Performance of Alternative Diets Containing Solvent‐Extracted Distillers Dried Grains with Solubles Compared to Traditional Diets for Pond‐Raised Channel Catfish,Ictalurus punctatus,and Hybrid Catfish,Ictalurus punctatus × Ictalurus furcatus

Two concurrent pond studies were initiated in April 2011 to evaluate feeds containing solvent‐extracted distillers dried grains with solubles (SE‐DDGS) in both 28 and 32% protein catfish feeds. Channel catfish, Ictalurus punctatus, were stocked in multiple‐batch production ponds at the University of Arkansas at Pine Bluff (UAPB) and hybrid catfish, ♀ Ictalurus punctatus × ♂ Ictalurus furcatus, in single‐batch production ponds at the National Warmwater Aquaculture Center (NWAC), Mississippi State University, Stoneville, Mississippi, USA. The experimental design was a 2 × 2 factorial with two protein levels (32 and 28% protein), with and without 20% SE‐DDGS. Fish were fed once daily to apparent satiation, and managed similarly to a commercial farm for 186 d at UAPB and 172 d at NWAC. For channel catfish, two‐way ANOVA showed significant effects of both protein level (28% being better than 32%) and protein source (20% SE‐DDGS diets being better than traditional diets) on yield, survival, total diet fed, and feed conversion ratio (FCR), due primarily to effects on the understocked fingerlings. Partial budget analysis suggested that the 28% protein diet with the 20% SE‐DDGS was preferred economically for the prevailing feed costs. For hybrid catfish, two‐way ANOVA did not show significant differences in total diet fed, yield, survival, and processing yields, but use of SE‐DDGS resulted in a lower FCR. Results showed that both channel and hybrid catfish can utilize 20% SE‐DDGS in the diet without adversely affecting production or processing characteristics.     

Surface Fuel Sampling Strategies: Linking Fuel Measurements and Fire Effects

We assessed the effectiveness of different sampling strategies in linking fine fuel load and crown scorch of ashe (Juniperus ashei) and redberry juniper (J. pinchotii) for prescribed fires conducted in wet and dry periods of the growing season on the Edwards Plateau, Texas, USA. Our aim was to determine if spatial and temporal variation in crown scorch was best predicted by estimates of fuel load sampled with spatially explicit, multiscale sampling strategies or with traditional, simple random sampling of fuel load. We found that multiscale sampling of fuel load underneath and adjacent to juniper crowns was more effective than simple random sampling in predicting crown scorch for the 14 fires conducted in the wet period and the five conducted in the dry period. The type of sampling strategy employed was critical in relating fuel load to crown scorch during the wet period. Percent crown volume scorched ranged from 0% to 100% in these conditions. In contrast, the type of sampling strategy was less important in the dry period when crown scorch was &spigt;90% for all juniper trees. We use these findings to illustrate how a multiscale sampling design can increase prediction power, thereby improving our ability to provide resource professionals with critical values to target in management. Using such a strategy in this study revealed that fine fuel loading of 2 670 kg · ha^–1 were needed to scorch juniper trees 100% for the conditions present in the wet period, whereas only 1 280 kg · ha^–1 were needed in the dry period. To provide managers with this type of information, we suggest that researchers shift from simple, random sampling of fuels to alternate sampling designs where randomization is maintained in the designation of treatments or selection of observations (i.e., individual juniper trees) but where fuel is systematically sampled at the location of the observation of interest.     

Effect of copper status, supplementation, and source on pituitary responsiveness to exogenous gonadotropin-releasing hormone in ovariectomized beef cows

