Milk fatty acid composition of dairy goats fed increasing levels of Flemingia macrophylla hay

Abstract

The effect of dietary inclusion of increasing levels of Flemingia macrophylla hay on the yield, composition and fatty acid profile of milk from Saanen x Boer goats was evaluated. The diets were composed of 40% concentrate and 60% forage. The treatments were defined by the level of inclusion of Flemingia hay in the diet (0, 80, 160, 240 and 320 g kg -1 dry matter) in replacement of the Cynodon dactylon cv. Tifton-85 hay, distributed according to a 5 x 5 Latin Square design. The inclusion of Flemingia in the diet did not change the milk yield or milk fat content but promoted a quadratic effect on the fat yield. A quadratic effect was observed on the milk protein and lactose contents, but this effect was not reflected in the daily production of these components. The concentrations of vaccenic, rumenic, elaidic and trans-10 C18:1 fatty acids in milk fat increased linearly in response to the dietary inclusion of Flemingia, whereas the contents of palmitic, stearic, oleic, linoleic and α-linolenic fatty acids were not modified. A linear reduction was observed in the lauric and myristic fatty acids concentrations, which was accompanied by a reduction in the atherogenic index of milk fat. A quadratic effect was also observed on the trans-10, cis-12 CLA milk fat content in response to the inclusion of Flemingia in the diet, as well as a linear increase in the apparent transfer of α-linolenic acid from the diet to milk. The inclusion of up to 320 g kg -1 of Flemingia hay as a replacement for Tifton-85 hay in the Saanen x Boer dairy goat diet does not modify the milk production and improves the nutritional quality of milk fat by increasing the contents of rumenic and vaccenic acids beneficial to human health and reducing the concentrations of hypercholesterolemic fatty acids. ResumoFoi avaliado o efeito da inclusão dietética de níveis crescentes de feno de Flemingia macrophylla sobre a produção, a composição e o perfil de ácidos graxos do leite de cabras Saanen x Boer. As dietas foram compostas por 40% de concentrado e 60% de forragem. Os tratamentos foram definidos pelo nível de inclusão de feno de Flemingia à dieta (0, 80, 160, 240 e 320 g kg -1 de matéria seca) em substituição ao feno de Cynodon dactylon cv. Tifton-85, distribuídos segundo delineamento em Quadrado Latino 5 x 5. A inclusão de Flemingia na dieta não alterou a produção de leite e seu teor de gordura, mas promoveu efeito quadrático sobre a produção de gordura. Houve efeito quadrático sobre os teores de proteína e lactose do leite, mas sem reflexo sobre as produções diárias destes componentes. Os teores dos ácidos rumênico, vacênico, elaídico e C18:1 trans-10 na gordura do leite aumentaram linearmente em resposta à inclusão de Flemingia na dieta, enquanto que os teores dos ácidos palmítico, esteárico, oleico, linoleico e α-linolênico não foram alterados. Houve redução linear nos teores dos ácidos láurico e mirístico, o que foi acompanhado por redução do índice de aterogenicidade da gordura do leite. Observou-se ainda efeito quadrático sobre o teor do CLA tran...

Sheep and Goats Respond Differently to Feeding Strategies Directed to Improve the Fatty Acid Profile of Milk Fat

“…(A) Mix: quebracho and chestnut extract[122]; olive leaves[121]; quebracho extract[82,120,123]; lentil straw[121]; chestnut extract[82,120]; flowering sulla[118]. (B) Flemingia hay[128]; gallnut[125]; pomegranate seed oil[57,129]; oak[126]; mimosa extract[127].…”