Influence of sire breed (Bos indicus versus Bos taurus) and interval from slaughter to oocyte aspiration on heat stress tolerance of in vitro-produced bovine embryos

Based on in vitro experiments, Bos indicus embryos were more resistant to heat stress (HS) than Bos taurus embryos. To increase knowledge regarding differences between Bos indicus and Bos taurus in resistance to HS, the primary objective of this study was to determine if tolerance to HS is due to the breed, origin of the oocyte, sperm, or both. Additionally, the influence of the interval between ovary acquisition (in the abattoir) and oocyte aspiration in the laboratory, on early embryo development was ascertained. Oocytes were collected from Nelore and Holstein cows in an abattoir; 4.0 or 6.5 h later, oocytes were aspired in the laboratory, and then matured and fertilized using semen from Nelore (N), Gir (GIR), or Holstein (H) bulls. Ninety-six h post insemination (hpi), embryos with >= 16 cells were divided in two groups: control and HS. In the control group, embryos were cultured at 39 degrees C, whereas in the HS group, embryos were subjected to 41 degrees C for 12 h, and then returned to 39 degrees C. Rates of cleavage, and formation of morula and blastocysts were higher (P < 0.05) for oocytes aspirated at 4.0 versus 6.5 h after ovaries were acquired. Heat stress decreased rates of blastocyst formation for all breeds (N X N; H x H; and H X GIR) and in both time intervals (4.0 and 6.5 h). However, N X N had higher cleavage rate (P < 0.05) in both time intervals when compared with H X H and H X GIR. In addition, Nelore oocytes fertilized with Nelore semen (N X N) had higher blastocyst yields (P < 0.05) in the control and HS group, when compared with the other two breeds (H X H and H X GIR). We concluded that the breed of origin of the oocyte was more important than that of the sperm for development of thermotolerance, because bull breed did not influence embryo development after HS, and in vitro early embryonic development was impaired by increasing (from 4 to 6.5 h) the interval between ovary acquisition and oocyte aspiration. (C) 2011 Elsevier B.V. All rights reserved.

Effects of Incubation Temperature and Relative Humidity on Embryonic Development in Eggs of Red-Winged Tinamou (Rhynchotus rufescens).

This study was conducted to assess the effects of incubation temperature (34 C, 36[degree]C and 38[degree]C) and relative humidity (RH, 50% and 60%) on egg weight loss, embryo mortality, hatchability, incubation time and chick weight in eggs from red-winged tinamou. The eggs were placed in incubators that were operated at 34[degree]C, 36[degree]C, or 38[degree]C and 50% or 60% RH (mean wet bulb temperatures of 28[degree]C and 30[degree]C, respectively) from day 1 to hatching. Each treatment had two replicate groups of 30 eggs each. Hatchability varied with incubation temperature and RH and was highest for eggs incubated at 36[degree]C and 60% RH and lowest for eggs incubated at 38[degree]C. Early, intermediate and late embryo mortality were highest at 38[degree]C, 38[degree]C/50% RH, and 50% RH, respectively. Incubation period was longest at 34[degree]C and shortest at 38[degree]C/50% RH. Present results show the highest hatchability of red-winged tinamou eggs after incubation at 36[degree]C and 60% RH; highest embryo sensitivity to high temperature in the early period of incubation (1 to 7 days), to high temperature and low RH in the second period of incubation (8-14 days) and to low RH in the late period of incubation (after 15 days) and shortest incubation period with increasing temperature and RH.

Validation of an immunohistochemistry assay to detect turkey coronavirus: A rapid and simple screening tool for limited resource settings

The objective of the present study was to develop and apply the direct immunohistochemistry (D-IHC) assay to search for turkey coronavirus (TCoV) antigens in formalin-fixed embedded-paraffin tissues by the use of biotin-labeled polyclonal antibody. Twenty-eight-day-old embryonated turkey eggs (n = 50) were inoculated with TCoV-purified virus, and 3 d after inoculation, sections from ileum, ileum-cecal junction, and ceca were harvested, fixed in neutral formalin, and embedded in paraffin blocks and used as positive control. In addition, a total of 100 field samples from ileum, ileum-cecal junction, and ceca, collected from 30 to 45-d-old turkeys poults experiencing an outbreak of acute enteritis, were used to search for TCoV by the same D-IHC. All results were compared with those obtained by conventional RT-PCR and indirect fluorescent antibody assay (IFA) for all tested samples. Turkey coronavirus was detected in experimentally infected embryo tissues and also in field samples in 100% of ileum-cecal junction and ceca by the 3 detection procedures. With IFA as a reference assay, sensitivity and specificity of D-IHC were 98 and 58%, whereas sensitivity and specificity of reverse transcription-PCR were 96 and 66%, calculated from the total of tested samples from experimental infection. Each of the examined procedures was highly specific (D-IHC, 93%; RT-PCR, 90%), sensitive (D-IHC, 85%; RT-PCR, 86%), and agreement of both D-IHC and RT-PCR was 99 and 100%, respectively, compared with IFA results obtained from all the field samples. These findings demonstrated the utility of D-IHC for direct detection of TCoV from field samples and considering the sensitivity and specificity found here, can be used as an alternative technique.