Serum albumin level of donor cows as indicator of development competence of oocytes

Abstract

Adequate nutrition is required for maintenance of normal production and reproduction in cattle. Strydom et al (2008) showed that albumin (the most abundant plasma protein) is the best predictor of malnourishment in South African cattle. Protein supplementation of in vitro embryo production (IVEP) media affects oocyte development into blastocysts. The objective of this study was to determine if serum albumin level of the donor cow could be used as a predictor of the developmental competence of oocytes, and if IVEP media can be optimised by additional protein supplementation for oocytes derived from donor cows with inadequate (≤35.9 g/l) levels of serum albumin. A total of 1024 oocytes were cultured during this prospective cohort study. Of these, 460 oocytes originated from cows with inadequate serum albumin levels and 564 from cows with adequate serum albumin (≥36.0 g/L). Oocytes of these two cohorts were randomly allocated to a control IVEP protocol or a protocol with additional protein supplementation. Mixed effects Poisson regression was performed for the number of oocytes that developed into blastocysts by the 7th day of culture. Adequate serum albumin level of donor cows independently resulted in 46% increased blastocyst formation in the control IVEP protocol (P = 0.02). Although protein supplementation of the IVEP protocol did not affect blastocyst formation in oocytes originating from cows with inadequate serum albumin, it independently reduced blastocyst formation by 30% in oocytes originating from cows with adequate serum albumin (P = 0.02). Other independent predictors of blastocyst outcome included higher serum urea nitrogen, lower beta-hydroxybutyric acid levels and lower fat grading of donor cows. It is concluded that adequate serum albumin of donor cows is a significant predictor of developmental competence of oocytes, and further research is required to determine optimal IVEP protein supplementation for oocytes originating from inadequately nourished cows. Vaccine matching: a different pathway to foot-and-mouth disease control Sirdar M.M.1, Blignaut B.1,2, Heath L.2, Gummow B.1,3, Fosgate G.T.1 1 Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, 0110, South Africa; e-mail: sirdar44@hotmail.com 2 Transboundary Animal Diseases, Onderstepoort Veterinary Research, Agricultural Research Council, Onderstepoort, 0110, South Africa 3 College of Public Health, Medical and Veterinary Sciences, James Cook University, QLD, Australia Foot-and-mouth-disease (FMD) is a highly contagious transboundary animal disease that affects cloven-hoofed animals. Vaccination is one of the most important approaches for FMD prevention and control. In the vaccinated FMD protection zone of South Africa, cattle are routinely vaccinated every four months with a trivalent vaccine (South African Territories (SAT) serotypes 1, 2 & 3). Vaccine matching is used to select the most effective vaccine to use during outbreaks by comparing the antigenic variability between field and vaccine viruses. The objectives of this study were to assess the vaccine match of 40 FMD field viruses and to develop a new vaccine matching technique that can be used when live vaccine virus is not available in the laboratory. A diverse group of 20 SAT1 and 20 SAT2 isolates collected from 1990-2015 were selected for study. Virus neutralization tests (VNT) were performed following the method described in the OIE Manual (2012). Two sets of pooled sera were used for each serotype; vaccinated bovine sera (4 to 16 weeks postvaccination) and convalescent bovine sera collected 3 weeks post experimental challenge. Novel r1-values were calculated using a new vaccine matching technique that incorporated reference strain viruses in the absence of information concerning the homologous vaccine viruses. Ratios were also calculated for the vaccine titre compared to a standardized positive control. Standard deviation and coefficient of variation were used to assess variability in titre measures. Scatter plots and Spearman’s rank correlation coefficient were used to evaluate agreement between the two methods. The kappa statistic was also used to assess agreement based on a “adequate match” cutoff of 0.3 as stated in the OIE FMD Diagnostics Manual. These new methods provide a feasible, rapid and reliable vaccine matching approach that will contribute to control of FMD in southern Africa.