Virulence of Fusarium oxysporum and F. commune to Douglas‐fir (Pseudotsuga menziesii) seedlings

Fusarium species can cause damping‐off and root rot of young conifer seedlings, resulting in severe crop and economic losses in forest nurseries. Disease control within tree nurseries is difficult because of the inability to characterize and quantify Fusarium spp. populations with regard to disease potential because of high variability in isolate virulence. Fusarium isolates were collected from healthy and diseased seedlings of Douglas‐fir (Pseudotsuga menziesii) and western white pine (Pinus monticola) from a nursery in Idaho, USA. Molecular markers such as DNA sequences (mitochondrial small subunit and nuclear translation elongation factor 1‐alpha) and amplified fragment length polymorphism were used to identify isolates as either F. oxysporum or F. commune. In addition, diagnostic primers were developed to detect and distinguish F. commune from F. oxysporum. In vitro and greenhouse virulence tests were completed on Douglas‐fir germinants and seedlings. For Douglas‐fir germinants and seedlings, F. oxysporum isolates generally caused less severe symptoms, whereas most F. commune isolates caused mortality through damping‐off. This is the first report of direct evidence that F. commune can cause damping‐off disease on Douglas‐fir seedlings under greenhouse conditions.     

Conversion of Cortisone to Cortisol and Prostaglandin F2α Production by the Reproductive Tract of Cows at the Late Luteal Stage In Vivo

Previous in vitro studies demonstrated that bovine endometrium has the capacity to convert inactive cortisone to biologically active cortisol (Cr) and that Cr inhibits cytokine‐stimulated prostaglandin F_2α (PGF) production. This study was carried out to test the hypothesis that bovine reproductive tract has the capacity to convert cortisone to Cr in vivo and to evaluate the effects of intravaginal application of exogenous cortisone on uterine PGF secretion during the late luteal stage. The temporal relationships between PGF and Cr levels in uterine plasma were also determined. Catheters were inserted into jugular vein (JV), uterine vein (UV), vena cava caudalis (VCC) and aorta abdominalis (AA) of six cows on Day 15 of the oestrous cycle (ovulation = Day 0) for frequent blood collection. On Day 16, the cows were divided randomly into two groups and infused intravaginally with vaseline gel (10 ml; control; n = 3) or cortisone dissolved in vaseline gel (100 mg; n = 3). Blood samples were collected at ?2, ?1, ?0.5, 0, 0.5, 1, 1.5, 2, 3, 4, 5 and 6 h after treatments (0 h). Intravaginal application of cortisone increased plasma concentrations of Cr between 0.5 and 1.5 h in UV, at 0.5 h in VCC, at 1 h in JV and at 1.5 h in AA. The plasma concentrations of PGF in UV and of PGF metabolite in JV were greater at 0.5 and 1 h in the cortisone‐treated animals than in control animals. The levels of PGF in UV blood plasma decreased after Cr reached its highest levels. The overall findings suggest that the female reproductive tract has the capacity to convert cortisone to Cr in vivo. Based on the temporal changes of PGF and Cr levels in the uterine plasma, a biphasic response in PGF secretion was found to be associated to the Cr increase induced by the cortisone treatment at the late luteal stage in non‐pregnant cows.     

Germany/Australia Index of Sperm Sex Sortability in Elephants and Rhinoceros

Flow cytometric sexing of spermatozoa followed by application in artificial insemination or in vitro fertilization provides a unique opportunity to predetermine the sex of offspring and might enhance the conservation management of endangered species in captivity such as the elephant and rhinoceros. To obtain an indication of the sortability of spermatozoa from these species, the relative DNA differences between X and Y chromosome bearing spermatozoa (fresh, frozen thawed, epididymal) from three rhinoceros species [white ( Ceratotherium simum ), black ( Diceros bicornis ), Indian ( Rhinoceros unicornis )] and both elephant species, the Asian and the African elephant ( Elephas maximus, Loxodonta Africana ), were determined through separation of spermatozoa into X and Y chromosome bearing populations, using a modified high speed flow cytometer. The head profile areas of spermatozoa from all five species were measured using light microscopy. By multiplying the relative DNA differences and the head profile areas, the sperm sorting indices were calculated to be 47, 48 and 51 for white, black and Indian rhinoceros respectively. The calculated sorting index for the Asian elephant was 66. In the African elephant, we determined the highest sorting index of 76. These results indicate the practicability of flow cytometric sex sorting of spermatozoa from the tested rhinoceros species and both elephant species. The lower sorting indices in rhinos indicate that sex sorting of spermatozoa from the rhinoceros will be more challenging than in elephants.     

