Effects of maternal care and selection for low mortality on tyrosine hydroxylase concentrations and cell soma size in hippocampus and nidopallium caudolaterale in adult laying hen.

Feather pecking and cannibalism in farm-kept laying hens are damaging behaviors both in terms of animal welfare and economic loss, and a major challenge in modern poultry farming. Both rearing with a foster hen and genetic selection have been demonstrated to reduce feather pecking in laying hens. We examined the effects of rearing with a foster hen, genetic selection for low mortality from cannibalism, and interactions between both, using cellular morphology and levels of the rate-limiting enzyme in dopamine production, tyrosine hydroxylase, in the hippocampus and nidopallium caudolaterale (NCL) as a potential measure for laying hen welfare. Hens from the second generation of a sib-selection scheme line derived from a pure-bred White Leghorn line, selected for low mortality and for production characteristics, or their control line (CL) selected only for production characteristics, were housed with or without a foster Silky hen for the first 7 wk of life. Aside from the presence or absence of a foster Silky hen during the first 7 wk of life, housing conditions were identical for all hens. The hens were then sacrificed and brains were removed at 52 wk of age. Brains were sectioned and stained using a Nissl staining to reveal cell soma morphology, or using immunocytochemistry for tyrosine hydroxlase. A greater degree of lateralization in the hippocampus was observed in hens reared without a foster hen, as measured by absolute difference in cell soma size between hemispheres (P<0.05). The low mortality line showed decreased concentrations of tyrosine hydroxylase in the NCL compared with the CL (P<0.005). Our results indicate that morphological changes in brain induced in very early life can be detected in adult hens, and that genetic selection against mortality due to cannibalism impacts tyrosine hydroxylase in the NCL of laying hens. These observations strengthen the notion that brain measures may be useful as potential readouts for animal welfare.

Effect of cumulus cell removal of in vitro matured bovine oocytes prior to in vitro fertilization on subsequent cleavage rate.

The aim of this study is to identify the effect of cumulus cells removal prior to the in vitro fertilization of matured bovine oocytes on cleavage rate. Denuded, matured oocytes were fertilized in presence or absence of loose cumulus cells, cumulus cell conditioned IVF medium (CCCM), charcoal-treated CCCM and charcoal-treated CCCM supplemented with progesterone at a final concentration of 150 ng/ml. After 18 h of incubation with sperm, the presumptive embryos were cultured on a BRL monolayer and the percentage of cleaved embryos was evaluated on Day 4. Removal of cumulus cells prior to IVF significantly reduced the cleavage rate (25% for denuded oocytes versus 56% for cumulus-oocyte complexes (COCs)). The addition of loose cumulus cells partially restored the effect of denudation (cleavage rate: 37% for denuded oocytes supplemented with loose cumulus cells versus 27% for denuded oocytes and 58% for COCs). CCCM also had a positive effect on the cleavage rate of oocytes denuded prior to IVF (36% for denuded oocytes fertilized in CCCM versus 14% for denuded oocytes). Treating the CCCM with charcoal resulted in complete loss of its effect on cleavage rate (18% for denuded oocytes fertilized in charcoal-treated CCCM versus 34% for denuded oocytes fertilized in CCCM). The addition of progesterone to charcoal-treated CCCM partially restored the reduction of the cleavage rate caused by charcoal treatment (27% for denuded oocytes fertilized in charcoal-treated CCCM supplemented with progesterone versus 14% for denuded oocytes fertilized in charcoal-treated CCCM and 36% for denuded oocytes fertilized in CCCM). In conclusion, removal of cumulus cells prior to IVF adversely affects the cleavage rate through loss of a factor secreted by these cells. This factor probably is progesterone.

Improved in vitro embryo development using in vivo matured oocytes from heifers superovulated with a controlled preovulatory LH surge.

