Performance of Dairy Cows Supplemented with By-Pass Fat under Heat Stress Conditions

The objective of this study was to determine the effect of supplementation with a protected fat source on the productive response, metabolic environment and physiological indicators in Holstein cows under heat stress conditions during a 12-week experimental period. Thirty Holstein cows were distributed in 15 blocks by parity (2.0 ± 1.1), days in milk (182 ± 80) and milk production (29.4 ± 5.7 kg·day-1) at the beginning of the trial and randomly assigned within each block to the following treatments (diets): SPF: supplementation with protected fat or WPF: without supplementation with protected fat. All the cows were kept in a dry-lot where they were given a partial mixed ration (PMR) ad libitum while in the milking parlor they received individual supplementation depending on the treatment. The SPF diet contained 4.0 kg·day-1 concentrate in pellet form + 0.6 kg·day-1 ground corn grain + 0.7 kg·day-1 protected fat, while the WPF diet was similar to that offered in SPF, but the protected fat was isoenergetically replaced by ground corn grain. The fat supplement contained fats of animal and vegetable origin and microencapsulation was used for its preparation. Total dry matter and metabolic energy intakes were similar (p > 0.05) between treatments. Fat corrected milk (4% FCM) production was higher (p = 0.04), while energy corrected milk and fat productions tended (p = 0.06) to be higher in cows from the SPF group, without effects (p > 0.05) on the rest of the milk production and composition parameters. These results could be attributed to an improvement in the efficiency of the use of the energy consumed. Protected fat supplementation neither modified the metabolic profile, nor reduced the respiratory rate and body temperature of heat-stressed cows. Future research is needed to explain this latter result.

Impact of Adrenaline or Cortisol Injection on Meat Quality Development of Merino Hoggets

Increased levels of stress hormones in the muscle could lead to post mortem metabolic/structural modiifcations that could be relfected on meat quality. The present study investigated the metabolic effect of either adrenaline or cortisol injected into lambs in order to obtain an animal model of acute stress. Results showed that adrenaline or cortisol injection lead to glucose metabolism and muscle temperature increase. Muscle pH immediately post mortem was affected by adrenaline treatment. Water holding capacity （WHC） of fresh muscle, ifnal muscle pH and temperature registered at 24 h post mortem were not affected by injected hormones. Hardness and adhesiveness of LD muscle evaluated 3 d post mortem tended to increase as a result of adrenaline or cortisol injection. Results demonstrated that injected hormones were able to affect the post mortem muscle biochemistry and the pH/T curve independently of ifnal muscle pH.

Plant cover as an estimator of above-ground biomass in semi-arid woody vegetation in Northeast Patagonia,Argentina

The quantification of carbon storage in vegetation biomass is a crucial factor in the estimation and mitigation of CO2 emissions.Globally,arid and semi-arid regions are considered an important carbon sink.However,they have received limited attention and,therefore,it should be a priority to develop tools to quantify biomass at the local and regional scales.Individual plant variables,such as stem diameter and crown area,were reported to be good predictors of individual plant weight.Stand-level variables,such as plant cover and mean height,are also easy-to-measure estimators of above-ground biomass(AGB)in dry regions.In this study,we estimated the AGB in semi-arid woody vegetation in Northeast Patagonia,Argentina.We evaluated whether the AGB at the stand level can be estimated based on plant cover and to what extent the estimation accuracy can be improved by the inclusion of other field-measured structure variables.We also evaluated whether remote sensing technologies can be used to reliably estimate and map the regional mean biomass.For this purpose,we analyzed the relationships between field-measured woody vegetation structure variables and AGB as well as LANDSAT TM-derived variables.We obtained a model-based ratio estimate of regional mean AGB and its standard error.Total plant cover allowed us to obtain a reliable estimation of local AGB,and no better fit was attained by the inclusion of other structure variables.The stand-level plant cover ranged between 18.7%and 95.2%and AGB between about 2.0 and 70.8 Mg/hm^(2).AGB based on total plant cover was well estimated from LANDSAT TM bands 2 and 3,which facilitated a model-based ratio estimate of the regional mean AGB(approximately 12.0 Mg/hm^(2))and its sampling error(about 30.0%).The mean AGB of woody vegetation can greatly contribute to carbon storage in semi-arid lands.Thus,plant cover estimation by remote sensing images could be used to obtain regional estimates and map biomass,as well as to assess and monitor the impact of land-use change on the carbon balance,for arid and semi-arid regions.

