Higher feeding diets effects on age and liveweight gain at puberty in crossbred Nelore × Hereford heifers.
Trop Anim Health Prod
; 46(6): 953-60, 2014 Aug.
Article
em En
| MEDLINE
| ID: mdl-24756466
ABSTRACT
This study was conducted to determine the age and liveweight at puberty of 120 crossbred beef heifers submitted to four diets to achieve predetermined weight gains (kg/day) 0.5 (G500; n = 32), 0.75 (G750; n = 32), 1.0 (G1000; n = 29), and 1.25 (G1250; n = 27). Animals were classified depending on their level of crossing between Nelore (N) and Hereford (H) 25%N-75%H, 37.5%N-63.5%H, 43.7%N-56.7%H, 50%N-50%H, and 75%N-25%H. Reproductive evaluation was performed at the beginning and at the end of the experimental period by ultrasonography and hormone analysis. The average age and liveweight at puberty were 388.0 ± 1.9 days and 331.4 ± 1.3 kg, respectively. Animals from the 25%N-75%H group reached puberty earlier than heifers from other genetic groups supplemented with G1250 diet (P < 0.05). Heifers with higher degree of Nelore (75%N-25%H) fed with G1000 diet showed estrus 42 days prior to mating, but only 57% reached puberty at mating (P < 0.05). Heifers with follicles of higher diameter reached puberty (P < 0.05) earlier. Higher average daily weight gain showed a positive effect on follicular diameter and IGF-I level at puberty (P < 0.01). Concentrations of GH were lower in heifers fed G1250 compared to G1000 diet (P < 0.05). There was a significant interaction between nutritional level and insulin levels at puberty (P < 0.01). We demonstrated the relationship between IGF-I and average daily gain on the onset of puberty in heifers. In conclusion, heifers submitted to the higher feeding level showed a higher follicular diameter and were younger at puberty.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Maturidade Sexual
/
Peso Corporal
/
Bovinos
/
Dieta
/
Ração Animal
/
Criação de Animais Domésticos
Tipo de estudo:
Diagnostic_studies
Limite:
Animals
Idioma:
En
Revista:
Trop Anim Health Prod
Ano de publicação:
2014
Tipo de documento:
Article
País de afiliação:
Brasil