A survey of yield differences between transgenic and non-transgenic crops

In the current survey, there was no clear evidence that GM (genetically modified) crops are higher yielding than those conventionally bred<fnoteref rid="fn1">1</fnoteref>. Furthermore, there were no trials to support valid comparisons of yield per se. This article investigates GM crop yields, introducing the importance of hybrid vigour and a non-stress environment for higher percentage heritability selection and therefore more productive conventional plant breeding and improved crops. GM technology and crops are compared with proven plant breeding methods, with respect to hybrid vigour and the economic viability of both systems. These proven methods of plant breeding are (1) traditional landrace cropping, (2) conventional Mendelian breeding and (3) Isolection Mendelian breeding, and are also considered historically.     

Assessing the usefulness of B‐mode and colour Doppler sonography,and measurements of circulating progesterone concentrations for determining ovarian responses in superovulated ewes

The main goal of this study was to assess the usefulness of two imaging modalities, namely the B‐mode and colour Doppler sonography, and serum progesterone (P₄) concentrations for determining the ovarian response in superovulated ewes. Twenty‐four sexually mature Santa Inês ewes underwent the superovulatory treatment consisting of eight injections of porcine FSH (total dose of 200 or 133 or 100 mg; n  =  8 ewes/total dose) given at 12‐hr intervals and initiated 48 hr before CIDR ^® (Pfizer Inc., Auckland, New Zealand) removal. Six days after natural mating, the ovaries of all donor ewes were visualized and examined with transrectal ultrasonography and then with videolaparoscopy to identify and enumerate corpora lutea (CL ) and luteinized unovulated follicles (LUF s). Jugular blood samples were collected just prior to ovarian examinations. The total number of CL (r  =  .78 and 0.83, p  <  .0001) and LUF s (r  =  .74 and 0.90, p  <  .0001) enumerated using the B‐mode and colour Doppler ultrasonographic technique, respectively, were correlated with that ascertained by videolaparoscopy. Circulating concentrations of P₄ were related directly to the number of healthy CL (r  =  .73, p  =  .0002) and inversely to the number of prematurely regressing CL (r  = ?.46, p  =  .03), but the accuracy of predicting the number of short‐lived CL with serum P₄ concentrations was very poor. The present results indicate that ultrasonographic imaging and serum P₄ measurements on the day of embryo recovery are useful indicators of total/normal CL numbers and both ultrasonographic techniques can be used to quantify LUF s in superovulated ewes.