Effects of adding a mixture of malate and yeast culture (Saccharomyces cerevisiae) on milk production of Murciano-Granadina dairy goats

Twenty-four Murciano-Granadina dairy goats were used to investigate the effects of supplementation with a mixture of malate and yeast (Saccharomyces cerevlslae) on milk production. The goats were machine milked once a day after parturition and were assigned to two balanced groups on week 4 of lactation. The experimental groups were kept separately in pens and were fed a daily diet based on a dehydrated forage mixture (alfalfa hay: maize whole plant, 1:1) ad libitum, 0.3 kg alfalfa pellets and 0.2 kg barley grain. The basal diet was completed with 0.6 kg concentrate pellets fed individually. Two different dietary treatments were randomly assigned to each goat group: control (without supplementation) and supplemented (with a mixture of malate and yeast included in the concentrate at a level of 10 g'kg-1). Feed intake, milk yield, milk composition and body weight were evaluated from week 4 to 16 of lactation. Malate content of the control and supplemented concentrate was 2.4 and 6.0 g'kg-1 DM, respectively. Supplementation with the malate and yeast culture mixture did not affect (P > 0.05) feed intake (2. 04 vs. 2.03 kg DM-d-1), milk yield (2.09 vs. 2.08 L-d-1), milk fat (5.17 vs. 4.85%), milk protein (3.70 vs. 3.63%) or milk casein (2.57 vs. 2.51%) for the control vs. the supplemented goats, respectively. Nevertheless, the supplemented goats gained more body weight than the control goats (39 vs. 19 g.d-1; P < 0.05). We conclude that supplementation with the mixture of malate and yeast culture, under the conditions of our experiment, had no beneficial effects on the performance of dairy goats. The relatively high contents of malic acid in the forage mixture (7.3 g'kg-1 DM) and in the alfalfa pellets (14.2 g-kg-1 DM) may have decreased the response to malate in the supplemented diet.