The Effects of Feeding Reduced-Lignin Alfalfa on Growing Beef Cattle Performance: a Preliminary Study

Gene suppression techniques down-regulating specific lignin biosynthesis pathway enzymes have permitted the development of an alfalfa variety with an altered lignin content and composition known as HarvXtra. This study was designed to compare the difference in forage nutrient quality between reduced-lignin alfalfa hay (variety HX-4114) and conventional alfalfa hay (variety WL336HQRR), and to evaluate Angus heifer performance when fed treatments of HX-4114 and WL336HQRR. Twenty-four Angus heifers (8 months of age; initial BW = 270 ± 21 kg) were selected to participate in an 84-day alfalfa hay feeding trial. Their performance was evaluated based on changes in body weight (BW), average daily gain (ADG), dry matter intake (DMI), and gain to feed ratio (G:F). Additionally, in situ dry matter disappearance was tested using four ruminally cannulated Hereford cows. Hay samples were collected and used to determine forage nutrient quality, leaf count, and leaf-to-stem ratio. Significance was set at P ≤ 0.05. There were no differences (P ³ 0.05) in forage nutrient quality between alfalfa treatments. Means did not differ by treatment for leaf count (P = 0.06), but leaf-to-stem ratio was higher (P = 0.04) for HX-4114 than WL336HQRR (1.67 vs. 1.17, respectively). There were no treatment or treatment by day interactions for BW, ADG, DMI, G:F, or in situ dry matter disappearance. Additionally, animal performance did not differ for growing Angus heifers consuming HX-4114 and WL336HQRR alfalfa hay. More research is warranted to determine the value of utilizing different genotypes of reduced-lignin alfalfa and their impact on the U.S beef industry.