Growth, blood parameters and reproductive performance in Friesian heifers treated with L-tyrosine

Abstract: A total of 30 Friesian heifers having average live body weight of 188.7 ±4.5 kg and 8.5 ±0.4 months of age were used in this study. At the beginning of the experiment, the experimental heifers were divided into three similar groups (10 each), according to their LBW and age. Heifers in the 1st group were received one oral dose from L-tyrosine (50 g/ heifers) at 8.5 months of age (G1), while those in 2nd group were received two oral dose from L-tyrosine (50 g/ heifers) at 8.5 and 10.5 months of age (G2). Heifers in the 3rd group were fed a basal diet and considered as a control group (G3). Results revealed that final live body weight (LBW), total weight gain and average daily gain (ADO) were significantly higher in Gland G2 treated groups than control one. Feed efficiency significantly (P<0.05) increased about 17% in Gl than in control heifers. Concentration of thyroxine (T4) in plasma was affected significantly (P<0.05) highest in Gland. G2 than the control group.
Red blood cells (RBCs) significantly (P<0.01) increased in Gl and G2 by about 13.1 and 6.1%, respectively, as compared to the control. Haemoglobin (Hb) concentration was significantly (P<0.05) higher by about 11.69 and 6.02% in blood of G2 and Gl than in control. White blood cells (WBCs) were significantly (P<0.05) higher in Gl (12.56 x 103/mm3) than those in G2 and control groups (11.95 and 11.60 x 103/mm3, respectively).
Percentage of PCV was significantly (P<0.001) higher in G 1 than in G2 and control heifers (32.94 and 33.0% vs. 35.88%, respectively). Concentration of GL in blood was significantly (P<0.05) higher in GI than in G2 and control groups (4.34, 3.98 and 3.85 g/dl, respectively).
Glucose concentrations in blood was significantly (P<0.001) higher in G1 and G2 (75.15 and 70.73 mg/dl, respectively) than in control (64.03 mg/dl). Concentration of urea-N was significantly (P<0.01) lower in Gl and G2 (28.71and 28.9 mg/dl, respectively) than in control (32.9 mg/dl). Number of services per conception and length of service period were lower GI and G2 treatments than in the control group. Conception rate of heifers in GI and G2 treatments were significantly higher (P<0.01) than the control group (100, 100 vs. 80%, respectively).
Keywords: Friesian, L-tyrosine, growth, blood parameters, reproductive performance

Publication year

2013

Pages

73-83

Availability location

معهد بحوث الانتاج الحيوانى-شارع نادى الصيد- الدقى- الجيزة

Availability number

Organization Name

Animal Production Research Institute (APRI)

serial title

The 4th Scientific Conference of Animal Production Research Institute (APRI)

Author(s) from ARC