No abstract

The objective of this study was to evaluate the effect of paternal high energy diets on blastocyst development during in vitro embryo production (IVP). Eight sires were stratified by body weight (initial BW = 946 ± 85 kg) and randomly assigned to the same diet (NEm = 2.10, NEg = 1.44, CP = 14.1%, NDF = 16.6%, DM basis) fed at two different inclusion rates while having ad libitum access to bermudagrass hay (NEm = 1.02, NEg = 0.45, CP = 10.2%, NDF = 71.6). After a 10-d adaptation period, sires were individually fed to receive 0.5% (MAINT) or 1.25% [High gain (HG)] of their BW daily for 67 days. At the end of the feeding period, semen was collected through electroejaculation and frozen. Antral follicles were aspirated from ovaries obtained from a slaughterhouse and utilized for IVP in 4 independent replicates (n = 2,227 total oocytes). Cleavage rates were evaluated 48 h after fertilization and blastocyst development rates were evaluated after 7 days of embryo culture. The proposed treatments successfully induced differences in BW gain (P < 0.01; 2.28 vs -0.04 kg/d) and carcass composition (Rump fat: 1.63 vs. 0.41 cm, P = 0.08; Rib fat: 1.06 vs. 0.41 cm, P = 0.02; intramuscular fat: 3.5 vs. 3.0%, P = 0.36; for HG vs. MAINT sires, respectively). There was a significant decrease in cleavage rates (69.9 ± 2.5 vs. 65.0 ± 2.7; P < 0.04), blastocyst rate as a percentage of oocytes (16.7 ± 2.9 vs. 11.5 ± 2.1; P < 0.01), and blastocyst rates as a percentage of cleaved structures (24.1 ± 3.8 vs. 11.5 ± 2.1; P < 0.01) for HG compared with MAINT sires. In conclusion, sires fed diets that induce highly anabolic conditions had impaired blastocyst development compared to sires fed a maintenance diet.

The aim of this study was to evaluate the supplementation of Nerve Growth Factor (β-NGF) in the maturation medium in in vitro embryo production routines. Antral follicles were aspirated from ovaries of cows obtained from slaughterhouses and then oocytes were selected for quality (grades I and II) for in vitro maturation and subjected to 4 successive in vitro embryo production routines (IVEP). Supplementation of 100 ng of β-NGF was performed in the oocyte maturation medium 22 hours before in vitro fertilization. 48 hours after fertilization of the oocytes, an analysis was made of their cleavage rate by counting blastomeres with the aid of a stereoscopic microscope (cleavage rate = number of embryos / number of initial oocytes). Seven days after fertilization, the blastocyst rate was determined through the relation to the number of oocytes that started cleavage and reached this stage of development (blastocyst rate = number of blastocyst / number of oocytes that started cleavage). To verify the existence of a difference between the supplemented and the non-supplemented groups, the paired T test was applied, using the Excel / Action software (Microsoft). In vitro embryo production routines supplemented with β-NGF in the maturation medium had, on average, a higher cleavage rate (P = 0.0072) and a higher blastocyst rate (P = 0.0033) compared to non-supplemented routines with β-NGF. In this study was demonstrated that Nerve Growth Factor supplementation in the maturation medium improves the efficiency of in vitro embryo production in cattle, and this protein has a probable action in the oocyte maturation process.