Implications of possible effects on beef cow efficiency from selection for maternal ability, yearling weight, or a combination of the two

The selection practiced in the beef industry lacks uniformity because breeders are unaware of the potential effects on lifetime productivity when certain traits are emphasized in a selection program. This study involved data collected from 120 Angus and 90 Polled Hereford cows and their progeny (913 calves) over a five year period (1985 to 1989). Data were obtained from the calves at weaning, cows at weaning of calf, calves at a year of age, and from the 1988 calves at slaughter. These data were analyzed, and correlations involving both live-animal and carcass variables were calculated from the error line in an analysis conducted according to SAS (1985). The initial Angus cows were randomly divided into groups: control group in which no selection would be practiced, a group in which increased maternal milk production would be favored by selection (referred to as the maternal group), a group in which increased yearling weight would be favored by selection (referred to as the yearling weight group), and a group in which both of these criteria of selection would be used (referred to as the composite group). The Foiled Herefords, because of a smaller number of available cows, were divided into only three groups: control, maternal, yearling weight. Inferences were drawn as to the possible relative effectiveness of using either of these traits or a combination of them as the basis for selection. Changes in cow efficiency, defined as the ratio of adjusted 205-day weight of calf to actual cow weight at weaning of calf, in these selection systems were compared. Upon visual evaluation of the means, it was apparent that the most efficient 1989 Angus group was the composite (50.3%). The most efficient 1989 Polled Hereford group was the control (39.5%). No complete comparison between the herds can be made due to absence of a composite group in the Polled Herefords. In both herds, the least efficient group was the maternal (45.7%, Angus and 38.2%, Polled Hereford). Trends toward improved cow efficiency were observed in the Angus herd between 1985 and 1989. Cows that failed to calve were the least efficient and in both herds, were fatter and heavier at time of calf weaning. In visually evaluating the mean adjusted 205-day weight, mean adjusted 365-day, and mean adjusted 550-day weight, there appeared to be some improvement between 1985 and 1989 in the Angus herd and less improvement in the Polled Hereford herd. One major problem when selecting solely for maternal milk production is that heifers tend to become too fat. There was an increase of .2 mm backfat in the Angus herd and .4 mm in the Polled Hereford herd. Carcass data from 1988 steers were analyzed, and the mean yield grade and quality grade of carcasses from the Angus composite group were 2.8 and high Select (11.8), respectively. The analysis of the carcass data was across herds. Yield grade was correlated with fat thickness (.89) and %KPH (.72). Quality grade was correlated with marbling (.7). Percentage cutability was correlated negatively with fat thickness (-.88) and yield grade (-.99)

Bionomics of the Sugarcane Borer, Diatraea Saccharalis (F.), in Sweet Sorghum, Sorghum Bicolor (L.) Moench.

Economic impact studies revealed that the sugarcane borer, Diatraea saccharalis (F.), reduced sweet sorghum yield of total sugars up to 46% in artificially infested field trials. A significant relationship was found between D. saccharalis damage and yield loss that indicated an economic injury level of 10% bored internodes. Stalk weight, percent sucrose, and total sugars were negatively correlated to D. saccharalis damage; and increased fiber content was positively correlated to percent bored internodes. Information from damage levels, along with survival records, indicated that the economic threshold was reached when approximately 5% of the sweet sorghum plants contained small D. saccharalis larvae in their leafsheaths. Comparisons of the predator-prey relationship between sweet sorghum and sugarcane plots revealed that the arthropod predator composition was similar for both crops, but predator abundance in sugarcane was 4- and 16-fold greater than that found in sweet sorghum during 1985 and 1986, respectively. Predator habitat disruption associated with cultivation practices in sweet sorghum and sugarcane is important in this relationship. The red imported fire ant, Solenopsis invicta Buren, was the dominant arthropod predator found in pitfall traps and canopy samples of each crop. Based upon pitfall trap determinations, carabid larvae, cicindelids, and the Araneae were significantly more abundant predators in sweet sorghum compared with sugarcane. Also populations of carabid larvae, chrysopids and Orius spp. were significantly greater in sweet sorghum canopy samples. Reduced damage by D. saccharalis in plots without predator suppression resulted in 22.4 and 18.6% greater yield of total sugars in sweet sorghum and sugarcane plots, respectively. Compared with sugarcane \u27CP74-383\u27, D. saccharalis larval survival inside stalk tunnels was significantly greater in sweet sorghum \u27Wray\u27 during 1985. Predators reduced D. saccharalis moth emergence in both crops by approximately 50% in 1986. A two year study was conducted to evaluate the effects of sweet sorghum stalk barrel diameter and fiber content on D. saccharalis populations. Larval survival and moth emergence were not significantly effected by resultant increased fiber content that accompanied decreased stalk barrel diameter

