Produção, análise química e perfil de ácidos graxos do leite de vacas em pastagem de azevém suplementadas com glicerina bruta

Abstract

The objective of this study was to evaluate the use of crude glycerin as an energetic supplement in the diet for lactating cows kept in a ryegrass (Lolium multiflorum) system. Eighteen Holstein cows were used in a experiment carried out at Regional Institute for Rural Development in Augusto Pestana, RS, Brazil, distributed in a block design (according to the days in lactation) in a simple reversion scheme, in three periods of 14 days each on. The diets were composed of grazing ryegrass, supplemented with corn silage and concentrate, with or without 10% crude glycerin on a total dry matter basis (DM). Samples of food and milk were collected and analyzed. Data were submitted to analysis of variance and the effect of treatment compared by the T test through the SAS statistical program. The inclusion of GB does not affect milk production and composition. The sum of saturated fatty acids (ΣAGS) and caprylic, capric and lauric acids were significant (P <0.05) in relation to the control group, increasing their values with the inclusion of crude glycerin in the diet. In relation to the monounsaturated acids the oleic acid the values were heigher when glycerin was not established in the diet (control group), as well as the sum of monounsaturated fatty acids (ΣAGMI). Polyunsaturated fatty acids did not differ between treatments (P> 0.05). We conclued that the inclusion of crude glycerin in the diet of dairy cows does not affect milk production or milk quality and is a good option for energy supplementation.