An economic evaluation of the differences between intensive and extensive beef production systems

A model to evaluate economic criteria involved when cattle are raised on high-forage diets prior to finishing or finished directly after weaning was developed using data from two experiments. In Exp. 1, each year for 3 yr, 136 Charolais-cross calves were weaned and allotted to either an intensive system, in which they were immediately finished on a high-grain diet, or an extensive system, in which they were wintered on crop residues, grazed on summer pasture and finished on a high-grain diet. In Exp. 2, 160 British breed steers were wintered, in one of eight different wintering systems utilizing crop residues, using supplemental protein and(or) alfalfa hay. After wintering, the steers grazed summer pasture and then were finished on a high-grain diet. Overall cost of gain and final "break-even" price were lower for cattle finished through the extensive system except when the price of corn was very low in relationship to other inputs. Interest costs were higher for cattle in the extensive system. Increasing the feeder calf purchase price had almost no effect on differences between the systems. Corn price and purchase price affected both systems similarly, whereas interest rate, wintering yardage and finishing yardage affected each system differently. Because of the additional weight produced through the extensive system, it yielded lower final "break-even" prices in most situations.     

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Effect of sodium hydroxide treatment on rate of passage and rate of ruminal fiber digestion

Ruminally fistulated lambs were used to measure the effect of sodium hydroxide treatment on rate of passage and rate of ruminal fiber digestion. Corncobs were raised to 60% moisture and treated to a final concentration of 0, 2.5, 5.0, 7.5 and 10.0% NaOH on a dry matter basis. The diets fed contained 80% cobs and 20% supplement, giving a complete mixed diet containing 0, 2.0, 4.0, 6.0 and 8.0% NaOH (dry basis). Chromic oxide was used as an external marker, and rumen samples were collected at 3, 6, 12, 24, 48 and 96 hr post-dosing. As level of NaOH treatment increased, rate of passage increased linearly (P less than .05). Mean ruminal retention time decreased from 32.4 hr for the control diet to 20.7 hr for the 8% NaOH diet. When rate of passage was regressed against NaOH level, the slope of the line was .142%/hr per unit NaOH, with r2 = .733. In another trial, sodium concentrations equal to the 4% NaOH diet were obtained by the addition of 7.3% NaCl to the basal diet. Rates of passage for lambs fed the diet containing NaCl were faster (P less than .05) than for lambs fed the control diet but slower (P less than .05) than for lambs on the 4% NaOH diet. These data suggest that both sodium intake and NaOH treatment affect rate of passage and are additive. Nylon bags containing .15 g cotton were used to measure the rate of ruminal fiber digestion in lambs fed the five NaOH-treated diets. Bags were removed from the rumen after 12, 24, 36 and 48 hr, and the loss in weight were used to estimate ruminal digestion. As level of NaOH increased, the rate of ruminal cotton digestion decreased linearly (P less than .05). When rate of cotton digestion was regressed against NaOH level, the slope of the line was -.488%/hr per unit NaOH, with r2 = .934.     

Metabolize methionine and lysine requirements of growing cattle

Two growth studies were conducted to determine the Met and Lys requirements of growing cattle. In each 84-d trial, steer calves were fed individually diets containing 44% sorghum silage, 44% corn cobs, and 12% supplement (DM basis) at an equal percentage of BW. In Trial 1, 95 crossbred steers (251 kg) were supplemented with urea or meat and bone meal (MBM). Incremental amounts of rumen-protected Met were added to MBM to provide 0, .45, .9, 1.35, 3, and 6 g/d metabolizable Met. In Trial 2, 60 steers (210 kg) were supplemented with urea or corn gluten meal (CGM). Incremental amounts of rumen-protected Lys were added to CGM to provide 0, 1, 2, 3, 4, 5, 6, 8, and 10 g/d metabolizable Lys. Supplementation with MBM and CGM increased the supply of metabolizable protein to the animal. Steers fed MBM plus 0 Met gained 49 g/d more than steers fed urea, whereas steers fed CGM plus 0 Lys gained 150 g/d more than steers fed urea. Supplementation of rumen-protected Met and Lys improved ADG in steers fed MBM and CGM, respectively (P < .10). Nonlinear analysis, comparing gain vs supplemental Met and Lys intake, predicted supplemental Met and Lys requirements of 2.9 and .9 g/d, respectively. This amount of additional Met promoted .13 kg/ d gain greater than MBM alone, and this amount of additional Lys promoted .10 kg/d gain greater than the CGM alone. Metabolizable Met and Lys requirements were predicted from Level 1 of NRC (1996) calculated metabolizable protein supply, amino acid analysis of abomasal contents, and the maximum response to supplemental AA. Steers gaining .39 kg/d required 11.6 g/ d Met or 3. 1% of the metabolizable protein requirement, whereas steers gaining .56 kg/d required 22.5 g/d Lys or 5.7% of the metabolizable protein requirement.     

Feeding corn milling byproducts to feedlot cattle.

Corn milling byproducts are expected to increase dramatically in supply as the ethanol industry expands. Distillers grains, corn gluten feed, or a combination of both byproducts offer many feeding options when included in feedlot rations. These byproduct feeds may effectively improve cattle performance and operation profitability. When these byproducts are fed in feedlot diets, adjustments to grain processing method and roughage level may improve cattle performance. Innovative storage methods for wet byproducts and the use of dried byproducts offer small operations flexibility when using byproducts. As new byproducts are developed by ethanol plants, they should be evaluated with performance data to determine their product-specific feeding values.     

