Major causes of mastitis and associated risk factors in smallholder dairy farms in and around Hawassa, Southern Ethiopia

A cross-sectional study was carried out from October 2008 to May 2009 in smallholder dairy farms in and around Hawassa to estimate the prevalence of mastitis, to isolate and characterize major bacterial pathogens, and to identify possible associated factors. The study involved a total of 201 milking cows randomly drawn from smallholder farms. The prevalence of clinical and subclinical mastitis was determined through clinical examination of the udder and using mastitis indicator paper (Bovivet indicator paper, Kruuse, Denmark). The prevalence of mastitis at cow and quarter level was 30.3 (61/201) and 10.3 (79/766), respectively. Subclinical mastitis was 25.4% and 5.0% was clinical. Stage of lactation significantly affected (P < 0.05) the prevalence of mastitis, with the highest prevalence observed in the late stage of lactation (41.3%) as compared to early (25.0%) and mid (22.1%) stages of lactation. Floor type and bedding had association (P < 0.05) with mastitis prevalence. Cows housed in concrete-floored houses had lower prevalence (19.0%) of mastitis compared to cows kept in soil-floored houses (47.6%). Mastitis prevalence was low in farms which do not use bedding (23.5%) as compared to farms using hay/straw bedding (37.4%). However, age, parity, and history of mastitis had no association (P > 0.05) on the prevalence of mastitis. The pathogens isolated from mastitic cows were Staphylococcus aureus (48.6%), other staphylococci species (15.7%), Streptococcus agalactiae (11.4%), other streptococci (17.1%), Bacillus species (2.9%), and coliforms (Escherichia coli and Klebsiella species) (4.3%). Strict hygienic measure of housing and bedding should be considered, in reducing the prevalence of mastitis.     

Graded replacing fishmeal with canola meal in diets affects growth and target of rapamycin pathway gene expression of juvenile blunt snout bream,Megalobrama amblycephala

A feeding trial was conducted to assess the effects of replacing fishmeal (FM) with canola meal (CM) on the growth performance, feed utilization and related gene expression of juvenile blunt snout bream (Megalobrama amblycephala). Fishes were fed with five isonitrogenous (330 g/kg crude protein) and isoenergetic (15 MJ/kg) diets for 16 weeks, which was graded replacing levels of fishmeal (replacing 0, 37.5, 75, 112.5 and 150 g/kg FM with CM). The results revealed that specific growth rate, feed efficiency ratio and protein efficiency ratio of the groups with replacement level up to half were significantly higher than the others, while feed intake was inverse. Peptide transporter 1 (PepT1) mRNA level in the gut was significantly up‐regulated in groups CM25 and CM50 compared to other groups. Relative gene expression of IGF‐1 among groups was extremely significant based on the nonparametric test. Replacement of FM with CM caused a reduction in the hepatic expression of target of rapamycin (TOR), while significant increase trends were observed in hepatic genes of protein kinase B (AKT) and eIF4‐binding protein (4E‐BP2). However, TOR gene expression in the gut was significantly up‐regulated first and then down‐regulated, while mRNA levels of 4E‐BP2 and S6K1 in the gut were first significantly decreased and then increased in CM75, finally significantly decreased to the lowest. The overall results indicated that up to 75 g/kg FM could be replaced by CM (350.5 g/kg CM) in the diets for juvenile blunt snout bream. Besides, these signalling molecules could explain further the mechanisms that juvenile blunt snout can only maintain optimal growth performance up to 75 g/kg FM replacement with CM.     

Assessment of total dietary phosphorus requirement of juvenile largemouth bass,Micropterus salmoides,using soybean meal‐based diets: Effects on production performance,tissue mineralization,physiological parameters in plasma and intestine and expression of head‐kidney genes

A 9‐week feeding trial was conducted to evaluate effects of supplemental phosphorus (P) in soybean meal (SBM)‐based diets for largemouth bass (LMB). Six isonitrogenous (~400 g/kg crude protein) and isolipidic (~130 g/kg crude lipid) diets containing non‐phytic acid phosphorus (nPA‐P) ranging from 4.1 to 10.5 g/kg were fed twice daily to triplicate groups of 20 feed‐trained LMB (9.5g). Upon conclusion of the feeding trial, regression analyses showed that growth, feed efficiency and survival of LMB were unaffected by diet. Intraperitoneal fat index and whole‐body lipid content of LMB decreased linearly as dietary nPA‐P increased from 4.1 to ~7.0 g/kg, while protein retention efficiency increased quadratically over the dietary range of nPA‐P. Regressions on whole‐body P and skeletal mineral (P, Ca, Mg and Zn) concentrations of LMB revealed optimal levels when dietary nPA‐P was ~7.0 g/kg. Increasing trends of MDA concentration and ALT activity in plasma and GP_x activity in intestine in response to dietary nPA‐P were observed. Head‐kidney genes responded to dietary treatments and expression of GH, IGF‐1 and TGF‐β1 were highest and that of TNF‐α was lowest when dietary nPA‐P was 6.9 g/kg. Based on our results, practical diets for juvenile LMB should contain a minimum of 7.0 g/kg total nPA‐P.     

