163 Effects of pre- and post-partum supplementation of molasses/urea with or without methionine fortification on growth performance of primiparous cows and their offspring

Abstract

Abstract The present study evaluated the performance of calves born from primiparous cows offered pre- and post-partum supplementation of sugarcane molasses/urea added or not with DL-methionine hydroxyl analog. On d 0 (~56 d before calving), 36 Brangus heifers were stratified by BW and BCS (345 ± 4.7 kg; 2 yr of age), and randomly allocated into 1 of 12 bahiagrass pastures (3 heifers and 1.2 ha/pasture). Treatments were randomly assigned to pastures (4 pastures/ treatment) and consisted of no supplementation (NOSUP) or supplementation of molasses/urea (7.2 kg DM/heifer/ wk; 75% TDN, 20% CP; DM basis) with (MOL+) or without (MOL-) fortification with 105 g/heifer/wk of methionine (Alimet, Novus International Inc., Romance, AR) from d 0 until all heifers within each pasture calved. Total weekly amount of molasses/urea (and methionine for MOL+ heifers) was divided by 2 and offered on Tuesdays and Wednesdays. After all cows calved, all pairs were fed 12.7 kg/cow/wk of molasses/urea (DM basis) and grazed a single bahiagrass pasture until calf early-weaning (d 147). Calves received a soybean hull-based supplement at 3.5% of BW (DM basis) and ad libitum stargrass hay from d 154 to 201. Calving date and cow BCS on d 44 did not differ between MOL+ and MOL- (P ≥ 0.50), but both groups calved at greater BCS than NOSUP cows (P ≤ 0.008). However, cow BCS on d 147 and pregnancy percentage on d 288 did not differ among treatments (P ≥ 0.27). Calf birth BW did not differ among treatments (P ≥ 0.21), but ADG from birth to d 201 was greater for MOL+ and MOL- vs. NOSUP calves (P ≤ 0.05). Therefore, pre- and post-partum supplementation of sugarcane molasses/urea improved cow BCS at calving and calf postnatal growth compared with no supplementation. Supplemental methionine did not further enhance cow and calf growth performance