Showing papers by "Antonello Cannas published in 2012"

Development and evaluation of empirical equations to predict ruminal fractional passage rate of forages in goats

Abstract: The objectives of the present paper were to develop and evaluate empirical equations to predict fractional passage rate (kp) of forages commonly fed to goats using chemical composition of the diet and animal information. Two databases were created. The first (development database) was assembled from four studies that had individual information on animals, diets and faecal marker concentrations over time (up to 120 h post-feeding); it contained 54 data points obtained from Latin square designs. The second (evaluation database) was built using published information gathered from the literature. The evaluation database was comprised of five studies, containing 39 data points on diverse types of diets and animal breeds. The kp was estimated using a time-dependent model based on the Gamma distribution with at least two and up to 12 (rumen)+one (post-rumen) compartments (i.e. G2G1–G12G1) developed from the development database. Statistical analyses were carried out using standard regression analysis and random coefficient model analysis to account for random sources (i.e. study). The evaluation of the developed empirical equation was conducted using regression analysis adjusted for study effects, concordance correlation coefficient and mean square error of prediction. Sensitivity analyses with the developed empirical equation and comparable published equations were performed using Monte Carlo simulations. The G2G1 model consistently had lower sum of squares of errors and greater relative likelihood probabilities than other GnG1 versions. The kp was influenced by several dietary nutrients, including dietary concentration or intake of components such as lignin, neutral detergent fibre (NDF), hemicellulose, crude protein (CP), acid detergent fibre (ADF) and animal body weight (BW). The selected empirical equation, adjusted for study effects, () had an R2 of 0·623 and root of mean square error (RMSE) of 0·0122/h. The evaluation of the adequacy of the selected equation with the evaluation database indicated no systematic bias (slope not different from 1), but a low accuracy (0·33) and a persistent mean bias of 0·0129/h. The sensitivity analysis indicated that the selected empirical equation was most sensitive to changes in dry matter intake (DMI, kg/d), BW(kg) and NDF (g/kg dry matter) with standardized regression coefficients of 0·98, −0·43 and −0·32, respectively. The sensitivity analysis also indicated that the greatest forage kp in goats is likely to be c. 0·0569/h. The comparison with a previously published empirical equation containing data on cattle, sheep and goats, suggested that the distribution of the present empirical equation, adjusted for mean bias, is wider and that kp of goats might be similar to cattle and sheep when fed high amounts of forage under confinement conditions.

Legume-cereal mixtures ensiling in Sardinia

Abstract: Animal feeding accounts more than 50% of farm production costs, often principally due to the protein component acquisition. Cereals and legume mixtures silage could represent an interesting source of high nutritive value forage in non-irrigated lands. Mixtures can provide an adequate proportion of nitrogen and carbohydrates in the ensiling substrates, needed to help lactic fermentation and pH reduction, essential to the conservation process. The aim of this trial was to compare silage of three leguminous-triticale mixtures, in order to obtain a preliminary evaluation for high quality and stable forages production, destined to ruminant feeding in Mediterranean areas. The trial was carried out in Sardinia between autumn 2010 and spring 2011. Mixtures of Triticale (Triticosecale WittMack)-white lupin (Lupinus albus L.), triticale-pea (Pisum sativum L.) and triticale-faba bean (Vicia faba minor L.) were evaluated. After six months of ensiling process in glass jars, silage was analyzed, by determining: pH, dry matter, fibrous fractions, crude protein, ash content, NFC+lipids and estimated DM digestibility. Mixtures with pea and triticale Amarillo reached the highest content of DM. When used in mixtures with triticale and in respect to lupin and pea, faba bean obtained the lowest values of NDF, ADF, and ADL and the highest content of NFC+lipids. Faba bean was also able to maintain the highest protein content. Considering the CP content of silage, the 30:70 seeding ratio resulted the more convenient. A more detailed evaluation of obtained results should be performed also considering the biomass production per hectare at farm level.