F. Paoletti

Effect of kind of dietary fat on the quality of milk fat from Italian Friesian cows

Four diets, supplemented with different fats of vegetable origin, were compared in a 4×4 Latin square design with eight primiparous Italian Friesian cows (two cows per cell). The four fats were: toasted full fat soy bean in diet WS; toasted full fat linseed in diet WL; calcium soap of palm oil in diet PS; and calcium soap of olive oil in diet OS. Scope of the trial was to study the effect of the four different fat sources on milk yield and composition and on the quality of milk fat in terms of safety for the consumer health, with particular attention to trans fatty acids and to conjugated linoleic acid isomers (CLA). Diet OS induced the highest milk yield (P<0.05), while diet PS gave the fattest milk (P<0.05), and the highest milk content of both saturated and medium chain fatty acids (P<0.05). Saturated to unsaturated ratio of milk fat was decreased when cows were fed diet WS (P<0.05), while the ratio was increased with cows fed on diet PS (P<0.05). With a closely similar behaviour milk CLA content was enhanced with diet WS and strongly depressed (P<0.05) with diet PS. Diet OS increased total CLA as well, probably as a consequence of the bio-hydrogenation process of large amounts of oleic acid, transformed into trans isomers of C18:1, including vaccenic acids. Full fat soy bean promoted some milk fatty acids with beneficial effects on consumer health, but calcium soap of olive oil similarly improved the fatty acid profile of milk fat, while meeting the cows’ requirements as an energy supplement.

Application of the "Tracking signal method" to the monitoring of udder health and oestrus in dairy cows

Abstract Two time series models, namely, the moving average model of lag 14 (MAM) and the tracking signal method (TSM), have been used to detect oestrus and udder health in dairy cows based on activity data and electrical conductivity, respectively. The results show that the use of on-line activity data allowed us to obtain high values of sensitivity and specificity for oestrus detection irrespective of the model used. Regarding udder health, sensitivity and specificity values showed that the number of clinical and subclinical mastitis cases detected was similar for the two models, but the specificity value using TSM resulted in a significantly higher value than MAM. Thus, the TSM method could be considered advantageous because of reduction in the number of false positive in healthy cows. The results show that electrical conductivity data of mixed milk samples are useful to detect both clinical and subclinical mastitis with a good sensitivity, if the milk electrical conductivity on-line is correctly measured.