The effects of inactive dry yeast (Saccharomyces cerevisiae) from sugar cane were studied in 18 primiparus Saanen dairy goats (51.07±1.43) on dry matter intake and digestibility, milk production and quality. Animals were distributed in a completely randomized design during 90 days (from day 60 of milking). Diets were composed of soybean meal; soybean meal + dry yeast; or dry yeast, as protein sources, and ground corn, mineral supplement and corn silage (40%). Animals fed the dry yeast diet showed lower intake of dry matter (DM), organic matter (OM), crude protein, ether extract and neutral detergent fiber. Diets did not influence milk yield; however the milk production efficiency (kg of milk produced/kg of crude protein ingested) was better in goats fed the dry yeast diet. Acidity, somatic cell counts and milk urea nitrogen values were not affected by treatments. Animals fed the soybean + dry yeast diet had higher fat and total solids than those fed the dry yeast diet. The digestibility of DM, OM and total carbohydrate was lower for soybean only and soybean + dry yeast diets. Total digestible nutrients were higher for dry yeast and soy bean diets than soybean + dry yeast diet. Dry yeast from sugar cane is a good alternative protein source for feeding lactating dairy goats and can be recommended because it maintains the production performance.

O experimento foi conduzido com o objetivo de avaliar a ingestão, digestibilidade da matéria seca e dos nutrientes, o balanço de nitrogênio e estimar os nutrientes digestíveis totais de rações com a inclusão da levedura seca (0, 25, 50, 75 e 100% da MS) em substituição ao farelo de soja nas rações para cabritos. Foram utilizados cinco cabritos SRD alojados em gaiolas metabólicas distribuídos em delineamento quadrado latino 5 x 5. As ingestões de matéria seca e de carboidratos totais não foram alteradas com a inclusão de levedura, no entanto, para a ingestão de matéria orgânica, proteína bruta, extrato etéreo e fibra em detergente neutro foi observado efeito quadrático. A digestibilidade do extrato etéreo apresentou efeito linear decrescente, porém, para digestibilidade da matéria seca, matéria orgânica, proteína bruta, carboidratos totais, fibra em detergente neutro e nutrientes digestíveis totais houve efeito quadrático. O balanço de nitrogênio não foi alterado em função da substituição do farelo de soja. A levedura seca pode ser incluída nas rações de cabritos como fonte proteica sem alterar a ingestão de matéria seca e o balanço de nitrogênio, porém, a inclusão acima de 5,9% de levedura seca nas rações reduz a digestibilidade da matéria seca.

The assay was carried out to evaluate feed intake, dry matter and nutrient digestibility, nitrogen balance, and to estimate total digestible nutrients of diets with inclusion of dry yeast (0, 25, 50, 75, 100% of DM) replacing soybean meal in diets for kid goats. Five goats were allotted in a 5 x 5 Latin square design and housed in digestibility cages. Dry matter intake and total carbohydrates were unchanged with inclusion of dry yeast; however, for organic matter, crude protein, ether extract and neutral detergent fiber, intake showed a quadratic effect. The digestibility of ether extract showed decreasing linear effect; however, for dry matter, organic matter, crude protein, total carbohydrates, neutral detergent fiber and total digestible nutrients digestibility showed quadratic effects. Dry yeast can be included in feed for kid goats as a protein source without changing dry matter intake and nitrogen balance; however, including over 5.9% dry yeast in the diets reduces dry matter digestibility.