Feed Efficiency in Growing Steers: Relationships between Efficiency and Carcass Ultrasound Traits

Phenotypic correlations between feed efficiency and carcass traits were examined in growing steers. Two feed efficiency trials were conducted using 233 Santa Gertrudis steers. Steers were individually fed a roughage-based for 77days. Individual feed intake was recorded weekly and body weight was measured bi-weekly. Ultrasound measurements of the 12th rib fat thickness (back fat), longissimus muscle area (REA) and percentage intramuscular fat were obtained on day 0 and 77, Residual feed intake (RFIp) is a measure of feed efficiency that attempts to measure variation in feed intake beyond that needed for growth and maintenance. Residual feed intake was calculated as the difference between actual feed intake and expected feed intake predicted by a linear regression model of dry matter intake (DMI) on mid-test BW0.75 (MBW) and average daily gain (ADG) with trial, trial × MBW, and trial × ADG as random effects. Steers were ranked by RFI into low, medium, and high RFI groups \u3c0.5 SD, ± 0.5, \u3e 0.5 SD, respectively, from the mean RFIp of 0.0 ± 1.01 kg/d. Overall means for ADG and DMI were 0.38 (SD = 0.57) and 9.79 (SD = 1.03), respectively. Stepwise regression indicated that inclusion of gain in back fat (GBF) into the base model increased the r2 (0.29 vs. 31). RFIp was positively correlated (P \u3c 0.5) with DMI (r = 0.85), and FCR (r = 0.47), but not with MBW or ADG. Feed to gain ratio (FCR) was negatively correlated (P \u3c 0.05) with ADG (r = -0.82). Carcass adjusted for RFI (RFIc) was not correlated with ADG, DMI, MBW, or FCR. Carcass ultrasound traits were not correlated (P \u3e 0.05) with feed efficiency traits. Gain in back fat was positively correlated with (P \u3c 0.05) with RFIp (r = 0.17), but not correlated (P \u3e 0.05) with FCR or RFIc. Gain in REA was negatively correlated (P \u3c 0.05) with FCR (r = -0.21) and RFIc (r = -0.17), but not with RFIp. The Spearman rank correlation between RFIp and RFIc was high (r = 0.91). Results suggest that RFI is independent of growth rate and mature size, but related to DMI. Selecting for favorable RFIp phenotypes can potentially improve feed efficiency in cattle. Adjusting RFI for ultrasound carcass traits could also improve feed efficiency independent of growth, body size, and carcass composition

A PRELIMINARY FEASIBILITY FOR ESTABLISHING A MULTI-SPECIES MEAT PROCESSING PLANT IN SOUTHWESTERN NORTH DAKOTA

The number of small commodity livestock slaughter plants in the Upper Northern Plains region continues to decline. Significant factors contributing to this decline include: 1) pressure to consolidate, thereby capturing economies of scale; 2) relatively stringent federal inspection specifications, along with; 3) HACCP (Hazardous Analysis Critical Control Points) requirements. At the same time, consumer demand (markets) for specialty, selected, and exotic meats appears to be growing. For example, the recent market successes in Europe evidenced by the North American Bison Cooperative based in New Rockford, North Dakota. Several alternative livestock producer groups have emerged which include lamb, ratite, elk, deer, goat, poultry, rabbit, specialty beef, and organic livestock. These groups have expressed a need for slaughter and processing facilities to meet market demand. The economic question which then becomes foremost to developing a viable business enterprise is: "What is the critical threshold volume (CTV) of product required to succeed in terms of economic profit?" Specialty livestock is relatively new and production volume small in comparison to established commodity livestock such as cattle or hogs. This fact led researchers to consider the preliminary feasibility of a multi-species processing facility as a means of addressing the expressed need.multi-species, specialty meats, specialty livestock, alternative livestock, economies of scale, HACCP (Hazardous Analysis Critical Control Points), slaughter plants, processing plants, Community/Rural/Urban Development, Agribusiness,

Effects of Intermittent Suckling on Sow and Piglet Performance

The objective of this study was to evaluate effects of intermittent suckling on sow and litter performance. Seventeen crossbred sows and litters were randomly assigned to treatment groups seven days prior to weaning: continuous suckling (CS) and intermittent suckling (IS; litters removed for 6 hr each from day 21 to 28). Litters were weaned at 28 days of age. Feed and water were available to litters and sows at all times. Feed intake was recorded. Body condition scores were collected on sows before farrowing and at weaning. Number of days to return-to-estrus for the sows was also recorded. Litters were weighed at birth and on days 7, 14, 21, 28, 35, and 42 of age. Litter weights were not different (P \u3e 0.15) between CS and IS pigs before or after weaning. No difference (P \u3e 0.10) was observed for feed intake between CS and IS litters before or after weaning. Body condition score at weaning was not different (P = 0.30) between CS and IS sows. Intermittent suckled sows returned-to-estrus in fewer days than CS sows (P \u3c 0.05). Results suggest that intermittent suckling did not alter average daily gain in litters, but reduced the number of days to return-to-estrus in sows

