Meta-analysis of nutritional effects on conjugated linoleic acid (CLA) in milk fat of dairy cows

A meta-analysis was carried out on 41 selected studies to obtain more reliable results about the influence of some nutritional factors on conjugated linoleic acid (CLA) in milk fat. Data were analysed with a linear mixed model, including the study as random variable, that highlighted a significant effect on milk CLA content of fat source and the physical form of the lipid supplement used in the diet. The content of fat in the diet and the forage/concentrate ratio seem do not have significant effects

Shearing influences the milk fatty acid profile of dairy ewes

In Mediterranean areas shearing is commonly performed during late spring and, therefore, ewes may be exposed to cold stress especially during the night. Short-term periods of cold exposure can increase hepatic glucose production, decrease insulin secretion and increase fat catabolism and plasma non-esterified free fatty acids (NEFA) concentration. These metabolic adaptations to cold exposure can increase the mammary uptake of long-chain fatty acid from plasma. The present study aimed to investigate the metabolic response of dairy ewes to shearing by monitoring their milk fatty acid (FA) profile. Twelve 2-4-year-old Sarda ewes, in mid-late lactation, were used. The trial lasted from 30th May to 9th June 2006. The pre-experimental period (pre-shearing, PrS) was from 30th May to 5th June (shearing day), being followed by the experimental period (post-shearing, PoS) until 9th June. On shearing day, the flock was divided in two groups (6 ewes each) which were then managed differently: non-confined group (NCG) and confined group (CG) which was kept in a sheepfold during the night. Four samplings during PrS and other four during PoS periods were performed. During the trial, ewes were fed concentrate at 1000g/d per head, during the two daily milking, and hay ad libitum, and grazed on green clover (3h/day). Daily milk production was recorded and daily milk samples were collected for analysis of fat content and FA profile. Shearing did not influence milk yield but increased significantly milk fat content (6.37 vs. 6.94% for PrS and PoS, respectively; P<0.01). Ewes confinement during the night did not affect milk yield and its fat content. Shearing modified significantly the FA profile of milk. The concentration of C8, C10, C12 and C16 increased significantly from PrS to PoS. On the other hand, the content of long-chain FA (>C18:0) did not change between PrS and PoS (46.26 vs. 46.40mg/100g of FAME, respectively). These results suggest that the increase of milk fat after shearing was related to the increase of the main FA synthesized by the mammary gland. However, the unexpected increase in the synthesis of short- and medium-chain FA after shearing suggests that these animals were not subjected to cold stress. Therefore, the mechanism involved in the modification of the FA profile caused by shearing in dairy ewes should be elucidated

Role of sensorial perceptions in feed selection and intake by domestic herbivores

Sensorial perceptions play an important role in feed selection and intake by herbivores. Much research has been carried out to study the sensorial perceptions evoked by forages and their effects on intake and feed selection. Certain specific compounds are clearly able to evoke positive or negative sensorial perceptions when forages are eaten. This might lead to the development of plant extracts and aromas that might be used to improve the intake of unpalatable feeds. In the case of concentrates, the little research available seems to support an important role of the interaction between sensorial perceptions and post-ingestive effects when simple unmixed concentrates are supplied. It is not clear to what extent these effects are important when compound concentrates are offered. Despite these advances, it appears that most of the research carried out so far has been exploratory and observational. More research is needed to better understand the mechanisms underlying feed palatability before it can be included in intake prediction models

Antimicrobial promotion of pig growth is associated with tissue-specific remodeling of bile acid signature and signaling

The spread of bacterial resistance to antimicrobials (AMA) have intensified efforts to discontinue the non-therapeutic use of AMA in animal production. Finding alternatives to AMA, however, is currently encumbered by the obscure mechanism that underlies their growth-promoting action. In this report, we demonstrate that combinations of antibiotics and zinc oxide at doses commonly used for stimulating growth or preventing post-weaning enteritis in pigs converge in promoting microbial production of bile acids (BA) in the intestine. This leads to tissue-specific modifications in the proportion of BA, thereby amplifying BA signaling in intestine, liver, and white adipose tissue (WAT). Activation of BA-regulated pathways ultimately reinforces the intestinal protection against bacterial infection and pathological secretion of fluids and electrolytes, attenuates inflammation in colon and WAT, alters protein and lipid metabolism in liver, and increases the circulating levels of the hormone FGF19. Conceivably, these alterations could spare nutrients for growth and improve the metabolic efficiency of AMA-treated animals. This work provides evidence that BA act as signaling molecules that mediate host physiological, metabolic, and immune responses to the AMA-induced alterations in gut microbial metabolism, eventually permitting the growth-promoting action of AMA. Consequently, BA emerge as a promising target for developing efficacious alternatives to AMA