Leucaena leucocephala seedling response to vesicular-arbuscular mycorrhizal inoculation in soils with varying levels of inherent mycorrhizal effectiveness

Summary The symbiotic effectiveness of vesicular-arbuscular mycorrhizal (VAM) fungi present in widely differring tropical soils was evaluated in a greenhouse experiment. Small volumes of field soil, a standard inoculum (Glomus aggregatum) or both were introduced into a fumigated sand-soil medium amended with nutrients for optimum VAM activity. Leucaena leucocephala (Lam.) de Wit var. K8 was grown in the medium as an indicator plant. VAM effectiveness was monitored as a function of time by determining the P status of pinnules. The soils differed from each other with respect to the time their endophytes required for the expression of initial and maximum effectiveness and in the level of maximum effectiveness they exhibited. The effect of mycorrhizal inoculation, calculated as the ratio of the areas enclosed by the effectiveness curve of G. aggregatum to that enclosed by the effectiveness curves of test soils, was found to be a good indicator of the response of L. leucocephala to inoculation of soils with G. aggregatum Hawaii Institute of Tropical Agriculture and Human Resources Journal series No. 3285     

Effect of soil solution phosphorus on seedling growth of the pejibaye palm in an oxisol 1

Two experiments were undertaken to determine the effect of mycorrhizal inoculation and soil solution phosphorus (P) concentration on the growth of pejibaye (Bactris gasipaes, Palmae) seedling progenies from two Amazonian populations in a Hawaiian Oxisol. Mycorrhizal colonization and effectiveness were insignificant, perhaps because of residual fumigant toxicity and apparent water stress. Soil solution P concentration had highly significant effects on seedling leaf number, leaf area, plant biomass, anthracnose damage to leaves, and growth and physiological parameters in both experiments. Genotype effects were significant in the experiment involving progenies from two different populations, but not in the experiment involving two progenies from the same population. Native soil solution P concentration in this Oxisol was insufficient for acceptable pejibaye growth, while 0.2 mg/L soil P gave very good growth.     

Relative importance of Ca,N, and P in enhancing mycorrhizal activity in leucaena leucocephala grown in an oxisol subjected to simulated erosion

Pot experiments were conducted in the greenhouse to determine the combined effects of lime, nitrogen and phosphorus and the relative importance of each of these nutrients in establishing nodulated and mycorrhizal Leucaena leucocephala (Lam.) de Wit Var. K8 in an oxisol subjected to simulated erosion. Leucaena was grown in the soil inoculated or not with the vesicular‐arbuscular mycorrhizal fungus Glomus aggregatum Schenck and Smith emend Koske, with or without a basal nutrient (basal) consisting of K, Mg, S, Zn, Cu, and B plus lime, N, and P (complete) or one of the latter three supplements.

The extent of mycorrhizal colonization of roots as well as mycorrhizal effectiveness, as measured by pinnule P content increased when the eroded soil was amended with combinations of all the nutrients and inoculated with G. aggregatum. Similar trends were observed when symbiotic effectiveness was measured in terms of shoot P, Cu, and Zn status and dry matter yield. Nodule dry matter was also responsive to amendment of the soil with the complete nutrients and to vesicular‐arbuscular mycorrhizal inoculation. Phosphorus was found to be the most important nutrient limiting mycorrhizal effectiveness in the eroded soil, followed by N and lime. It is concluded that lost nutrients, particularly P, need to be replaced before legumes can be established successfully on highly weathered eroded soils inoculated with vesicular‐arbuscular mycorrhizal fungi.     

Dependency of Cassia siamea on vesicular arbuscular mycorrhizal fungi

Thirty‐day‐old seedlings of Cassia siamea were transplanted into pots containing a subsurface Oxisol uninoculated or inoculated with Glomus agaregatum at two target soil solution phosphorus (P) concentrations. While no evidence of Vesicular‐arbuscular mycorrhizal fungal (VAMF) colonization was noted in the uninoculated soil, C. siamea roots were colonized to the extent of 63 and 61% at soil P concentrations of 0.02 and 0.2 mg/L, respectively. VAMF colonization led to significant increases in tissue P concentrations measured at harvest at both soil P concentrations. However, shoot dry matter yield was significantly increased only at the first soil P concentration. Shoot dry matter yield of mycorrhizal C. siamea at soil P concentration of 0.02 mg/L was comparable to mycorrhizal growth of C. siamea at soil P concentration of 0.2 mg/L but inferior to the nonmycorrhizal growth of the legume. Based on these response patterns, C. siamea was classified as a highly mycorrhizal dependent species.     

Influence of Initial Spacing on Growth and Branching Characteristics of Cordia africana Trees Established on Eritrean Highland

The study reports on the influence of initial spacing on growth and branching habit of Cordia africana trees established on Eritrean highland. The initial spacings used in this study were 1.0×1.0 m, 1.5×1.5 m, 2.0×2.0 m, 2.5×2.5 m, 3.0×3.0 m, and 3.5×3.5 m; these are equivalent to 1 m², 2.25 m², 4 m², 6.25 m², 9 m² and 12.25 m² in growing space per tree, respectively. No significant relationship between spacing and tree height was found, but increased spacing increased crown diameter and root-collar-diameter. On the other hand, an increase in spacing reduced wood quality because it increased branch diameter (knot size). Thus, from a wood quality perspective, adopting close spacing in plantations of C. africana could be advantageous.