Selecting the best set of gas chromatography-derived fatty acids to discriminate between two finishing diets using linear discriminant analysis.

Linear discriminant analysis (LDA) was investigated as a method for identifying the type of finishing diet fed to bulls (n=169) based on gas chromatography fatty acid (FA) analysis. The bulls were fed ad libitum a high concentrate diet comprised of a cereal-soybean meal based concentrate plus straw offered separately (HC) or a total mixed ration made of cereal, soybean meal, maize silage and straw (TMR). Eleven variables (10 FA and one FA ratio) were selected as statistically significant predictors out of 41 variables tested. The Mahalanobis squared distance between the HC and TMR groups was 3.386 and F-test of the distance was highly significant (P>0.001). In cross-validated classification matrices, 18 cases were misclassified in the HC group and 16 cases were misclassified in the TMR group. As a result, 79.9% of original grouped cases were classified correctly. We concluded that it was possible to classify beef samples according to their finishing diets using LDA.

Animal performance and milk fatty acid profile of dairy goats fed diets with different unsaturated plant oils.

The effect of supplementing a basal diet with 1 of 3 plant oils on productive efficiency and milk fatty acid composition was studied in dairy goats. Sixteen Malagueña goats were used in a 4×4 Latin square experiment with 21-d periods and 4 goats per treatment. The basal diet comprised 30% alfalfa hay and 70% pelleted concentrate. Experimental treatments were control (basal diet without added oil) and the basal diet supplemented with 48g/d of high oleic sunflower oil (HOSFO), regular sunflower oil (RSFO), or linseed oil (LO). Dry matter intake and body weight were not affected by treatments. Milk production was higher in HOSFO treatment and milk fat content was higher in RSFO and LO treatments, although no differences in milk energy production or milk renneting properties were found. The RSFO and LO treatments increased the proportion of vaccenic acid in milk fat more so than the HOSFO diet, and rumenic acid followed the same pattern. The content of trans10-18:1 remained low in all experimental diets (<0.7% of total fatty acid methyl esters) although HOSFO and RSFO diets increased it. The variations in the fatty acid profiles observed with the 4 diets, mainly the unsaturated fatty acid isomer contents, are extensively discussed. Compared with that in the control diet, the n-6:n-3 fatty acid ratio in milk fat substantially decreased with the LO, increased with RSFO, and did not change with HOSFO. The addition of moderate amounts of LO to the diets of dairy goats has favorable effects on milk fatty acid composition from the point of view of the human consumer, without negative effects on animal performance.

Calcium soaps of olive fatty acids in the diets of Manchega dairy ewes: effects on digestibility and production.

Two experiments were carried out with dairy ewes to determine the effects of supplementation of calcium soaps of olive fatty acids at 10% of the basal diet on digestibility, roughage intake, milk production and composition, and response to early induced ovulation. The addition of calcium soaps of olive fatty acids to the diets of dairy ewes significantly decreased the digestibility of dietary dry matter but not the digestibility of other components. The digestibility of crude fat was enhanced. Voluntary intake of roughage, with fixed concentrate allowances, was slightly, but not significantly, reduced for ewes fed the supplemented diet. After weaning at 35 d postpartum and during the next 5-wk period of twice daily milking, ewes fed the supplemented diet produced more total solids in milk than did ewes fed the basal diet. Ewes fed the supplemented diet also tended to produce more milk protein, and milk energy and tended to have greater milk fat percentages. The composition of milk fatty acids was changed by the calcium soaps of olive fatty acids. Fewer short- and medium-chain fatty acids (C6:0, C8:0, C10:0, C12:0, C14:0, and C16:0), less C18:2, and more C18:1 and C18:0 were obtained in the milk of ewes fed the supplemented diet. Responses to ovulation induced at 60 d after lambing, while ewes were still lactating, were significantly higher for ewes fed the diet supplemented with calcium soaps of olive fatty acids than for ewes fed the basal diet. The calcium soaps of olive fatty acids appeared to be a useful source of energy for dairy ewes, and dairy ewes may be a good model for the study of the effects of nutrition during early lactation on reproductive performance of dairy ruminants.