Sixteen steers were used to investigate the efficacy of the sustained-release implant of bovine somatotropin (bST) in improving growth and feed:gain ratio during 12 weeks. Administration of the 400 mg bST implant resulted in a 16.1% increase in growth rate, and this increase was significant (p less than .05). The use of the sustained-release implant did not alter (p greater than .05) feed intake and feed:gain ratio. Thirty-four cows were used to investigate the efficacy of the sustained-release implant of bST in milk production during 4 weeks. Administration of the 200 mg bST implant resulted in an 8.7% increase in milk production, and this increase was significant (p less than .05). Twenty-four barrows were used to investigate the efficacy of the sustained-release implant of porcine somatotropin (pST) in improving growth, feed:gain ratio and backfat thickness during 6 weeks. Administration of the 120 mg pST implant resulted in a 11.4% increase in feed:gain ratio and a 60% decrease in backfat thickness, and these results were significant (p less than .05). But the use of the sustained-release implant did not alter (p greater than .05) growth rate and feed intake.

The present study was carried out to examine the sustained release effect of the implantable bovine somatotropin (SRI-BST) formula. In the blood profile test in steers, the bovine somatotropin concentration in serum by radioimmunoassay showed the peak concentration on the first day after the implantation of the SRI-BST formula, and concentration proceeded for 5 days (p less than 0.05). The insulin-like growth factor-1 concentration showed the peak concentration on the seventh day after implantation of the SRIF-BST formula, and concentration proceeded for 10 days (p less than 0.05). The glucose showed the peak concentration on the first day after implantation of the SRI-BST formula, and concentration continued for 3 days (p less than 0.05). The blood urea nitrogen showed the lowest concentration on the third day after implantation of the SRI-BST formula, and concentration continued for 7 days (p less than 0.05). these results proved that the SRIF-BST formula was the sustained release effects in steers.

The present study was carried out to develop a sustained release implantable formula of bovine somatotropin (SRIF-BST) and to examine its sustained ralease effect. The SRIF-BST was produced by coating a solid pellet, which was comprised of BST and an excipient, made of a biodegradable polymer and poloxamer, which are capable of regulating the rate of BST release. The coated membrane of SRIF-BST was observed with a field emission scanning election microscope. The thickness of the coated membrane was approximately 1 ㎛, and the pore sizes of the coated membrane surface were below 10 ㎛. In dissolution test, the release duration of the SRIF-BST maintained for 10 days, whereas the release duration of the control BST formula maintained for 3 days. In weight gain assay and tibia test of hypophysectomized rats, the release duration of the SRIF-BST treated group was 12 days and the net weight gain was 53.16 g, also the tibia length and strength of the SRIF-BST treated group was increased 10.5% and 23.1% compared with those of the control group, respectively.

One of the first potential biotechnology products for animals production is BST. Effect of BST on lactating buffaloes was studied 8 buffaloes (Bubalus bubalis) were injected with sustained release formation Boosting-250, after 60 plus minus 5 days of calving. The overall increase in milk production was observed 18 percent and in milk fat 6.1 percent. BST is a protein hormone. Quality of management is the major factor affecting the magnitude of milk response to BST.

Crotalaria spectabilis (crotalária) e a Senna occidentalis (fedegoso) can grow in corn fields and during harvesting this cereal can be contaminated with the seeds of those plants which presents toxicity to animals. The aim of this study was to investigate the erythrocytes morphometric parameters, haematological variables and plasma hormones concentrations of broilers chickens fed rations of two energy levels to which were added 0,1% e 0,5% of Crotalaria spectabilis e a Senna occidentalis seeds, respectively. One hundred and eighty broilers chicks were divided into 6 groups according to a factorial analysis 3 x 2 (control, crotalaria and fedegoso as main treatments and two energy levels, 2,900 and 3,200 kcal ME/kg of ration). The results of this experiment showed that the crotalaria toxin reduced the number of the red blood cells, the haematocrit and mean corpuscular volume (MCV) with no effect on the morphometric studied parameters. These seeds due to its hepatic toxicity induced a high incidence of ascites. The fedegoso seeds were not able to induce ascite in the broilers. | Crotalaria spectabilis (crotalária) e a Senna occidentalis (fedegoso) podem crescer em plantações de milho e, durante a colheita, este cereal pode ser contaminado com as sementes dessas plantas, que apresenta toxicidade para os animais. O objetivo deste estudo foi investigar os parâmetros morfométricos dos eritrócitos, as variáveis hematológicas e a concentração plasmática hormonal dos frangos de corte tratados com ração de dois níveis de energia, que foi adicionada de 0,1% e 0,5% de sementes de Crotalaria spectabilis e Senna occidentalis, respectivamente. Cento e oitenta frangos de corte foram divididos em seis grupos, de acordo com uma análise fatorial 3 x 2 (controle, crotalária e fedegoso como tratamentos principais e dois níveis de energia, 2.900 e 3.200 kcal ME/kg de ração). Os resultados deste experimento mostraram que o efeito tóxico da crotalária determinou uma redução no número de hemácias, no valor do hematócrito e do VCM, não influenciando os parâmetros morfométricos avaliados. A semente de crotalária induziu, também, aumento na incidência de ascite, em função de sua toxicidade hepática. Já a semente de fedegoso não mostrou toxicidade suficiente para induzir ascite nos frangos.