An integrated approach shows different use of water resources from Mediterranean maquis species in a coastal dune ecosystem

An integrated approach has been used to analyse the dependence of three Mediterranean species, A. unedo L., Q. ilex L., and P. latifolia L. co-occurring in a coastal dune ecosystem on two different water resources: groundwater and rainfed upper soil layers. The approach included leaf level gas exchanges, sap flow measurements and structural adaptations between 15 May and 31 July 2007. During this period it was possible to capture different species-specific response patterns to an environment characterized by a sandy soil, with a low water retention capacity, and the presence of a water table. The latter did not completely prevent the development of a drought response and, combined with previous studies in the same area, response differences between species have been partially attributed to different root distributions. Sap flow of A. unedo decreased rapidly with the decline of soil water content, while that of Q. ilex decreased only moderately. Midday leaf water potential of P. latifolia and A. unedo ranged between 122.2 and 122.7MPa throughout the measuring period, while in Q. ilex it decreased down to 123.4MPa at the end of the season. A. unedo was the only species that responded to drought with a decrease of its leaf area to sapwood area ratio from 23.9\ub11.2 (May) to 15.2\ub11.5 (July). While A. unedo also underwent an almost stepwise loss on hydraulic conductivity, such a loss did not occur for Q. ilex, whereas P. latifolia was able to slightly increase its hydraulic conducitivity. These differences show how different plant compartments coordinate differently between species in their responses to drought. The different responses appear to be mediated by different root distributions of the species and their relative resistances to drought are likely to depend on the duration of the periods in which water remains extractable in the upper soil layers

Effect of different inorganic phosphorus sources on growth performance, digestibility, retention efficiency and discharge of nutrients in rainbow trout (Oncorhynchus mykiss)

This study aims to evaluate the effect of different sources of inorganic phosphate, monosodium phosphate (MSP), monocalcium phosphate (MCP) and monoammonium phosphate (MAP), included in a diet for rainbow trout, on growth performance, nutrient digestibility, nutrient retention efficiency and discharge of nutrients to the water. Juvenile rainbow trout (Oncorhynchus mykiss) with an initial weight of 120 g were fed for 56 days four experimental diets: basal diet containing 430 g kg−1 protein, 210 g kg−1 lipids and 6.7 g kg−1 total phosphorus (P) (Control), and three experimental diets consisting in the basal diet plus 4 g P kg−1 from MSP, MCP and MAP, respectively. Both MSP and MAP resulted in higher levels of P apparent digestibility (≈90%) compared to MCP (70%), increasing the dry matter digestibility of the nutrient in the feed. The retention efficiency of P in fish tissues was increased by nearly 15% units over the Control when MSP and MAP were used as P supplement, whereas in agreement with the lower digestibility observed in MCP, P retention efficiency from this phosphate source was lower than the other sources. Total P discharge to the water was similar for MSP, MCP and MAP (4.12–4.58 g kg−1 BW fish gain). However, fish fed with MCP showed higher solid/particulate P discharge to the water through faeces due to the lower digestibility of this P–source within the gut of the fish. Among the phosphate salts evaluated, fish fed MSP and MCP did not show differences for soluble or solid N discharged fractions. However, fish fed the diet supplemented with MAP released a higher amount of non–protein N fraction to the water, probably as undigested ammonium through the faeces released by fish.Fil: Morales, Gabriel Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Unidad Ejecutora de Investigaciones en Producción Animal. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias. Unidad Ejecutora de Investigaciones en Producción Animal; ArgentinaFil: Azcuy, Rosendo Lucas. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Animal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Casaretto, Matías Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Unidad Ejecutora de Investigaciones en Producción Animal. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias. Unidad Ejecutora de Investigaciones en Producción Animal; ArgentinaFil: Márquez, Lorenzo. Universidad Católica de Temuco; ChileFil: Hernández, Adrián J.. Universidad Católica de Temuco; ChileFil: Gómez, Federico. Yara International ASA; NoruegaFil: Koppe, Wolfgang. Simplyfish AS; NoruegaFil: Mereu, Alessandro. Yara International ASA; Norueg

Improved sapflow methodology reveals considerable night-time ozone uptake by Mediterranean species

