Brunette T, Baurhoo B, Mustafa A F
Department of Animal Science, MacDonald Campus, McGill University, Ste-Anne-de-Bellevue, QC, H9X 3V9, Canada.
Department of Animal Science, MacDonald Campus, McGill University, Ste-Anne-de-Bellevue, QC, H9X 3V9, Canada; Bélisle Solution Nutrition Inc., St-Mathias sur Richelieu, QC, J3L 6A7, Canada.
J Dairy Sci. 2016 Jan;99(1):269-79. doi: 10.3168/jds.2015-9619. Epub 2015 Nov 18.
This study investigated the effects of dietary replacement of grass silage (GS) with forage millet silages that were harvested at 2 stages of maturity [i.e., vegetative stage and dough to ripe seed (mature) stage] on milk production, apparent total-tract digestibility, and ruminal fermentation characteristics of dairy cows. Fifteen lactating Holstein cows were used in a replicated 3 × 3 Latin square experiment and fed (ad libitum) a total mixed ration (60:40 forage:concentrate ratio). Dietary treatments included control (GS), vegetative millet silage (EM), and mature millet silage (MM) diets. Experimental silages comprised 24% of dietary dry matter (DM). Soybean meal and slow-release urea were added in millet diets to balance for crude protein (CP). Three additional ruminally fistulated cows were used to determine the effect of treatments on ruminal fermentation and total-tract nutrient utilization. Cows fed the GS diet consumed more DM (22.9 vs. 21.7 ± 1.02 kg/d) and CP (3.3 vs. 3.1 ± 0.19 kg/d), and similar starch (4.9 ± 0.39 kg/d) and neutral detergent fiber (NDF; 8.0 ± 0.27 kg/d) compared with cows fed the MM diet. Replacing the EM diet with the MM diet did not affect DM, NDF, or CP intakes. Cows fed the MM diet produced less milk (26.1 vs. 29.1 ± 0.79 kg/d), energy-corrected milk (28.0 vs.30.5 ± 0.92 kg/d), and 4% fat-corrected milk (26.5 vs. 28.3 ± 0.92 kg/d) yields than cows fed the GS diet. However, cows fed diets with EM and GS produced similar yields of milk, energy-corrected milk, and 4% fat-corrected milk. Feed efficiency (milk yield:DM intake) was greater only for cows fed the GS diet than those fed the MM diet. Milk protein yield and concentration were greater among cows fed the GS diet compared with those fed the EM or MM diets. Milk fat and lactose concentrations were not influenced by diet. However, milk urea N was lower for cows fed the GS diet than for those fed the MM diet. Ruminal NH3-N was greater for cows fed the EM diet than for those fed the GS diet. Total-tract-digestibility of DM (average = 66.1 ± 3.3%), NDF (average = 55.1 ± 2.4%), CP (average = 63.6 ± 4.2%), and gross energy (average = 64.5 ± 2.6%) were not influenced by experimental diets. We concluded that cows fed GS and EM diets had comparable performance, whereas milk yield was significantly reduced with the MM diet, likely because reduced intakes of DM and net energy for lactation.
本研究调查了用在两个成熟阶段（即营养期和面团期至成熟种子期）收获的饲用粟青贮料替代青草青贮料（GS）对奶牛产奶量、表观全消化道消化率和瘤胃发酵特性的影响。15头泌乳期荷斯坦奶牛用于重复的3×3拉丁方试验，自由采食全混合日粮（粗饲料与精饲料比例为60:40）。日粮处理包括对照（GS）、营养期粟青贮料（EM）和成熟粟青贮料（MM）日粮。试验青贮料占日粮干物质（DM）的24%。在粟日粮中添加豆粕和缓释尿素以平衡粗蛋白（CP）。另外使用3头瘤胃造瘘奶牛来确定处理对瘤胃发酵和全消化道养分利用的影响。与饲喂MM日粮的奶牛相比，饲喂GS日粮的奶牛消耗更多的DM（22.9对21.7±1.02千克/天）和CP（3.3对3.1±0.19千克/天），淀粉（4.9±0.39千克/天）和中性洗涤纤维（NDF；8.0±0.27千克/天）摄入量相似。用MM日粮替代EM日粮不影响DM、NDF或CP摄入量。与饲喂GS日粮的奶牛相比，饲喂MM日粮的奶牛产奶量（26.1对29.1±0.79千克/天）、能量校正乳（28.0对30.5±0.92千克/天）和4%脂肪校正乳（26.5对28.3±0.92千克/天）产量更低。然而，饲喂EM和GS日粮的奶牛产奶量、能量校正乳和4%脂肪校正乳产量相似。仅饲喂GS日粮的奶牛的饲料效率（产奶量:DM摄入量）高于饲喂MM日粮的奶牛。与饲喂EM或MM日粮的奶牛相比，饲喂GS日粮的奶牛乳蛋白产量和浓度更高。乳脂肪和乳糖浓度不受日粮影响。然而，饲喂GS日粮的奶牛乳尿素氮低于饲喂MM日粮的奶牛。饲喂EM日粮的奶牛瘤胃NH₃-N高于饲喂GS日粮的奶牛。试验日粮对DM（平均=66.1±3.3%）、NDF（平均=55.1±2.4%）、CP（平均=63.6±4.2%）和总能（平均=64.5±2.6%）的全消化道消化率没有影响。我们得出结论，饲喂GS和EM日粮的奶牛性能相当，而饲喂MM日粮时产奶量显著降低，可能是因为泌乳期DM和净能摄入量减少。
