Cabras leiteiras alimentadas com diferentes dietas basais e uma fonte lipídica : perfil de ácidos graxos do leite

Abstract

This study aimed to evaluate the fatty acids profile of milk of Saanen dairy goats fed with different basal diets and one lipid source. Twelve goats weighing 48.9±7.3 kg, with a mean milk yield of 2.8 kg per day at 84 days on average, were distributed into three Latin square designs (4 × 4) according to their productivities. The experimental periods lasted 21 days each, and 14 days comprised the adaptation time, while the others were used to collect samples and data. The experimental diets were composed of maize silage (MS), sorghum silage (SS), pangola grass hay (PH), or sugarcane bagasse (SB) associated with forage cactus, plus a concentrate containing extra-fat whole corn germ added as a lipid source. Individual proportions and the primary fatty acid groups (FA) from dairy goats’ milk were assessed. Data were analyzed with the statistical package from SAS®, and the differences were stated as statistically significant when P<0.05. The proportions of short and intermediate-chain FA were higher in the milk from goats fed with MS and SS, while the proportion of long-chain FA was greater in the milk from goats that received PH or SB. Conversely, the saturated FA concentration in milk was higher when goats received silages, whereas the polyunsaturated FA content was higher in the milk of goats fed with SB or PH. PH or SB-based diets provided more exhaust of bio-hydrogenation intermediates, mainly the C18:1 trans-11, which made the CLA cis-9 trans-11 proportion superior to the other treatments. The sum of omega-3 FA (n-3) in milk was higher for the basal diet containing forage cactus and SS, and consequently, the n-6/n-3 ratio was lower for this treatment. Based on the results obtained, it is concluded that PH or SB-based diets are more indicated to improve the FA profile of milk of Saanen dairy goats, owing to reduce the concentrations of saturated FA and increase those polyunsaturated FA beneficial to human health (C18:1 trans-11 and CLA cis-9 trans-11). Despite that, the SS-based diet led to the lowest milk n-6/n-3 ratio, providing the best quality for human nutrition and health.