Effects of grazing residues or feeding corn from a corn rootworm-protected hybrid (MON 863) compared with reference hybrids on animal performance and carcass characteristics

One grazing and two feeding experiments were conducted to compare the feeding value of corn residue or corn grain from a genetically enhanced corn hybrid (corn rootworm-protected; event MON 863) with nontransgenic, commercially available, reference hybrids. In Exp. 1, two 13.7-ha fields, containing corn residues from either a genetically enhanced corn root-worm-protected hybrid (MON 863), or a near-isogenic, nontransgenic control hybrid (CON) were divided into four equal-sized paddocks. Sixty-four steer calves (262 +/- 15 kg) were stratified by BW and assigned randomly to paddock to achieve a stocking rate of 0.43 ha/steer for 60 d, with eight steers per paddock and 32 steers per hybrid. A protein supplement was fed at 0.45 kg/steer daily (DM basis) to ensure protein intake did not limit performance. Steer ADG did not differ (P = 0.30) between steers grazing the MON 863 (0.39 kg/d) and CON (0.34 kg/d) corn residues for 60 d. The four treatments for the feeding experiments (Exp. 2 and 3) included two separate reference hybrids, the near-isogenic control hybrid (CON), and the genetically enhanced hybrid (MON 863) resulting in two preplanned comparisons of CON vs. MON 863, and MON 863 vs. the average of the reference hybrids (REF). In Exp. 2, 200 crossbred yearling steers (365 +/- 19 kg) were fed in 20 pens, with five pens per corn hybrid. In Exp. 3, 196 crossbred yearling steers (457 +/- 33 kg) were fed in 28 pens, with seven pens per corn hybrid. In Exp. 2, DMI and G:F did not differ (P > 0.10) between MON 863 and CON; however, steers fed MON 863 had a greater (P = 0.04) ADG than steers fed CON. Gain efficiency was greater (P = 0.05) for MON 863 cattle than for REF cattle in Exp. 2, but other performance measurements (DMI and ADG) did not differ (P > 0.10) between MON 863 and REF. No differences (P > 0.10) were observed for performance (DMI, ADG, and G:F) between MON 863 and CON or MON 863 and REF in Exp. 3. In terms of carcass characteristics, no differences (P > 0.10) were observed between MON 863 and CON, as well as MON 863 and REF, for marbling score, LM area, or 12th rib fat thickness in both Exp. 2 and 3. Overall, performance was not negatively affected in the corn residue grazing or feedlot experiments, suggesting the corn rootworm-protected hybrid (event MON 863) is similar to conventional, nontransgenic corn grain and residues when utilized by beef cattle.     

An evaluation of production and economic efficiency of two beef systems from calving to slaughter

