Associations of a Leptin Gene Polymorphism with Beef Carcass Traits

The objective was to evaluate associations of leptin genotype with fat and muscle traits in cattle. A single nucleotide polymorphism located in exon 2 of the leptin gene in cattle codes for an amino acid change from arginine (R) to cysteine (C). Genotypes for the polymorphism were determined on 492 crossbred calves by AciI digestion of amplified PCR product (C allele: 130bp; R allele: 73bp and 57bp). Data were analyzed by least-squares, accounting for effects of genotype, sex, year, location, breed-type, and calf sire. Genotype was not significantly associated with carcass weight or ribeye area in any of the analyses. Associations of genotype with external fat thickness, KPH fat, and overall cutability were small and generally not statistically significant. Subjective marbling scores (assigned by USDA grader; 350 = slight 50, 400 = small 0, 450 = small 50) were higher (P = .02) for CC (411 units) than for RR (388 units) genotype when adjusted to a constant slaughter age of 433 days. Similar differences between genotypes in marbling scores were observed when adjusting to a constant carcass weight or external fat thickness. Given the relatively modest association between genotype and marbling, potential application of the marker in the industry as a selection tool would be most relevant in herds with a large proportion of market animals possessing marbling scores that are near a price threshold level (e.g., select/choice quality grade)

Leafy Spurge Biological Control Using Black Dot Flea Beetles and Deleterious Rhizobacteria: Final Report Submitted to South Dakota Department of Agriculture Weed and Pest Control

Size of leafy spurge (Euphorbia esula L) roots and their location in the soil profile are important factors relating to survival offirst-instar black dot flea beetle (Aphthona nigriscutis Foudras) larvae. First-instar larvae must find leafy spurge roots between 1 to 4 mm diam in the first 2 days after hatching from eggs for survival. In field studies, we ddermined that most flea beetle larvae reside within 7.6 em ofthe soil surface. Their location in the upper areas ofthe soil profile allows accessibility to desirable size roots, however the larvae are more susceptible to freezing temperatures in this region. Overall, there were fewer black dot flea beetle larvae in the soil at the Pollock site in 1997 compared to 1995 and 1996. In 1997, harsh winter weather conditions may have resulted in high mortality of larvae

Genetic Variation in Aphthona nigriscutis Foudras (Coleoptera: Chrysomelidae) Populations Introduced into the United States to Biologically Control Leafy Spurge

Cellulose acetate electrophoresis was used to examine the levels and distribution of genetic diversity in Aphthona nigriscutis Foudras populations 5 to 9 yrs following their introduction to sites in North and South Dakota for the purpose of biologically controlling leafy spurge, Euphorbia esula L. Gene expression patterns of two enzymes, phosphoglucomutase (PGM) and malate dehydrogenase (MDH), were analyzed to determine the genetic variation and distance among and between populations in North America and Hungary where the species is indigenous. Dakota populations were variable and more similar to each other genetically than they were to the Hungarian population. North American populations were also genetically differentiated from each other as well as the Hungarian population according to geography and environment