Due to the evident tropospheric ozone impact on plant productivity, an accurate ozone risk assessment for the vegetation has become an issue. There is a growing evidence that ozone stomatal uptake may also take place at night and that the night-time uptake may be more damaging than diurnal uptake. Estimation of night-time uptake in the field is complicated because of instrumental difficulties. Eddy covariance technology is not always reliable because of the low turbulence at night. Leaf level porometry is defective at relative humidity above 70% which often takes place at night. Improved sap flow technology allows to estimate also slow flows that usually take place at night and hence may be, at present, the most trustworthy technology to measure night-time transpiration and hence to derive canopy stomatal conductance and ozone uptake at night. Based on micrometeorological data and the sap flow of three Mediterranean woody species, the night-time ozone uptake of these species was evaluated during a summer season as drought increased. Night-time ozone uptake was from 10% to 18% of the total daily uptake when plants were exposed to a weak drought, but increased up to 24% as the drought became more pronounced. The percentage increase is due to a stronger reduction of diurnal stomatal conductance than night-time stomatal conductance

The ACCENT-VOCBAS field campaign on biosphere-atmosphere interactions in a Mediterranean ecosystem of Castelporziano (Rome): site characteristics, climatic and meteorological conditions, and eco-physiology of vegetation

Biosphere-atmosphere interactions were investigated on a sandy dune Mediterranean ecosystem in a field campaign held in 2007 within the frame of the European Projects ACCENT and VOCBAS. The campaign was carried out in the Presidential estate of Castelporziano, a periurban park close to Rome. Former campaigns (e.g. BEMA) performed in Castelporziano investigated the emission of biogenic volatile organic compounds (BVOC). These campaigns focused on pseudosteppe and evergreen oak groves whereas the contribution of the largely biodiverse dune vegetation, a prominent component of the Mediterranean ecosystem, was overlooked. While specific aspects of the campaign will be discussed in companion papers, the general climatic and physiological aspects are presented here, together with information regarding BVOC emission from the most common plant species of the dune ecosystem. During the campaign regular air movements were observed, dominated by moderate nocturnal land breeze and diurnal sea breeze. A regular daily increase of ozone concentration in the air was also observed, but daily peaks of ozone were lower than those measured in summer on the same site. The site was ideal as a natural photochemical reactor to observe reaction, transport and deposition processes occurring in the Mediterranean basin, since the sea-land breeze circulation allowed a strong mixing between biogenic and anthropogenic emissions and secondary pollutants. Measurements were run in May, when plant physiological conditions were optimal, in absence of severe drought and heat stress. Foliar rates of photosynthesis and transpiration were as high as generally recorded in unstressed Mediterranean sclerophyllous plants. Most of the plant species emitted high level of monoterpenes, despite measurements being made in a period in which emissions of volatile isoprenoids could be restrained by developmental and environmental factors, such as leaf age and relatively low air temperature. Emission of isoprene was generally low. Accounting for the high monoterpene spring emission of the dune ecosystem may be important to correct algorithms at regional and ecosystem levels, and to interpret measurements of fluxes of volatile isoprenoids and secondary pollutants

(Evapo)transpiration measurements over vegetated surfaces as a key tool to assess the potential damages of air gaseous pollutants for plants

Biological damages of a variety of plant organisms are evaluated according their evapotranspiration capacit

Interactions among vegetation and ozone, water and nitrogen fluxes in a coastal Mediterranean maquis ecosystem

Ozone, water and energy fluxes were measured over a Mediterranean maquis ecosystem from 5 May until 31 July 2007 by means of the eddy covariance technique. Additional measurements of NOx fluxes were performed by the aerodynamic gradient technique. Stomatal ozone fluxes were obtained from water fluxes by a Dry Deposition Inferential Method based on a big leaf concept. The maquis ecosystem acted as a net sink for ozone. The different water availability between late spring and summer was the major cause of the changes observed in stomatal fluxes, which decreased, together with evapotranspiration, when the season became drier. NOx concentrations were significantly dependent on the local meteorology. NOx fluxes resulted less intense than the ozone fluxes. However an average upward flux of both NO and NO2 was measured. The non-stomatal pathways of ozone deposition were investigated. A correlation of non-stomatal deposition with air humidity and, in a minor way, with NO2 fluxes was found. Ozone risk assessment was performed by comparing the exposure and the dose metrics: AOT40 (Accumulated dose over a threshold of 40 ppb) and AFst 1.6 (Accumulated stomatal flux of ozone over a threshold of 1.6 nmolm 122 s 121). AOT40, both at the measurement height and at canopy height was greater than the Critical Level for the protection of forests and semi-natural vegetation (5000 ppb h) adopted by UN-ECE. Also the AFst 1.6 value (12.6 mmolm 122 PLA, Projected Leaf Area) was higher than the provisional critical dose of 4 mmolm 122 PLA for forests. The cumulated dose showed two different growth rates in the spring and in the summer periods, while the exposure showed a more irregular behavior in both periods