A 3-yr experiment was conducted with cows and their calves to evaluate resource inputs, animal performance, and carcass characteristics of two production systems. In the control system, cows (CON; n = 99/yr) grazed pasture and were fed hay during the winter, and CON steer calves were finished in the feedlot for 211 d after weaning. In the treatment system (TRT; n = 100/yr), cows grazed pasture and crop residue during the winter and were fed hay. Treatment steer calves grazed crop residue after weaning, grazed pasture in the spring and summer, and were finished in the feedlot for 90 d. Body condition scores after TRT cows returned from crop residue grazing were greater (P < 0.01) for CON than for TRT cows. Calving rates were similar for both groups (CON = 91%; TRT = 93%). In the feedlot, CON steers had lower (P < 0.05) ADG and DMI, but were more efficient (P < 0.01) than TRT steers. Treatment steers had greater (P < 0.05) final weight, hot carcass weight and longissimus muscle area, and decreased marbling score. The cost per weaned calf and weaning breakeven were greater (P = 0.07) for the CON system than for the TRT system (CON = 455.12 dollars, 0.91 dollar/0.45 kg; TRT = 421.43 dollars, 0.84 dollar/0.45 kg). When steers were priced into the postweaning phase on an economic basis, slaughter breakeven was lower (P = 0.01), and profit potential tended (P = 0.14) to be greater for TRT steers when they were sold on a live basis. When steers were priced into the postweaning phase on a financial basis, slaughter breakeven was lower (P = 0.03) and profit potential from the sale of steers on a live basis was greater (P = 0.07) for TRT than for CON steers. Economic evaluation of the total system resulted in greater (P = 0.06) profit potential for the TRT system when steers were priced into the system on either an economic or a financial basis and when steers were sold on a live basis, but no differences were observed when steers were sold on a grid basis. Despite differences in cow weight and body condition, calving rates did not differ between systems. Although calves were herdmates, feedlot performance and carcass characteristics differed between systems. The TRT system had lower weaning and slaughter breakeven, lower cost per weaned calf, and greater profit potential when finished steers were sold on a live basis.     

Supplementation to meet metabolizable protein requirements of primiparous beef heifers: I. Performance,forage intake,and nutrient balance

Three experiments were conducted to evaluate the response of supplementing primiparous heifers based on the metabolizable protein (MP) system during pregnancy and lactation. In Exp. 1, 12 pregnant, March-calving heifers (432 +/- 10 kg) grazing Sandhills range were randomly allotted to one of two treatments: supplementation based on either the MP system (MPR) or the CP system (CPR). Supplements were fed to individual heifers from October to February and no hay was offered. Grazed forage organic matter intake (FOMI) was measured in November, January, and February. In Exp. 2, 18 heifers (424 +/- 8 kg) were randomly allotted to one of three treatments: 1) supplementation based on the MP system with hay fed in January and February (average 2.0 kg/d; MPR/hay), 2) supplementation based on the CP system, with hay fed in January and February (CPR/hay), or 3) supplementation based on the MP system, with no hay fed (MPR/no hay). Supplements were fed from October to February, and FOMI was measured in December and February. In Exp. 3, lactating 2-yr-old cows (394 +/- 7 kg) maintained on meadow hay were supplemented to meet either 1) MP requirements (LMPR) or 2) degradable intake protein requirements (LDIPR). Body weight (BW) and body condition score change, hay intake, and milk production were measured. In Exp. 1, grazed FOMI decreased (P = 0.0001) from 1.9% of BW in November to 1.2% in February, but no differences among treatments were detected for FOMI or BW change. In Exp. 2, grazed FOMI declined (P = 0.0001) from 1.7% of BW in December to 1.1% in February, with no differences among treatments. Heifers on the MPR/hay and CPR/hay treatments had higher (P = 0.0018) total intake (grazed forage + hay intake) in February (1.7% BW) than the MPR/no hay heifers (1.1% BW). Heifers on the MPR/no hay treatment had a lower weight (P = 0.02) and tended (P = 0.11) to have a lower BCS than heifers on other treatments. In Exp. 3, the LMPR cows had higher (P = 0.02) ADG than LDIPR cows (0.41 and 0.14, respectively), but treatment did not affect milk production. Organic matter hay intake averaged 2.4% of BW. We conclude that supplementation to meet MP requirements had little benefit to heifer performance during gestation, but increased weight change during lactation. Because grazed forage intake decreased from 1.9 to 1.1% of BW with advancing gestation, supplemental energy is necessary to reduce weight and condition loss of gestating hefiers grazing dormant Sandhills range.     

