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<p>This study evaluated whether accelerated growth during early development could hasten puberty in early-weaned Angus × Nellore heifers. Thirty-eight heifers (92 ± 2&#xa0;kg BW; 3.0 ± 0.1 months of age) were randomly assigned to a 2 × 2 factorial design. Treatments consisted of high (H) or control (C) average daily gain (ADG) during Phase I (3–7 months; 1.0 vs. 0.5&#xa0;kg/day) and Phase II (7 months to puberty; 0.9 vs. 0.6&#xa0;kg/day), resulting in four groups (HH, HC, CH, CC). All heifers received the same diet, differing only in intake level (<i>ad libitum</i> or restricted to 50%). Puberty was determined by serum progesterone (P4 &gt; 1.5 ng/mL) and follicular development was monitored by ultrasonography; blood samples were analyzed for leptin, insulin-like growth factor-1 (IGF-1), and luteinizing hormone (LH). High ADG in Phase I increased BW by 58&#xa0;kg at 7 months. Puberty occurred earlier in HH, HC, and CH (12.4 ± 0.1 months) compared with CC (14.4 ± 0.4 months; <i>P</i> &lt; 0.05). From 9 to 11 months, dominant follicle diameter was greater in HH, HC, and CH than in CC. Elevated leptin, IGF-1, and LH pulse frequency were also observed in heifers with accelerated early growth. Nevertheless, these endocrine changes were not sufficient to markedly advance puberty onset. In conclusion, nutritional strategies that enhance early growth improve body development and transient endocrine responses but do not significantly reduce the age at puberty in Angus × Nellore heifers.</p>

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Effect of high growth rate in prepubertal age on hormonal and puberty status in crossbred (Angus x Nellore) heifers

  • 期刊论文

  • 发表日期：

    2025年12月23日

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  • Marcos Vinicius de Castro Ferraz Junior,
  • Marcelo Henrique Santos,
  • Gabriela Baggio de Oliveira,
  • Daniel Montanher Polizel,
  • Guilherme de Paula Nogueira,
  • Vinícius Nunes de Gouvêa,
  • Janaina Socolovski Biava,
  • Evandro Maia Ferreira,
  • Nelma Pinheiro Fragata Beltrão,
  • Alexandre Vaz Pires

摘要

This study evaluated whether accelerated growth during early development could hasten puberty in early-weaned Angus × Nellore heifers. Thirty-eight heifers (92 ± 2 kg BW; 3.0 ± 0.1 months of age) were randomly assigned to a 2 × 2 factorial design. Treatments consisted of high (H) or control (C) average daily gain (ADG) during Phase I (3–7 months; 1.0 vs. 0.5 kg/day) and Phase II (7 months to puberty; 0.9 vs. 0.6 kg/day), resulting in four groups (HH, HC, CH, CC). All heifers received the same diet, differing only in intake level (ad libitum or restricted to 50%). Puberty was determined by serum progesterone (P4 > 1.5 ng/mL) and follicular development was monitored by ultrasonography; blood samples were analyzed for leptin, insulin-like growth factor-1 (IGF-1), and luteinizing hormone (LH). High ADG in Phase I increased BW by 58 kg at 7 months. Puberty occurred earlier in HH, HC, and CH (12.4 ± 0.1 months) compared with CC (14.4 ± 0.4 months; P < 0.05). From 9 to 11 months, dominant follicle diameter was greater in HH, HC, and CH than in CC. Elevated leptin, IGF-1, and LH pulse frequency were also observed in heifers with accelerated early growth. Nevertheless, these endocrine changes were not sufficient to markedly advance puberty onset. In conclusion, nutritional strategies that enhance early growth improve body development and transient endocrine responses but do not significantly reduce the age at puberty in Angus × Nellore heifers.