Effect of some antibiotics as growth promoters on performance of broiler chicks fed different protein levels

This work was carried out to study the effect of different sources of dietary antibiotics (Zinc bacitracin, Flavomycin, Virginiamycin) in rations with optimal protein levels (starter phase: 23.5%, finisher phase: 20.0%) and low protein levels (starter phase: 19.6%, finisher phase: 17.0%) on broiler performance with 8 groups of 75 broiler each. The supplement of diets, containing the optimal and low protein level, with antibiotics increased the body weight after 7 weeks of age and improved the feed conversion as compared with control groups. Virginiamycin was superior in increasing body weights after 7 weeks of age and in improving the feed conversion with rations containing low protein level when compared with zinc bacitracin and Flavomycin. When broiler rations, low in the protein content, were supplemented with antibiotics, they could not substitute the difference in optimal protein level. Antibiotics supplementation increased the value of improvement in production efficiency and this was more pronounced with Virginiamycin.     

Cumulative discounted expressions of dairy and beef traits in cattle production systems

Gene-flow methodology was used to calculate the cumulative discounted expressions (CDE) for annual/lactation, replacement heifer, cull cow, birth, yearling, and slaughter traits in alternative cattle production systems. Generic equations were presented and parameters representing dairy-beef production systems in Ireland and Brazil were inputted. Cumulative discounted expressions using input parameters from a hypothetical purebred dairy production system with poor cow longevity were also calculated. Cumulative discounted expressions were calculated assuming either an initial purebred or crossbred mating within each production system. Absolute and relative differences in CDE existed among trait categories across the three alternative production systems investigated. For example, the CDE of beef-related traits accruing from an initial purebred mating ranged from 0.42 to 0.75 CDE of an annual/lactation trait across the three contrasting systems investigated which differed in various input parameters. Such variation may alter the relative emphasis of traits on overall profitability thereby contributing to genotype by environment interactions. The results of this study highlight the necessity to consider auxiliary traits in sire selection over and above those representing the principal intended use of the sire. This was particularly so for integrated dairy-beef cattle production systems.     

Disposition kinetics of florfenicol in goats by using two analytical methods

Florfenicol, a monofluorinated analogue of thiamphenicol, has antibacterial activity against a broad spectrum of bacterial strains, including enteric bacteria that are resistant to chloramphenicol and thiamphenicol. The pharmacokinetics of florfenicol was studied following a single intravenous bolus or intramuscular injections at a dose of 20 mg/kg body weight, in five healthy goats. Serum florfenicol concentrations were determined using two analytical methods: microbiological assay and high-performance liquid chromatography (HPLC). Pharmacokinetic analysis was performed using redundant routine equations and the results derived from each method were compared. While florfenicol was detected for up to 4 and 8 h after administration by the bioassay, the drug was recovered in serum after 12 and 24 h by HPLC following intravenous and intramuscular injections, respectively. Comparison of the concentration profiles obtained by the two methods revealed substantial differences in the resultant kinetic data. Values for the initial serum concentration, elimination half-life, the area under the serum concentration-time curve, the mean residence time, and the systemic bioavailability were significantly (P < 0.01) higher when florfenicol concentrations were determined using HPLC. In conclusion, differences between analytical methodologies should be considered when interpreting the kinetic data for clinical use. However, both the hepatic biotransformations and the interchangeability of enantiomers need further investigation.     

Identity and public health potential of Cryptosporidium spp. in water buffalo calves in Egypt

Little is known about the diversity and public health significance of Cryptosporidium species in water buffaloes. In this study, we examined the distribution of Cryptosporidium spp. in water buffalo calves in Egypt. Rectal fecal specimens from 179 calves and 359 adults were screened microscopically for Cryptosporidium oocysts using modified Ziehl–Neelsen stain. Cryptosporidium spp. in 17 microscopy-positive specimens from calves were genotyped by DNA sequence analysis of the small-subunit rRNA gene, and Cryptosporidium parvum was subtyped by sequence analysis of the 60 kDa glycoprotein gene. Cryptosporidium ryanae was found in 10 specimens and C. parvum in 7 specimens, with the former belonging to the newly identified C. ryanae buffalo variant and the latter belonging to the subtypes IIdA20G1 (in 5 specimens) and IIaA15G1R1 (in 2 specimens). The prevailing occurrence of C. ryanae and the subtype family IId of C. parvum and the absence of C. bovis and C. andersoni represent some features of Cryptosporidium transmission in water buffaloes in Egypt.     

