In a commercial hatchery, chicks (or poults) hatch over a 24-48 hour period. All chicks remain in the incubator until the majority of the chicks have emerged from the shell. Once removed from the incubator, the newly hatched chick has to undergo several hatchery treatments and is then transported before being placed on the broiler farm. This means that, under practical conditions, chicks are deprived of feed and water for up to 72 hours. In addition, the time of hatch within the hatching window and the spread of hatch cause variability in the amount of time that chicks are feed deprived. Literature on feed deprivation after hatch clearly demonstrates the detrimental effects of any delay in feed access on performance of the chicks with respect to growth, immune system activation, digestive enzyme stimulation and organ development. Improved management strategies, such as shortening the hatching window or the time to first feeding by specific management measures, provide an alternative in dealing with the negative effects caused by a delay in feed access. The development of pre-starter diets that better meet the needs of the newly hatched chicks or in ovo feeding to bridge the gap between hatch and first feeding provide other alternatives in overcoming these problems. However, speculation remains regarding the importance of in ovo or early feeding, or whether the in ovo or early feeding itself is responsible for the beneficial effects reported. The aim of the following review is to discuss the current status of research into early feeding and to stimulate future and further research regarding these topics.

Temperatures continuously higher and lower than the standard incubation temperature by 3°C from embryonic d 16 until embryonic d 18.5 result in differential effects on embryonic development, the hatching process, and embryonic metabolism. Embryos in the high-temperature group were forced into a state of malnutrition by the temperature treatment, as reflected by reduced embryo growth and yolk consumption, resulting in a significantly lower chick weight at hatch. In addition, altered air cell and blood gases as well as a retarded hatching process further indicated reduced growth of embryos exposed to higher incubation temperatures during the latter part of incubation. In addition, hatchability was significantly reduced by the high-temperature treatment due to higher embryonic mortality during the treatment period and the hatching process. Levels of blood glucose, lactate, liver glycogen, plasma triglycerides, and nonesterified fatty acids indicated an altered carbohydrate and lipid metabolism for the high-temperature group. Although the hatching process of embryos exposed to lower incubation temperatures was also significantly retarded, their embryonic development and growth were strikingly similar to those of the control group.

It has been suspected for many years that cattle possess two functional IgH gene loci, located on Bos taurus autosome (BTA) 21 and BTA11, respectively. In this study, based on fluorescence in situ hybridization and additional experiments, we showed that all functional bovine IgH genes were located on BTA21, and only a truncated μCH2 exon was present on BTA11. By sequencing of seven bacterial artificial chromosome clones screened from a Hostein cow bacterial artificial chromosome library, we generated a 678-kb continuous genomic sequence covering the bovine IGHV, IGHD, IGHJ, and IGHC genes, which are organized as IGHVn-IGHDn-IGHJn-IGHM1-(IGHDP-IGHV3-IGHDn)3-IGHJn-IGHM2-IGHD-IGHG3-IGHG1-IGHG2-IGHE-IGHA. Although both of two functional IGHM genes, IGHM1 and IGHM2, can be expressed via independent VDJ recombinations, the IGHM2 can also be expressed through class switch recombination. Likely because more IGHD segments can be involved in the expression of IGHM2, the IGHM2 gene was shown to be dominantly expressed in most tissues throughout different developmental stages. Based on the length and identity of the coding sequence, the 23 IGHD segments identified in the locus could be divided into nine subgroups (termed IGHD1 to IGHD9). Except two members of IGHD9 (14 nt in size), all other functional IGHD segments are longer than 30 nt, with the IGHD8 gene (149 bp) to be the longest. These remarkably long germline IGHD segments play a pivotal role in generating the exceptionally great H chain CDR 3 length variability in cattle.

Addition of the CSM to an MVR procedure can decrease the risk of stroke or death and high sinus rhythm at 1 year without increasing the operative risk. CSM is a safe and effective approach to treating AF associated with RMVD.

BackgroundCytokines are important mediators and regulators of host responses against foreign antigen, with their main function to orchestrate the functional activities of the cells of the immune system. However little is known about the role of cytokines in pathogenesis and immune responses caused by infectious bursa disease virus (IBDV). The aim of this study was to examine the transcripts of cell-mediated immune response-related cytokine genes in the bursal tissues of chickens infected with IBDVs of varying virulence to gain an understanding of pathological changes and mechanisms of immunosuppression caused by IBDV infection and the immune responses evoked.ResultsReal-time quantitative PCR analysis revealed that the expression levels of both Th1 [interferon (IFN)-γ, interleukins (IL)-2 and IL-12p40] and Th2 (IL-4, IL-5, IL-13 and IL-10) cytokines were significantly up-regulated following challenge with the H strain (vvIBDV) and up to 2- and 30-fold, respectively (P < 0.05). Following infection with the Ts strain (cell-adapted virus) these cytokine transcripts were up-regulated at 5 days post-infection (dpi), 2- and 13-fold respectively (P < 0.05), while the expression levels of IL-2 and IL-4 were not significantly different (P > 0.05). A higher degree of cytokine expression was induced by the H strain compared with the Ts strain.ConclusionThe results indicate that the expression of cell-mediated immune-related cytokine genes is strongly induced by IBDV, especially by the vvIBDV, H strain and reveal that these cytokines could play a crucial role in driving cellular immune responses during the acute phase of IBDV infection, and the cellular immune responses caused by IBDV of varying virulence are through different signaling pathways.