Fecha/hora: 06/06/2024 22:57:55

Biblioteca(s): 	INIA Treinta y Tres.	
Fecha corriente: 	12/09/2014	
Fecha de la última actualización: 	11/10/2019	
Autoria: 	FIOL, C.; QUINTANS, G.; UNGERFELD, R.	
Afiliación: 	GRACIELA QUINTANS ILARIA, Instituto Nacional de Investigación Agropecuaria (INIA), Uruguay.	
Título: 	Response to biostimulation in peri-puberal beef heifers: Influence of male-female proximity and heifer's initial body weight.	
Año de publicación: 	2010	
Fuente/Imprenta: 	Theriogenology, 2010, v. 74, no.4,  p. 569-575.	
ISSN: 	0093-691X	
DOI: 	10.1016/j.theriogenology.2010.03.015	
Idioma: 	Inglés	
Notas: 	Article history: Received 9 July 2009; received in revised form 23 December 2009; accepted 17 March 2010.	
Contenido: 	Abstract:
The objectives were to determine if exposure of 12 mo old peri-puberal beef heifers to androgenized steers for 35 d hastened puberty, and if the response was related to the physical proximity between males and females and to heifer?s initial body weight.
Hereford x Aberdeen Angus heifers (n = 131), 12 mo old, were assigned to two treatments: 1) Exposed group, exposed to androgenized steers from Day 0 to Day 35 (E, n = 66); or 2) Control group, isolated from the steers and other males (C, n = 65). Cyclic activity was determined through estrous behavior detection (twice daily) and weekly ultrasound imaging to detect a CL. 
For each Exposed heifer, an association index (with males) was determined thrice weekly, based on the distance to androgenized steers every 10 min for 4 h (until cyclic activity began). Data were analyzed according to heifer?s initial body weight, which was categorized into three ranges (low, medium, and high, designated LW, MW, and HW, respectively). The cumulative proportion of cyclic heifers was greater for Exposed than Control heifers as of Day 21. By the end of the exposure period, more Exposed than Control heifers had attained puberty (16/66 vs. 2/65; P  0.001). Within the HW classification, more Exposed than Control heifers became puberal (11/20 vs. 2/21; P = 0.002). However, there were no differences between MW and LW in the proportions of heifers that reached puberty. Association index in Exposed heifers was greater in HW than in MW and LW (0.10  0.09 vs.
0.06  0.03 and 0.06  0.04; P  0.05), and in heifers that began cyclic activity compared to those that did not in the MW heifers (0.09  0.05 vs. 0.05  0.02; P = 0.01) and tended to be different in the HW treatment (0.12  0.10 vs. 0.06  0.02; P = 0.09).
In conclusion, exposure of peri-puberal beef heifers to androgenized steers for 35 d advanced puberty in heavier heifers; an earlier response occurred in heifers with greater proximity to androgenized steers.	
Palabras-Clave: 	BEEF HEIFERS; BIOSTIMULATION; MALE EFFECT; PUBERTY; SOCIO-SEXUAL STIMULUS.	
Thesagro: 	BOVINOS; CONDICION CORPORAL; ENTORE; TERNERAS.	
Categoría del tema: 	L53 Fisiología Animal - Reproducción	
Registro original: 	INIA Treinta y Tres (TT)	
Ejemplares: 	TT - (100030-1) - PXI - AP - DD - PP/Quintans/Arb/2010/2 -  -  - DIS