In-vivo evaluation of adjuvants for more effective control of celery leaf-spot (Septoria apiicola) and powdery mildew (Erysiphe graminis) of wheat with fungicides

The effects of seven adjuvants (at 0, 0.5, 1.0 and 2.0 g litre^?1) on the efficacies of four fungicides al 0.5 g litre^?1 were studied in the laboratory for the control of leaf-spot in celery (caused by Septoria apiicola) and powdery mildew on winter wheat (caused by Erysiphe graminis). The most effective fungicides for controlling leaf-spot were: tebuconazole + triadimenol = flutriafol > mancozeb + oxadixyl > prochloraz. However, addition of adjuvant to the fungicides gave a modified pattern of effectiveness. The efficacy of flutriafol was strongly enhanced by addition of all adjuvants, but those of prochloraz and mancozeb+oxadixyl only partially so. The tested adjuvants were mineral oil + surfactant, a polymer/alkoxylated alkyl ether blend, an ethoxylated alkylphenol, an ethoxylated hexitan ester blend, an ethoxylated nonylphenol and an alkylpolysaccharide- based adjuvant mixture. However, the addition of adjuvants to tebuconazole + triadimenol had a negative effect. Of all the adjuvants tested, the nonylphenol ethoxylate and a mixture of mineral oil /surfactant and alkylpolysaccharides gave the highest efficacy with the fungicides, while the mineral oil/surfactant and the alkylpolysaccharides alone were less effective. There was a positive relationship between high concentrations of adjuvants and their effectiveness, but there were some exceptions. The most effective fungicides for control of powdery mildew in wheat were prochloraz, mancozeb + oxadixyl and tebuconazole + triadimenol. There was a linear relationship between the high efficacy of the fungicide and the concentration of adjuvants to control powdery mildew in wheat. The highest concentration of adjuvant (2-0 g litre^?1) gave the highest efficacy for the fungicides.     

Effects of antimicrobial peptides derived from the beetle Allomyrina dichotoma defensin on mouse peritoneal macrophages stimulated with lipopolysaccharide

We previously reported that synthetic peptides, RLYLRIGRR-NH2 (peptide A) and RLRLRIGRR-NH2 (peptide B), derived from the beetle Allomyrina dichotoma defensin, showed antimicrobial activity against both Gram-positive and negative bacteria and suppressed lipopolysaccharide (LPS)-induced tumor necrosis factor-alpha (TNF-alpha) mRNA expression in a murine macrophage cell line. In this study, inhibitory effects of these peptides in LPS-induced mouse peritoneal macrophage activation were investigated. The supplement of peptide A to macrophages cultured with LPS resulted in a significant decrease in nitric oxide and TNF-alpha production. Furthermore, NF-kappaB activation was also blocked by addition of peptide A. These results indicated that peptide A blocked macrophage activation induced by LPS.     

Assessment of a germplasm bank for the autochthonous cattle breed Asturiana de la Montaña: Extender (Biociphos vs. BIOXCell) affected sperm quality but not field fertility

Semen banking is critical to preserving rare and autochthonous breeds. However, protocols can change with time, leaving heterogeneous semen batches. The objective of this study was to assess differences in sperm quality and field fertility. We report differences between batches frozen with the Biociphos and BIOXCell extenders in the Asturiana de la Montaña cryobank (autochthonous and endangered breed, Northern Spain). Doses from 48 bulls were analysed by CASA and flow cytometry. The 85‐days non‐return rates from AI records were used to assess the fertility of 23,853 AI. BIOXCell showed higher quality post‐thawing. Differences increased after a 5‐hr incubation at 37°C, and Biociphos yielded doses with lower resilience. Field fertility did not differ between extenders (Biociphos: 57.4% ± 1.2; BIOXCell: 56.6% ± 3.0), possibly because of AI protocols compensating for differences in quality. However, this needs to be confirmed by controlled intervention studies. In conclusion, batches frozen with Biociphos may require specific strategies for compensating for the lower sperm quality. Regular surveys and evaluation of cryobank procedures may be useful to characterizing stored batches and defining strategies to guaranteeing success in their future use.     

Assessment of the genetic and economic impact of performance recording and genotyping in Australian commercial sheep operations

With the new opportunities from DNA technology, multitier breeding schemes have the potential to become more effective and more integrated. Integrated breeding schemes can also be better adapted to account for potential genotype by environment interactions (G × E) between tiers. In this case, phenotypic and genotype information from lower tiers becomes more valuable as it involves measurement of traits that directly represent the breeding objective. The objective of this study was to compare scenarios that represented different selection strategies and their economic effectiveness in fine‐wool commercial sheep operations that exploit multitier breeding structures. Genomic selection (GS) applied in the multiplier and the commercial tier presented the largest additional revenue among all scenarios, as it resulted in the largest amount of genetic progress. The largest benefits from GS were outweighed by the genotyping costs, which made DNA parentage the most feasible strategy for the multiplier tier, resulting in the highest cumulative net present value (CNPV). The benefits of phenotypes and genotype information from the commercial environment were larger in the presence of G × E between the nucleus and the commercial tier. The CNPV was larger with a 50% reduction in genotyping costs, which increased the returns of GS scenarios by 2.7‐fold on average. Higher selection intensity when selecting multiplier rams also resulted in larger benefits. In this case, returns for the breeding scheme were 3.5‐fold higher when 33% of multiplier males were selected based on commercial information, compared to scenarios selecting 50% of the available multiplier rams. The benefits of collecting commercial phenotypes and genotypes were long term, which means that return on investment often took more than 10 years to be achieved, and were largely dependent on two‐stage selection to reduce cost while maintaining selection efficiency and on the cost of a genotype test.