Morphological Diversity of Populations of the Genus <i>Prosopis</i>in the Semiarid Chaco of Northern Cordoba and Southern Santiago Del Estero

The objective of this study consisted in the characterization of morphological variability presented in the Prosopis population in the corridor that unites the semiarid with the arid region in Argentina. In this region, four species of Prosopis get in contact (P. chilensis, P. flexuosa, P. alba and P. nigra). Due to the fact that these species make fertile hybrids, this corridor has an enormous diversity. The mother’s allowed the differentiation of five morphologic groups, which from the point of view of classic taxonomy have been classified in 16 taxa. Only groups 3 and 4 presented intermediate characteristics. The morphologic study of the descendants showed that the regrouping of the intermediate groups had a high error rate. This fact reaffirms the condition of intermediate groups. The canonical correlation analysis between the morphologic variables of the mothers and the seedlings revealed that each morphologic group had its own association of canonical variables between mothers and their seedlings, and that the variability observed in the set of the mothers and their seedlings follows a certain order. The enormous existing morphologic diversity in the Prosopis populations of the semi-arid Chaco of the north of Córdoba and southeast of Santiago del Estero was ordered in five morphologic groups. The descendant’s morphologic studies confirmed the existence of the defined morphologic-genetic groups.

Research Priorities and the Future of Alfalfa in Latin America

Agro-food and agro-industrial systems in Latin America must anticipate future trends and ensure permanent adjustment ofresearch priorities to the evolving global needs. Innovations should follow the logic of productive chains, which are highly dependentupon knowledge and technology. Agribusiness sector needs to reinvent itself for efficiently providing new products based on stricterquality controls, traceability, and greater diversification. In the region, alfalfa has an enormous potential to be cultivated for multiplepurposes other than just animal products, going from pharmaceutical and cosmetic industry to human consumption. No singleorganization or isolated group of scientists hold alone the capacity to deal with increasingly complex and dynamic productionsystems in order to efficiently compete in a globalized market. These challenges require an interdisciplinary approach, not only to adomestic level but also to an international one. The present paper proposed the constitution of a virtual alfalfa network platform forarticulating and guiding alfalfa research efforts in Latin America. The network will focus on identifying the most important needs forLatin America, promoting an active interaction among educational and scientific institutions through collaborative research projects.The platform comprises four main research axes: (1) efficient production (agronomy);(2) animal production (diversified feeds);(3)quality and innocuousness applied (human feeding);(4) novel products (pharmaceutical and cosmetics). During the initial phase, theBrazilian Agricultural Research Corporation (EMBRAPA, Brazil) and National Institute of Agricultural Technology (INTA,Argentina) will jointly coordinate the network.

Ion Accumulation, Water Relations and Osmotic Adjustment in Atriplex argentina, A. crenatifolia, A.lampa and A. nummularia under Saline Conditions

Salinity is a major stress that adversely affects growth and productivity in plants. There are species that tolerate this stresswithin the genus Atriplex. Four species, A. lampa, A. crenatifolia, A. nummularia and A. argentina were compared for their ionaccumulation and water relations under saline conditions. A greenhouse study was conducted by irrigating the four species with NaCIsolutions at concentrations 0%, 1%, 2% and 4% starting when plants were six months old. Plants were harvested 45 d after startingthe salinity treatments and analyzed for their ion contents. In the four Atriplex species, Na^＋ and Cl^- contents in plants increased, whileCa^2＋ and Mg^2＋ decreased with the increase of salinity in the irrigation solution. The results suggested that A. argentina and A.nummularia were able to maintain a higher leaf relative water content （RWC） at low leaf water potential, which was associated witha greater capacity of osmotic adjustment. A. lampa showed lower ion accumulation and minor osmotic adjustment than the otherspecies. It can be concluded that the accumulation of ions favors the lower osmotic potential and contributes to osmotic adjustment inthese halophytes.