Personal and family backgrounds of first-year veterinary science students at The University of Queensland

Objective To provide information on changes in the social and educational backgrounds of veterinary students over a 10 year period in an effort to determine the extent to which they are representative of the community.
Methods Questionnaires were completed by first-year veterinary students at The University of Queensland in 1985 and 1986 (152 students), and 1995 and 1996 (154), and the data were analysed using the SAS System for Windows.
Results The gender ratio of first-year veterinary students was 50:50 (male:female) in 1985 and 1986 but 10 years later it had changed to 38:62. In 1985 and 1986 77% had come directly from school, with 43% of the total coming from government schools, 17% from Catholic schools and 34% from other private (Independent) schools. A decade later the percentage coming directly from school had decreased to 40%, that from Independent schools increased to 45% and that from cities increased from 53% to 64%. The educational backgrounds of parents varied widely though a high percentage had university degrees; mothers had received less formal education than fathers, and the educational attainments of both parents were higher at the beginning than at the end of the study. More than half (57% initially; 67% 10 years later) the fathers were in professional or managerial occupations, and a similar number (50% initially; 48% 10 years later) of mothers were teachers, nurses or clerks. The number of males from country areas decreased from 26 to 16 over this period.
Conclusion These veterinary students differed from the community generally in that progressively more were female, more were from Independent schools, their parents had more formal education and more of their parents were in professional, managerial or clerical occupations.     

PCR‐based identification of Erysiphe pulchra and Phyllactinia guttata from Cornus florida using ITS‐specific primers

The internal transcribed spacer (ITS) regions of rDNA and the intervening 5.8S rRNA gene for the powdery mildew fungi Erysiphe (sect. Microsphaera) pulchra and Phyllactinia guttata were amplified using standard polymerase chain reaction (PCR) protocols and the universal primer pairs, ITS₁ and ITS₄. PCR products for ITS were analysed by electrophoresis in a 1.5% agarose gel and sequenced. The size of the amplified ITS products (approximately 650 bp) were not sufficiently different to allow reliable differentiation of E. pulchra and P. guttata; however, their sequences were distinct. Specific primers for E. pulchra and P. guttata were developed and evaluated for use as diagnostic tools. The diagnostic band size from E. pulchra‐specific primer pair was 568 bp while the P. guttata band was 597 bp; the two primer pairs were highly specific to E. pulchra and P. guttata. Comparison of ITS sequences with information in the GenBank showed a very close similarity between sequences of E. pulchra isolates from Cornus florida in the USA and isolates collected on Cornus kousa in Japan. BLAST analysis of the sequence of the 650‐bp band from P. guttata revealed a close alignment with sequences of P. moricola (92%), P. kakicola (94%), and P. fraxini (92%). The sequence of P. guttata in C. florida also had a 98% identity with P. guttata in Calycanthus occidentalis and 94% identity with P. guttata in Corylus cornuta.     

The potential of biotechnology in temperate agroforestry practices

Technologies in forest molecular biology and tissue culture could play an increasing role in the choice of genotypes for successful establishment of agroforestry practices. Research areas such as micropropagation, somatic embryogenesis, genetic engineering, marker-aided selection, and molecular diagnostics are merging with traditional forest biological studies to help identify and produce better-suited trees for agroforestry plantings. A combination of classical and molecular biological research could be used to improve pest and stress resistance of selected genotypes, modify structure and function, and monitor pests of trees. This merger of approaches, as well as continued technological development, could accelerate the production and selection of suitable tree genotypes for agroforestry plantings.The US Government right to retain a non-exclusive, royalty free licence in and to any copy-right is acknowledged.     

Phylogeographic patterns of Armillariaostoyae in the western United States

Nuclear ribosomal DNA regions (i.e. large subunit, internal transcribed spacer, 5.8S and intergenic spacer) were sequenced using a direct‐polymerase chain reaction method from Armillaria ostoyae genets collected from the western USA. Many of the A. ostoyae genets contained heterogeneity among rDNA repeats, indicating intragenomic variation and likely intraspecific hybridization. Intragenomic variation was verified by visually editing base‐sequence offsets in regions with insertions/deletions, and using sequence‐specific internal primers to resequence heterogeneous regions. Phylogenetic analyses with Bayesian Inference methods were used to define groups within A. ostoyae. Analysis of A. ostoyae from outside the western USA indicated the presence of a Circumboreal group of A. ostoyae that also occurs in Utah; two other phylogeographic groups were associated with the Rocky Mountain and Pacific Northwest regions of the USA. Mixed sequence types, an indication of intraspecific hybrids, were common in some geographic regions. Hybridization events may have influenced species evolution, contributing to variation in pathogenicity and virulence. The occurrence of these groups and intraspecific hybrids also indicates that paleogeography and paleoclimate may have influenced the phylogeography of A. ostoyae. In addition, other Armillaria species were examined for evolutionary relationships with the groups of A. ostoyae. These findings will provide a basis for future research relating ecological function to genetic diversity within A. ostoyae.