Optimisation of the predictive ability of NIR models to estimate nutritional parameters in elephant grass through LOCAL algorithms.

Elephant grass is a tropical forage widely used for livestock feed. The analytical techniques traditionally used for its nutritional evaluation are costly and time consuming. Alternatively, Near Infrared Spectroscopy (NIRS) technology has been used as a rapid analysis technique. However, in crops with high variability due to genetic improvement, predictive models quickly lose accuracy and must be recalibrated. The use of non-linear models such as LOCAL calibrations could mitigate these issues, although a number of parameters need to be optimized to obtain accurate results. The objective of this work was to compare the predictive results obtained with global NIRS calibrations and with LOCAL calibrations, paying special attention to the configuration parameters of the models. The results obtained showed that the prediction errors with the LOCAL models were between 1.6 and 17.5 % lower. The best results were obtained in most cases with a low number of selected samples (n = 100-250) and a high number of PLS terms (n = 20). This configuration allows a reduced computation time with high accuracy, becoming a valuable alternative for analytical determinations that require ruminal fluid, which would improve the welfare of the animals by avoiding the need to surgically prepare animals to estimate the nutritional value of the feeds.

Feasibility of near infrared spectroscopy for estimating suppressiveness of carnation (Dianthus cariophyllus L.) fusarium wilt in different plant growth media.

Fusarium wilt is one of the most widespread diseases in carnation crops in a large number of countries. Plant protection products commonly used to remedy the disease have been considered ineffective and environmentally unsafe for commercial use. As an alternative, the use of suppressive growth media has been proposed. The aim of this study was to evaluate the use of a rapid method such as near infrared spectroscopy (NIRS) to monitor and evaluate suppressive media potential. The NIR spectra were collected from 6 plant growth media used in a series of trials to evaluate suppressiveness to carnation Fusarium wilt namely grape marc compost, cork compost, olive oil husk + cotton gin trash composted and mixed with rice husk, spent mushroom composted and mixed with peat, coir fiber and light peat. The NIR calibration models showed promising results for estimating pH, ß-glucosidase activity, disease severity (AUDPC and RLSBX) in the growth media evaluated, with coefficients of determination of 0.99, 0.98, 0.98 and 0.90; SECV of 0.09, 11.63, 0.05 and 0.10; and RPD values of 13.86, 6.62, 7.19 and 3.24; respectively. NIR spectroscopy could become a useful non-destructive and fast analytical tool for the identification of Fusarium wilt suppressive composts, avoiding the use of reagents.

Feasibility of use of fatty acid and triacylglycerol profiles for the authentication of commercial labelling in Iberian dry-cured sausages.

In the present study, fatty acid and triacylglycerol profiles were used to evaluate the possibility of authenticating Iberian dry-cured sausages according to their label specifications. 42 Commercial brand 'chorizo' and 39 commercial brand 'salchichón' sausages from Iberian pigs were purchased. 36 Samples were labelled Bellota and 45 bore the generic Ibérico label. In the market, Bellota is considered to be a better class than the generic Ibérico since products with the Bellota label are manufactured with high quality fat obtained from extensively reared pigs fed on acorns and pasture. Analyses of fatty acids and triacylglycerols were carried out by gas chromatography and a flame ion detector. A CP-SIL 88 column (highly substituted cyanopropyl phase; 50 m × 0.25 mm i.d., 0.2 µm film thickness) (Varian, Palo Alto, USA) was used for fatty acid analysis and a fused silica capillary DB-17HT column (50% phenyl-50% methylpolysiloxane; 30 m × 0.25 mm i.d., 0.15 µm film thickness) was used for triacylglycerols. Twelve fatty acids and 16 triacylglycerols were identified. Various discriminant models (linear quadratic discriminant analyses, logistic regression and support vector machines) were trained to predict the sample class (Bellota or Ibérico). These models included fatty acids and triacylglycerols separately and combined fatty acid and triacylglycerol profiles. The number of correctly classified samples according to discriminant analyses can be considered low (lower than 65%). The greatest discriminant rate was obtained when triacylglycerol profiles were included in the model, whilst using a combination of fatty acid and triacylglycerol profiles did not improve the rate of correct assignation. The values that represent the reliability of prediction of the samples according to the label specification were higher for the Ibérico class than for the Bellota class. In fact, quadratic and Support Vector Machine discriminate analyses were not able to assign the Bellota class (0%) when combined fatty acids and triacylglycerols were included in the model. The use of fatty acid and triacylglycerol profiles to discriminate Iberian dry-cured sausages in the market according to their labelling information is unclear. In order to ensure the genuineness of Iberian dry-cured sausages in the market, identification of fatty acid and triacylglycerol profiles should be combined with the application of quality standard traceability techniques.

Genetic variation at the goat hormone-sensitive lipase ( LIPE) gene and its association with milk yield and composition.

Hormone-sensitive lipase (LIPE) plays a fundamental role in the regulation of energy balance by releasing free fatty acids from adipose triacylglycerol stores. These fatty acids can be subsequently transferred to other body compartments to be oxidized or employed in other biochemical reactions. This enzymic function is particularly important in lactating animals because the synthesis of milk components involves the mobilization of lipid depots to satisfy the large energy demands of the mammary gland. In the current study, we partially sequenced the goat LIPE gene in several individuals. In doing so, we identified two synonymous polymorphisms at exons 2 (c.327C>A>T, triallelic polymorphism) and 3 (c.558C>T). Moreover, we found a mis-sense polymorphism at exon 6 (c.1162G>T) that involves an alanine to serine substitution at position 388. Analysis with Polyphen and Panther softwares revealed that this amino acid replacement is expected to be neutral. Performance of an association analysis with a variety of milk traits revealed that goat LIPE genotype has highly suggestive effects on milk yield (P=0.0032) as well as on C18:3 n-6g (P=0.0051), trans-10 cis-12 CLA (P=0.007) and C12:0 (P=0.0084) milk contents. These associations are concordant with the preference of LIPE to selectively mobilize medium-chain and unsaturated fatty acids.

Factors affecting rabbit meat consumption among Spanish university students.

This study investigates the rabbit meat consumption patterns among students. Results of the 342 students surveyed at the University of Seville, Spain showed that more men than women consumed rabbit meat. More students consumed wild rabbit meat than farmed rabbit meat. The practice of hunting by students or their relatives, and the raising of rabbits for self-consumption, positively influenced the proportion of students that currently consumed rabbit meat. Most of the students that had eaten rabbit meat before but are currently non-eaters do so because of the meat's organoleptic characteristics or from lack of consumption habit.