Hemoglobin genotype has minimal influence on the physiological response of juvenile atlantic cod (Gadus morhua) to environmental challenges

Hemoglobin (Hb) polymorphism in cod is associated with temperature‐related differences in biogeographical distribution, and several authors have suggested that functional characteristics of the various hemoglobin isoforms (HbIs) directly influence phenotypic traits such as growth rate. However, no study has directly examined whether Hb genotype translates into physiological differences at the whole animal level. Thus, we generated a family of juvenile Atlantic cod consisting of all three main Hb genotypes (HbI‐1/1, HbI‐2/2, and HbI‐1/2) by crossing a single pair of heterozygous parents, and we compared their metabolic and cortisol responses to an acute thermal challenge (10&deg;C to their critical thermal maximum [CTM] or 22&deg;C, respectively) and tolerance of graded hypoxia. There were no differences in routine metabolism (at 10&deg;C), maximum metabolic rate, metabolic scope, CTM (overall mean 22.9&deg; &plusmn; 0.2&deg;C), or resting and poststress plasma cortisol levels among Hb genotypes. Further, although the HbI‐1/1 fish grew more (by 15%&ndash;30% during the first 9 mo) when reared at 10&deg; &plusmn; 1&deg;C and had a slightly enhanced hypoxia tolerance at 10&deg;C (e.g., the critical O2 levels for HbI‐1/1, HbI‐2/2, and HbI‐1/2 cod were 35.56% &plusmn; 1.24%, and 40.20% &plusmn; 1.99% air saturation, respectively), these results are contradictory to expectations based on HbI functional properties. Thus, our findings (1) do not support previous assumptions that growth rate differences among cod Hb genotypes result from a more efficient use of the oxygen supply&mdash;that is, reduced standard metabolic rates and/or increased metabolic capacity&mdash;and (2) suggest that in juvenile cod, there is no selective advantage to having a particular Hb genotype with regards to the capacity to withstand ecologically relevant environmental challenges.<br /

Effects of Second Implant on Feedlot Gain and Carcass Traits

Two hundred eighteen steers were finished in a total confinement deep-bedded system at the Armstrong Research Farm, Lewis, IA during 2009. All steers were implanted with Synovex-Choice on day 1 and half the steers in each pen were implanted with Synovex-Choice on day 56. All steers were harvested on day 118. The 2nd implant resulted in an immediate and significant improvement in average daily gain. In the 76 day weigh period following reimplantation the group receiving the 2nd implant gained .66 lb/day more than the group not receiving an additional implant. The overall average daily gain of steers implanted once compared to the steers implanted twice was 3.81 vs. 4.10. The 2nd implant group produced significantly heavier carcasses. There were no significant differences in carcass fat cover or ribeye area. The twice implanted steers had a lower percentage low Choice or better (P=.0571) and a greater percentage Select (P=.0555). Implanting a second time resulted in an increase in carcass weights, an almost significant reduction in % Choice but still resulted in a numerical, non-significant increase in carcass value

Effect of Implant Timing on Feedlot Gain and Carcass Traits

One hundred sixty one steers were finished in a total confinement deep-bedded system at the Armstrong Research Farm, Lewis, IA during 2008. The three treatment groups were implanted with Synovex-Choice 112, 82 and 56 days prior to harvest. The implant resulted in an immediate and significant improvement in average daily gain. In the weigh period immediately after receiving the implant average daily gains increased from .72 to 1.35 lb/day compared to treatment groups or group that had not yet received their implant. The overall average daily gain of steers implanted 112 days (3.76 lb/day) and 82 days (3.70 lb/day) prior to harvest was significantly more than steers implanted 56 days (3.44 lb/day) prior to harvest. The 112 day implant group produced significantly heavier carcasses than the 56 day implant group While the 82 day implant group average carcass weight was intermediate and not significantly different from the other treatment groups. There was no significant difference in carcass fat cover, however, steers implanted 112 and 82 days had significantly larger ribeyes than steers implanted 56 days prior to harvest. Numerically the 53% low Choice or better was lower for the steers implanted 56 days prior to harvest compared to 60% low Choice or better for the other two treatments. The increase in carcass weights resulted in incremental, nonsignificant increases in carcass value

Determination of Carcass and Live Body Weight of Finishing Cattle from Front Body Weights Taken at a Scale—Electronic Identification Equipped Water Fountain

A water fountain oriented cattle weight monitoring system was designed to automatically identify cattle and weigh cattle when they approached the in-pen water fountain to drink. This system provides a labor free means to monitor cattle in terms of daily weight gain and also provides an objective method to evaluate the health of cattle based on frequency of drinking and deviations from their normal pattern

Determination of Carcass and Live Body Weight Finishing Cattle from Front Body Weights Taken at a Scale—Electronic Identification Equipped Water Fountain

Utilizing a platform scale capable of weighing the ”front end” of feedlot cattle coupled with an electronic identification system provided a means by which both live and carcass weights of growing cattle can be monitored daily without disturbing normal routines for both cattle and the farm labor force

Soil Bacteria and Fungi Respond on Different Spatial Scales to Invasion by the Legume Lespedeza cuneata

The spatial scale on which microbial communities respond to plant invasions may provide important clues as to the nature of potential invader–microbe interactions. Lespedeza cuneata (Dum. Cours.) G. Don is an invasive legume that may benefit from associations with mycorrhizal fungi; however, it has also been suggested that the plant is allelopathic and may alter the soil chemistry of invaded sites through secondary metabolites in its root exudates or litter. Thus, L. cuneata invasion may interact with soil microorganisms on a variety of scales. We investigated L. cuneata-related changes to soil bacterial and fungal communities at two spatial scales using multiple sites from across its invaded N. American range. Using whole-community DNA fingerprinting, we characterized microbial community variation at the scale of entire invaded sites and at the scale of individual plants. Based on permutational multivariate analysis of variance, soil bacterial communities in heavily invaded sites were significantly different from those of uninvaded sites, but bacteria did not show any evidence of responding at very local scales around individual plants. In contrast, soil fungi did not change significantly at the scale of entire sites, but there were significant differences between fungal communities of native versus exotic plants within particular sites. The differential scaling of bacterial and fungal responses indicates that L. cuneata interacts differently with soil bacteria and soil fungi, and these microorganisms may play very different roles in the invasion process of this plant

Progress Report: A Water Fountain Orientated Cattle Monitoring System

An automated system for collecting in-pen drinking activity and weight gain was developed for group fed cattle using off-the-shelf radio frequency (RF) tags, RF readers, a ball-water fountain, floor scale and a wireless communications bridge. These items were coordinated using a custom software application and technical assistance provided by I.D.ology of Eau Claire, WI for the purpose of continually measuring in-pen weight gain and drinking behavior. These points of data collection then could be used to monitor animal health and development with minimal animal handling. This system has been installed at the Iowa State University – Armstrong research facility located near Lewis, Iowa. Initial data collection started in late fall 2007