16 HOURS PHOTOPERIOD IN HOLSTEIN HEIFERS IN THE SUBTROPICS: EFFECTS IN DEVELOPMENT AND AGE TO FIRST ESTRUS

Autores/as

  • Nicolás Valenzuela-Jiménez Departamento de Fisiología y Farmacología, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, Ciudad Universitaria. 04510.
  • Karla Rodríguez-Hernández Instituto Nacional de Investigaciones Forestales Agrícolas y Pecuarias.
  • Joel Hernández-Cerón Departamento de Reproducción, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México.
  • Héctor Vera-Ávila Instituto Nacional de Investigaciones Forestales Agrícolas y Pecuarias.
  • Gregorio Núñez-Hernández Instituto Nacional de Investigaciones Forestales Agrícolas y Pecuarias.
  • Alejandro Villa-Godoy Departamento de Fisiología y Farmacología, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, Ciudad Universitaria. 04510.

DOI:

https://doi.org/10.19136/era.a2n4.717

Palabras clave:

Photoperiod, development, heifers calvez, estrus, subtropical,

Resumen

Both growth and milk production in heifer calves are stimulated by a long photoperiod, though this has not been proven yet in subtropical areas. To evaluate the effect of 16 hr of light (L16) on calves suckling (LAC) and/or pre-pubertal stages (PP) in a subtropical area, 325 calves (36 ± 0.4 kg) were randomized into two groups: L16 or natural photoperiod (LNAT). At seven months of age, 198 of these calves (195 ± 2 kg) were randomly assigned to L16 or LNAT. The following were determined at the beginning and end of LAC and PP stages: Weight (PC, kg), height (AC, cm), thickness of back-fat (GG, cm) and of Longissimus dorsi (LD, cm); pelvic area (AP, cm2), body condition (CC), age at first estrus, mammary gland depth (PGM, cm) and width (AGM, cm). The statistical analysis was made using ANOVA for a 2 X 2 factorial arrangement. At the end of LAC, GG was lower and LD greater in L16 animals, while, at the end of PP, L16 heifer calves had a greater PC (260 ± 3 vs 250 ± 3), AP (166 ± 1.2 vs 153 ± 1.2), LD (3.18 ± 0.04 vs 2.90 ± 0.04), and AGM (2.41 ± 0.02 vs 2.21 ± 0.02), but a lower GG (0.114 ± 0.003 vs 0.139 ± 0.003) as compared to LNAT heifer calves. More L16 animals (67 %) presented estrus versus LNAT (38 %)

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Publicado

2015-01-12

Cómo citar

Valenzuela-Jiménez, N., Rodríguez-Hernández, K., Hernández-Cerón, J., Vera-Ávila, H., Núñez-Hernández, G., & Villa-Godoy, A. (2015). 16 HOURS PHOTOPERIOD IN HOLSTEIN HEIFERS IN THE SUBTROPICS: EFFECTS IN DEVELOPMENT AND AGE TO FIRST ESTRUS. Ecosistemas Y Recursos Agropecuarios, 2(4), 53-67. https://doi.org/10.19136/era.a2n4.717

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ARTÍCULOS CIENTIFICOS