Potential Use of a Poultry Manure Digestate as a Biofertiliser:Evaluation of Soil Properties and Lactuca sativa Growth

Anaerobic digestion is a process that is widely used for the treatment of organic wastes. The digestate can be used as a soil amendment or crop fertiliser. The aims of our work were to evaluate 1) the physicochemical composition and pathogen content in a digestate from poultry manure, according to international regulations, and 2) the effect of its soil application on the major chemical and biological soil properties and on the growth of Lactuca sativa. The experiment consisted of two groups of pots(with and without crop). Treatments applied to each group were as follows: low and high doses of digestate and inorganic fertiliser, and no application(control)(low dose: 70 kg nitrogen(N) ha^(-1) and 21 kg phosphorus(P) ha^(-1); high dose: 210 kg N ha^(-1) and 63 kg P ha^(-1)). Soil samples were taken 7 and 34 d(harvest) after treatment applications. Heavy metal and pathogen contents in the digestate were below the upper limit values. Despite the high pH and electrical conductivity values of the digestate, both soil parameters presented acceptable values for crop growth. Although there were no initial increases in total inorganic N and available P in soil with digestate application, an increase in the fresh weight of crop was observed with the high dose application. This is probably associated with the slow nutrient release from the digestate during the development of the crop. Changes in the microbial community were temporary and occurred at the initial sampling stage of the experiment.

Dynamics of the ruminal microbial ecosystem, and inhibition of methanogenesis and propiogenesis in response to nitrate feeding to Holstein calves

It is known that nitrate inhibits ruminal methanogenesis,mainly through competition with hydrogenotrophic methanogens for available hydrogen(H2)and also through toxic effects on the methanogens.However,there is limited knowledge about its effects on the others members of ruminal microbiota and their metabolites.In this study,we investigated the effects of dietary nitrate inclusion on enteric methane(CH4)emission,temporal changes in ruminal microbiota,and fermentation in Holstein calves.Eighteen animals were maintained in individual pens for 45 d.Animals were randomly allocated to either a control(CTR)or nitrate(NIT,containing 15 g of calcium nitrate/kg dry matter)diets.Methane emissions were estimated using the sulfur hexafluoride(SF6)tracer method.Ruminal microbiota changes and ruminal fermentation were evaluated at 0,4,and 8 h post-feeding.In this study,feed dry matter intake(DMI)did not differ between dietary treatments(P>0.05).Diets containing NIT reduced CH4 emissions by 27%(g/d)and yield by 21%(g/kg DMI)compared to the CTR(P<0.05).The pH values and total volatile fatty acids(VFA)concentration did not differ between dietary treatments(P>0.05)but differed with time,and post-feeding(P<0.05).Increases in the concentrations of ruminal ammonia nitrogen(NH3-N)and acetate were observed,whereas propionate decreased at 4 h post-feeding with the NIT diet(P<0.05).Feeding the NIT diet reduced the populations of total bacteria,total methanogens,Ruminococcus albus and Ruminococcus flavefaciens,and the abundance of Succiniclasticum,Coprococcus,Treponema,Shuttlewortia,Succinivibrio,Sharpea,Pseudobutyrivibrio,and Selenomona(P<0.05);whereas,the population of total fungi,protozoa,Fibrobacter succinogenes,Atopobium and Erysipelotrichaceae L7 AE11 increased(P<0.05).In conclusion,feeding nitrate reduces enteric CH4 emissions and the methanogens population,whereas it decreases the propionate concentration and the abundance of bacteria involved in the succinate and acrylate pathways.Despite the altered fermentation profile and ruminal microbiota,DMI was not influenced by dietary nitrate.These findings suggest that nitrate has a predominantly direct effect on the reduction of methanogenesis and propionate synthesis.