Forage cactus associated with different fiber sources for lactating Sindhi cows: intake, digestibility and microbial protein production

This experiment was carried to evaluate the effect of forage cactus with different fiber sources (elephant grass hay [EGH], corn straw [CS], hay of cassava shoots [HCS], fresh sugarcane bagasse [FSB], and hydrolyzed sugarcane bagasse [HSB]) on intake, apparent digestibility and macrobiotic protein production of cows. Five cows with 265 kg average body weight, 4.95 kg average daily milk yield and 5.22 kg 4% fat-corrected milk yield were randomly allocated to a 5 × 5 Latin square design. The animals fed cactus associated with CS, EGH and HCS showed higher intake of DM and nutrients. However, regarding the digestibility, diets with sugarcane bagasse showed higher digestibility compared with those with CS and hay. For microbial protein, the excretion of purine derivatives, synthesis of microbial N and microbial protein production were higher in the treatment with CS than in the treatment with sugarcane bagasse. On the other hand, the treatment with EGH and HCS did not have statistical differences compared with the other cases. The mean efficiency of microbial protein synthesis of the experiment was 131 g microbial crude protein/kg of TDN. The treatment with CS showed better efficiency; however, it was statistically superior only compared with FSB. The other treatments did not show statistical difference compared with the other cases. Diets with cactus associated with corn straw, hay of elephant grass or hay of cassava shoots provide higher intake of dry matter and nutrients and better metabolic response compared with diets with cactus associated with sugarcane bagasse for lactating Sindhi cows.

本试验旨在探究饲用仙人掌配合不同纤维源（象草干草[EGH]、玉米秸秆[CS]、木薯嫩枝干草[HCS]、新鲜甘蔗渣[FSB]、水解甘蔗渣[HSB]）对奶牛采食量、表观消化率及微生物蛋白产量的影响。选取5头平均体重265kg、平均日产奶量4.95kg、4%乳脂校正奶产量5.22kg的奶牛，随机分配至5×5拉丁方试验设计中。饲喂仙人掌配合CS、EGH及HCS的试验组，其干物质（Dry Matter, DM）及营养物质采食量更高。而就消化率而言，添加甘蔗渣的试验组日粮消化率高于CS及干草组日粮。就微生物蛋白（Microbial Protein）相关指标而言，CS组的嘌呤衍生物（Purine Derivatives）排泄量、微生物氮（Microbial Nitrogen, N）合成量及微生物蛋白产量均高于甘蔗渣组。另一方面，EGH与HCS组与其余各组间无统计学差异。本试验的微生物蛋白合成平均效率为131g微生物粗蛋白/kg总可消化养分（Total Digestible Nutrients, TDN）。CS组的合成效率更佳，但仅相较于FSB组存在统计学优势。其余试验组与其他各组间均无统计学差异。与添加甘蔗渣的日粮相比，饲用仙人掌配合玉米秸秆、象草干草或木薯嫩枝干草的日粮，可提升泌乳期辛地红（Sindhi）奶牛的干物质及营养物质采食量，并带来更优的代谢响应。