Red Nuggets at z~1.5: Compact passive galaxies and the formation of the Kormendy Relation

We present the results of NICMOS imaging of a sample of 16 high mass passively evolving galaxies with 1.3<z<2, taken primarily from the Gemini Deep Deep Survey. Around 80% of galaxies in our sample have spectra dominated by stars with ages >1 Gyr. Our rest-frame R-band images show that most of these objects have compact regular morphologies which follow the classical R^1/4 law. These galaxies scatter along a tight sequence in the Kormendy relation. Around one-third of the massive red objects are extraordinarily compact, with effective radii under one kiloparsec. Our NICMOS observations allow the detection of such systems more robustly than is possible with optical (rest-frame UV) data, and while similar systems have been seen at z>2, this is the first time such systems have been detected in a rest-frame optical survey at 1.3<z<2. We refer to these compact galaxies as "red nuggets". Similarly compact massive galaxies are completely absent in the nearby Universe. We introduce a new "stellar mass Kormendy relation" (stellar mass density vs size) which isolates the effects of size evolution from those of luminosity and color evolution. The 1.1 < z < 2 passive galaxies have mass densities that are an order of magnitude larger then early type galaxies today and are comparable to the compact distant red galaxies at 2 < z < 3. We briefly consider mechanisms for size evolution in contemporary models focusing on equal-mass mergers and adiabatic expansion driven by stellar mass loss. Neither of these mechanisms appears able to transform the high-redshift Kormendy relation into its local counterpart. Comment: Accepted version (to appear in ApJ

Open source Direct Simulation Monte Carlo (DSMC) chemistry modelling for hypersonic flows

An open source implementation of chemistry modelling for the direct simulation Monte Carlo (DSMC) method is presented. Following the recent work of Bird [1] an approach known as the quantum kinetic (Q-K) method has been adopted to describe chemical reactions in a 5-species air model using DSMC procedures based on microscopic gas information. The Q-K technique has been implemented within the framework of the dsmcFoam code, a derivative of the open source CFD code OpenFOAM. Results for vibrational relaxation, dissociation and exchange reaction rates for an adiabatic bath demonstrate the success of the Q-K model when compared with analytical solutions for both inert and reacting conditions. A comparison is also made between the Q-K and total collision energy (TCE) chemistry approaches for a hypersonic flow benchmark case

Associations between residual feed intake and apparent nutrient digestibility, in vitro methane-producing activity, and volatile fatty acid concentrations in growing beef cattle

The objectives of this study were to examine the relationship between residual feed intake (RFI) and DM and nutrient digestibility, in vitro methane production, and volatile fatty acid (VFA) concentrations in growing beef cattle. Residual feed intake was measured in growing Santa Gertrudis steers (Study 1; n = 57; initial BW = 291.1 ± 33.8 kg) and Brangus heifers (Study 2; n = 468; initial BW = 271.4 ± 26.1 kg) fed a high-roughage-based diet (ME = 2.1 Mcal/kg DM) for 70 d in a Calan-gate feeding barn. Animals were ranked by RFI based on performance and feed intake measured from day 0 to 70 (Study 1) or day 56 (Study 2) of the trial, and 20 animals with the lowest and highest RFI were identified for subsequent collections of fecal and feed refusal samples for DM and nutrient digestibility analysis. In Study 2, rumen fluid and feces were collected for in vitro methane-producing activity (MPA) and VFA analysis in trials 2, 3, and 4. Residual feed intake classification did not affect BW or BW gain (P \u3e 0.05), but low-RFI steers and heifers both consumed 19% less (P \u3c 0.01) DMI compared with high-RFI animals. Steers with low RFI tended (P \u3c 0.1) to have higher DM digestibility (DMD) compared with high-RFI steers (70.3 vs. 66.5 ± 1.6% DM). Heifers with low RFI had 4% higher DMD (76.3 vs. 73.3 ± 1.0% DM) and 4 to 5% higher (P \u3c 0.01) CP, NDF, and ADF digestibility compared with heifers with high RFI. Low-RFI heifers emitted 14% less (P \u3c 0.01) methane (% GE intake; GEI) calculated according to Blaxter and Clapperton (1965) as modified by Wilkerson et al. (1995), and tended (P = 0.09) to have a higher rumen acetate:propionate ratio than heifers with high RFI (GEI = 5.58 vs. 6.51 ± 0.08%; A:P ratio = 5.02 vs. 4.82 ± 0.14%). Stepwise regression analysis revealed that apparent nutrient digestibilities (DMD and NDF digestibility) for Study 1 and Study 2 accounted for an additional 8 and 6%, respectively, of the variation in intake unaccounted for by ADG and mid-test BW0.75. When DMD, NDF digestibility, and total ruminal VFA were added to the base model for Study 2, trials 2, 3, and 4, the R2 increased from 0.33 to 0.47, explaining an additional 15% of the variation in DMI unrelated to growth and body size. On the basis of the results of these studies, differences in observed phenotypic RFI in growing beef animals may be a result of inter-animal variation in apparent nutrient digestibility and ruminal VFA concentrations