Herbage yield in Signalgrass pastures as affected by grazing management

Signalgrass is largely planted as cultivated pasture in Brazil, but no management targets have been identified. The objective of this study was to evaluate daily herbage accumulation rate (HAR) in Signalgrass pastures grazed at two intensity x two frequency treatments using steers. Target intensities corresponded to 5 and 10 cm post-graze sward height and frequencies were determined by pre-graze sward light interception (LI = 95 or 100%) by the canopy. The trial was carried out from January 2007 to April 2008 on an Entisol. Less frequently grazed pastures had higher HAR during the entire period (29 and 36 kg/ha for 95 and 100%-LI, respectively). There was no intensity effect on HAR, except in the 2007 summer season (January to March) when pastures grazed to 10 cm had a higher HAR (59 kg/ha) than those grazed to 5 cm (45 kg/ha). Total leaf yield increased when regrowth was longer (7930vs. 8729 kg/ha for 95 and 100%-LI, respectively), but stem and dead material yield increased as well (4877 vs. 7155 kg/ha for 95 and 100%-LI, respectively). The advantages of extending the rest period due to increased HAR was counterbalanced by the great influence of stem and dead material, decreasing pasture leafiness and likely forage nutritive value on the grazed stratum

Influence of BMP-2 on early follicular development and mRNA expression of oocyte specific genes in bovine preantral follicles cultured in vitro

This study evaluates the effect of different concentrations (0, 10, 50 and 100ng/mL) of bone morphogenetic protein-2 (BMP-2) on primordial and secondary follicle development. It also investigates the effects of FSH and BMP-2 on the growth, morphology, ultrastructure and expression of mRNA for GDF9, NLRP5 and NPM2 genes in secondary follicles cultured for 18 days. The presence of BMP-2 at all tested concentrations increased the development of primordial follicles in vitro, but the highest concentration of BMP-2 (100 ng/mL) reduced the percentage of normal follicles when compared with tissues cultured with 10 ng/mL BMP-2. During culture of secondary follicles, in contrast to higher concentrations (50 or 100 ng/mL), 10 ng/mL BMP-2 kept the morphology of follicles during initial stages of in vitro culture. This concentration of BMP-2 also benefits maintenance of the ultrastructure of 18-day cultured follicles. The presence of both BMP-2 and FSH in culture medium resulted in a significant (P<0.05) increase in follicular diameter after 18 days of culture. However, both FSH and BMP-2 reduced follicular mRNA expression of GDF9 and NLRP5 when compared to follicles cultured in media containing only FSH. In combination with FSH, BMP-2 reduced the mRNA levels of NPM2, when compared to follicles cultured in control medium. It is concluded from these data that 10 ng/mL BMP-2 promotes the growth of primordial in vitro and it helps to maintain the ultrastructure of secondary follicles, while FSH is more important for better expression of follicular markers like GDF9 and NLRP5