The Role and Impacts of Growth Hormones in Maximizing Animal Production- A review

The purpose of the study is to examine the role and impacts of growth hormone in maximizing animal products. Growth hormones are biological stimulants that are found either naturally in the organism or synthetically manufactured. Phytoestrogens, phytoprogestrons and Phenolic compounds are hormones from plants. Drugs from of placenta and colostrums of cow`s contain progesterone, estrogene, gonadotropin, and prostaglandins hormones. Growth hormones have got popular applications in dairy, beef, feed improvement and Biopharmaceutical productions with the aim of producing valuable products: fat free meat (Porcine Somatotropin hormone in pigs), nutritionally and medicinally reach milk (Bovine Somatotropin hormone in cattle), palatable and disease and insect pest resistant forage crop production. They have got also contribution in maximizing livestock production by involving in adjusting animals’ reproductive process such as oestrus synchronization and superovulation mainly during artificial insemination and embryo transfer. Controversially, these hormones have wide impacts on human being, animal welfare, environment and etc. Contamination of ground water by hormones that are found in the animals` excreta will cause deleterious effects such as cancer, loss of fertility, and some imbalance of minerals in the water and soil.

Exogenous bovine somatotropin and mist-fan cooling synergistically promote the intramammary glucose transport for lactose synthesis in crossbred Holstein cows in the tropics

Background and Aim: Milk synthesis by the mammary gland is negatively influenced in part by high ambient temperature (AT). This study aimed to clarify the pathway of intramammary glucose utilization involved in mediating lactose synthesis during treatment with somatotropin under housing with misters and fans. Materials and Methods: A single subcutaneous injection of 500 mg of recombinant bovine somatotropin (rbST) was administered 3 times once every 14 days to 87.5% crossbred Holstein cattle in early-/mid-/late lactation, under housing in a normal shaded barn and in a shaded barn with a mist-fan cooling system. Results: The milk yields of the cooled cows tended to increase compared with those of uncooled cows and exhibited more potentiated effects in response to rbST treatment, coinciding with increases in mammary plasma flow and glucose uptake, but not in the mammary extraction of glucose. Treatment with rbST in the cooled cows resulted in a greater increase in the milk glucose concentration and a greater decrease in the milk glucose-6-phosphate concentration at all stages of lactation. Conclusion: rbST treatment exerted its galactopoietic action more by local intramammary factors than by other extramammary factors at a low AT and the synergistic effect between rbST treatment and low AT increased the availability of intramammary glucose transport in activating the process of lactose synthesis.

Effects of administering exogenous bovine somatotropin to beef heifers during the first trimester on conceptus development as well as steroid and eicosanoid metabolizing enzymes

ABSTRACT The aim of this study was to evaluate the effect of bovine somatotropin (bST) on fetal and placental development during the first third of gestation in beef heifers. Angus heifers (n = 97) were randomly assigned to either receive a 500 mg injection of bST (BST) biweekly on d 0, 15, 29, 43, and 57 of gestation, or not receive bST (CTL) throughout the experiment. Body weight (BW) was assessed on d -9, -3, 0, 15, 22, 29, 43, 50, 57, 64, and 77, while blood samples were collected on d 0, 22, 50, and 64. Pregnancy status was determined via transrectal ultrasonography on d 29 and 64. A subset of pregnant heifers (BST, n = 7; CTL, n = 5) were harvested on d 84 and complete gravid reproductive tracts and liver tissue were collected for analysis. Cytochrome P450 1A (CYP1A), 2C (CYP2C), 3A (CYP3A), and uridine 5’-diphospho-glucuronosyltransferase (UGT) activities were determined. Mean change in BW and average daily gain of heifers between fixed-time artificial insemination (d 0) and d 77 did not differ between treatments (P ≥ 0.05). Mean concentrations of insulin-like growth factor 1 (IGF-1) were greater (P < 0.001) in BST (347 ± 27.7 ng/mL) compared to CTL (135 ± 32.8 ng/mL) heifers. Mean placental weight, fetal membrane weight, uterine weight, ovarian and corpus luteum (CL) weights, as well as fetal morphometric data did not differ (P ≥ 0.05) between treatments. However, BST heifers had greater (P = 0.03) quantities of combined fetal fluid compared to CTL (521.6 ± 22.9 g vs. 429.6 ± 27.14 g, respectively). Tendencies were observed for BST heifers to have reproductive tracts with fewer placentomes (P = 0.08) and fetuses with greater umbilical diameters (P = 0.09) compared to CTL. Activity of CYP1A did not differ (P ≥ 0.05) within maternal and fetal liver, caruncle, cotyledon, or CL tissue samples between treatments. Furthermore, CYP3A activity was only observed in maternal liver samples and was not different between treatments (P ≥ 0.05). Interestingly, CYP2C activity was greater (P = 0.01) in the liver of BST vs. CTL heifers, and UGT activity was greater (P = 0.02) in the CL from BST heifers compared to CTL. In conclusion, administration of bST during the first third of gestation increased plasma concentrations of IGF-1, which resulted in an increase in fetal fluid, decrease in placentome number, and greater umbilical diameter, but failed to alter fetal development.

Recombinant bovine somatotropin in the synchronization of ovulation in crossbred dairy cows (Bos taurus indicus × Bos taurus taurus)

Aim: The aim of this study was to evaluate the effects of the administration of recombinant bovine somatotropin (rbST) at the moment of implementation of the timed artificial insemination protocol, on follicular dynamics and pregnancy rate in crossbred cows. Materials and Methods: A total of 346 cows were used in two experiments with a factorial 2×2 design. The cycling cows (Tcycling) and the anestrous cows (Tanestrous) were considered as factor 1 and the administration of rbST (TrbST) or not (Tcontrol) as factor 2. The experimental protocol: (1) Tcontrol – day 0 (D0), insertion of a progesterone-release intravaginal device (PRID) plus 2 mg of estradiol benzoate (EB); D8, PRID removal, plus 0.150 mg of prostaglandin F2α, and 400 IU of equine chorionic gonadotropin; D9, 1 mg of EB; and with artificial insemination at day 10; (2) TrbST – similar to Tcontrol plus 500 mg of rbST on D0. In experiment I, ultrasound examinations were performed in all treatments. In experiment II, the cows' pregnancy rate was evaluated. Data were analyzed with 5% probability. Results: There was no effect of the protocols on cows cyclicity or follicular growth rate (p>0.05). There was no interaction of the effects, administration of rbST, and the cyclicity of cows on the pregnancy rate. The total pregnancy rate observed was 49.0%. The pregnancy rate in cows receiving rbST was lower for anestrous compared with cycling cows (p<0.05). Conclusion: The administration of rbST did not alter the patterns of follicular dynamics nor the ovulation rate. However, cows in anestrous that received rbST had lower pregnancy rates than cycling cows.