Abstract :
The experiment was conducted to evaluate the nutritional indices of milk fat of 1/2
Boer×Saanen goats on diets supplemented with three roughages. Eighteen goats under
a semi-intensive system were divided into groups, and fed an ad libitum supplement of
sorghum silage, maize silage or mulberry hay. Nutritional indices were determined from
three milk samples taken during winter (August) and spring–summer (average of November
and December). Using mixed statistical models, the animal error was computed as a
random effect. The season and supplement were fixed. The winter season was markedly
better for all variables (P < 0.01), while short-chain fatty acids did not change (P > 0.05).
Interactions only occurred between the thrombogenic index and the C12:0/C10:0 ratio,
where the higher values that are potentially more harmful to human health were obtained
in the spring–summer season in animals fed maize silage, followed by the averages of other
treatments during the same season. The values for unsaturated fatty acids, atherogenic
index and thrombogenic index indicated differences between supplements, with better
values for goats fed with sorghum silage and mulberry hay. Grazing Boer×Saanen goats
supplemented with mulberry hay or sorghum silage provided milk with better lipid indices
for the prevention of human coronary diseases
