decreased daily body weight gain (P<.01) and increased feed to gain ratio (P<.01) in all genetic groups. Differences between genetic groups existed in backfat (0>L=C), carcass length and longissimus muscle area (0<L=C). There were no diet × genetic group interactions for daily weight gain, feedrgain or carcass traits. Serum glucose and triglycerides tended to be lower in pigs fed 20% alfalfa meal than in those fed 0 alfalfa meal, but the difference was significant only at weeks 8 and 16 for glucose and at weeks 4 and 12 for triglycerides. Serum cholesterol was not affected by diet. Serum glucose was lower in obese pigs than in lean or contemporary pigs at weeks 4 (P<.01) and 16 (P<.05); serum triglycerides were lower in obese pigs than in lean or contemporary pigs at week 4 (P<.01) and higher at weeks 12 and 16 (P<.01); and serum cholesterol was lower in obese pigs than in lean or contemporary pigs at week 4, but higher at week 16. There were no diet × genetic group interactions for any of the blood serum metabolites measured. The data provide no evidence of diet × genetic group interactions on body weight gain; feed: gain or carcass measurements among the populations of pigs used in this experiment.