The effect of Cu status, supplementation, and source on pituitary responsiveness to exogenous GnRH was evaluated using nine multiparous, nonpregnant, nonsuckling, ovariectomized Angus cows (7.1 +/- 3.3 yr; 622.9 +/- 49.8 kg; BCS = 6.0 +/- 0.5). Cows were considered Cu-deficient based on liver Cu concentrations (< 30 mg of Cu/kg of DM) after receiving a low-Cu, forage-based diet supplemented (DM basis) with 5 mg of Mo/kg and 0.3% S for 216 d. Copper-deficient cows were stratified based on age, BW, BCS, and liver Cu concentration and assigned randomly to repletion-phase treatments. Treatments included 1) control (no supplemental Cu); 2) organic (ORG; 100% organic Cu); and 3) inorganic (ING; 100% inorganic CuSO4). Treatments were formulated to meet all NRC recommendations, except for Cu, which was supplemented to ORG and ING cows at 10 mg of Cu/kg of dietary DM. During the 159-d repletion phase, Cu status was monitored via liver biopsy samples, and all cows received exogenous progesterone. A controlled intravaginal drug-release device (replaced every 14 d) was used to maintain luteal phase progesterone as a means to provide negative feedback on the hypothalamic-pituitary axis. During the repletion phase, liver Cu concentrations did not differ between ORG and ING cows at any time. By d 77 of the repletion phase, all supplemented cows were considered adequate in Cu, and liver Cu concentrations were greater in supplemented than in nonsupplemented control cows on d 77 (P < 0.05) and throughout (P < 0.01) the repletion phase. Beginning on d 99, exogenous GnRH was administered to all cows at low (0, 3, and 9 microg; Exp. 1) and high doses (0, 27, and 81 microg; Exp. 2) at six different times. Cows were catheterized every fifth day, and blood samples were collected every 15 min for 1 h before and 4 h after GnRH administration and analyzed for LH concentration. In Exp. 1, Cu status and supplementation did not affect basal or peak LH concentrations, but total LH released tended (P < 0.07) to be greater in Cu-supplemented vs. control cows when 3 microg of GnRH was administered. In Exp. 2, there was no effect of Cu supplementation or source on basal, peak, or total LH released, regardless of GnRH dose. Pituitary LH concentrations did not differ across treatments. In conclusion, Cu status, supplementation, and source did not affect GnRH-induced LH secretion or pituitary LH stores in ovariectomized, progesterone-supplemented cows in this experiment.     

Effects of dietary copper on the expression of lipogenic genes and metabolic hormones in steers

An experiment was conducted to determine the effects of Cu supplementation on performance, subcutaneous adipose tissue mRNA expression of acetyl CoA carboxylase (ACC), stearoyl CoA desaturase (SCD), uncoupling protein 2 (UCP2), and leptin in growing and finishing steers. Forty-eight purebred Angus steers were allotted to one of five treatments: 1) control (no supplemental Cu); 2) 10 mg Cu/kg DM from CuSO4; 3) 10 mg Cu/kg DM from a Cu amino acid complex (Availa Cu); 4) 20 mg Cu/kg DM from CuSO4; 5) 20 mg Cu/kg DM from Availa Cu. Steers were fed an alfalfa hay corn-based diet for 56 d (basal diet contained 7.1 mg Cu/kg DM) and switched to a high-concentrate diet for 144 d (basal diet contained 6.1 mg Cu/kg DM). Blood samples were obtained every 28 d throughout the entire experiment. On d 112 of the finishing period, subcutaneous adipose tissue biopsies were obtained from the tailhead of three animals per treatment and analyzed for ACC, SCD, UCP2, and leptin mRNA expression. Animal performance was not affected by Cu supplementation during the growing phase. Steers receiving 10 mg Cu/kg DM from Availa Cu had higher (P < 0.05) ending body weights and tended (P < 0.10) to have higher ADG than steers receiving 10 mg Cu/kg DM from CuSO4 during the finishing phase. Serum concentrations of nonesterified fatty acid and insulin were not affected by Cu supplementation. Steers receiving supplemental Cu tended (P < 0.11) to have less backfat relative to controls. However, dietary Cu did not influence the level of subcutaneous adipose tissue ACC and SCD mRNA. Neither UCP2 nor leptin gene expression was affected by Cu supplementation. These results indicate that dietary Cu supplementation (10 to 20 mg Cu/kg DM diet) may alter lipid metabolism of subcutaneous adipose tissue; however, it does not seem to affect expression of certain lipogenic genes.     

The Effect of On-Farm Production of Various Sizes of Stocker Caffish Ictalurus punctatus on Farm Profitability.

