Desempenho produtivo e composição do leite de cabras alimentadas com dietas contendo diferentes níveis da leguminosa Flemingia macrophylla (willd.) Merrill com e sem polietilenoglicol

Abstract

The dairy goat in Brazil has shown evolution trend in activity, consolidating with an alternatively in the Brazilian livestock, and overcoming the constant challenge of getting and keeping new markets for milk and dairy products. However, although promising, still shows numerous problems and difficulties. Among them include the seasonal forage productions. Thus, the use of shrub legumes with high levels of crude protein and tolerant to low soil fertility, as Flemingia macrophylla, becomes a viable option in systems where the family farm prevails, thus represent a possible alternative for the substitution of inputs more expensive of diets. In this context, this study aimed to evaluate the inclusion of different levels of F. macrophylla in the diet of crossbred goats during lactation on physiological and hematological parameters, productive performance and chemical and physical quality of milk. The experimental design was Latin square (6 x 6), (3 x 2) factorial, with six animals and six treatments with three levels of inclusion of the legume (0%, 12.5% and 25%) on the total dry matter. The roughage: concentrate ratio was 50:50, where the treatments were: T1: 0% of Flemingia + 50% Tifton hay, T2: 0% of Flemingia + 50% of Tifton hay + PEG (polyethylene glycol), T3: 12.5% of Flemingia + 37.5% of Tifton hay, T4: 12.5% of Flemingia + 37.5% of Tifton hay + PEG, T5: 25% of Flemingia + 25% of Tifton hay; T6: 25% of Flemingia + 25% of Tifton hay + PEG. The parameters evaluated were subjected to analysis of variance (ANOVA) and the test medium used was the Tukey at 5% probability. The legume showed high levels of TC, lignin, protein and the fraction of non-structural carbohydrates (NSC). Its protein content exhibited high concentrations of B3 fractions (protein slowly degraded in the rumen) and C (protein unavailable to the animal). 25% levels of inclusion, showed less acceptability and negatively influencing the intake of hemicellulose, the digestibility of DM, OM, CP, NDF, TC (total carbohydrates) and ruminal ammonia concentration. However, these effects were inactivated by addition of PEG. There was no difference in the values of fat, lactose, protein, dry matter, total solids, pH, acidity, density and SCC between the different treatments, however, observed values of freezing point lower (P <0.05) for the diet with 12.5% of Flemingia supplemented with PEG. The addition of PEG, to level of 12.5%, promoted an increase in body temperature and cardiac frequency, reduced the percentage of medium and short chain fatty acids, and increased content of C17: 0 in milk. However, the inclusion levels of Flemingia in the replacement of soybean meal and Tifton did not cause differences for hematological and physiological responses of animals, and provided no significant changes in intake, milk yield, chemical composition and fatty acid profile of milk.