Genetic Analysis of the Iowa Beef Tenderness and Carcass Evaluation Project

Steers from the Iowa Beef Tenderness and Carcass Evaluation Project were harvested and carcass data, including Warner-Bratzler shear force values, were collected. The heritability estimate of Warner-Bratzler shear force in this data set was 0.45, and the genetic correlation between tenderness and marbling score was -0.40. Steers with more marbling were more tender. Heritabilities for feed consumed per pound of gain and for feed consumed per day were 0.25 and 0.26 respectively. These traits were highly correlated with gain, but had no relationship to each other. The heritability of dressing percentage was 0.52. These preliminary estimates can be expected to change as more data are collected

Ribeye Area Trends in Yearling Angus Bulls

Ultrasound carcass data from yearling Angus bulls were analyzed to determine trends in ribeye area. Bulls with a heavier scan weight had larger ribeyes. Also, bulls with an increased amount of 12-13th rib fat had larger ribeyes. The most efficient bulls with the largest ribeyes had the greatest amount of external rib fat

Ribeye Area Trends in Yearling Angus Heifers

Ultrasound carcass data from yearling Angus heifers were analyzed to determine trends in ribeye area. Heavier heifers at scanning had larger ribeyes. Also, heifers with an increased amount of external rib fat had larger ribeye areas. The most efficient heifers with the largest ribeyes had the greatest amount of 12-13th rib fat

Heritability and Correlation Estimates of Carcass Data from Angus-Sired Steers

Carcass data including Warner-Bratzler shear force, marbling score, hot carcass weight, 12-13th rib fat, and ribeye area from 589 Angus-sired steers in the National Cattlemen’s Beef Association Carcass Merit Project were analyzed to estimate heritabilities and genetic correlations. Genetic parameters were estimated using the sire/maternal-grandsire model with the relationship matrix. The heritabilities for tenderness, marbling, hot carcass weight, ribeye area and rib fat were .25, .29, .79, .59, and .07, respectively

Relationship between Body Composition and Reproduction in Heifers

Carcass and reproductive data including scan weight, ribeye area, rump fat, 12-13th rib fat and percentage intramuscular fat and reproductive tract scores (RTS) at 344 days were collected on 180 1998-born and 70 1999-born Angus heifers to determine the relationship between these traits. 1998-born heifers with higher RTS tended to be heavier and have more rump fat at 405 days (P \u3c .05). Heavier heifers and heifers with more rump fat had higher RTS when adjusted to 395 days (P \u3c .05). 1999-born heifers showed a similar pattern, with heavier heifers having higher RTS (P \u3c .05). Rump fat was not as significant for 1999-born heifers compared with 1998-born heifers. Heavier heifers with more rump fat are more likely to have more mature reproductive tracts at breeding

Tales of diversity: Genomic and morphological characteristics of forty-six <i>Arthrobacter</i> phages

<div><p>The vast bacteriophage population harbors an immense reservoir of genetic information. Almost 2000 phage genomes have been sequenced from phages infecting hosts in the phylum Actinobacteria, and analysis of these genomes reveals substantial diversity, pervasive mosaicism, and novel mechanisms for phage replication and lysogeny. Here, we describe the isolation and genomic characterization of 46 phages from environmental samples at various geographic locations in the U.S. infecting a single <i>Arthrobacter</i> sp. strain. These phages include representatives of all three virion morphologies, and Jasmine is the first sequenced podovirus of an actinobacterial host. The phages also span considerable sequence diversity, and can be grouped into 10 clusters according to their nucleotide diversity, and two singletons each with no close relatives. However, the clusters/singletons appear to be genomically well separated from each other, and relatively few genes are shared between clusters. Genome size varies from among the smallest of siphoviral phages (15,319 bp) to over 70 kbp, and G+C contents range from 45–68%, compared to 63.4% for the host genome. Although temperate phages are common among other actinobacterial hosts, these <i>Arthrobacter</i> phages are primarily lytic, and only the singleton Galaxy is likely temperate.</p></div