Effects of Concentrate Level on Lactation Performance of Horro Cows Fed Rhodes Grass Hay (RGH) as a Basal Diet at Guduru Animal Production and Research Center, Western Ethiopia

An experiment was conducted at Guduru Animal Production and Research Center (GAPRC) of Wollega University to evaluate effects of different levels of formulated concentrate supplementation on milk yield, milk compositions, feed intake and body weight gain of Horro cows. Sixteen early lactating Horro cows with the same body weight and condition were selected from GAPRC. Experimental cows were assigned to four dietary treatments using a randomized complete block design with four replications. Cows that varied in parity were used as blocking factors in the present trial. The treatments used were: RGH +0.5Kg of concentrate (T1), RGH +2Kg of concentrate (T2), RGH + 3Kg of concentrate (T3), and RGH + 4Kg of concentrate (T4). The experiment was conducted for 90 days with an acclimatization period of 15 days. Dry matter and nutrient intakes of cows significantly (p<0.05) varied between treatment groups. Mean dry matter intake was 5.98%. Mean total crude protein, total neutral detergent fiber, total acid detergent fiber, total acid detergent lignin and total organic matter intake (%) were, 0.78, 4.74, 2.26, 1.44, and 4.89 respectively. Total dry matter intake of cows fed on T4 was higher than those cows maintained on dietary T1, T2, and T3. The mean milk yield per cow per day was 3.12 liter. It has increased across the dietary treatment with an increase in the rate of concentrate supplementation. Protein, fat, total solid, solid-not-fat, and Ash composition of milk (%) were, , 3.41, 3.48, 13.37, 9.89, and 0.75 respectively, where milk compositions except for Lactose (5.73%) content had significant difference (P<0.05) among the treatment groups. Milk fat contents of cows fed on T1was higher than those cows maintained on dietary T2, T3 and T4. Except the numerically higher body weight observed for cows receiving T4, initial and final body weights of experimental cows didn’t show variation (P>0.05) with changes in dietary treatments. In general, cows supplemented with 4kg of formulated concentrate had improved feed intake, milk yield and milk nutrient compositions than cows on the remaining dietary treatments. The further study shall be conducted on the productive and economic response of local cows maintained on such diet over successive lactation to evaluate the significance of the study at the field level.

本实验于沃莱加大学古杜鲁畜牧生产与研究中心（Guduru Animal Production and Research Center, GAPRC）开展，旨在评估不同水平配制精补料对霍罗（Horro）奶牛产奶量、乳成分、采食量及体增重的影响。研究从该中心选取16头体重、体况一致的早期泌乳霍罗奶牛，采用随机完全区组设计，以胎次差异作为区组因素，将实验奶牛随机分配至4个日粮处理组，每组设4个重复。本次实验设置的四个处理组分别为：RGH+0.5kg精补料组（T1）、RGH+2kg精补料组（T2）、RGH+3kg精补料组（T3）以及RGH+4kg精补料组（T4）。实验周期共计90天，其中预适应期为15天。
各组奶牛的干物质及营养物质采食量存在显著差异（p<0.05）。平均干物质采食量为5.98%。粗蛋白质、中性洗涤纤维、酸性洗涤纤维、酸性洗涤木质素及有机质的平均总采食量（%）依次为0.78、4.74、2.26、1.44及4.89。饲喂T4组的奶牛总干物质采食量显著高于T1、T2及T3组。
奶牛日均产奶量为3.12升，且随精补料添加比例提升呈递增趋势。乳蛋白质、乳脂肪、总固形物、非脂固形物及灰分的含量（%）依次为3.41、3.48、13.37、9.89及0.75；除乳糖（Lactose）含量（5.73%）外，其余乳成分在各组间均存在显著差异（P<0.05）。其中T1组奶牛的乳脂肪含量高于T2、T3及T4组。
仅观测到T4组奶牛的体况数值略高，实验奶牛的初始与终末体重随日粮处理变化未出现显著差异（P>0.05）。
总体而言，与其余日粮处理组相比，补充4kg配制精补料的奶牛采食量、产奶量及乳营养成分均得到显著改善。未来可开展后续研究，针对连续泌乳期内饲喂此类日粮的本地奶牛的生产性能与经济响应展开评估，以明确本研究在田间尺度的应用价值。