02801naa a2200277 a 450000100080000000500110000800800410001902200140006002400460007410000150012024501760013526000090031150004060032052014970072665300140222365300220223765300120225965300220227165300090229365300290230265300380233170000150236970000180238470000170240277301040241910647482024-07-25       2024    bl uuuu     u00u1 u    #d  a0093-691X7 a10.1016/j.theriogenology.2024.07.0072DOI1 aBRIANO, C.  aMetabolic and hormonal profiles and productive performance in primiparous and multiparous cows grazing different forage allowance in late gestation.h[electronic resource]  c2024  aArticle history: Received 8 December 2023; Received in revised form 5 July 2024; Accepted 8 July 2024; Available online 9 July 2024. -- Corresponding author:   Briano, C.; Lautaro Guerra 1626, Treinta y Tres, Uruguay; email:cbriano@mgap.gub.uy  -- Funding: This work was supported by the National Institute for Agricultural Research (INIA), Uruguay and by ANII - BE_POS_2010_1_2566/PR_FVM_2009_1_3121.  aABSTRACT.- The aim of this study was to evaluate two levels of forage allowance (FA) during the prepartum period on metabolic, hormonal, productive, and reproductive variables in primiparous (P) and multiparous (M) beef cows. Six weeks before calving, 40 P and 42 M cows were assigned to two FA (native pastures) treatments until calving (day 0): High (15 kg DM/100 BW; H) and Low (5 kg DM/100 BW; L). After calving all cows were managed together. High FA cows presented greater intake than L cows, while M tended to have greater intake than P cows. Increased herbage allowance in late gestation in beef cows successfully improved forage intake and energy balance reflected in body condition score and metabolic and endocrine markers. Also, high forage allowance increased milk yield (5.4 vs 4.6 kg/d, P < 0.05) and calves daily gain rate during the first two months of age (0.88 vs 0.82 kg/d, P < 0.05) in H respect to L cows. Pregnancy rate was greater in H vs L cows (40 vs 28 %, P < 0,05). The endocrine metabolic response to higher forage allowance depended on parity, as primiparous cows showed a greater imbalance around calving. Moreover, most primiparous cows were not pregnant at the end of the breeding season, consistent with their prolonged anestrous. Multiparous cows had better productive and reproductive performance than primiparous cows, showing that growing cows have a pronounced negative energy balance reflected in most of the evaluated parameters. © 2024 Elsevier Inc.  aBeef cows  aEnergy metabolism  aGrazing  aHerbage allowance  aMilk  aReproductive performance  aSISTEMA GANADERO EXTENSIVO - INIA1 aMEIKLE, A.1 aVELAZCO, J.I.1 aQUINTANS, G.  tTheriogenology, 2024, Volume 227, Pages 68-76. https://doi.org/10.1016/j.theriogenology.2024.07.007