Dietary supplements for lactating goats by polyunsaturated fatty acid-rich protected fat. Effects after supplement withdrawal

Abstract

The objective of this study was to investigate the persistence of the effects of supplements after they were withdrawn. Two groups of 12 goats were maintained under semiextensive breeding conditions; they were fed indoors with a concentrate with alfalfa hay and olive-tree leaves. Goats were in their sixth month of lactation at initiation of the study. During the first month of the trials, the concentrate supplied to the goats was either nonsupplemented (group 1) or supplemented with 9% polyunsaturated fatty acids (PUFA)-rich protected fat (group 2). After this period, the 2 groups were given the nonsupplemented until the average daily production of milk per animal within each group had decreased to 300 g or less. The fat supplementation supplied increased milk production and also improved fat and protein yield. These effects persisted after the supplement was withdrawn. The supplement, moreover, produced noticeable changes in the fatty acids profile of the milk fat, namely a reduction in the concentration of saturated fatty acids and an increase in that of PUFA. In contrast to the effects on milk production and on the yield of its main constituents, the effects on fat composition disappeared when the supplement was withdrawn.