HCN Determination in Sorghums by the Picric Acid Test

Agronom

Best Management Practices for Corn Production in South Dakota: Corn Insect Pests

Historically, the major corn insect pests have been corn rootworms (northern and western), European corn borer, and black cutworm. Bt-corn hybrids are effective against most of these pests. However, Bt-corn hybrids are not effective against corn leaf aphid, corn root aphid, sap beetles, corn rootworm adults, grasshoppers, white grubs, wireworms, seed corn beetle, and seed corn maggots. These insect pests can reduce corn yields. This chapter discusses the management and biology of important corn insect pests commonly observed in South Dakota

Extended Sentinel Monitoring of Helicoverpa zea Resistance to Cry and Vip3Aa Toxins in Bt Sweet Corn: Assessing Changes in Phenotypic and Allele Frequencies of Resistance

Transgenic corn and cotton that produce Cry and Vip3Aa toxins derived from Bacillus thuringiensis (Bt) are widely planted in the United States to control lepidopteran pests. The sustainability of these Bt crops is threatened because the corn earworm/bollworm, Helicoverpa zea (Boddie), is evolving a resistance to these toxins. Using Bt sweet corn as a sentinel plant to monitor the evolution of resistance, collaborators established 146 trials in twenty-five states and five Canadian provinces during 2020–2022. The study evaluated overall changes in the phenotypic frequency of resistance (the ratio of larval densities in Bt ears relative to densities in non-Bt ears) in H. zea populations and the range of resistance allele frequencies for Cry1Ab and Vip3Aa. The results revealed a widespread resistance to Cry1Ab, Cry2Ab2, and Cry1A.105 Cry toxins, with higher numbers of larvae surviving in Bt ears than in non-Bt ears at many trial locations. Depending on assumptions about the inheritance of resistance, allele frequencies for Cry1Ab ranged from 0.465 (dominant resistance) to 0.995 (recessive resistance). Although Vip3Aa provided high control efficacy against H. zea, the results show a notable increase in ear damage and a number of surviving older larvae, particularly at southern locations. Assuming recessive resistance, the estimated resistance allele frequencies for Vip3Aa ranged from 0.115 in the Gulf states to 0.032 at more northern locations. These findings indicate that better resistance management practices are urgently needed to sustain efficacy the of corn and cotton that produce Vip3Aa

Petaluma River, Channel Constriction Project, Sonoma County, California: Hydraulic Model Investigation

Source: https://erdc-library.erdc.dren.mil/jspui/The model study was conducted to validate the preliminary design of the constriction weir, to modify the weir dimensions as necessary to provide the desired upstream water-surface elevations, and to determine if the riprap protection blanket was adequately sized. The 1 : 10-scale model indicated the need for extending the riprap blanket downstream from the weir to ensure protection of the streambed inside the reach of the modeled area. It was also necessary to modify the constriction weir to achieve the desired upstream water-surface elevations and erosion protection. For the flow conditions tested, the riprap blanket and constriction weir design presented will provide erosion protection. _x000D_ _x000D_ NOTE: Plates 6-7 and 10-11 were removed from the final report, and thus are blank pages in the final report. They are not missing

Transgenic Insecticidal Corn: The Agronomic and Ecological Rationale for Its Use

We agree with Obrycki et al. (2001) that a broad-based ecological approach for new pest management technologies is desirable, but we unanimously and strongly disagree with some of their assumptions and conclusions about Bt corn. Bt corn is corn that has been genetically engineered to produce insecticidal proteins from the bacterium Bacillus thuringiensis. Because Bt corn is important for effective and ecologically sound management of lepidopteran pests of corn,we provide here relevant data, some of which is new, to help clarify the issues raised by Obrycki et al. (2001). Obrycki et al. (2001), citing Barry and Darrah (1991), claim that traditional plant breeding has developed corn plants that adequately protect against European corn borer. However, Barry and Darrah (1991) reported only “some resistance to whorl leaf feeding...[or] some resistance to sheath and sheath collar feeding,” which is not comparable with the nearly complete protection provided by Bt corn. Carpenter and Gianessi (2001) estimated that, nationally, during “10 of the 13 years between 1986 and 1998, European corn borer infestations...were such that corn growers would have realized a gain from planting Bt corn.” Similarly, the Environmental Protection Agency (USEPA 2000) estimated a net benefit to growers of $8.18 per hectare on 8 million hectares of Bt corn planted in 1999, or a national benefit of$65.4 million (USEPA 2000). Even considering the inherent year-to-year variability in pest population density, the EPA estimated the annual benefit to corn growers at $38–$219 million (USEPA 2001)