Alfredo Emílio Silveira de Borba

Effects of plasma urea nitrogen levels on the bovine oocyte ability to develop after in vitro fertilization.

The overall aim of the present study was to evaluate in vitro development ability of oocytes recovered from 56 Holstein Frisian heifers with low [group 1 (G1): <13 mg /dl], moderate [group 2 (G2): 13-16 mg /dl] and high [group 3 (G3): >16 mg /dl] plasma urea nitrogen (PUN) concentrations, to determine whether PUN concentrations affect the competence of oocytes to progress to blastocysts after in vitro fertilization. In vitro oocyte and embryo development was assessed by blastocyst rates, embryo total cell numbers and apoptosis. Blood samples for the determination of PUN were collected 24 h prior to collection of the ovaries at the slaughter. A total of 112 ovaries were collected at a local abattoir and oocytes (n = 697) were aspirated, in vitro matured and fertilized. On day 8, blastocysts were assigned to the terminal dUTP nick end labelling assay. Cleavage rates were significantly higher (p < 0.001) for groups 1 and 2 than for group 3 (i.e. 72.5% and 72.2% vs 61.7%, respectively). The proportion of fertilized oocytes that developed into blastocysts was higher (p < 0.05) for group 1 than for group 3 (34.0% vs 23.0%, respectively). Day 8 blastocysts showed higher total cell counts (p < 0.05) for group 1 than for group 3 (123.7 vs 76.3), and a higher (p < 0.05) total apoptotic cell rate was found in group 3 (25.9 and 19.0 vs 43.2 for G1, G2 and G3, respectively). In conclusion, the ability of oocytes from heifers with increased levels of PUN to develop to the blastocyst stage was significantly reduced when standard routines for in vitro maturation, fertilization and culture were followed. These detrimental effects can be mediated in part through direct effect of urea and/or by the metabolic products on the process of follicle-enclosed oocyte nuclear and cytoplasmic development.

Effects of grass silage and soybean meal supplementation on milk production and milk fatty acid profiles of grazing dairy cows.

The effects of supplementation with grass silage and replacement of some corn in the concentrate with soybean meal (SBM) on milk production, and milk fatty acid (FA) profiles were evaluated in a replicated 4 x 4 Latin square study using 16 dairy cows grazing pasture composed of ryegrass, Kentucky bluegrass, and white clover. Each experimental period lasted for 3 wk. The 4 dietary treatments were PC, 20 h of access to grazing pasture, supplemented with 6 kg/d of corn-based concentrate mixture (96% corn; C); PCSB, 20 h of access to grazing pasture, supplemented with 6 kg/d of corn- and SBM-based concentrate mixture (78% corn and 18% SBM; CSB); SC, 7 h of access to grazing pasture during the day and 13 h of ad libitum access to grass silage at night, supplemented with 6 kg/d of C concentrate; and SCSB, 7 h of access to grazing pasture during the day and 13 h of ad libitum access to grass silage at night, supplemented with 6 kg/d of CSB concentrate. The concentrate mixtures were offered twice each day in the milking parlor and were consumed completely. Grass silage supplementation reduced dietary crude protein and concentration of total sugars, and dietary SBM inclusion increased dietary crude protein concentration and decreased dietary starch concentration. Milk yield and energy-corrected milk were increased by SBM supplementation of cows with access to grass silage. Milk protein concentration was lower in cows offered grass silage, regardless of whether SBM was fed. Dietary SBM inclusion tended to increase milk fat concentration. Plasma urea N was reduced by silage feeding and increased by SBM supplementation. Supplementation with grass silage overnight could represent a useful strategy for periods of lower pasture availability. Dietary inclusion of SBM in solely grazing cows had no effects on milk production and composition, exacerbated the inefficient capture of dietary N, and increased diet cost. Grass silage supplementation affected milk FA profiles, increasing both the FA derived from de novo synthesis and those derived from rumen microbial biomass, and decreasing the sum of C18 FA (mostly derived from diet or from mobilization of adipose tissue reserves). Milk fat concentrations of conjugated linoleic acid cis-9, trans-11, vaccenic acid (18:1 trans-11), and linolenic acid (18:3n-3) were unaffected by grass silage supplementation, suggesting that partial replacement of pasture by unwilted grass silage does not compromise the dietary quality of milk fat for humans.

Effects of chlorogenic acid on the maturation and fertilisation of bovine oocytes and their embryonic development with a comparative bovine granulosa cell co-culture

Chlorogenic acid (CGA) plays several biological roles, but lacks studies that demonstrate how this phenolic compound affects animal reproduction. The aim of the present study was to evaluate the effects of different CGA concentrations on bovine oocyte maturation and embryo development in vitro. This study also evaluates co-culture systems involving bovine granulosa cells (BGC) from fed with CGA containing plant, Pittosporum Undulatum. The ovaries were recovered after slaughter and the oocytes were removed, maturated, in vitro fertilized and cultured in medium containing CGA in 5 different concentrations 1.25; 2.5; 5; 10; 20 μm and a control group (0 μm) for seven days. Selected oocytes (n = 1040) were maturated in any of the 5 treatment or control groups. Significantly lower (P < 0.05) maturation rates were observed for the highest CGA concentrations 10 μm, and 20 μm, compared to the control group (Control = 93.4 ± 2.1% vs. 10 μm = 80.9 ± 2.2%; 20 μm 77.9 ± 3.3%). We observed that the higher the concentration of CGA present, the lower the rate of cleavage and development after 3 and 7 days, respectively. It was observed that the significant difference recorded in regards to embryonic development were evident between control and group (20; 51.1 ±5.6 vs. 19.4 ± 2.2%). In respects to the study involving co-culture of embryos with BGC the only difference recorded involved the block rate. No differences (P > 0.05) were identified between control and experimental groups in relation to the progesterone production by BGC. These results suggest that CGA may affect oocyte maturation and inhibit the progression of meiosis and consequently the entire embryo development in vitro.

Effect of feed with Pittosporum undulatum in vivo on bovine progesterone levels and embryos produced in vitro

Abstract: Feeding ruminants with Pittosporum undulatum can adversely affect the immune, endocrine, and reproductive systems. The aim of the present study was to evaluate how feeding with P. undulatum alters progesterone levels during the oestrus cycle, and fertilization and development of oocytes after in vitro fertilization (IVF). Heifers were fed a diet containing (n = 4) or not containing (n = 4) this plant. Peripheral blood samples were collected every 3 d and progesterone levels were analyzed by enzyme-linked immunosorbent assay (ELISA). The heifers’ ovaries were recovered after slaughter, and the oocytes were removed, maturated, in vitro fertilized, and cultured for 7 d, during which time their development was evaluated every 2 d. Results indicated that plasma concentrations of progesterone during the oestrus cycle were significantly higher (P < 0.01) in the luteal and follicular phases of the animals fed without Pittosporum when compared with those fed with Pittosporum. Statistical differences (P < 0.05) in maturation, cleavage rate, and embryonic development were observed between oocytes belonging to the experimental and control group. Rates of maturation, fertilization, and embryo development in the experimental group were, respectively, 78.3 ± 5.8, 29.92 ± 4.31, and 7.30 ± 3.1 compared with 90.5 ± 3.0, 41.86 ± 5.58, and 21.88 ± 6.85 in the control group. These differences can be explained because compounds from this plant can directly or indirectly inactivate cyclooxygenase-2 (COX-2), which may diminish follicular development through the inhibition of prostaglandins synthesis and oocyte maturation and, consequently, reduce the ability of oocytes to be fertilized and developed.