Corn processing method in finishing diets containing wet corn gluten feed

Two trials were conducted to determine the effect of corn processing method on performance and carcass traits in steers fed finishing diets containing wet corn gluten feed (WCGF). In Trial 1, 480 steer calves (303 kg initial BW) were fed eight finishing diets: 1) dry-rolled corn (DRC) without; and 2) with 32% (DM basis) WCGF; 3) steam-flaked corn (SFC) without; and 4) with WCGF; 5) a combination of DRC and SFC without WCGF; 6) finely-ground corn (FGC) with WCGF; 7) high-moisture corn (HMC) with WCGF; and 8) whole corn (WC) with WCGF. Feeding WC + WCGF increased (P < 0.10) DMI and decreased gain:feed compared with all other treatments. Feeding DRC + WCGF increased (P < 0.10) DMI and decreased (P < 0.10) gain:feed compared with treatments other than WC + WCGF. Steers on treatments that included WCGF gained similarly, regardless of corn processing method, and at a rate 6% faster (P < 0.10) than steers fed diets that did not include WCGF. Gain:feed did not differ among steers fed SFC, SFC + WCGF, SFC + DRC, and HMC + WCGF. Steers fed SFC or SFC + WCGF were more efficient (P < 0.10) than steers fed DRC or FGC + WCGF. In Trial 2, 288 steer calves (382 kg initial BW) were fed six finishing diets: 1) DRC without; and 2) with 22% (DM basis) WCGF; 3) SFC without; and 4) with WCGF; 5) finely rolled corn (FRC) with WCGF; and 6) HMC corn with WCGF. Steers fed DRC + WCGF or FRC + WCGF consumed more DM (P < 0.10) than steers fed DRC, SFC, or SFC + WCGF. Feed intake did not differ between steers fed SFC + WCGF and HMC + WCGF. All treatment groups receiving WCGF consumed more DM (P < 0.10) feed than steers fed DRC or SFC without WCGF. Steers fed SFC + WCGF gained 8% faster (P < 0.10), and steers fed DRC 9.5% slower (P < 0.10) than steers receiving all other treatments. Daily gains did not differ among other treatment groups. Steers fed SFC or SFC + WCGF gained 10% more (P < 0.10) efficiently than all other treatment groups. Feed efficiency did not differ among steers fed DRC, DRC + WCGF, FRC + WCGF, and HMC + WCGF. Estimates for the NEg of WCGF calculated from animal performance indicated that WCGF contained approximately 25.3% more energy when fed with SFC than when fed with DRC. In general, more intensively processing corn improved gain:feed in finishing diets containing WCGF.     

Utilization of distillers grains from the fermentation of sorghum or corn in diets for finishing beef and lactating dairy cattle

Beef finishing and dairy lactation experiments were conducted to evaluate the nutritional value of distillers grains (DG) from sorghum or corn fermentation, in both wet (35.4% DM) and dry (92.2% DM) form (dairy trial only). In the finishing experiment, 60 yearling steers were used in a completely randomized design with three diets that were fed for 127 d: 1) control diet with 86% (DM basis) dry-rolled corn and no DG; 2) 30% of ration DM as wet corn DG in place of dry-rolled corn; and 3) 30% of ration DM as wet sorghum DG in place of dry-rolled corn. All diets contained a minimum of 6.8% degradable intake protein and 13.0% CP. Steers fed DG had 10% greater ADG (< 0.01) and 8% greater efficiency of gain (P < 0.01) than steers fed the control diet. Wet corn and sorghum DG resulted in similar ADG and efficiency of gain. Hot carcass weights, fat thickness, and yield grades were greater for steers fed DG than for controls (P < 0.07). Improvements in ADG and feed efficiency observed when DG replaced dry-rolled corn indicated that the NEg content of wet DG is approximately 29% greater than that of dry-rolled corn. In the dairy lactation experiment, 16 lactating Holstein cows (eight multiparous, including four fistulated) were used in a replicated 4 x 4 Latin square design with 4-wk periods. Corn and sorghum DG were fed at 15% of the ration DM in either wet or dry form. Diets were fed as total mixed rations that contained 50% of a 1:1 mixture of alfalfa and corn silages, 24.3% ground corn, and 9.1% soybean meal (DM basis). There was no effect of source or form of DG on DMI, ruminal pH and VFA, or in situ digestion kinetics of NDF from DG. Efficiency of milk production was unaffected by diet. Corn and sorghum DG resulted in relatively similar performance when fed to beef or dairy cattle in this study.