In bovine in vitro embryo production, the IVM step is rather successful with 80% of the oocytes reaching the MII stage. However, the extent to which the process limits the yield of viable embryos is still largely unknown. Therefore, we compared embryonic developmental capacity during IVC of IVF oocytes which had been matured in vitro with those matured in vivo. In vitro maturation was carried out for 22 h using oocytes (n = 417) obtained from 2- to 8-mm follicles of ovaries collected from a slaughterhouse in M199 with 10% fetal calf serum (FCS), 0.01 IU/mL LH, and 0.01 IU/mL FSH. In vivo matured oocytes (n = 219) were aspirated from preovulatory follicles in eCG/PG/anti-eCG-superovulated heifers 22 h after a fixed time GnRH-induced LH surge; endogenous release of the LH surge was suppressed by a Norgestomet ear implant. This system allowed for the synchronization of the in vitro and in vivo maturation processes and thus for simultaneous IVF of both groups of oocytes. The in vitro developmental potential of in vivo matured oocytes was twice as high (P < 0.01) as that of in vitro matured oocytes, with blastocyst formation and hatching rates 11 d after IVC of 49.3 +/- 6.1 (SEM; n = 10 heifers) vs 26.4 +/- 1.0% (n = 2 replicates), and 39.1 +/- 5.1% vs 20.6 +/- 1.4%, respectively. It is concluded that IVM is a major factor limiting in the in vitro production of viable embryos, although factors such as the lack of normal preovulatory development of IVM oocytes contributed to the observed differences.

Gas conductance and metabolism of shorebird eggs: variation within and between species.

Fresh egg mass (M0; g), water vapor conductance of the egg shell (GH2O; mg.[Torr.d]-1), and neonate mass (Mn; g) were measured in the ruff (Philomachus pugnax), common redshank (Tringa totanus), northern lapwing (Vanellus vanellus), black-tailed godwit (Limosa limosa), and Eurasian curlew (Numenius arquata). In addition, the development of embryonic O2 consumption (MO2; ml.d-1) and CO2 production (MCO2; ml.d-1) were measured in these species, except the ruff. In northern lapwing and black-tailed godwit eggs the coefficients of variation for GH2O were 3.8 and 2.3 times higher, respectively, than those for M0. In these two species only about 10% of the variation for GH2O was attributable to M0, and about 77% to differences between clutches, suggesting a strong maternal component. In the northern lapwing, embryonic MO2 plateaued prior to internal pipping, but not in the common redshank and black-tailed godwit. The latter result is in contrast to embryonic patterns previously described for other precocial species. In shorebirds the occurrence of an embryonic MO2 plateau is not related to the neonatal level of cold-induced thermogenesis.

Acetoacetate and glucose as substrates for lipid synthesis by rat brain oligodendrocytes and astrocytes in serum-free culture.

We have compared glucose and acetoacetate as precursors for lipogenesis and cholesterogenesis by oligodendrocytes and astrocytes, using mixed glial cultures enriched in oligodendrocytes. In order to differentiate between metabolic processes in oligodendrocytes and those in astrocytes, the other major cell type present in the mixed culture, we carried out parallel incubations with cultures from which the oligodendrocytes had been removed by treatment with anti-galactocerebroside serum and guinea-pig complement. The following results were obtained: 1. Both oligodendrocytes and astrocytes in culture actively utilize acetoacetate as a precursor for lipogenesis and cholesterogenesis. 2. In both cell types, the incorporation of acetoacetate into fatty acids and cholesterol exceeds that of glucose by a factor of 5-10 when the precursors are present at concentrations of 1 mM and higher. 3. Glucose stimulates acetoacetate incorporation into fatty acids and cholesterol, whereas acetoacetate reduces the entry of glucose into these lipids. This suggests that glucose is necessary for NADPH generation, but that otherwise the two precursors contribute to the same acetyl-CoA pool. 4. Both with acetoacetate and with glucose as precursor, oligodendrocytes are more active in cholesterol synthesis than astrocytes. 5. Using incorporation of 3H2O as an indicator for total lipid synthesis, we estimated that acetoacetate contributes one third of the acetyl groups and glucose one twentieth when saturating concentrations of both substrates are present.