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The onset of puberty, hormones and blood -metabolites in Friesian heifers treated with L-tyrosine
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Abstract: To study the influence of L-tyrosine on puberty incidence of Friesian heifers in relation to progesterone (P4), oestradiol-17β, insulin like growth factor I (IGF-I), triiodothyronine (T3), thyroxin (T4) hormones, glucose and urea'-N in blood plasma, total of 30 Friesian heifers having 182.6±5.6 kg live body weight and 8.2±0.5 months of age were divided into three similar groups, 10 animals each. Heifers of the 1st group were received oral single dose L-tyrosine 50 g/heifer at 8.2 month of age (G1) while those of the 2nd group (G2) were received two dose of L-tyrosine 50 g/heifer at 8.2 and 10.2 months of age pre-puberty. Heifers of3rd group (G3) were fed concentrate feed mixture (CFM) (control group). Feeding system and management were the same for all groups. Results show oestradiol-17P concentrations at prior to puberty and overall during the experimental period were significantly higher (P<0.05) in G1 and G2 than in the control group. Average P4 at prior to puberty, P4 peak determined prior to puberty and overall concentration of P4 during the experimental period and interval from P4 peak to puberty incidence was significantly (p<0.05) higher in G1 and G2 than in control group. Age at puberty in Gland G2 groups was significantly (P<0.01) earlier than in control group (335.3 and 333.0 vs. 383.3 day). Overall concentration of IGF-I during the experimental period was significantly (P<0.05) higher in GI and G2 than in control group (207.1 and 215.1 vs. 185.2 ng/ml). Concentration of IGF-I pre- and at puberty was significantly (P<0.01) higher in GI and G2 than in control group. Concentrations of T3 and T4 were higher (P<0.05) in G2 and G3 than in G1 as overall mean. or pre- and at puberty. Overall concentration of glucose during the experimental period increased (P<0.05) in L-tyrosine groups (72.1 and 73.68 mg/dl) as compared to the control group (64.67 mg/dl), although glucose concentration pre- and at puberty was not affected significantly by L-tyrosine treatment. Concentration of urea-N was lower (P<0.001) in G2 and G3 than in G1 as overall mean (25.67 and 25.42 vs. 29.58 mg/dl). Concentration of urea-N reduced (P<0.05) in G2 and G3 compared with G 1 pre- and at puberty.
In conclusion L-tyrosine treatment of 50 g/heifer single or two dose at pre-puberty is strongly in relation to concentration of P4, oestradiol-17β, IGF-I and T3 and in less extend to glucose and urea-N concentration to induce precocious puberty in Friesian heifers.
Keywords: Friesian, L-tyrosine, puberty, progesterone, hormones and blood metabolites.
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| Publication year |
2013
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| Pages |
93-105
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| Availability location |
معهد بحوث الانتاج الحيوانى-شارع نادى الصيد- الدقى- الجيزة
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| Availability number |
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| Organization Name |
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| serial title |
The 4th Scientific Conference of Animal Production Research Institute (APRI)
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| Author(s) from ARC |
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| Agris Categories |
Animal physiology - Reproduction
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AGROVOC
TERMS |
Hormones.
Progesterone.
Sexual maturity.
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| Proposed Agrovoc |
blood metabolites;L-tyrosine;Friesian;oestradiol-17β;
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| Publication Type |
Conference/Workshop
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