Abstract— The effect of on‐farm production of various sizes of stocker catfish Ictalurus punctatus on farm profitability was compared to profitability of understocking fingerlings directly into multiple‐batch growout production. Vat‐graded catfish averaging 9 × 2 g (10 cm total length) and 27× 8 g (15 cm total length) were stocked into eight 0.1‐ha ponds at 100,000 fingerlingdha. Fish were fed once daily to apparent satiation and harvested 210 d after stocking. There were no significant differences (P < 0.10) in yield, feed conversion ratio (FCR), and survival across treatments. Mean gross yield (× SD) was 9,469 × 852 kg/ha and 8,846 × 2,099 kg/ha; net yield averaged 8,531× 885 and 6,374 × 2,189 kg/ha; FCR averaged 1.8 × 0.1 and 2.4 × 0.7, and survival averaged 38 × 7% and 26 ×11% for the 10‐cm and 15‐m fingerling stocking treatments, respectively. While experimental survival was low, varying survival rates of stockers in the economic analysis did not affect selection of the most profitable stocking strategies. The 15‐cm hgerlings reached a size significantly larger (361× 81 g or 32.8 × 2.2 cm) than the 10‐cm fingerlings (255 × 28 g or 29.6 × 1.4 cm) (P < 0.07). Whole‐farm budgets were developed based on three sizes of farm (65, 130, and 260 ha) and eight production strategies involving the purchase of different sizes of fingerlings for either understocking growout ponds (6,12, or 37‐g fingerlings) or to grow into stockers (114,135, 176, 255, or 361 9). Purchasing 37‐g advanced fingerlings for multiple‐batch production was the most profitable strategy for the three sizes of farm. The second most important profit‐maximizing strategy for larger farm sizes was single‐batch production with 255‐g stockers produced on‐farm, but purchasing 12‐g fingerlings to stock into multiple‐batch production was the second most profitable strategy for the smallest farm. Sensitivity analysis indicated that the results were robust to variation in survival, prices, and other production characteristics. Risk analysis indicated that purchasing 37‐g advanced fingerlings for multiple‐batch production was associated with the lowest levels of economic risk for growout production.     

Landscape cover type and pattern dynamics in fragmented southern Great Plains grasslands,USA

We documented land cover and landscape pattern changes in an area of northwestern Oklahoma, USA using aerial photography from 1965, 1981, and 1995. This region of the southern Great Plains is fragmented by agricultural activity, and in recent years many remnant native grasslands have experienced extensive invasion by woody juniper (Juniperus virginiana L.). Concurrently, many cropland areas are being planted into perennial forage grasses and converted to intensively managed introduced grasslands as part of the U.S. Conservation Reserve Program (CRP). Our objectives were to document land cover and landscape pattern changes in the region relative to the expansion of juniper and CRP activity. We then examined how local landscape dominance by either anthropogenic or woody vegetation patches affected landscape pattern indices. Land cover changes from 1965 to 1995 included substantial increases in juniper woodlands and mixed woodlands that resulted from juniper encroachment into deciduous woodlands. Introduced grasslands also increased in many areas as a result of CRP implementation. Changes in landscape pattern generally reflected the influx of juniper into many areas. Landscapes dominated by woody vegetation had significantly more patches, smaller patches and patch core areas, more total edge, and higher patch diversity than landscapes dominated by anthropogenic cover types. Results indicate that expanding juniper is exacerbating the fragmentation process initiated by previous human activity, and represents a serious threat to the continued integrity and conservation of remaining southern Great Plains grasslands.This revised version was published online in May 2005 with corrections to the Cover Date.     

Effects of soybean oil and dietary copper on ruminal and tissue lipid metabolism in finishing steers

An experiment was conducted to determine the effects of Cu and soybean oil (SBO) supplementation on ruminal and tissue lipid metabolism and carcass characteristics in finishing steers. Sixty Angus steers (369.0 +/- 10.1 kg) were stratified by weight and randomly assigned to treatments in a 2 x 2 factorial arrangement, with factors being 0 or 20 mg of supplemental Cu/kg DM from Cu sulfate and 0 or 4% SBO. Steers were fed a high-concentrate basal diet that contained 5.3 mg Cu/kg DM. Average daily gain and feed intake were reduced (P < 0.01) by SBO but were not affected by Cu. Gain:feed ratio was not affected by treatment. Liver Cu concentrations were higher (P < 0.01) in steers receiving supplemental Cu and lower (P < 0.04) in SBO-supplemented steers. Copper supplementation tended to reduce (P < 0.12) and SBO supplementation tended to increase (P < 0.11) serum cholesterol concentrations. Backfat depth was reduced (P < 0.10) by Cu and SBO supplementation. Marbling scores and longissimus muscle lipid content were not affected by Cu supplementation; however, SBO supplementation reduced (P < 0.01) marbling scores. Longissimus muscle polyunsaturated fatty acids tended to be increased (P < 0.14) in Cu-supplemented steers. Longissimus muscle C18-conjugated dienes and the 18:1 trans isomer were increased (P < 0.05) in SBO-supplemented steers. Ruminal fluid 18:3 was increased (P < 0.05) and the 18:1 trans isomer was decreased (P < 0.05) in Cu-supplemented steers. These results indicate that as little as 20 mg of supplemental Cu/kg DM can reduce backfat and may alter lipid metabolism in steers fed high-concentrate diets.